Final Report Summary - APPLE (Autonomous Printed Paper products for functional Labels and Electronics)
Executive Summary:
A new generation of sustainable paper-based products with specific autonomous functionalities aiming at interacting with their users and/or reporting changes in their environment is developed in the frame of A3Ple project. A major focus is placed on the development of electronic circuit with printing technology and low power consumption.
12 research and industry partners with different backgrounds, going from materials science and engineering, to chemistry, physics, electronics and micro/nano-technologies worked in a multidisciplinary approach and developed:
• Advanced functional materials (paper, fibres, inks), functional components (battery, temperature and gas sensors, electrochemical display and transistors), and peripheral components (conductive lines, resistors and interconnections (bridges)).
• Electrical simulation tools in order to define the electrical design and physical layout of printed circuits.
• Specific on-line quality control of the printed electronic paper products.
• Cost-effective manufacturing process flows based on printing and embedding techniques commonly used in the printing industry.
During the international conference LOPEC (March 2015), the final demonstrators were awarded by OE-A as the best demonstrator realized in the frame of a collaborative public funded project (Figure 1):
• Demo1: an “on/off” device that gives information on the occurrence of a dangerous gas. The label can detect the lethal gas H2S in a room. However, for live demonstration in a show room a temperature sensor is used instead of the H2S gas sensor.
• Demo2: a paper poster (A0 format) that is able to distinguish 3 gas levels and shows the value reached instantaneously.
The manufacturing process flow takes into account the need to split the printing of the electronic components from the printing of the aesthetic visual label that covers and protects the electronic circuit. The electronic printing parameters influence the conditions of graphic printing and vice-versa. The printer has to master these influences before launching the manufacturing of final products.
For both Demos, the printing design takes into account physical constraints for electronic behaviour and printing issues, and graphic identity of the real product such as poster size, display dimension, how to read / understand the colour change, etc…
The methodology developed for these Demos can be used efficiently for developing any other electronic printed paper product based on the combination of a sensor, display, battery integrated in a dedicated electrical circuit. Furthermore other components (capacitor, NOx sensor and memory transistor) were also optimized. They can be introduced into more complex circuits developed in the future.
Finally the Life Cycle Analyses (LCA) of printed circuits on paper shows a very low impact on CO2 emission and other environmental factors compared to conventional electronics. Interviews with different potential end-user show the possibility of a rather huge market development and the social impact of such technologies.
Project Context and Objectives:
Paper is a green, renewable and recyclable commodity product. With a production of about 100 million tons and a recycling rate above 66% in Europe , the industrial sector is currently facing difficulties, mainly because of the competition of electronic media, and needs the development of new high value added products.
Paper and fibres, as a substrate, have very interesting properties, in particular the thermal and mechanical dimensional stability of paper compared to for example plastics, for the printing of electronics as well as the capacity of electric charge accumulation at the fibre surface for the integration of electronic components. In addition, the use of paper as main printing substrate has led to the development of specific knowledge in printing technology and long-term experience in large area roll-to-roll (R2R) printing processes. Besides, the miniaturized flexible electronic components (battery, sensors, display, etc) developed during the last few years open new opportunities. The combination of the advanced properties of paper/fibres and the transfer of knowledge developed in paper printing together with the actuation properties of electronic components could enable the development of new integrated multi-functional products.
The objective of the APPLE project is to develop the next generation of sustainable paper-based products with specific autonomous functionalities aiming at interacting with their users and/or reporting changes in their environment. A major focus is placed on the development of new and flexible manufacturing concepts based on printing technology to produce large area hybrid organic/inorganic papers with improved performance at competitive cost.
To this aim, the APPLE project is focused on 1) the integration of recent advances in functional materials (paper, fibres, inks) and functional components (battery, sensors, display, memory) and their production process upscale and 2) the development of innovative, flexible and cost-effective manufacturing processes based on printing and embedding techniques for the integration of all these functional components on the smart paper substrate. Figure 1 illustrates the concept of the APPLE project.
A very special highlight of this project is the fact that the new APPLE products will make extensive use of the specific properties of both fibre based products and (nano)fibres individually. Indeed, the paper is not only used as substrate providing the required mechanical, surface and barrier properties for the printing and integration of the functional components, but the fibres including the incorporation of nanofibres are also used as active elements with integrated high levels of intelligence, namely the display and the memory.
The project is expected to open new opportunities for the paper and printing industries (132 000 printers in Europe, among which 85% are SMEs) in the growing market of low-cost and high value added printed electronics. We will then be able to produce a plethora of low cost and disposable applications, of great impact for SMEs, such as smart labels and packaging to control product quality (e.g. food and medicine industry) and air quality (car cockpits, in house and industry environments, etc.) answering societal needs. This will generate a wide range of spin-off products.
The project is built on a set of main technical objectives towards the development of the APPLE product manufacturing concept and the fabrication of APPLE demonstrators for defined markets.
The 4 main technical objectives are described below.
Develop new functional materials at industrial relevant scale (paper, fibers and inks)
• To develop an advanced paper/board with functional barrier properties and very low surface roughness achieved using bio-sourced materials (extrusion coating of biopolymers) “green” chemistry (innovative grafting process) and with fibre charge accumulation properties, as required for the integration of all the electronic components.
• To optimize advanced materials, including organic polymers for conductive inks, functionalised carbon nanotubes and inorganic nanomaterials oxide based for battery, display and sensor components.
Develop printable functional components at industrial relevant scale
• To adapt and optimize a printed thin-film battery (power, capacity and voltage) for the different sensors (sensitivity) and the displays (size and contrast).
• To print gas sensors (CO, domestic pollution and H2S, oil refineries pollution) and temperature control sensor.
• To adapt and print display and memory transistor components able to satisfy the application requirements regarding voltage bias and power consumption, display contrast ratio, information retaining and switching times.
Optimise design integration and develop a new manufacturing process
• To design the integration of the different components on paper substrate for the different targeted labels or poster sizes
• To develop cost-effective manufacturing processes essentially based on printing (ink jet, R2R, reduced assembling steps, combining lamination) and with a new quality-controlled, flexible concept.
• To assess the sustainability of APPLE products (LCA, recyclability, end-life and industrial safety) and to evaluate their potential for further development.
Demonstrate the manufacturing process: To manufacture on industrial printing and converting lines 3 smart multifunctional demonstrators through technical and cost assessment:
• Autonomous paper labels for environment and safety – novel dynamic concepts for pollutant control management and person safety (to identify pollutants emission in interior buildings or emergency situations and alert personnel).
• Multifunctional paper posters for environment and advertising – innovative self-powered and long autonomy gas sensor solutions for environment with integrated displays and memory for delivery of information. The expected gains on the ratio performance cost will be over 100% of today’s technology.
• Multifunctional paper labels for smart packaging – innovative track and trace systems, displays for information delivery with integrated temperature sensors for consumer satisfaction and safety.
The scope of the project requires a multidisciplinary approach, involving research and industry with different backgrounds, going from materials science and engineering, to chemistry, physics, electronics and micro/nano-technologies. The consortium is then composed of:
• RTD providers for development of functional materials (paper, fibres by CTP and UNL) and components (sensors by CEA and TNO, display; memory by UNL), design and integration (CEA, UNL, VTT, CTP), printing processes (CTP and VTT);
• Industry/SME technology providers for development of functional inks (Poly), advanced base paper (FS) and components (printed battery by Varta), the integration of the components (BA, Poly and Varta), the development of the APPLE manufacturing process (printing technology and equipment by LT) and finally the on-line product control (ICS);
• SME end-users (RGP and LT as end-producers)
Project Results:
1.3.1. - WP1. APPLE Value chain (RGP)
Task 1.1: Specifications (RGP)
End-user functions and constrains were defined for the three demonstrators. Then the global technical specifications were specified according to foreground results and discussions between partners.
Task 1.2: Environmental sustainability and safety (CTP)
LCA (life cycle analysis) methodology for printed electronic consists of a comparison between a “paper demonstrator” and a “conventional demonstrator” that present the same electrical function. Conclusion on the functional unit defined as “Produce a surface of conductive lines which will support the same electronic functions” shows that all environmental impact factors are 1000 times lower for a paper demonstrator.
Several scenarii for product end of lives were assessed. Evaluation of recyclability, incineration and compostability leads to the conclusion that the three demonstrators, as they are currently produced, are compatible with those 3 types of end-life. These studies also underlined the necessity to explain to the consumer what a Printed Electronics product is and how to handle the end of life of such a product.
Main assessment of printed electronic is the impact of silver ink on safety, recycling and the environment. The impact was studied in detail for each aspect; the selected silver ink is recyclable and does not disturb biodegradability and phytotoxicity of paper.
Task 1.3: Potential market development (RGP)
For each demonstrator an evaluation of the potential direct market and other possible markets was performed. The price affordable by the consumers was also estimated. This was realized via an inquiry: several persons operating in different fields such as fire-brigade or city hall were invited to deliver their opinions towards the interest of the A3Ple’s demonstrators.
The interest of the demonstrators goes far beyond the specific functionalization targeted in the 3 demonstrators. The industrial development performed can serve a very important field of applications and different new markets.
Demo1: All the interviewed persons were interested by the product. However the following conditions were outlined:
• The final system should detect several gas if possible.
• It must be easy to use.
• It must be secure.
• The price must be reasonable.
In conclusion this product can open several markets that lead to big quantities.
Demo2: This demonstrator doesn’t seem to have a big interest for the people questioned. They are not enthusiastic as they find it complicated to set in place and not really needed or expected. Some electronic panels already exist in big cities; there is no need for new systems. Anyway these new Demo2s must be tested and approved by the end-users before being implemented at larger scale.
Demo3: The food industry is not interested in this system at the moment. Its organization is efficient in regards to the “cool chain”. The system of a label could engage the responsibility of the food industry that is reluctant because it is impossible to control the attitude of the final consumer.
Some other activities, such as following of human implant or medicine, could find an interest in the functionalities aimed in Demo3. In that case the cost of the label is not a key problem and the final user is ready to pay if the safety of the product is guaranteed.
Conclusion: The 3 demonstrators have a potential to find a market. They have to be adapted to the real need of the consumer or the industries concerned. A specific label or poster needs to be developed according to the final require from the final end-user or industry targeted.
1.3.2. - WP2. Functional materials (Poly)
This WP deals with the development of functional materials needed to manufacture the functional components and final products: 1) Functional and barrier extrusion coated paper, 2) Functional fibres for paper memory and 3) Functional inks.
Task 2.1: Functional barrier extrusion coated paper (CTP)
Three commercial papers derived from commercial available paper grades, already developed by Felix Schoeller for printed electronics purposes (Figure 3), were selected as reference papers (Ref FS1, FS2 and FS3 in the project).
Figure 3: Description of the three reference paper grades
A new paper, referenced as FS4, was developed from paper FS2. Its design is the same as FS2, but based on a thinner and lower weight raw paper. In accordance with the needs of all partners and printing tests performed in WP4 and WP6, finally FS3 paper was chosen for Demo1 and 2.
When needed, the barrier layer is made of polyethylene. However, polyethylene is known to have major drawbacks when married with paper. It can possibly create issues in waste paper recycling streams and it is non-biodegradable. This task intends to minimise the environmental impact of the barrier paper by associating either bioplastics or biodegradable plastics with a paper substrate.
5 polymers were selected to substitute the PE and they were tested at laboratory scale. Production of samples was completed and comparative biodegradability tests were performed on the CTP’s pilot platform. Coated samples show a good biodegradability, close to cellulose. As expected, the polyethylene coating is not biodegradable. However, the cost of all biodegradable substitute candidates for polyethylene are significantly (factor of 5 or more) higher than that for polyethylene, and the substitution generates some processing issues lowering coating process efficiency and yield. Furthermore, all biodegradable substitute candidates naturally show lower barrier properties for water and water vapour.
Task 2.2: Functional fibres for paper memory paper (CTP)
UNL was responsible for the development of conventional transistors and memory transistors starting from different paper samples developed by CTP. The difference between the devices is the fact that in a conventional transistor it is expected that the hysteresis effect is small (or even negligible) while in the memory transistors a large hysteresis cycle must exist on the transfer characteristics (variation of the source-drain current, VDS, as a function of the gate voltage, VGS).
Many papers and micro fibril cellulose (MFC) self-standing films were produced by CTP, characterized and selected as memory transistor or regular transistor. Initial results showed that pure MFCs and MFCs coated papers are the most promising ones regarding their application as dielectric, suggesting that MFCs are highly relevant in achieving high capacitance, extremely useful for transistor application. It was also observed that the treatment of the MFCs in acid or alkaline medium results in different electrical behaviour of the transistor. The acid treatment is more suitable for memory transistor (counter clockwise hysteresis) while alkaline treatment seems more suitable for regular transistor (low hysteresis), as seen in Figure 4.
a) behaviour suitable for memory b) behaviour suitable for regular transistor
Figure 4: Transfer characteristics of transistors produced in the classical configuration using MFCs paper a) microfibrils treated in acidic medium, and b) microfibrils treated in alkaline medium
Task 2.3: Functional inks (Poly)
Sub-Task 2.3.1: Primer layer ink
The purpose of the primer layer ink is to treat a substrate in order to modify surface properties as smoothness, surface tension, barrier effect and electrical insulation. This is useful in a multi-layer component if a substrate requirement for a functional ink is different from another. A UV-curing ink was selected to have a quick drying. Two inks were developed, for inkjet and for flexography.
Sub-task 2.3.2: Advanced functional ink
An aqueous transparent conductive ink, based on carbon nanotubes and a conductive polymer (Pedot-Pss), was developed for inkjet printers. Different kinds on CNTs and grades of Pedot-Pss were evaluated, and the best combination allowed obtaining a high transparency of 90 %, a low sheet resistance of 75 Ω/sq on PET and FS1, with a high flexibility and a low cost.
Electrical and optical performance of the printed ink was similar to ITO, an oxide used in the electrochromic display concept (task 3.3). Samples on PET were tested by UNL to be used instead of ITO. Electrical and optical performance was interesting but, in this configuration, the Pedot-Pss has the same electrochromic behaviour and colour changes as WO3.
An adaptation of the conductive ink was performed to fulfil the requirement of the flexographic process. Due to a too low viscosity at the rotation speed of the flexography, there are a low ink deposition and a high resistance of the printed film (few kΩ/sq on FS1). The ink cannot be used in the project and was replaced by commercial flexographic silver ink.
1.3.3. - WP3. Functional components (CEA)
Task 3.1 – Thin film batteries (CEA)
The Thin Film Battery (TFB) selected to supply the A3PLE demonstrators is based on the lithium-ion technology, because of its higher energy density and its ability to be implemented in flat and flexible configuration. Taking into account several key criteria such as state-of-charge operating range, safety and cost, the 3.2V Graphite/LiFePO4 couple was selected among the possible Li-ion systems. Indeed, this technology remains hugely competitive in terms of performances compared to the commercial primary TFB even if its rechargeable properties are not used.
