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Capacitive Identification Tokens

Periodic Reporting for period 2 - CAPID (Capacitive Identification Tokens)

Reporting period: 2018-07-01 to 2019-12-31

Imec, TNO, Rebased, simply-X and Cartamundi have developed a flexible capacitive identification tag that communicates with standard touch screens. C-token tags can be integrated in a wide range of paper and plastic based objects such as tickets, certified documents, payment cards, realizing smart products. The connection to the internet was established simply by placing the tagged object on a touchscreen device or vice-versa.

During the project CAPID objectives were as follows:

• Develop component technology ready for use in applications
• Implement scalable manufacturing processes for component assembly and integration in applications
• Demonstrate CAPID technology in three product prototypes

At first, the project has focused on defining the application requirements for the new technology, as well as on the engineering feasibility of these requirements. Presenting CAPID technology to the business world was done by 3 demo applications.

A number of fundamental technological challenges were studied to demonstrate the overall feasibility of the capacitive communication concept in thin-film transistor technology. Experimental lab studies were combined with basic system level modeling to assess the power consumption of CAPID tokens featuring various functionalities required by the applications. Power consumption was optimized using a selection of engineering strategies. A 30x reduction in the power consumption compared to the state-of-the-art of oxide thin-film transistor chips was demonstrated. This power consumption was benchmarked against the limits of power harvesting from a touchscreen device.

A decision was taken about what power harvesting mechanism will be used in project demonstrators. Lab scale tests were completed, guidelines were developed about transferring the CAPID chip development into a pilot-line manufacturing environment of the consortium partners. Using a pilot-line setting allows for a larger scale demonstration and test by the application partners of the consortium.

Thin-film chips were prepared and converted into a formfactor for integration in mass market integration facilities.

Hardware does not run without software and this was an important work package within the consortium. Without any real product available emulator, devices were created to allow the parallel software development and investigation of touchscreen behavior for various devices available in the market.
As from the start of the project, exploitation and commercialization were not forgotten. Several business cases were assessed to bring CAPID R&D to CAPID business as fast as possible.

The project aimed for a disruptive change, bringing a basic, NFC-like communication capability to every device that has a touchscreen. And this was without the need for a special reader. This was an opportunity to increase the number of IoT participating devices dramatically.

These tags offer security thanks to the very short communication range; general compatibility thanks to the presence of capacitive touchscreens everywhere; and the potential to be produced at low cost thanks to the monolithically integrated antenna.

Compared to existing RFID technologies such as NFC, the new tag does not require an external antenna. The tiny antenna is part of the chip itself, making the tag much smaller compared to current NFC tags. The small size enables integration into everyday objects. Thus, C-tokens or CAPID tags are an alternative in all those use cases where interaction via touchscreens is feasible, but RFID/NFC tags are either too large or too expensive or where contactless reading is a disadvantage.

The tag is powered by a thin-film battery, capacitive energy harvester or a thin-film photovoltaic cell that converts light from the touchscreen. The 12-bit thin-film capacitive identification tag achieves up to 36bps data transfer rates at 0.6V supply voltage, which is compatible with commercially available touchscreen devices without requiring modifications. The flexible thin-film integrated circuit has a 0.8cm2 on-chip monolithic antenna and