As the final design of the A3PLE battery is strongly linked to the manufacturing process flow, two specifications were considered: the Thin Film Battery will be reported (i.e. hybridizised) onto the paper substrate in a continuous way and it will be manufactured in a R2R process. As a consequence, it was decided to develop the manufacturing process with the objective to produce a rolled band of operational batteries. The process is based on the combination of techniques in continuous mode with screen printing, co-lamination and thermosealing. It consists of co-laminating two rolls (Figure 5):
• the first one carries patterned negative electrodes printed onto structured Cu current collector and covered by printed membrane;
• the second one carries corresponding patterned positive electrodes printed onto Al current collector
where the base material of the rolls will constitute finally the soft packaging of the battery.
Figure 5: Roll to roll process for battery manufacturing
The process in line based on the combination of the use of smart packaging, printed components with specific design and screen printing techniques for thick layers (~100µm) was assessed. The manufacturing of the battery core was demonstrated at labscale. Several solutions for hermetically closing the smart packaging were tested. Finally, the obtained battery exhibits the expected recovered capacities with stable behavior fully compatible with conventional Cgr/LFP based batteries.
Figure 6: overview of battery at different steps and electrical characterization
Task 3.2 – Printable gas and temperature sensors (TNO)
Task 3.2.1 – CO and NO2 sensors (CEA)
The gas sensors provided in the A3Ple project are based on single walled carbon nanotube CNT network as the sensitive material working at room temperature and low power consumption. Electrical detection is studied for two gas targets along the project: CO and NO2 gases.
Water based inks were developed for spray coating of the CNT network (Figure 7). Gas characterization was performed in a gas probe station allowing good control of the gas concentration.
Figure 7: Process flow of the gas sensor elaboration
Pristine CNTs were then platinum-coated to produce CO sensors on paper. Poor resistance variations were obtained with the fabricated devices. Compared to the sensor’s sensitivity to relative humidity (average resistance variation of the CNT network is around 15-20% from the initial value for relative humidity between 40 to 70%), CNTs hybrids show poor CO sensitivity (less than 1% of resistance variation under 100ppm CO). These observations clearly push the consortium to modify the gas target to the NO2 gas which is a strong environmental pollutant and toxic for the respiratory system. In this case, raw CNT networks exhibited more than 50% of resistance variation under NO2 exposure (50ppm).
The objective of the project was to integrate the NO2 sensor into a smart poster for air quality monitoring (Demo2). For that, 3 levels of NO2 detection were required (< 5 ppm - 5 to 50 ppm - > 50 ppm of NO2)
Figure 8: NO2 sensing and it integration into poster
Clear increase in resistance variation under various gas concentrations was observed. More than 25% of resistance variation was measured between 5 and 50 ppm gas exposure (Figure 8). This significant resistance variation promoted development of 3 distinct levels of sensing (< 5 ppm - 5 to 50 ppm - > 50 ppm). The resistance variations were correlated to the gas concentrations allowing the detection of the level of exposure in the range previously defined in the project. The resistance variations were compatible with the electronic on paper provided in A3ple project.
In the framework of the A3Ple project, NO2 gas sensors based on printing of carbon nanotube networks on paper were developed. Strong resistance variation under gas exposure has allowed clear measurement of three levels of detection.
Task 3.2.2 – H2S sensor (TNO)
The H2S sensor is based on copper(II)acetate (CuAc2) in water. There are no environmental issues with respect to application as the system is waterborne. An interdigitated finger structure is the basis of the sensor. Then, the CuAc2 solution is inkjet printed on this structure, (Figure 9a). This H2S sensor on a specific commercial paper is humidity independent up to about 80% of humidity.
The sensor gives a good response by exposure to H2S gas. The resistivity drops from non conductive to 10 kΩ at 2 ppm of H2S gas (Figure 9c). The formation of the conductive path of CuS between the Ag fingers takes approximately 15 minutes. The colour of the greenish CuAc2 layer changes to a brownish colour (Figure 9b).
(a) c)
(b)
Figure 9: (a) Ink jet printed CuAc2 on commercial paper with flexo gravure printed silver. (b) color change of cuAc2 after H2S exposure; c) Response of H2S sensor based on ink jet printed CuAc2 implemented
The sensor was integrated in a security label, Demo1 (Figure 10). The fingers were printed on an industrial machine (at LT) and the active solution was inkjet printed at TNO.
Figure 10: Printed H2S sensor integrated in Demo1.
Task 3.2.3 – Temperature sensor (TNO)
Ceramic thermistor material based on inorganic spinel structures were made at TNO with a multistep synthesis and firing. Two kind of particles were tested: CuFe2O4 and a newly developed material built up from Mn/Zn/Cu Oxide doped with Ni and Co (general formula is Mn1,71Ni0,45Co0,15Cu0,45Zn0,24O4 - manganese spinel oxide). The resulting material shows thermistor behavior with a lot of advantages; low overall resistance and high temperature stability are the most important.
The sensitive ink was stencil printed on an interdigitated finger structure printed on FS3. The active layer shows a thickness of 38μm. In Figure 11 the resistance vs temperature of the manganese spinel thermistor was compared to the CuFe2O4 thermistor.
The conductivity vs temperature response of the manganese spinel markedly exceeds the CuFe2O4 thermistor performance (ie: the resistance of the manganese spinel thermistor was much lower than the CuFe2O4). Consequently less material can be deposited to get the same efficiency. In an optimal form the temperature response corresponds to a variation rate (α) of -4%K-1 at 25ºC and to a resistance at 25ºC of only 175kΩ.
Figure 11: Comparison of copper-iron oxide and the new manganese spinel oxide
Thermistor material sent to LT and CTP were flexography printed at lab and industrial scales. As the ink layer is not thick enough using this technique, the sensor on the final Demo1 and Demo2 was stencil printed by TNO (Figure 12).
Figure 12: Demo1 and Demo2, with printed temperature sensor in blue circle
Task 3.3 – Electrochromic (EC) displays (UNL)
A notable achievement in the EC display development was the realization of a fully printed (at lab-scale) all-solid-state device based on cheap, safe and stable chemical materials while simultaneously providing proper performance under operation. The EC displays prototypes developed for the A3Ple project demonstrate that there are no major obstacles in development of this component and its application in demonstrators.
The architecture and process flow of the printed EC cells in the final demonstrators is presented in Figure 13. Some typical operational characteristics were determined at lab-conditions. As an example, the peak consumption power for coloring/bleaching ranges 100/400 W/cm2, respectively, and switching time is 3s for a maximum operation voltage of 4 V.
Figure 13: Schematic diagram of the process of fully printed EC display.
The first prototypes of Demo1 with a fully printed EC display on paper were demonstrated at M34. These already included a new approach for integration of the EC display with the transistor on the same PET foil. The EC display and the transistor integrated in Demo1 is shown in Figure 14a.
a) b)
Figure 14: Layout and EC display on a) Demo1 and b) Demo2.
The display layout for Demo2 was developed together by UNL, CTP and BA (Figure 14b). Each segment of the display is powered by silver electrodes reaching the circle from outside, while the contact to the PET/ITO foils is done from inside using a common electrode (aiming equal power repartition). Like the EC display for Demo1, silver, carbon and electrolyte films are deposited on top of the paper substrate, while WO3 based ink is printed on ITO PET substrate. The effective EC display diameter after encapsulation is 100 mm.
There are no major obstacles in material development for the EC displays. However, there is room for improvement concerning the mechanical integrity of the devices, namely concerning the detachment of the PET foil from the electrolyte, which compromises the functionality of both EC display and EG-FETs. This is critical in the case of Demo2 EC display due to its dimensions.
Task 3.4 – Fiber-based floating gate memory (UNL)
The work performed demonstrated that paper substrates produced from micro-nano fibril cellulose (MFC) have a strong influence on the performance of an oxide based memory transistor. The effect of the fiber’s type, structure and dimension was studied regarding the use of paper as the dielectric in such devices. However we must highlight that these devices were aimed only for Demo3. This means they were not integrated in a demonstrator since Demo3 was not realized.
A first set of 26 long fiber papers and 10 MFC self-standing films were produced by CTP during the first 18 months. Memory transistors were produced by UNL on both sides of the paper with a staggered-bottom gate structure as can be seen in Figure 15a. On one side a 40 nm thick GIZO (Ga2O3-In2O3-ZnO; 1:2:2 mol) film was deposited by RF magnetron sputtering to create the channel region. Then, Al source/drain (S/D) electrodes (200 nm thick) were deposited by e-beam evaporation. Finally, a 200 nm thick IZO (In2O3-ZnO; 89.3:10.7 wt.%) film was deposited on the other side of the paper substrate to be used as gate (G) electrode. The most remarkable observation was that CTP23 paper, with extra ionic charge added to the pulp, is the one that presents the longest retention time (time while source and drain current (IDS) ratio between on and off states is above 10) of around 107 seconds (~4 months).
a) b)
Figure 15 – a) Schematic representation of the memory transistors and b) charge retention time extrapolation for memory transistor on samples CTP 23.
Memory transistors were also made on the MFC membranes (samples CTP61 to 70) formed on top of FS3 paper with silver electrodes, that were used as gate in memory transistors (Figure 16). This approach is particularly interesting when moving towards printable devices, meaning that it is possible to have a functional cellulose layer in the transistors, with tailored properties different from those of the substrate/backplane.
The memory transistors produced with these membranes have lower retention time than those produced on paper samples, being, in the best scenario, around 46 days. Nevertheless this clearly shows that cellulose based dielectric layers can be formed on foreign substrates by printing-compatible methods, representing a big step towards printable memories integrating cellulosic materials as active component.
a) b)
Figure 16: a) Photo of a printed MFC membrane (with transistors) on top of silver layer deposited on FS3 paper and b) charge retention time for different MFC membranes.
1.3.4. - WP4. Peripheral components. (LT)
Task 4.1 – Design and development of printed integrated devices
Active component -Transistors
UNL developed the transistors for the A3Ple demonstrators. The final strategy was based on electrolyte gated devices (EGFETs). This was the strategy followed for the transistors to be integrated in the demonstrators. GIZO was deposited on PET/ITO substrates by sputtering in order to be used as oxide semiconductor. The ITO was patterned in order to create S/D regions. The EGFETs were then hybridized on the Demos’ backplane (containing the printed silver conductive lines and electrolyte, Figure 17). The connection between the electrodes of the PET foil and the printed silver conductive lines on the backplane was done by filling vias with silver paste. An adhesive layer was used in order to assure the encapsulation of the electrolyte and a better adhesion to the backplane.
a) b) c)
Figure 17: a) Scheme of EGFET and hybridization strategy, b) Layout with W/L ratio of 45 with adhesive layer location (green rectangle) and c) EGFET hybridized on Demo1.
With the new approach (PET hybridized system), an improvement of the current modulation was observed; a ION/IOFF ratio (maximum/minimum current) up to 1.35x104 was obtained on devices with a channel width/length (W/L) = 45. It is relevant that these devices still showed an adequate operation mode three weeks after production, with a ION/IOFF ratio still above 1000, regardless of the W/L used.
Passive component - Resistors
VTT tested different inks and designs to combine resistance design and target values (Figure 18-b). Lab and pilot tests on PET and FS papers validated the way to make resistor components. In the project’s final stage, VTT fine-tuned the quest for resistors by examining at lab-scale the variations, deviations and reliability of resistors with a final conclusion that resistors can be produced in a large range with high reliability.
CTP has development tests and method to manage and predict resistor target values: the distance between the silver square defines the length of the resistor (L) and the width (W) of the resistive square sets the resistance of the resistor. The dimensions of the resistor (W, L) are predicted by a simulation program. This program uses lab and industrial resistance values measured on samples printed at CTP and LT as input data to build this component layout (Figure 18a).
a) b) c)
Figure 18: a) CTP’s design for the study of the influence of the printed area on the resistance; b) Resistor made with screen printing on PET, VTT; c)”line” and “snake” resistors, two design proposed for low and high (respectively) target values.
Industrial transfer to LT was performed since April 2012. The ink and printing parameters were chosen to reach specifications of both demonstrators (target resistor value= 100ohm to 20 Mohm). Thanks to BA’s suggestion, “snake” resistors have been developed for high resistor targets in order to optimize components dimension (Figure 18c).
Passive component – Capacitors
Though capacitors were not needed as part of the electrical design, VTT worked on this component and succeed to create a workable capacitor configuration printed at lab-scale.
Task 4.2 – Interconnection techniques on paper (VTT)
VTT printed interconnection structures based on a single sided arrangement. Bridges were made by flexo printing or a combination of flexo and rotary screen printing. All printing tests were conducted on FS3 paper. Both lab scale sheet based printing and pilot level R2R printing were used. In R2R pilot level printing, 100% yield of bridge structures was achieved by printing
1) bottom silver tracks either by flexo or rotary screen (commercial micro particle silver inks)
2) insulator ink by rotary screen with double layer of UV curable commercial dielectric
3) top silver tracks by rotary screen or optionally by dual layer of flexo (Figure 19)
Figure 19: a) Dual layer flexo printed silver conductor going over the edge of screen printed insulator and b) Single layer flexo printed conductor on FS3 paper and edge of screen printed insulator.
The fully flexo printed bridge structure was achieved at lab scale with table top printing machines. This achievement would be very practical since the industry predominantly works with the flexo-printing method. Working insulator layers were obtained with a yield of 100 %. These results applied for bridges with areas between 1 mm² and 400 mm². Working bridges were obtained when at least 2 layers of insulator were printed to remove any pinholes and inhomogeneity of the insulator layer. This also applied to the case of rotary screen printed insulator layers where the yield was significantly reduced when only one insulator layer was used. The results are presented in Figure 20.
Figure 20. Printed bridges (left) and their performance as a function of layer thickness/amount of layers and printing method.
It is possible to manufacture fully-printed bridges. An excellent working yield is achieved when the layer thickness is adequate and the amount of printed layers is at least two. Both rotary screen printing and flexography were able to reproduce working bridges. In flexography, the printing parameters needed more careful optimization than in rotary screen printing.
Task 4.3 – Hybridization on paper (LT)
Optimization of hybridization parameter
All systems based on electronics use a power source to supply electrons in the circuitry. Printed electronics are no exemption to this so in the project the use of a Thin Film Battery (TFB), single or multiple, is required. The relevant parameters for the hybridization of the TFB were defined.
Functional TFBs in roll format were not available in sufficient volume to deliver a realistic test setup and make a practical assessment for TFBs hybridization onto the printed electronics labels. However, dummy batteries with physical characteristics close to the TFBs under development allowed to define the relevant parameters of hybridization:
1) Position and orientation of the electrodes (battery poles connectors) on the demo label.
2) Electrical connection and physical fixation of the battery
These parameters drive the technology and the process to properly and solidly connect the TFB on paper. The final step is to check and control the functional connection and the battery functionality.
a) b) c)
Figure 21: a) and b) materials for the production of the dummy battery roll; c) roll of dummy batteries
Development of on-line hybridization machine
For the development of the hybridization system, rolls of dummy batteries were used. A first system concept was proposed at M30 and further developed with the final R2R design of Demo1 and Demo2.
At the end, the testing was performed with commercial batteries manually placed on the test roll according to Figure 22.
Figure 22: schematic of material flow for hybridisation
1.3.5. - WP5. Integration (BA)
The integration of components into a full functional circuit requires to define:
1. the electrical design (task 5.1) which depends on electrical behavior of printed components,
2. the printing design of layout (task 5.2) which defines the mapping of the ink layers for i) each component and simultaneously ii) for the Demo in a global manner.
The complexity of the integration required a step by step method where the electrical and physical designs evolve by iteration (task 5.3). The table 1 sums up designs and layouts that were printed in the frame of the A3Ple project.
Table 3: Summery of electrical design and physical layout (name: specification) for each demonstrator.
ELECTRICAL design PHYSICAL design of layout
Demo 1 Demo1-A: Resistor values compatible
with LED as display & light sensor chip Demo1-V1: Resistors and lines
Demo1-V2: […] and electrodes of components
Demo1-B: Resistor values compatible with printed EC-Display & H2S gas sensor Demo1-V3 & - V4: […] and physical constrain link to final product and graphic label
Demo 2 Demo2-A: 3 levels switch on/off progressively, compatible with LEDs as display & sensor chip, Demo2-V1: Resistors and lines
Demo2-V2: […] and electrodes of components
Demo2-B: Resistor values and design compatible with EC display behaviour Demo2-V3: Resistors and lines and electrodes of components and physical constrains link to final product and graphic label
Demo 3 Demo3-A: Design using memory effect of EC-display. Demo3-V1: Resistors and lines and electrodes of components
Task 5.1 – Electrical design and simulation of circuits (BA)
Demo1. The goal of Demo1 is to make an “on/off” device that gives information about the presence of a dangerous gas. The label is used only one time and replaced after the gas detection. This “one-shut” label permits to BA to design the simplest electronic circuit: one sensor, one battery, one transistor, one display, conductive lines and a few resistors (Figure 23a). Demo1 designs do not require any interconnection (bridge).
The parameters of this circuit were estimated by a simulation tool developed in the frame of the project. The input data were electrical characterization of chips (since printed components were not ready) and then, the characteristic measured on the printed components (inputs from WP3 and WP4). BA also realized a specific Excel spreadsheet to simulate the behaviour of the Demo1 for different conditions of gas concentration.
(a) (b)
Figure 23: (a) Final electrical design of Demo1; (b) «H» cell configuration inside Demo2 electrical design
Demo2. The objective of Demo2 is to distinguish 3 levels of gas content and informs witch one is reached. Therefore the circuit was more complex compared to Demo1:
• Number of components increased: 14 resistors and 8 transistors.
• Gas sensor and displays had to show a reversible behaviour.
• Double conductive layer with interconnections was required. In a conventional circuit, the two layers are realized on the two opposite faces of the substrate and connected using drilled vias. In the project, the connection on paper substrate was made with the bridge method (task 4.2).
The first electrical design was produced with a LED as display (Demo2-A): the LED light switched off when the applied voltage drops to zero. However, a printed EC-display behaves differently and the electrical configuration did not permit to switch off the display. To solve this issue, BA introduced an “H configuration” that applied -3V to the display in the “off” state (Demo2-B, Figure 23-b). This solution required the same number of transistors as for Demo2-A, which is important in order not to increase circuit complexity.
Demo3. The Demo3 circuit should measure temperature (T) at the moment and keep its past maximum value in memory. The associated electrical circuits require a memory transistor, measurement initialisation, many displays, p- and n-type transistors, etc… In order to solve the complexity of such circuit, BA proposed to use the memory effect of the EC-display to “store” information linked to the maximum of the past temperature. The Demo3 electrical design could be seen as the combination of Demo2-A (for maximum past T) and Demo2-B (for present T).
Task 5.2 – Physical design of layout for component implantation (BA)
Each electrical design (only made of line connections and chips position) was validated by BA with a conventional (PCB) circuit. This conventional layout was used as the starting point (step 0) for the physical layout of the printed circuit. The physical layouts are progressively modified according to the following steps:
0- Conventional layout with only draws of conductive and insulating layers.
1- Circuit layout adapted to printed circuit dimensions.
2- Each chip area replaced by a surface corresponding to the future printed component.
3- Each chip connector replaced by the electrode layout of the associated printed component.
4- Physical layout associated to the other functional inks.
At each step, the conductive lines are arranged regarding physical constraints (components dimensions, electrode orientation, etc…).
Demo1. Development of the circuit layout on Demo1 (and the other demos) was made incollaboration between CTP (printing constraints) and BA (electronic constraints). The “physical design rules” were defined together for printed electronic on paper. These rules were very different to conventional electronic ones.
For each physical design reported in Table 3, BA & CTP proposed several layouts. The selected solution was decided by all the partners according to the other constraints (for example, display position inside the label was important for final physical aspect of the product). The validated layout was printed on industrial equipment. For Demo1, only the conductive silver ink and the resistive ink were printed at LT. At the end, the final physical design (Demo1-V4, Figure 24-a) took into account physical and graphic constraints of a real product.
a) b) c)
Figure 24: a) Demo 1- V4 printed on FS paper, b) Demo 2-V3 layout of industrial printed steps, c) Demo3 layout; Color code: grey or red = conductive ink, black = resistive ink and green = insulator ink.
Demo2. The development of the Demo2 physical design was based on knowledge acquired on Demo1. However, introduction of new components induced new design rules and other developments:
• Locations of interconnections/bridges was not easy to define because they shouldn’t cover components that will be printed later on.
• The pixels of the EC display required a specific lines layout to split correctly the current flow.
The final design (Figure 24-b) took into account physical and graphic constraints of the real A0 poster.
Demo3. The physical dimension of Demo3 (Figure 24-c) was equivalent to an A4 format. It was four times larger than the one planned (A6 standard paper sheet) but it was not possible to make it smaller.
Task 5.3 – Components integration, lab testing and control
The complexity of the components integration required an iterative method. The printed components were introduced one after the other. The “ready to use” components were printed at industrial or laboratory level; then the other components were replaced by hybridized chips. The objective of this “hybrid circuit” was to identify problems linked to the “just introduced” component. When solved, the integration of this component was validated and the next component integration could start.
Demo1. Components integration started with resistor and conductive lines. Industrial printing of these two layers was validated at the early stage of the project. Reproducibility and value deviation during the trial were evaluated in detail by BA and ICS. The hybrid circuit had the expected electrical behaviour. They were presented in 2013 at LOPE-C in the OE-A booth for a competition.
The H2S and the temperature sensors, and then the battery were introduced with success in the circuit (Figure 25a). Integration of EC- display showed electrical issues that lead to changes in the electrical design (resistor values in particular). The final fully printed Demo1 was composed by 2 steps made at industrial level (on LT machines) and 3 steps at laboratory level at TNO, UNL and CEA (Figure 25c).
a) b) c)
Figure 25: a) hybrid Demo1-V3.0 with printed T sensor and thin film battery; b) hybrid Demo1-V3.1 with printed T sensor and commercial EC-display; c) Demo1-V4 fully printed
Demo2. The same strategy was performed for the Demo2, thanks to the knowledge acquired in the Demo1 development. The final Demo2 was produced in 4 steps (lines, resistors and bridges) printed at LT at industrial level (Figure 1a) and 2 steps at laboratory level at TNO and CEA for the T sensor and the battery respectively. Chips were used as transistors because only one printed transistor failure prevents the full circuit to work.
Control. The image acquisition component of the inspection solution was reviewed in order to optimise the overall performance of the system for printed electronics applications. In order to achieve high contrast at all the print or production steps to be inspected, laboratory feasibility studies were performed on samples provided by partners. Depending on the material inspected, visible or ultra-violet light sources were deployed in combination with monochrome or colour line scan cameras.
Image acquisition parameters such as resolution and angular setting were optimised. Furthermore, contact image sensors (CIS) were evaluated as a valid way to perform inspection tasks in compact print machines that do not permit further components with large mounting volume. This work let to the definition and implementation of an inspection system based on line-scan cameras placed in the framework of a dynamic study at LT (image on the right side). The system, placed on a machine used to rewind the finished print, permitted due to its flexible design to record the afore on-line printed silver and carbon print steps in different conditions and allowed to reproduce lab findings in an industrial setting. The diffuse reflection image acquisition condition was the most suitable and the 50µm resolution was suitable considering current process variations and feature sizes.
1.3.6. - WP6. Flexible manufacturing process (LT)
Task 6.1 – Manufacturing process flow (LT)
The results of the lab-tests performed within WP3 and 4 were transferred into several series of test runs performed by LT and CTP on LT’s machines. In 12 print sessions (trials LT01 – LT12), various aspects of the printing process were examined with the following goals:
1. Observation of conductive and various resistive inks’ behaviour in relation to the machines,
2. Observation of specific paper behaviour in relation to the machines and electronic inks,
3. Optimisation of printing parameters for selected inks,
4. Optimisation of the printed patterns (lines, fingers, electrodes, resistive, etc.) in their consistency during production using the visual inspection system developed by ICS,
5. Production of dummy materials to use for the WP4 related task to hybridize TFB,
6. Printing Demo1, 2 and 3 in several versions and checking the electrical behaviour against the target values defined by BA
7. Generating a procedure for the layout of print plates in order to define the functional layout of the Demo and checking elements to control print quality during or after production.
Manufacturing process flow for Demo1
The process flow realised for Demo1 manufacturing is shown in the following schematic.
Figure 26: Process flow realised for Demo1 manufacturing
Each (numbered) step represents a production phase in the process flow. The images explain what is done by which partner and how the printing step is processed. Another picture shows the physical component.
Example: the 1st step is devoted to the printing of conductive lines and resistors. It is performed by LT on an industrial printing machine. Silver ink for conductive lines are grey while; resistive ink corresponds to the black colour layer. The 3rd step is devoted to the printing of the sensor. This step is produced at lab scale (hand image) at TNO directly on the label. Etcetera, until step 7 for the reporting of the graphic label.
The picture of the printed layout at the end of the process is shown in the centre of the diagram. Each component respects the colour code.
Converting (steps 2 and 7) and hybridization (steps 4, 5 and 6) steps could be made at industrial scale in the future, because they are linked to existing technologies. In the frame of the project, the hybridization at industrial scale was developed only for the batteries. This result may be adapted for transistor and display hybridization in the future.
The sensor printing (step 3), the battery roll preparation and the printing steps of the display film could be performed in LT’s plant in the future. However, they couldn’t be done at this moment due to technical or financial reasons.
Manufacturing process flow for Demo2
The process flow realised for Demo2 manufacturing is mainly based on knowledge developed for Demo1. However, the increase of the electrical circuit complexity requires interconnections (crossed conductive line without electrical connection). These “bridges” (step 2) are printed at industrial scale just after the printing of the conductive tracks and the resistors. The schematics of Demo2 follow the same logic as for Demo-1 above.
The following schematic details steps and components pictures for this Demo2.
Figure 27: Process flow realised for Demo2 (and Demo3) manufacturing
Manufacturing process flow for Demo3
For Demo 3 the structure is very similar to Demo2 apart from the function of the memory and electrochromic display. The main differences are the final size of the functional label, the dimensions of the display and the increased number of components. The manufacturing process flow of Demo3 is the same as that of Demo2.
Task 6.2 – On-line quality control (ICS)
Developed algorithms and software modules were implemented into the ICS software infrastructure to generate an inspection application dedicated to the quality control of printed electronic circuitry. The below shown software infrastructure comprises of real-time inspection software and off-line inspection tools to control the quality of products and trace it over multiple production steps (Figure 28). In the context of the A3Ple project, this capability could be deployed to add multiple inspection stations at strategic production steps, i.e. not every print step needed to be inspected separately, but only those that mattered. For example, a combined inspection of the first silver and carbon print steps needs to be foreseen in order to control their quality before potentially opaque active materials are printed onto the sensor finger structure. This would impede short detection or circuit break detection.
Figure 28: Inspection software and off-line inspection tools
The latest software version was successfully evaluated on the first silver and resistive inks printing steps of the different demonstrators as those were printed in longer print runs (task 6.1). Focussing on the finger structure of the sensor element, inspection settings permitted good and stable defect detection on the sensor element with a very high detection ratio for short defects in the sensor elements (Figure 29) and few false detection.
Figure 29: Screen capture of the inspection software.
1.3.7. - WP7. APPLE demonstrators (LT)
All the work performed in WPs 1-6 drove the state of art of printed electronics on paper at the end of the project. The goal was to demonstrate the production testing and evaluation of Demos1, 2 and 3 under industrial circumstances. The work demonstrated the principle of what the common printer can manufacture with his equipment and how this was made. It showed the results both from the point of production, eg the way to make the demos, and the economics behind it. Thus giving a good overview and set of information about the possibilities a common printer can expect if he considers the production of printed electronics on paper. The 3 Demos initially planned in the project were as below.
1. Environment & safety
labels (A5-A6) 2. Environment & advertising posters (A3-A1) 3. Smart packaging
labels (A6-A7)
Difficulty of demonstrators
Low technological risk
(small-size display) Medium technological risk
(large-size display) Medium-high technological risk
(small-size display and memory)
Chosen approach for the realization of WP7 – A3Ple Demonstrators
The demonstration per Demo was arranged as if the Demo was a real production order taken by LabelTech at IJsselstein to go to an End-User. The Demos were taken up in the production stream of the factory and treated as a normal job as part of the factory’s planning and work flow.
The materials and equipment used for the 3 demos’ manufacturing are summarized in Table 4. The industrial printing machines are presented in Figure 30 and Figure 31.
Table 4: Materials and equipment used for the 3 demos’ manufacturing
Demo1 Demo2 Demo3
Materials Substrate: FS3 + one specific commercial paper as reference X X X
Ink-1: A commercial silver ink X X X
Ink-2: A resistive ink X X X
Ink-3: An isolator ink X X
Ink-4: A commercial silver ink X X
Adhesive (on a transfer roll) X
TFB: Dummies and functional Thin Film Battery X
Equipments Flexoprint: MA-2200 6-color Flexopress (Figure 30a)
X X X
Rotary Screen (Figure 30b)
X X
Inspection: ICS-developed visual inspection by camera and software X X X
Finishing: table-top slitter / spooler X X X
Conversion: adhesion application and cutting to end format X
Hybridization: LT-1 (dedicated conversion equipment) X
End control: table-top slitter / spooler equipped with dedicated hybridization checker X X X
Work plan for all Demos as common practice and reporting
Per demonstrator the following stages of production were performed:
1) Technical evaluation “How-to Make” and feasibility of production leading to a “Go/No-Go”
2) Registration of the job in the work flow / data system
3) Description of needed materials and tooling / Bill of Materials
4) Designation to specific production slot; machine number(s)
5) Preparation of the work; clearance to start
6) Production – 1st phase: building the Demo
7) Production – 2nd phase: running the job for the Demo
9) Production – 3rd phase: finishing the job for the Demo
10) Results – physical product for the Demo
11) Registration and evaluation of the job
12) Conclusion
a) b)
Figure 30: Industrial flexo printing machines used for the demos manufacturing: a) overview of the machine; b) Anilox roll for flexo printing
a) b)
Figure 31: a) Industrial screen printing machine, b) Inspection system developed by ICS installed on screen printing machine.
Task 7.1 – Production and testing of Demo1
Demo1 is an environment and safety label. The goal of Demo1 is to make an “on/off” device that gives information about the presence of a dangerous gas. The label can detect lethal H2S gas in a room. However, for live demonstration in a show room a temperature sensor is used instead of the H2S gas sensor.
a) b) c)
Figure 32: a) Transfer of resistive ink by flexo printing; b) Roll of Demo1 converted into adhesive labels; c) Final demonstrator fully printed: functional electronic label below the graphic label.
Task 7.2 – Production and testing of Demo2
Demo2 is an advertising poster. The objective of Demo2 is to distinguish 3 levels of gas content and informs which one is reached. It is a paper poster (A0 format) able to distinguish 3 gas levels and show the value reached instantaneously.
a) b) c)
Figure 33: a) Printing unit of ink n°1; b) Demo2 rolls produced during trial at LT; c) Final demonstrator fully printed: functional electronic label below the graphic poster.
During the international conference LOPEC (March 2015), final demonstrators were awarded by OE-A as the best demonstrator realized in the frame of a collaborative public funded project (Figure 1-b).
Task 7.3 – Production and testing of Demo3
Demo3 is a smart packaging label. Demo3 should measure temperature (T) at the moment and keep its past maximum value in memory. The physical dimension of Demo3 was equivalent to an A4 format. It was four times larger than the one planned (A6 standard paper sheet) but it was not possible to make it smaller.
Potential Impact:
Benefit for paper industry. FS
During the recent years the declining real prices of paper products have been one of the main reasons for the paper industry’s poor profitability. The results of the project may cause a renewal of the paper industry’s products with more added-value functional products for new applications and markets. Unfortunately, although the demonstration was realized in the frame of the APPLE project, the demand from the market (end-users) must still emerge in order to make this new market opportunity become real sales volume for the paper industry.
Benefit for printing industry. LT
The new sustainable high-added value products demonstrated in the APPLE project, i.e. labels with integrated gas and temperature sensors, display functions, as well as the new and flexible manufacturing process, have been developed in a state where the used technologies are already used at industrial scale.
For the passive components (resistors, bridges), the printing technologies recommended are flexography and screen printings commonly used in the printing industry. The same technologies can be used for temperature and gas sensors.
Battery, and active components as display and transistors have to be hybridized. This hybridization step is also something commonly used in a printing shop. Furthermore, the manufacturing flow defined involves a roll to roll process.
The integration of components was performed on a manufacturing printing/converting small-scale production line. Such production lines are common for SMEs everywhere. The printing industry in the EU comprises some 121,000 firms and employs some 714,000 people. The turnover in the printing industry is about 88 billion EUR. The industry throughout Europe consists mainly of very small enterprises, as 90% of the graphic companies employ less than 20 persons.
The manufacturing process developed in the frame of APPLE project is based on already existing printing lines. That means that the opportunities linked to the development of the new labels, posters, advertising don’t require completely new production lines. The existing printing lines can be adapted, thanks to additional printing units (mainly flexible ink-jet units) and battery hybridisation in order to create new added-value products for the printing industry.
The different foregrounds of the project offer further development potential of new multi-functional fibre-based products that can open new markets for the SME dominated sector of the printing industry:
• Further applications in a growing market sector of integrated self-powered printable display and memory devices based on breakthrough technology using paper as passive and electronic material,
• Further industrial developments of the low-cost and flexible manufacturing concepts investigated in this project, with focus on printing technology.
Through the development on new manufacturing processes opening new markets, the APPLE project is expected to increase the European printing industry turnover by 10% by 2020 and by 25% by 2025, leading to the creation of highly-skilled jobs.
The market of flexible electronics is predicted to dramatically grow over the next years as shown in Figure 20 a). The growth over the longer timescale, from 2007-2027, will be very similar to the early growth of the silicon chip market in the same interval; the twenty years from 1978 to 1998 saw a similar starting and finishing value of sales of silicon chips. The Figure 20 b) confirms the high potential market for printable electronics materials.
Figure 20: a) Estimated market of the main flexible electronics segments and market forecast to 2027
b) Revenue projection for printable electronics market
Unfortunately, even though the forecast for printed electronics showed a huge increase from 2008 until 2018, the printing industry has not been able to benefit yet of such an increase.
The explanation for this low benefit could be in the fact that applications and printed electronic products fulfilling needs from the market are still hard to realize in a one-on-one “Demand/Supply” relationship on end user level. The level of innovation in this industry is low and introduction of new products depends in principle on the demand by the end users or the possibility to show products to end users. The presence of printing industries in the EU and its direct contact with many end users should allow quick adoption of new products. This is not the case. The printing industry is a reactive business where demand is driving the reaction and propositions of the industry. The products can only be introduced into the market when they can be printed and shown. Due to lack of functional inks to turn into building blocks for electronic functions produced in print by ordinary, mainstream printers it is hard to move end users into adoption. But it proves the fact that end users need to see working products to motivate their adoption of the possibilities offered by the printers. It is a matter of availability of know-how on electronics combined with availability of functional inks.
LabelTech (LT) will get direct gain from the project. These results find their base in the capability developed in the project to handle materials and functional inks on standard printing equipment. The main benefit for LT in particular is directly linked to the confirmation triggered by the work in this project to be able to handle under standard industry conditions functional inks with other characteristics to print colour or contrast in patterns done in the industry for centuries. LT can now create in printed patterns with characteristics to facilitate every combination of conductive and resistive electronics. New markets showed up and new requests are “in the cocking pot”.
An example comes from recent contacts by LT with its end users. Coming from these contacts LT was able to show conductive tracks printed for the project and this lead directly to a new request to realize a new product based on simple printed electronics functions, proving the direct potential.
Another field of application directly coming as results to LT is the capability to create RFID antennae structures in various alternative ways based on techniques of material and ink handling realized during the project. Overall LT has moved forward by innovation.
Benefit for BA (electrical circuit designer)
The designing of electronic circuits printed on paper and functional inks is a novel and a very innovative matter, for this reason there aren’t mature software CAD tools to use in this field. The main innovation of this exploitation is the opportunity to use a well-tested commercial CAD software (developed to design standard PCB circuits based on discrete components and rigid substrates) to design very complex electronic circuits printed on paper. This goal has been reached thanks to the development of a Designing Tool Kit that can be used to realize a library of electronic components to be printed on paper. Thanks to the electronics printed on paper it is possible to realize electronic devices in high volume and very low cost, without having to use a chemical etching process and with a low impact on the environment. The company will be able to provide these new services in its portfolio, to increase its turnover and its number of customers.
The following table shows an internal analysis based on new business activities (made in collaborations with other companies) and a new European project that our company has been involved in since May 2015.
Year 2016 2017 2018 2019 2020 2021 2022
MM
New Hiring
New hiring C
Turnover 6
0
0
0% 6
1
1
5% 0
1
2
7% 0
2
4
10% 0
2
6
17% 0
0
6
20% 0
0
6
20%
MM: internal MM allocated to R&D for printed electronic development
New hiring: number of new hiring related to printed electronic business
New hiring cumulative related to printed electronic business
Turnover: Increase in turnover due to the activities related to the printed electronics
TURNOVER: increase due only to the activities related to the printed electronics
NEW HIRINGS PER YEAR: Number of new hirings related to the printed electronics business; NEW HIRINGS CUMULATIVE: Number of new hirings related to the printed electronics business
NOTE: The internal R&D activities is specified only for the first years, in particular 2016 and 2017. This means that in the future years the Research and Developed activities will be carried out by the newly hired, for this reasons the internal MMS allocated for the future years is 0 and the future R&D activities are included in the turnover.
Benefit for Poly (ink supplier)
The added value of the APPLE project is to have a concentration of needs from substrates suppliers (papers), printing industry, electrical design and components (inks and active materials). For an ink supplier, the project offers a better knowledge of the requirements of each step of the smart label fabrication, in order to improve performance and specifications of the developed inks.
The constraint of the choice of the printing process is hard to solve from the point of view of an ink supplier. Due to the active materials requirements in printed components, many functional inks are hard to develop for flexography printing. Some inks require a high concentration of active materials to print an efficient component and the best printing process is screen printing. At the opposite, some active materials cannot be dispersed in a high concentration and resulting inks have a very low viscosity, more suitable for inkjet printing than flexography. The last point is the difficulty of drying printed inks. Many of them require a long time of drying which is not compatible with the high speed of flexography. An added value of the project is that ink suppliers can develop different grades of their inks. A first product grade that fits well with the active material requirement can be developed, followed by other grades to be developed to fit better with the printing process needed by the project, such as flexography or screen printing.
Finally, each ink supplier has developed different grades of their functional inks which can be used by most of the printing processes on the market. Flexography appears to be the best choice to print fast a high quantity of labels but, actually, this process is little used in printed electronics.
Concerning the market of flexible electronics, one of the major parts for ink suppliers will be transparent conductive films, with the substitution of ITO in many devices like displays, OLED or photovoltaics. This market is estimated to be 4 billion $ in 2023 and more than 30 companies are actually involved, including many SME’s, developing different technologies (copper and silver nanowires, organic polymers, metal grids, nanotubes…).
Benefit for Varta (battery supplier)
The printed batteries developed in the A3Ple project can also be used in other products. In a workshop these markets were analysed. Typical markets for Printed Batteries are:
• Healthcare: Cosmetics & Healthcare, Wellness, Healthcare, active wound healing fabric, flexible body sensor, specific (single use) disposable Healthcare/Fitness/Medical devices
• Logistics:Logistics, akt. RFID, active Battery-assisted RFID, active RFID, cold chain, Logistics customized products, Supply and Cold chain, Logistics
• Smart Packaging: Smart Packaging, Smart Cards with electric functions, illuminated packages, intelligent Packackaging, Smart tags & textile, Wireless Communication
• Sensors: Sensors, Disposable Monitoring System, Wireless sensor systems, health monitoring, Disposable Long Life Ambient Sensors, Wireless sensor systems, building control, TFB Wall Paper – 5x2 m² → 200 Ah?
• Gaming: Gaming Products, Active Games, Spare Battery in the back of writing block (A4 → 1 Ah), Integration in Card Board & Paper, mobile product (foldable phone, …)
a) b)
c)
Figure 34: a) Evaluation of the new markets in different categories ; b) Relation between Price and Complexity ; c) Relation between Price and Volume
These markets were evaluated in different categories.
• Pick&Place / Printegrate: For Smart Packaging (including greeting cards and gimmics) printegration is prefered, all others (especially sensors) prefer secondary cells.
• Primary / Secondary: Primary cells are preferred for Smart Packaging, gaming and sensors require secondary cells
• Complexity: The cells are allowed to be complex, except of Smart packaging. Here a simple solution is preferred
• Green: The green aspect is important for Smart Packaging and Gaming (perhaps because of the disposeability), for the other categories the green aspect is medium important
For a high-class manufacturer it is important to offer high complex devices for a high price. For VARTA it is important to enter markets like Healthcare and Sensors. These markets offer a high margin for low quantities. These markets seem to be present.
Benefit for ICS (quality control supplier)
The participation in the A3Ple project allowed ICS as a system integrator for optical inspection and traceability solution to improve multiple aspects of the existing LineaVision® inspection solution. Resulting is a LineaVision® printed electronics software application using algorithms and software features dedicated to the inspection of printed electronics on paper or other substrates.
Furthermore there have been improvements performed concerning the image acquisition components of the vision system. Novel monochrome and colour line-scan imaging sensors have been implemented, contact imaging sensors were tested and the range of ICS light source wavelengths was increased to the ultra-violet regime. These new means in the image acquisition part allowed us to optimise the optical image acquisition for print steps that are transparent in the visible light or of faint optical appearance, giving better detection results in multi-step processes and integration of vision systems under tight mechanical conditions.
The developed software components and most of the integrated hardware components are part of the industrial inspection solutions and are deployed in several installations for printed electronics and other applications. However, considering the market forecasts for the printed electronics sector, the printed electronics inspection application will show its real value when more PE production capacities are installed in the following years.
Benefit for RGP (packaging industry)
The marketing inquiry confirms that the food industry is well organised in regards to the cold chain and therefore there is no need for a new system for controlling the cold chain.
Nevertheless the results of A3Ple project could be interesting in order to use a label to apply on the pallets in order to be sure that that the cold chain is maintained in the different storage areas not systematically controlled.
The possibility to use a label on each packaging is only realistic if the price is low compared to the final cost of the product.
The 3 demonstrators have a potential to find a market. They have to be adapted to the real need of the consumer or the industries concerned. A specific label or poster needs to be developed according to the final request of the final end user or industry targeted. The A3Ple project opens several ways of development and probably huge markets in different directions.
Benefit for RTO (CTP, CEA, VTT, TNO, UNL)
In the APPLE project much know-how has been developed.
CTP. The technologies for producing memory fibre-based paper, for manufacturing and hybridizing batteries, for printing transistors and resistors, displays and gas sensors will be developed and scaled up for EU SME's printing companies. With the development of these new technologies, new wide markets will be addressed.
CEA. All the knowhow acquired during the A3PLE project on the battery components and manufacturing, will be used in a large R&D program performed by CEA for a major international chemical group. The objective of this new project is to develop flexible batteries for new wearable applications.
The technologies for manufacturing and batteries will be developed and scaled up for EU SME's printing companies. With the development of these new technologies, new wide markets will be addressed.
VTT. Considering VTT’s development work in the A3Ple project, passive components (resistor, capacitor, conductor), and bridge interconnections are enabling components for almost all printed electronics systems. The development done in the A3Ple project enables plenty of further development and other electronics products and printed electronics systems on paper substrates since the work done in the project lead to a useful library of passive components to be utilized in different circuits.
TNO. TNO has learned extensively about the development of sensors and printing of these sensors. A lot of R&D efforts about such sensors are requested by both industrial and governmental entities. The development done in the A3Ple project enables TNO to give answers to these requests. Also plenty of further development on sensors together with the partners in A3PLE is possible. Last, the paper electronics roadmap was given a large boost with the A3PLE project and allows further development in the application of paper in security and communication products.
UNL. The work developed during A3Ple project was crucial in allowing UNL to implement and develop new strategies for printing oxide based electronic and electrochemical devices on paper. Before A3Ple, UNL was internationally recognized by transistors and memories on paper, but produced exclusively by PVD techniques. Printing techniques, and just inkjet, were being used only for the production of electrochromic (EC) displays. The constant focus of A3Ple in the up-scaling of all developments led UNL to develop EC displays using other large scale techniques, such as flexo or screen printing. The same happened for the oxide based transistors and memories: it was demonstrated they can now be printed, with a clear identification of barriers and challenges towards fully printed devices. Finally, all the collaborative work performed with all partners also contributed to strength the UNL knowhow on the topic of “paper electronics”. All this was crucial in creation of new background (or even future IP) with strong impact in the participation in other collaborative research projects.
List of Websites:
http://www.a3ple.eu/
Coordinator: Véronique Morin (veronique.morin@webCTP.com)
A new generation of sustainable paper-based products with specific autonomous functionalities aiming at interacting with their users and/or reporting changes in their environment is developed in the frame of A3Ple project. A major focus is placed on the development of electronic circuit with printing technology and low power consumption.
12 research and industry partners with different backgrounds, going from materials science and engineering, to chemistry, physics, electronics and micro/nano-technologies worked in a multidisciplinary approach and developed:
• Advanced functional materials (paper, fibres, inks), functional components (battery, temperature and gas sensors, electrochemical display and transistors), and peripheral components (conductive lines, resistors and interconnections (bridges)).
• Electrical simulation tools in order to define the electrical design and physical layout of printed circuits.
• Specific on-line quality control of the printed electronic paper products.
• Cost-effective manufacturing process flows based on printing and embedding techniques commonly used in the printing industry.
During the international conference LOPEC (March 2015), the final demonstrators were awarded by OE-A as the best demonstrator realized in the frame of a collaborative public funded project (Figure 1):
• Demo1: an “on/off” device that gives information on the occurrence of a dangerous gas. The label can detect the lethal gas H2S in a room. However, for live demonstration in a show room a temperature sensor is used instead of the H2S gas sensor.
• Demo2: a paper poster (A0 format) that is able to distinguish 3 gas levels and shows the value reached instantaneously.
The manufacturing process flow takes into account the need to split the printing of the electronic components from the printing of the aesthetic visual label that covers and protects the electronic circuit. The electronic printing parameters influence the conditions of graphic printing and vice-versa. The printer has to master these influences before launching the manufacturing of final products.
For both Demos, the printing design takes into account physical constraints for electronic behaviour and printing issues, and graphic identity of the real product such as poster size, display dimension, how to read / understand the colour change, etc…
The methodology developed for these Demos can be used efficiently for developing any other electronic printed paper product based on the combination of a sensor, display, battery integrated in a dedicated electrical circuit. Furthermore other components (capacitor, NOx sensor and memory transistor) were also optimized. They can be introduced into more complex circuits developed in the future.
Finally the Life Cycle Analyses (LCA) of printed circuits on paper shows a very low impact on CO2 emission and other environmental factors compared to conventional electronics. Interviews with different potential end-user show the possibility of a rather huge market development and the social impact of such technologies.
Project Context and Objectives:
Paper is a green, renewable and recyclable commodity product. With a production of about 100 million tons and a recycling rate above 66% in Europe , the industrial sector is currently facing difficulties, mainly because of the competition of electronic media, and needs the development of new high value added products.
Paper and fibres, as a substrate, have very interesting properties, in particular the thermal and mechanical dimensional stability of paper compared to for example plastics, for the printing of electronics as well as the capacity of electric charge accumulation at the fibre surface for the integration of electronic components. In addition, the use of paper as main printing substrate has led to the development of specific knowledge in printing technology and long-term experience in large area roll-to-roll (R2R) printing processes. Besides, the miniaturized flexible electronic components (battery, sensors, display, etc) developed during the last few years open new opportunities. The combination of the advanced properties of paper/fibres and the transfer of knowledge developed in paper printing together with the actuation properties of electronic components could enable the development of new integrated multi-functional products.
The objective of the APPLE project is to develop the next generation of sustainable paper-based products with specific autonomous functionalities aiming at interacting with their users and/or reporting changes in their environment. A major focus is placed on the development of new and flexible manufacturing concepts based on printing technology to produce large area hybrid organic/inorganic papers with improved performance at competitive cost.
To this aim, the APPLE project is focused on 1) the integration of recent advances in functional materials (paper, fibres, inks) and functional components (battery, sensors, display, memory) and their production process upscale and 2) the development of innovative, flexible and cost-effective manufacturing processes based on printing and embedding techniques for the integration of all these functional components on the smart paper substrate. Figure 1 illustrates the concept of the APPLE project.
A very special highlight of this project is the fact that the new APPLE products will make extensive use of the specific properties of both fibre based products and (nano)fibres individually. Indeed, the paper is not only used as substrate providing the required mechanical, surface and barrier properties for the printing and integration of the functional components, but the fibres including the incorporation of nanofibres are also used as active elements with integrated high levels of intelligence, namely the display and the memory.
The project is expected to open new opportunities for the paper and printing industries (132 000 printers in Europe, among which 85% are SMEs) in the growing market of low-cost and high value added printed electronics. We will then be able to produce a plethora of low cost and disposable applications, of great impact for SMEs, such as smart labels and packaging to control product quality (e.g. food and medicine industry) and air quality (car cockpits, in house and industry environments, etc.) answering societal needs. This will generate a wide range of spin-off products.
The project is built on a set of main technical objectives towards the development of the APPLE product manufacturing concept and the fabrication of APPLE demonstrators for defined markets.
The 4 main technical objectives are described below.
Develop new functional materials at industrial relevant scale (paper, fibers and inks)
• To develop an advanced paper/board with functional barrier properties and very low surface roughness achieved using bio-sourced materials (extrusion coating of biopolymers) “green” chemistry (innovative grafting process) and with fibre charge accumulation properties, as required for the integration of all the electronic components.
• To optimize advanced materials, including organic polymers for conductive inks, functionalised carbon nanotubes and inorganic nanomaterials oxide based for battery, display and sensor components.
Develop printable functional components at industrial relevant scale
• To adapt and optimize a printed thin-film battery (power, capacity and voltage) for the different sensors (sensitivity) and the displays (size and contrast).
• To print gas sensors (CO, domestic pollution and H2S, oil refineries pollution) and temperature control sensor.
• To adapt and print display and memory transistor components able to satisfy the application requirements regarding voltage bias and power consumption, display contrast ratio, information retaining and switching times.
Optimise design integration and develop a new manufacturing process
• To design the integration of the different components on paper substrate for the different targeted labels or poster sizes
• To develop cost-effective manufacturing processes essentially based on printing (ink jet, R2R, reduced assembling steps, combining lamination) and with a new quality-controlled, flexible concept.
• To assess the sustainability of APPLE products (LCA, recyclability, end-life and industrial safety) and to evaluate their potential for further development.
Demonstrate the manufacturing process: To manufacture on industrial printing and converting lines 3 smart multifunctional demonstrators through technical and cost assessment:
• Autonomous paper labels for environment and safety – novel dynamic concepts for pollutant control management and person safety (to identify pollutants emission in interior buildings or emergency situations and alert personnel).
• Multifunctional paper posters for environment and advertising – innovative self-powered and long autonomy gas sensor solutions for environment with integrated displays and memory for delivery of information. The expected gains on the ratio performance cost will be over 100% of today’s technology.
• Multifunctional paper labels for smart packaging – innovative track and trace systems, displays for information delivery with integrated temperature sensors for consumer satisfaction and safety.
The scope of the project requires a multidisciplinary approach, involving research and industry with different backgrounds, going from materials science and engineering, to chemistry, physics, electronics and micro/nano-technologies. The consortium is then composed of:
• RTD providers for development of functional materials (paper, fibres by CTP and UNL) and components (sensors by CEA and TNO, display; memory by UNL), design and integration (CEA, UNL, VTT, CTP), printing processes (CTP and VTT);
• Industry/SME technology providers for development of functional inks (Poly), advanced base paper (FS) and components (printed battery by Varta), the integration of the components (BA, Poly and Varta), the development of the APPLE manufacturing process (printing technology and equipment by LT) and finally the on-line product control (ICS);
• SME end-users (RGP and LT as end-producers)
Project Results:
1.3.1. - WP1. APPLE Value chain (RGP)
Task 1.1: Specifications (RGP)
End-user functions and constrains were defined for the three demonstrators. Then the global technical specifications were specified according to foreground results and discussions between partners.
Task 1.2: Environmental sustainability and safety (CTP)
LCA (life cycle analysis) methodology for printed electronic consists of a comparison between a “paper demonstrator” and a “conventional demonstrator” that present the same electrical function. Conclusion on the functional unit defined as “Produce a surface of conductive lines which will support the same electronic functions” shows that all environmental impact factors are 1000 times lower for a paper demonstrator.
Several scenarii for product end of lives were assessed. Evaluation of recyclability, incineration and compostability leads to the conclusion that the three demonstrators, as they are currently produced, are compatible with those 3 types of end-life. These studies also underlined the necessity to explain to the consumer what a Printed Electronics product is and how to handle the end of life of such a product.
Main assessment of printed electronic is the impact of silver ink on safety, recycling and the environment. The impact was studied in detail for each aspect; the selected silver ink is recyclable and does not disturb biodegradability and phytotoxicity of paper.
Task 1.3: Potential market development (RGP)
For each demonstrator an evaluation of the potential direct market and other possible markets was performed. The price affordable by the consumers was also estimated. This was realized via an inquiry: several persons operating in different fields such as fire-brigade or city hall were invited to deliver their opinions towards the interest of the A3Ple’s demonstrators.
The interest of the demonstrators goes far beyond the specific functionalization targeted in the 3 demonstrators. The industrial development performed can serve a very important field of applications and different new markets.
Demo1: All the interviewed persons were interested by the product. However the following conditions were outlined:
• The final system should detect several gas if possible.
• It must be easy to use.
• It must be secure.
• The price must be reasonable.
In conclusion this product can open several markets that lead to big quantities.
Demo2: This demonstrator doesn’t seem to have a big interest for the people questioned. They are not enthusiastic as they find it complicated to set in place and not really needed or expected. Some electronic panels already exist in big cities; there is no need for new systems. Anyway these new Demo2s must be tested and approved by the end-users before being implemented at larger scale.
Demo3: The food industry is not interested in this system at the moment. Its organization is efficient in regards to the “cool chain”. The system of a label could engage the responsibility of the food industry that is reluctant because it is impossible to control the attitude of the final consumer.
Some other activities, such as following of human implant or medicine, could find an interest in the functionalities aimed in Demo3. In that case the cost of the label is not a key problem and the final user is ready to pay if the safety of the product is guaranteed.
Conclusion: The 3 demonstrators have a potential to find a market. They have to be adapted to the real need of the consumer or the industries concerned. A specific label or poster needs to be developed according to the final require from the final end-user or industry targeted.
1.3.2. - WP2. Functional materials (Poly)
This WP deals with the development of functional materials needed to manufacture the functional components and final products: 1) Functional and barrier extrusion coated paper, 2) Functional fibres for paper memory and 3) Functional inks.
Task 2.1: Functional barrier extrusion coated paper (CTP)
Three commercial papers derived from commercial available paper grades, already developed by Felix Schoeller for printed electronics purposes (Figure 3), were selected as reference papers (Ref FS1, FS2 and FS3 in the project).
Figure 3: Description of the three reference paper grades
A new paper, referenced as FS4, was developed from paper FS2. Its design is the same as FS2, but based on a thinner and lower weight raw paper. In accordance with the needs of all partners and printing tests performed in WP4 and WP6, finally FS3 paper was chosen for Demo1 and 2.
When needed, the barrier layer is made of polyethylene. However, polyethylene is known to have major drawbacks when married with paper. It can possibly create issues in waste paper recycling streams and it is non-biodegradable. This task intends to minimise the environmental impact of the barrier paper by associating either bioplastics or biodegradable plastics with a paper substrate.
5 polymers were selected to substitute the PE and they were tested at laboratory scale. Production of samples was completed and comparative biodegradability tests were performed on the CTP’s pilot platform. Coated samples show a good biodegradability, close to cellulose. As expected, the polyethylene coating is not biodegradable. However, the cost of all biodegradable substitute candidates for polyethylene are significantly (factor of 5 or more) higher than that for polyethylene, and the substitution generates some processing issues lowering coating process efficiency and yield. Furthermore, all biodegradable substitute candidates naturally show lower barrier properties for water and water vapour.
Task 2.2: Functional fibres for paper memory paper (CTP)
UNL was responsible for the development of conventional transistors and memory transistors starting from different paper samples developed by CTP. The difference between the devices is the fact that in a conventional transistor it is expected that the hysteresis effect is small (or even negligible) while in the memory transistors a large hysteresis cycle must exist on the transfer characteristics (variation of the source-drain current, VDS, as a function of the gate voltage, VGS).
Many papers and micro fibril cellulose (MFC) self-standing films were produced by CTP, characterized and selected as memory transistor or regular transistor. Initial results showed that pure MFCs and MFCs coated papers are the most promising ones regarding their application as dielectric, suggesting that MFCs are highly relevant in achieving high capacitance, extremely useful for transistor application. It was also observed that the treatment of the MFCs in acid or alkaline medium results in different electrical behaviour of the transistor. The acid treatment is more suitable for memory transistor (counter clockwise hysteresis) while alkaline treatment seems more suitable for regular transistor (low hysteresis), as seen in Figure 4.
a) behaviour suitable for memory b) behaviour suitable for regular transistor
Figure 4: Transfer characteristics of transistors produced in the classical configuration using MFCs paper a) microfibrils treated in acidic medium, and b) microfibrils treated in alkaline medium
Task 2.3: Functional inks (Poly)
Sub-Task 2.3.1: Primer layer ink
The purpose of the primer layer ink is to treat a substrate in order to modify surface properties as smoothness, surface tension, barrier effect and electrical insulation. This is useful in a multi-layer component if a substrate requirement for a functional ink is different from another. A UV-curing ink was selected to have a quick drying. Two inks were developed, for inkjet and for flexography.
Sub-task 2.3.2: Advanced functional ink
An aqueous transparent conductive ink, based on carbon nanotubes and a conductive polymer (Pedot-Pss), was developed for inkjet printers. Different kinds on CNTs and grades of Pedot-Pss were evaluated, and the best combination allowed obtaining a high transparency of 90 %, a low sheet resistance of 75 Ω/sq on PET and FS1, with a high flexibility and a low cost.
Electrical and optical performance of the printed ink was similar to ITO, an oxide used in the electrochromic display concept (task 3.3). Samples on PET were tested by UNL to be used instead of ITO. Electrical and optical performance was interesting but, in this configuration, the Pedot-Pss has the same electrochromic behaviour and colour changes as WO3.
An adaptation of the conductive ink was performed to fulfil the requirement of the flexographic process. Due to a too low viscosity at the rotation speed of the flexography, there are a low ink deposition and a high resistance of the printed film (few kΩ/sq on FS1). The ink cannot be used in the project and was replaced by commercial flexographic silver ink.
1.3.3. - WP3. Functional components (CEA)
Task 3.1 – Thin film batteries (CEA)
The Thin Film Battery (TFB) selected to supply the A3PLE demonstrators is based on the lithium-ion technology, because of its higher energy density and its ability to be implemented in flat and flexible configuration. Taking into account several key criteria such as state-of-charge operating range, safety and cost, the 3.2V Graphite/LiFePO4 couple was selected among the possible Li-ion systems. Indeed, this technology remains hugely competitive in terms of performances compared to the commercial primary TFB even if its rechargeable properties are not used.
As the final design of the A3PLE battery is strongly linked to the manufacturing process flow, two specifications were considered: the Thin Film Battery will be reported (i.e. hybridizised) onto the paper substrate in a continuous way and it will be manufactured in a R2R process. As a consequence, it was decided to develop the manufacturing process with the objective to produce a rolled band of operational batteries. The process is based on the combination of techniques in continuous mode with screen printing, co-lamination and thermosealing. It consists of co-laminating two rolls (Figure 5):
• the first one carries patterned negative electrodes printed onto structured Cu current collector and covered by printed membrane;
• the second one carries corresponding patterned positive electrodes printed onto Al current collector
where the base material of the rolls will constitute finally the soft packaging of the battery.
Figure 5: Roll to roll process for battery manufacturing
The process in line based on the combination of the use of smart packaging, printed components with specific design and screen printing techniques for thick layers (~100µm) was assessed. The manufacturing of the battery core was demonstrated at labscale. Several solutions for hermetically closing the smart packaging were tested. Finally, the obtained battery exhibits the expected recovered capacities with stable behavior fully compatible with conventional Cgr/LFP based batteries.
Figure 6: overview of battery at different steps and electrical characterization
Task 3.2 – Printable gas and temperature sensors (TNO)
Task 3.2.1 – CO and NO2 sensors (CEA)
The gas sensors provided in the A3Ple project are based on single walled carbon nanotube CNT network as the sensitive material working at room temperature and low power consumption. Electrical detection is studied for two gas targets along the project: CO and NO2 gases.
Water based inks were developed for spray coating of the CNT network (Figure 7). Gas characterization was performed in a gas probe station allowing good control of the gas concentration.
Figure 7: Process flow of the gas sensor elaboration
Pristine CNTs were then platinum-coated to produce CO sensors on paper. Poor resistance variations were obtained with the fabricated devices. Compared to the sensor’s sensitivity to relative humidity (average resistance variation of the CNT network is around 15-20% from the initial value for relative humidity between 40 to 70%), CNTs hybrids show poor CO sensitivity (less than 1% of resistance variation under 100ppm CO). These observations clearly push the consortium to modify the gas target to the NO2 gas which is a strong environmental pollutant and toxic for the respiratory system. In this case, raw CNT networks exhibited more than 50% of resistance variation under NO2 exposure (50ppm).
The objective of the project was to integrate the NO2 sensor into a smart poster for air quality monitoring (Demo2). For that, 3 levels of NO2 detection were required (< 5 ppm - 5 to 50 ppm - > 50 ppm of NO2)
Figure 8: NO2 sensing and it integration into poster
Clear increase in resistance variation under various gas concentrations was observed. More than 25% of resistance variation was measured between 5 and 50 ppm gas exposure (Figure 8). This significant resistance variation promoted development of 3 distinct levels of sensing (< 5 ppm - 5 to 50 ppm - > 50 ppm). The resistance variations were correlated to the gas concentrations allowing the detection of the level of exposure in the range previously defined in the project. The resistance variations were compatible with the electronic on paper provided in A3ple project.
In the framework of the A3Ple project, NO2 gas sensors based on printing of carbon nanotube networks on paper were developed. Strong resistance variation under gas exposure has allowed clear measurement of three levels of detection.
Task 3.2.2 – H2S sensor (TNO)
The H2S sensor is based on copper(II)acetate (CuAc2) in water. There are no environmental issues with respect to application as the system is waterborne. An interdigitated finger structure is the basis of the sensor. Then, the CuAc2 solution is inkjet printed on this structure, (Figure 9a). This H2S sensor on a specific commercial paper is humidity independent up to about 80% of humidity.
The sensor gives a good response by exposure to H2S gas. The resistivity drops from non conductive to 10 kΩ at 2 ppm of H2S gas (Figure 9c). The formation of the conductive path of CuS between the Ag fingers takes approximately 15 minutes. The colour of the greenish CuAc2 layer changes to a brownish colour (Figure 9b).
(a) c)
(b)
Figure 9: (a) Ink jet printed CuAc2 on commercial paper with flexo gravure printed silver. (b) color change of cuAc2 after H2S exposure; c) Response of H2S sensor based on ink jet printed CuAc2 implemented
The sensor was integrated in a security label, Demo1 (Figure 10). The fingers were printed on an industrial machine (at LT) and the active solution was inkjet printed at TNO.
Figure 10: Printed H2S sensor integrated in Demo1.
Task 3.2.3 – Temperature sensor (TNO)
Ceramic thermistor material based on inorganic spinel structures were made at TNO with a multistep synthesis and firing. Two kind of particles were tested: CuFe2O4 and a newly developed material built up from Mn/Zn/Cu Oxide doped with Ni and Co (general formula is Mn1,71Ni0,45Co0,15Cu0,45Zn0,24O4 - manganese spinel oxide). The resulting material shows thermistor behavior with a lot of advantages; low overall resistance and high temperature stability are the most important.
The sensitive ink was stencil printed on an interdigitated finger structure printed on FS3. The active layer shows a thickness of 38μm. In Figure 11 the resistance vs temperature of the manganese spinel thermistor was compared to the CuFe2O4 thermistor.
The conductivity vs temperature response of the manganese spinel markedly exceeds the CuFe2O4 thermistor performance (ie: the resistance of the manganese spinel thermistor was much lower than the CuFe2O4). Consequently less material can be deposited to get the same efficiency. In an optimal form the temperature response corresponds to a variation rate (α) of -4%K-1 at 25ºC and to a resistance at 25ºC of only 175kΩ.
Figure 11: Comparison of copper-iron oxide and the new manganese spinel oxide
Thermistor material sent to LT and CTP were flexography printed at lab and industrial scales. As the ink layer is not thick enough using this technique, the sensor on the final Demo1 and Demo2 was stencil printed by TNO (Figure 12).
Figure 12: Demo1 and Demo2, with printed temperature sensor in blue circle
Task 3.3 – Electrochromic (EC) displays (UNL)
A notable achievement in the EC display development was the realization of a fully printed (at lab-scale) all-solid-state device based on cheap, safe and stable chemical materials while simultaneously providing proper performance under operation. The EC displays prototypes developed for the A3Ple project demonstrate that there are no major obstacles in development of this component and its application in demonstrators.
The architecture and process flow of the printed EC cells in the final demonstrators is presented in Figure 13. Some typical operational characteristics were determined at lab-conditions. As an example, the peak consumption power for coloring/bleaching ranges 100/400 W/cm2, respectively, and switching time is 3s for a maximum operation voltage of 4 V.
Figure 13: Schematic diagram of the process of fully printed EC display.
The first prototypes of Demo1 with a fully printed EC display on paper were demonstrated at M34. These already included a new approach for integration of the EC display with the transistor on the same PET foil. The EC display and the transistor integrated in Demo1 is shown in Figure 14a.
a) b)
Figure 14: Layout and EC display on a) Demo1 and b) Demo2.
The display layout for Demo2 was developed together by UNL, CTP and BA (Figure 14b). Each segment of the display is powered by silver electrodes reaching the circle from outside, while the contact to the PET/ITO foils is done from inside using a common electrode (aiming equal power repartition). Like the EC display for Demo1, silver, carbon and electrolyte films are deposited on top of the paper substrate, while WO3 based ink is printed on ITO PET substrate. The effective EC display diameter after encapsulation is 100 mm.
There are no major obstacles in material development for the EC displays. However, there is room for improvement concerning the mechanical integrity of the devices, namely concerning the detachment of the PET foil from the electrolyte, which compromises the functionality of both EC display and EG-FETs. This is critical in the case of Demo2 EC display due to its dimensions.
Task 3.4 – Fiber-based floating gate memory (UNL)
The work performed demonstrated that paper substrates produced from micro-nano fibril cellulose (MFC) have a strong influence on the performance of an oxide based memory transistor. The effect of the fiber’s type, structure and dimension was studied regarding the use of paper as the dielectric in such devices. However we must highlight that these devices were aimed only for Demo3. This means they were not integrated in a demonstrator since Demo3 was not realized.
A first set of 26 long fiber papers and 10 MFC self-standing films were produced by CTP during the first 18 months. Memory transistors were produced by UNL on both sides of the paper with a staggered-bottom gate structure as can be seen in Figure 15a. On one side a 40 nm thick GIZO (Ga2O3-In2O3-ZnO; 1:2:2 mol) film was deposited by RF magnetron sputtering to create the channel region. Then, Al source/drain (S/D) electrodes (200 nm thick) were deposited by e-beam evaporation. Finally, a 200 nm thick IZO (In2O3-ZnO; 89.3:10.7 wt.%) film was deposited on the other side of the paper substrate to be used as gate (G) electrode. The most remarkable observation was that CTP23 paper, with extra ionic charge added to the pulp, is the one that presents the longest retention time (time while source and drain current (IDS) ratio between on and off states is above 10) of around 107 seconds (~4 months).
a) b)
Figure 15 – a) Schematic representation of the memory transistors and b) charge retention time extrapolation for memory transistor on samples CTP 23.
Memory transistors were also made on the MFC membranes (samples CTP61 to 70) formed on top of FS3 paper with silver electrodes, that were used as gate in memory transistors (Figure 16). This approach is particularly interesting when moving towards printable devices, meaning that it is possible to have a functional cellulose layer in the transistors, with tailored properties different from those of the substrate/backplane.
The memory transistors produced with these membranes have lower retention time than those produced on paper samples, being, in the best scenario, around 46 days. Nevertheless this clearly shows that cellulose based dielectric layers can be formed on foreign substrates by printing-compatible methods, representing a big step towards printable memories integrating cellulosic materials as active component.
a) b)
Figure 16: a) Photo of a printed MFC membrane (with transistors) on top of silver layer deposited on FS3 paper and b) charge retention time for different MFC membranes.
1.3.4. - WP4. Peripheral components. (LT)
Task 4.1 – Design and development of printed integrated devices
Active component -Transistors
UNL developed the transistors for the A3Ple demonstrators. The final strategy was based on electrolyte gated devices (EGFETs). This was the strategy followed for the transistors to be integrated in the demonstrators. GIZO was deposited on PET/ITO substrates by sputtering in order to be used as oxide semiconductor. The ITO was patterned in order to create S/D regions. The EGFETs were then hybridized on the Demos’ backplane (containing the printed silver conductive lines and electrolyte, Figure 17). The connection between the electrodes of the PET foil and the printed silver conductive lines on the backplane was done by filling vias with silver paste. An adhesive layer was used in order to assure the encapsulation of the electrolyte and a better adhesion to the backplane.
a) b) c)
Figure 17: a) Scheme of EGFET and hybridization strategy, b) Layout with W/L ratio of 45 with adhesive layer location (green rectangle) and c) EGFET hybridized on Demo1.
With the new approach (PET hybridized system), an improvement of the current modulation was observed; a ION/IOFF ratio (maximum/minimum current) up to 1.35x104 was obtained on devices with a channel width/length (W/L) = 45. It is relevant that these devices still showed an adequate operation mode three weeks after production, with a ION/IOFF ratio still above 1000, regardless of the W/L used.
Passive component - Resistors
VTT tested different inks and designs to combine resistance design and target values (Figure 18-b). Lab and pilot tests on PET and FS papers validated the way to make resistor components. In the project’s final stage, VTT fine-tuned the quest for resistors by examining at lab-scale the variations, deviations and reliability of resistors with a final conclusion that resistors can be produced in a large range with high reliability.
CTP has development tests and method to manage and predict resistor target values: the distance between the silver square defines the length of the resistor (L) and the width (W) of the resistive square sets the resistance of the resistor. The dimensions of the resistor (W, L) are predicted by a simulation program. This program uses lab and industrial resistance values measured on samples printed at CTP and LT as input data to build this component layout (Figure 18a).
a) b) c)
Figure 18: a) CTP’s design for the study of the influence of the printed area on the resistance; b) Resistor made with screen printing on PET, VTT; c)”line” and “snake” resistors, two design proposed for low and high (respectively) target values.
Industrial transfer to LT was performed since April 2012. The ink and printing parameters were chosen to reach specifications of both demonstrators (target resistor value= 100ohm to 20 Mohm). Thanks to BA’s suggestion, “snake” resistors have been developed for high resistor targets in order to optimize components dimension (Figure 18c).
Passive component – Capacitors
Though capacitors were not needed as part of the electrical design, VTT worked on this component and succeed to create a workable capacitor configuration printed at lab-scale.
Task 4.2 – Interconnection techniques on paper (VTT)
VTT printed interconnection structures based on a single sided arrangement. Bridges were made by flexo printing or a combination of flexo and rotary screen printing. All printing tests were conducted on FS3 paper. Both lab scale sheet based printing and pilot level R2R printing were used. In R2R pilot level printing, 100% yield of bridge structures was achieved by printing
1) bottom silver tracks either by flexo or rotary screen (commercial micro particle silver inks)
2) insulator ink by rotary screen with double layer of UV curable commercial dielectric
3) top silver tracks by rotary screen or optionally by dual layer of flexo (Figure 19)
Figure 19: a) Dual layer flexo printed silver conductor going over the edge of screen printed insulator and b) Single layer flexo printed conductor on FS3 paper and edge of screen printed insulator.
The fully flexo printed bridge structure was achieved at lab scale with table top printing machines. This achievement would be very practical since the industry predominantly works with the flexo-printing method. Working insulator layers were obtained with a yield of 100 %. These results applied for bridges with areas between 1 mm² and 400 mm². Working bridges were obtained when at least 2 layers of insulator were printed to remove any pinholes and inhomogeneity of the insulator layer. This also applied to the case of rotary screen printed insulator layers where the yield was significantly reduced when only one insulator layer was used. The results are presented in Figure 20.
Figure 20. Printed bridges (left) and their performance as a function of layer thickness/amount of layers and printing method.
It is possible to manufacture fully-printed bridges. An excellent working yield is achieved when the layer thickness is adequate and the amount of printed layers is at least two. Both rotary screen printing and flexography were able to reproduce working bridges. In flexography, the printing parameters needed more careful optimization than in rotary screen printing.
Task 4.3 – Hybridization on paper (LT)
Optimization of hybridization parameter
All systems based on electronics use a power source to supply electrons in the circuitry. Printed electronics are no exemption to this so in the project the use of a Thin Film Battery (TFB), single or multiple, is required. The relevant parameters for the hybridization of the TFB were defined.
Functional TFBs in roll format were not available in sufficient volume to deliver a realistic test setup and make a practical assessment for TFBs hybridization onto the printed electronics labels. However, dummy batteries with physical characteristics close to the TFBs under development allowed to define the relevant parameters of hybridization:
1) Position and orientation of the electrodes (battery poles connectors) on the demo label.
2) Electrical connection and physical fixation of the battery
These parameters drive the technology and the process to properly and solidly connect the TFB on paper. The final step is to check and control the functional connection and the battery functionality.
a) b) c)
Figure 21: a) and b) materials for the production of the dummy battery roll; c) roll of dummy batteries
Development of on-line hybridization machine
For the development of the hybridization system, rolls of dummy batteries were used. A first system concept was proposed at M30 and further developed with the final R2R design of Demo1 and Demo2.
At the end, the testing was performed with commercial batteries manually placed on the test roll according to Figure 22.
Figure 22: schematic of material flow for hybridisation
1.3.5. - WP5. Integration (BA)
The integration of components into a full functional circuit requires to define:
1. the electrical design (task 5.1) which depends on electrical behavior of printed components,
2. the printing design of layout (task 5.2) which defines the mapping of the ink layers for i) each component and simultaneously ii) for the Demo in a global manner.
The complexity of the integration required a step by step method where the electrical and physical designs evolve by iteration (task 5.3). The table 1 sums up designs and layouts that were printed in the frame of the A3Ple project.
Table 3: Summery of electrical design and physical layout (name: specification) for each demonstrator.
ELECTRICAL design PHYSICAL design of layout
Demo 1 Demo1-A: Resistor values compatible
with LED as display & light sensor chip Demo1-V1: Resistors and lines
Demo1-V2: […] and electrodes of components
Demo1-B: Resistor values compatible with printed EC-Display & H2S gas sensor Demo1-V3 & - V4: […] and physical constrain link to final product and graphic label
Demo 2 Demo2-A: 3 levels switch on/off progressively, compatible with LEDs as display & sensor chip, Demo2-V1: Resistors and lines
Demo2-V2: […] and electrodes of components
Demo2-B: Resistor values and design compatible with EC display behaviour Demo2-V3: Resistors and lines and electrodes of components and physical constrains link to final product and graphic label
Demo 3 Demo3-A: Design using memory effect of EC-display. Demo3-V1: Resistors and lines and electrodes of components
Task 5.1 – Electrical design and simulation of circuits (BA)
Demo1. The goal of Demo1 is to make an “on/off” device that gives information about the presence of a dangerous gas. The label is used only one time and replaced after the gas detection. This “one-shut” label permits to BA to design the simplest electronic circuit: one sensor, one battery, one transistor, one display, conductive lines and a few resistors (Figure 23a). Demo1 designs do not require any interconnection (bridge).
The parameters of this circuit were estimated by a simulation tool developed in the frame of the project. The input data were electrical characterization of chips (since printed components were not ready) and then, the characteristic measured on the printed components (inputs from WP3 and WP4). BA also realized a specific Excel spreadsheet to simulate the behaviour of the Demo1 for different conditions of gas concentration.
(a) (b)
Figure 23: (a) Final electrical design of Demo1; (b) «H» cell configuration inside Demo2 electrical design
Demo2. The objective of Demo2 is to distinguish 3 levels of gas content and informs witch one is reached. Therefore the circuit was more complex compared to Demo1:
• Number of components increased: 14 resistors and 8 transistors.
• Gas sensor and displays had to show a reversible behaviour.
• Double conductive layer with interconnections was required. In a conventional circuit, the two layers are realized on the two opposite faces of the substrate and connected using drilled vias. In the project, the connection on paper substrate was made with the bridge method (task 4.2).
The first electrical design was produced with a LED as display (Demo2-A): the LED light switched off when the applied voltage drops to zero. However, a printed EC-display behaves differently and the electrical configuration did not permit to switch off the display. To solve this issue, BA introduced an “H configuration” that applied -3V to the display in the “off” state (Demo2-B, Figure 23-b). This solution required the same number of transistors as for Demo2-A, which is important in order not to increase circuit complexity.
Demo3. The Demo3 circuit should measure temperature (T) at the moment and keep its past maximum value in memory. The associated electrical circuits require a memory transistor, measurement initialisation, many displays, p- and n-type transistors, etc… In order to solve the complexity of such circuit, BA proposed to use the memory effect of the EC-display to “store” information linked to the maximum of the past temperature. The Demo3 electrical design could be seen as the combination of Demo2-A (for maximum past T) and Demo2-B (for present T).
Task 5.2 – Physical design of layout for component implantation (BA)
Each electrical design (only made of line connections and chips position) was validated by BA with a conventional (PCB) circuit. This conventional layout was used as the starting point (step 0) for the physical layout of the printed circuit. The physical layouts are progressively modified according to the following steps:
0- Conventional layout with only draws of conductive and insulating layers.
1- Circuit layout adapted to printed circuit dimensions.
2- Each chip area replaced by a surface corresponding to the future printed component.
3- Each chip connector replaced by the electrode layout of the associated printed component.
4- Physical layout associated to the other functional inks.
At each step, the conductive lines are arranged regarding physical constraints (components dimensions, electrode orientation, etc…).
Demo1. Development of the circuit layout on Demo1 (and the other demos) was made incollaboration between CTP (printing constraints) and BA (electronic constraints). The “physical design rules” were defined together for printed electronic on paper. These rules were very different to conventional electronic ones.
For each physical design reported in Table 3, BA & CTP proposed several layouts. The selected solution was decided by all the partners according to the other constraints (for example, display position inside the label was important for final physical aspect of the product). The validated layout was printed on industrial equipment. For Demo1, only the conductive silver ink and the resistive ink were printed at LT. At the end, the final physical design (Demo1-V4, Figure 24-a) took into account physical and graphic constraints of a real product.
a) b) c)
Figure 24: a) Demo 1- V4 printed on FS paper, b) Demo 2-V3 layout of industrial printed steps, c) Demo3 layout; Color code: grey or red = conductive ink, black = resistive ink and green = insulator ink.
Demo2. The development of the Demo2 physical design was based on knowledge acquired on Demo1. However, introduction of new components induced new design rules and other developments:
• Locations of interconnections/bridges was not easy to define because they shouldn’t cover components that will be printed later on.
• The pixels of the EC display required a specific lines layout to split correctly the current flow.
The final design (Figure 24-b) took into account physical and graphic constraints of the real A0 poster.
Demo3. The physical dimension of Demo3 (Figure 24-c) was equivalent to an A4 format. It was four times larger than the one planned (A6 standard paper sheet) but it was not possible to make it smaller.
Task 5.3 – Components integration, lab testing and control
The complexity of the components integration required an iterative method. The printed components were introduced one after the other. The “ready to use” components were printed at industrial or laboratory level; then the other components were replaced by hybridized chips. The objective of this “hybrid circuit” was to identify problems linked to the “just introduced” component. When solved, the integration of this component was validated and the next component integration could start.
Demo1. Components integration started with resistor and conductive lines. Industrial printing of these two layers was validated at the early stage of the project. Reproducibility and value deviation during the trial were evaluated in detail by BA and ICS. The hybrid circuit had the expected electrical behaviour. They were presented in 2013 at LOPE-C in the OE-A booth for a competition.
The H2S and the temperature sensors, and then the battery were introduced with success in the circuit (Figure 25a). Integration of EC- display showed electrical issues that lead to changes in the electrical design (resistor values in particular). The final fully printed Demo1 was composed by 2 steps made at industrial level (on LT machines) and 3 steps at laboratory level at TNO, UNL and CEA (Figure 25c).
a) b) c)
Figure 25: a) hybrid Demo1-V3.0 with printed T sensor and thin film battery; b) hybrid Demo1-V3.1 with printed T sensor and commercial EC-display; c) Demo1-V4 fully printed
Demo2. The same strategy was performed for the Demo2, thanks to the knowledge acquired in the Demo1 development. The final Demo2 was produced in 4 steps (lines, resistors and bridges) printed at LT at industrial level (Figure 1a) and 2 steps at laboratory level at TNO and CEA for the T sensor and the battery respectively. Chips were used as transistors because only one printed transistor failure prevents the full circuit to work.
Control. The image acquisition component of the inspection solution was reviewed in order to optimise the overall performance of the system for printed electronics applications. In order to achieve high contrast at all the print or production steps to be inspected, laboratory feasibility studies were performed on samples provided by partners. Depending on the material inspected, visible or ultra-violet light sources were deployed in combination with monochrome or colour line scan cameras.
Image acquisition parameters such as resolution and angular setting were optimised. Furthermore, contact image sensors (CIS) were evaluated as a valid way to perform inspection tasks in compact print machines that do not permit further components with large mounting volume. This work let to the definition and implementation of an inspection system based on line-scan cameras placed in the framework of a dynamic study at LT (image on the right side). The system, placed on a machine used to rewind the finished print, permitted due to its flexible design to record the afore on-line printed silver and carbon print steps in different conditions and allowed to reproduce lab findings in an industrial setting. The diffuse reflection image acquisition condition was the most suitable and the 50µm resolution was suitable considering current process variations and feature sizes.
1.3.6. - WP6. Flexible manufacturing process (LT)
Task 6.1 – Manufacturing process flow (LT)
The results of the lab-tests performed within WP3 and 4 were transferred into several series of test runs performed by LT and CTP on LT’s machines. In 12 print sessions (trials LT01 – LT12), various aspects of the printing process were examined with the following goals:
1. Observation of conductive and various resistive inks’ behaviour in relation to the machines,
2. Observation of specific paper behaviour in relation to the machines and electronic inks,
3. Optimisation of printing parameters for selected inks,
4. Optimisation of the printed patterns (lines, fingers, electrodes, resistive, etc.) in their consistency during production using the visual inspection system developed by ICS,
5. Production of dummy materials to use for the WP4 related task to hybridize TFB,
6. Printing Demo1, 2 and 3 in several versions and checking the electrical behaviour against the target values defined by BA
7. Generating a procedure for the layout of print plates in order to define the functional layout of the Demo and checking elements to control print quality during or after production.
Manufacturing process flow for Demo1
The process flow realised for Demo1 manufacturing is shown in the following schematic.
Figure 26: Process flow realised for Demo1 manufacturing
Each (numbered) step represents a production phase in the process flow. The images explain what is done by which partner and how the printing step is processed. Another picture shows the physical component.
Example: the 1st step is devoted to the printing of conductive lines and resistors. It is performed by LT on an industrial printing machine. Silver ink for conductive lines are grey while; resistive ink corresponds to the black colour layer. The 3rd step is devoted to the printing of the sensor. This step is produced at lab scale (hand image) at TNO directly on the label. Etcetera, until step 7 for the reporting of the graphic label.
The picture of the printed layout at the end of the process is shown in the centre of the diagram. Each component respects the colour code.
Converting (steps 2 and 7) and hybridization (steps 4, 5 and 6) steps could be made at industrial scale in the future, because they are linked to existing technologies. In the frame of the project, the hybridization at industrial scale was developed only for the batteries. This result may be adapted for transistor and display hybridization in the future.
The sensor printing (step 3), the battery roll preparation and the printing steps of the display film could be performed in LT’s plant in the future. However, they couldn’t be done at this moment due to technical or financial reasons.
Manufacturing process flow for Demo2
The process flow realised for Demo2 manufacturing is mainly based on knowledge developed for Demo1. However, the increase of the electrical circuit complexity requires interconnections (crossed conductive line without electrical connection). These “bridges” (step 2) are printed at industrial scale just after the printing of the conductive tracks and the resistors. The schematics of Demo2 follow the same logic as for Demo-1 above.
The following schematic details steps and components pictures for this Demo2.
Figure 27: Process flow realised for Demo2 (and Demo3) manufacturing
Manufacturing process flow for Demo3
For Demo 3 the structure is very similar to Demo2 apart from the function of the memory and electrochromic display. The main differences are the final size of the functional label, the dimensions of the display and the increased number of components. The manufacturing process flow of Demo3 is the same as that of Demo2.
Task 6.2 – On-line quality control (ICS)
Developed algorithms and software modules were implemented into the ICS software infrastructure to generate an inspection application dedicated to the quality control of printed electronic circuitry. The below shown software infrastructure comprises of real-time inspection software and off-line inspection tools to control the quality of products and trace it over multiple production steps (Figure 28). In the context of the A3Ple project, this capability could be deployed to add multiple inspection stations at strategic production steps, i.e. not every print step needed to be inspected separately, but only those that mattered. For example, a combined inspection of the first silver and carbon print steps needs to be foreseen in order to control their quality before potentially opaque active materials are printed onto the sensor finger structure. This would impede short detection or circuit break detection.
Figure 28: Inspection software and off-line inspection tools
The latest software version was successfully evaluated on the first silver and resistive inks printing steps of the different demonstrators as those were printed in longer print runs (task 6.1). Focussing on the finger structure of the sensor element, inspection settings permitted good and stable defect detection on the sensor element with a very high detection ratio for short defects in the sensor elements (Figure 29) and few false detection.
Figure 29: Screen capture of the inspection software.
1.3.7. - WP7. APPLE demonstrators (LT)
All the work performed in WPs 1-6 drove the state of art of printed electronics on paper at the end of the project. The goal was to demonstrate the production testing and evaluation of Demos1, 2 and 3 under industrial circumstances. The work demonstrated the principle of what the common printer can manufacture with his equipment and how this was made. It showed the results both from the point of production, eg the way to make the demos, and the economics behind it. Thus giving a good overview and set of information about the possibilities a common printer can expect if he considers the production of printed electronics on paper. The 3 Demos initially planned in the project were as below.
1. Environment & safety
labels (A5-A6) 2. Environment & advertising posters (A3-A1) 3. Smart packaging
labels (A6-A7)
Difficulty of demonstrators
Low technological risk
(small-size display) Medium technological risk
(large-size display) Medium-high technological risk
(small-size display and memory)
Chosen approach for the realization of WP7 – A3Ple Demonstrators
The demonstration per Demo was arranged as if the Demo was a real production order taken by LabelTech at IJsselstein to go to an End-User. The Demos were taken up in the production stream of the factory and treated as a normal job as part of the factory’s planning and work flow.
The materials and equipment used for the 3 demos’ manufacturing are summarized in Table 4. The industrial printing machines are presented in Figure 30 and Figure 31.
Table 4: Materials and equipment used for the 3 demos’ manufacturing
Demo1 Demo2 Demo3
Materials Substrate: FS3 + one specific commercial paper as reference X X X
Ink-1: A commercial silver ink X X X
Ink-2: A resistive ink X X X
Ink-3: An isolator ink X X
Ink-4: A commercial silver ink X X
Adhesive (on a transfer roll) X
TFB: Dummies and functional Thin Film Battery X
Equipments Flexoprint: MA-2200 6-color Flexopress (Figure 30a)
X X X
Rotary Screen (Figure 30b)
X X
Inspection: ICS-developed visual inspection by camera and software X X X
Finishing: table-top slitter / spooler X X X
Conversion: adhesion application and cutting to end format X
Hybridization: LT-1 (dedicated conversion equipment) X
End control: table-top slitter / spooler equipped with dedicated hybridization checker X X X
Work plan for all Demos as common practice and reporting
Per demonstrator the following stages of production were performed:
1) Technical evaluation “How-to Make” and feasibility of production leading to a “Go/No-Go”
2) Registration of the job in the work flow / data system
3) Description of needed materials and tooling / Bill of Materials
4) Designation to specific production slot; machine number(s)
5) Preparation of the work; clearance to start
6) Production – 1st phase: building the Demo
7) Production – 2nd phase: running the job for the Demo
9) Production – 3rd phase: finishing the job for the Demo
10) Results – physical product for the Demo
11) Registration and evaluation of the job
12) Conclusion
a) b)
Figure 30: Industrial flexo printing machines used for the demos manufacturing: a) overview of the machine; b) Anilox roll for flexo printing
a) b)
Figure 31: a) Industrial screen printing machine, b) Inspection system developed by ICS installed on screen printing machine.
Task 7.1 – Production and testing of Demo1
Demo1 is an environment and safety label. The goal of Demo1 is to make an “on/off” device that gives information about the presence of a dangerous gas. The label can detect lethal H2S gas in a room. However, for live demonstration in a show room a temperature sensor is used instead of the H2S gas sensor.
a) b) c)
Figure 32: a) Transfer of resistive ink by flexo printing; b) Roll of Demo1 converted into adhesive labels; c) Final demonstrator fully printed: functional electronic label below the graphic label.
Task 7.2 – Production and testing of Demo2
Demo2 is an advertising poster. The objective of Demo2 is to distinguish 3 levels of gas content and informs which one is reached. It is a paper poster (A0 format) able to distinguish 3 gas levels and show the value reached instantaneously.
a) b) c)
Figure 33: a) Printing unit of ink n°1; b) Demo2 rolls produced during trial at LT; c) Final demonstrator fully printed: functional electronic label below the graphic poster.
During the international conference LOPEC (March 2015), final demonstrators were awarded by OE-A as the best demonstrator realized in the frame of a collaborative public funded project (Figure 1-b).
Task 7.3 – Production and testing of Demo3
Demo3 is a smart packaging label. Demo3 should measure temperature (T) at the moment and keep its past maximum value in memory. The physical dimension of Demo3 was equivalent to an A4 format. It was four times larger than the one planned (A6 standard paper sheet) but it was not possible to make it smaller.
Potential Impact:
Benefit for paper industry. FS
During the recent years the declining real prices of paper products have been one of the main reasons for the paper industry’s poor profitability. The results of the project may cause a renewal of the paper industry’s products with more added-value functional products for new applications and markets. Unfortunately, although the demonstration was realized in the frame of the APPLE project, the demand from the market (end-users) must still emerge in order to make this new market opportunity become real sales volume for the paper industry.
Benefit for printing industry. LT
The new sustainable high-added value products demonstrated in the APPLE project, i.e. labels with integrated gas and temperature sensors, display functions, as well as the new and flexible manufacturing process, have been developed in a state where the used technologies are already used at industrial scale.
For the passive components (resistors, bridges), the printing technologies recommended are flexography and screen printings commonly used in the printing industry. The same technologies can be used for temperature and gas sensors.
Battery, and active components as display and transistors have to be hybridized. This hybridization step is also something commonly used in a printing shop. Furthermore, the manufacturing flow defined involves a roll to roll process.
The integration of components was performed on a manufacturing printing/converting small-scale production line. Such production lines are common for SMEs everywhere. The printing industry in the EU comprises some 121,000 firms and employs some 714,000 people. The turnover in the printing industry is about 88 billion EUR. The industry throughout Europe consists mainly of very small enterprises, as 90% of the graphic companies employ less than 20 persons.
The manufacturing process developed in the frame of APPLE project is based on already existing printing lines. That means that the opportunities linked to the development of the new labels, posters, advertising don’t require completely new production lines. The existing printing lines can be adapted, thanks to additional printing units (mainly flexible ink-jet units) and battery hybridisation in order to create new added-value products for the printing industry.
The different foregrounds of the project offer further development potential of new multi-functional fibre-based products that can open new markets for the SME dominated sector of the printing industry:
• Further applications in a growing market sector of integrated self-powered printable display and memory devices based on breakthrough technology using paper as passive and electronic material,
• Further industrial developments of the low-cost and flexible manufacturing concepts investigated in this project, with focus on printing technology.
Through the development on new manufacturing processes opening new markets, the APPLE project is expected to increase the European printing industry turnover by 10% by 2020 and by 25% by 2025, leading to the creation of highly-skilled jobs.
The market of flexible electronics is predicted to dramatically grow over the next years as shown in Figure 20 a). The growth over the longer timescale, from 2007-2027, will be very similar to the early growth of the silicon chip market in the same interval; the twenty years from 1978 to 1998 saw a similar starting and finishing value of sales of silicon chips. The Figure 20 b) confirms the high potential market for printable electronics materials.
Figure 20: a) Estimated market of the main flexible electronics segments and market forecast to 2027
b) Revenue projection for printable electronics market
Unfortunately, even though the forecast for printed electronics showed a huge increase from 2008 until 2018, the printing industry has not been able to benefit yet of such an increase.
The explanation for this low benefit could be in the fact that applications and printed electronic products fulfilling needs from the market are still hard to realize in a one-on-one “Demand/Supply” relationship on end user level. The level of innovation in this industry is low and introduction of new products depends in principle on the demand by the end users or the possibility to show products to end users. The presence of printing industries in the EU and its direct contact with many end users should allow quick adoption of new products. This is not the case. The printing industry is a reactive business where demand is driving the reaction and propositions of the industry. The products can only be introduced into the market when they can be printed and shown. Due to lack of functional inks to turn into building blocks for electronic functions produced in print by ordinary, mainstream printers it is hard to move end users into adoption. But it proves the fact that end users need to see working products to motivate their adoption of the possibilities offered by the printers. It is a matter of availability of know-how on electronics combined with availability of functional inks.
LabelTech (LT) will get direct gain from the project. These results find their base in the capability developed in the project to handle materials and functional inks on standard printing equipment. The main benefit for LT in particular is directly linked to the confirmation triggered by the work in this project to be able to handle under standard industry conditions functional inks with other characteristics to print colour or contrast in patterns done in the industry for centuries. LT can now create in printed patterns with characteristics to facilitate every combination of conductive and resistive electronics. New markets showed up and new requests are “in the cocking pot”.
An example comes from recent contacts by LT with its end users. Coming from these contacts LT was able to show conductive tracks printed for the project and this lead directly to a new request to realize a new product based on simple printed electronics functions, proving the direct potential.
Another field of application directly coming as results to LT is the capability to create RFID antennae structures in various alternative ways based on techniques of material and ink handling realized during the project. Overall LT has moved forward by innovation.
Benefit for BA (electrical circuit designer)
The designing of electronic circuits printed on paper and functional inks is a novel and a very innovative matter, for this reason there aren’t mature software CAD tools to use in this field. The main innovation of this exploitation is the opportunity to use a well-tested commercial CAD software (developed to design standard PCB circuits based on discrete components and rigid substrates) to design very complex electronic circuits printed on paper. This goal has been reached thanks to the development of a Designing Tool Kit that can be used to realize a library of electronic components to be printed on paper. Thanks to the electronics printed on paper it is possible to realize electronic devices in high volume and very low cost, without having to use a chemical etching process and with a low impact on the environment. The company will be able to provide these new services in its portfolio, to increase its turnover and its number of customers.
The following table shows an internal analysis based on new business activities (made in collaborations with other companies) and a new European project that our company has been involved in since May 2015.
Year 2016 2017 2018 2019 2020 2021 2022
MM
New Hiring
New hiring C
Turnover 6
0
0
0% 6
1
1
5% 0
1
2
7% 0
2
4
10% 0
2
6
17% 0
0
6
20% 0
0
6
20%
MM: internal MM allocated to R&D for printed electronic development
New hiring: number of new hiring related to printed electronic business
New hiring cumulative related to printed electronic business
Turnover: Increase in turnover due to the activities related to the printed electronics
TURNOVER: increase due only to the activities related to the printed electronics
NEW HIRINGS PER YEAR: Number of new hirings related to the printed electronics business; NEW HIRINGS CUMULATIVE: Number of new hirings related to the printed electronics business
NOTE: The internal R&D activities is specified only for the first years, in particular 2016 and 2017. This means that in the future years the Research and Developed activities will be carried out by the newly hired, for this reasons the internal MMS allocated for the future years is 0 and the future R&D activities are included in the turnover.
Benefit for Poly (ink supplier)
The added value of the APPLE project is to have a concentration of needs from substrates suppliers (papers), printing industry, electrical design and components (inks and active materials). For an ink supplier, the project offers a better knowledge of the requirements of each step of the smart label fabrication, in order to improve performance and specifications of the developed inks.
The constraint of the choice of the printing process is hard to solve from the point of view of an ink supplier. Due to the active materials requirements in printed components, many functional inks are hard to develop for flexography printing. Some inks require a high concentration of active materials to print an efficient component and the best printing process is screen printing. At the opposite, some active materials cannot be dispersed in a high concentration and resulting inks have a very low viscosity, more suitable for inkjet printing than flexography. The last point is the difficulty of drying printed inks. Many of them require a long time of drying which is not compatible with the high speed of flexography. An added value of the project is that ink suppliers can develop different grades of their inks. A first product grade that fits well with the active material requirement can be developed, followed by other grades to be developed to fit better with the printing process needed by the project, such as flexography or screen printing.
Finally, each ink supplier has developed different grades of their functional inks which can be used by most of the printing processes on the market. Flexography appears to be the best choice to print fast a high quantity of labels but, actually, this process is little used in printed electronics.
Concerning the market of flexible electronics, one of the major parts for ink suppliers will be transparent conductive films, with the substitution of ITO in many devices like displays, OLED or photovoltaics. This market is estimated to be 4 billion $ in 2023 and more than 30 companies are actually involved, including many SME’s, developing different technologies (copper and silver nanowires, organic polymers, metal grids, nanotubes…).
Benefit for Varta (battery supplier)
The printed batteries developed in the A3Ple project can also be used in other products. In a workshop these markets were analysed. Typical markets for Printed Batteries are:
• Healthcare: Cosmetics & Healthcare, Wellness, Healthcare, active wound healing fabric, flexible body sensor, specific (single use) disposable Healthcare/Fitness/Medical devices
• Logistics:Logistics, akt. RFID, active Battery-assisted RFID, active RFID, cold chain, Logistics customized products, Supply and Cold chain, Logistics
• Smart Packaging: Smart Packaging, Smart Cards with electric functions, illuminated packages, intelligent Packackaging, Smart tags & textile, Wireless Communication
• Sensors: Sensors, Disposable Monitoring System, Wireless sensor systems, health monitoring, Disposable Long Life Ambient Sensors, Wireless sensor systems, building control, TFB Wall Paper – 5x2 m² → 200 Ah?
• Gaming: Gaming Products, Active Games, Spare Battery in the back of writing block (A4 → 1 Ah), Integration in Card Board & Paper, mobile product (foldable phone, …)
a) b)
c)
Figure 34: a) Evaluation of the new markets in different categories ; b) Relation between Price and Complexity ; c) Relation between Price and Volume
These markets were evaluated in different categories.
• Pick&Place / Printegrate: For Smart Packaging (including greeting cards and gimmics) printegration is prefered, all others (especially sensors) prefer secondary cells.
• Primary / Secondary: Primary cells are preferred for Smart Packaging, gaming and sensors require secondary cells
• Complexity: The cells are allowed to be complex, except of Smart packaging. Here a simple solution is preferred
• Green: The green aspect is important for Smart Packaging and Gaming (perhaps because of the disposeability), for the other categories the green aspect is medium important
For a high-class manufacturer it is important to offer high complex devices for a high price. For VARTA it is important to enter markets like Healthcare and Sensors. These markets offer a high margin for low quantities. These markets seem to be present.
Benefit for ICS (quality control supplier)
The participation in the A3Ple project allowed ICS as a system integrator for optical inspection and traceability solution to improve multiple aspects of the existing LineaVision® inspection solution. Resulting is a LineaVision® printed electronics software application using algorithms and software features dedicated to the inspection of printed electronics on paper or other substrates.
Furthermore there have been improvements performed concerning the image acquisition components of the vision system. Novel monochrome and colour line-scan imaging sensors have been implemented, contact imaging sensors were tested and the range of ICS light source wavelengths was increased to the ultra-violet regime. These new means in the image acquisition part allowed us to optimise the optical image acquisition for print steps that are transparent in the visible light or of faint optical appearance, giving better detection results in multi-step processes and integration of vision systems under tight mechanical conditions.
The developed software components and most of the integrated hardware components are part of the industrial inspection solutions and are deployed in several installations for printed electronics and other applications. However, considering the market forecasts for the printed electronics sector, the printed electronics inspection application will show its real value when more PE production capacities are installed in the following years.
Benefit for RGP (packaging industry)
The marketing inquiry confirms that the food industry is well organised in regards to the cold chain and therefore there is no need for a new system for controlling the cold chain.
Nevertheless the results of A3Ple project could be interesting in order to use a label to apply on the pallets in order to be sure that that the cold chain is maintained in the different storage areas not systematically controlled.
The possibility to use a label on each packaging is only realistic if the price is low compared to the final cost of the product.
The 3 demonstrators have a potential to find a market. They have to be adapted to the real need of the consumer or the industries concerned. A specific label or poster needs to be developed according to the final request of the final end user or industry targeted. The A3Ple project opens several ways of development and probably huge markets in different directions.
Benefit for RTO (CTP, CEA, VTT, TNO, UNL)
In the APPLE project much know-how has been developed.
CTP. The technologies for producing memory fibre-based paper, for manufacturing and hybridizing batteries, for printing transistors and resistors, displays and gas sensors will be developed and scaled up for EU SME's printing companies. With the development of these new technologies, new wide markets will be addressed.
CEA. All the knowhow acquired during the A3PLE project on the battery components and manufacturing, will be used in a large R&D program performed by CEA for a major international chemical group. The objective of this new project is to develop flexible batteries for new wearable applications.
The technologies for manufacturing and batteries will be developed and scaled up for EU SME's printing companies. With the development of these new technologies, new wide markets will be addressed.
VTT. Considering VTT’s development work in the A3Ple project, passive components (resistor, capacitor, conductor), and bridge interconnections are enabling components for almost all printed electronics systems. The development done in the A3Ple project enables plenty of further development and other electronics products and printed electronics systems on paper substrates since the work done in the project lead to a useful library of passive components to be utilized in different circuits.
TNO. TNO has learned extensively about the development of sensors and printing of these sensors. A lot of R&D efforts about such sensors are requested by both industrial and governmental entities. The development done in the A3Ple project enables TNO to give answers to these requests. Also plenty of further development on sensors together with the partners in A3PLE is possible. Last, the paper electronics roadmap was given a large boost with the A3PLE project and allows further development in the application of paper in security and communication products.
UNL. The work developed during A3Ple project was crucial in allowing UNL to implement and develop new strategies for printing oxide based electronic and electrochemical devices on paper. Before A3Ple, UNL was internationally recognized by transistors and memories on paper, but produced exclusively by PVD techniques. Printing techniques, and just inkjet, were being used only for the production of electrochromic (EC) displays. The constant focus of A3Ple in the up-scaling of all developments led UNL to develop EC displays using other large scale techniques, such as flexo or screen printing. The same happened for the oxide based transistors and memories: it was demonstrated they can now be printed, with a clear identification of barriers and challenges towards fully printed devices. Finally, all the collaborative work performed with all partners also contributed to strength the UNL knowhow on the topic of “paper electronics”. All this was crucial in creation of new background (or even future IP) with strong impact in the participation in other collaborative research projects.
List of Websites:
http://www.a3ple.eu/
Coordinator: Véronique Morin (veronique.morin@webCTP.com)
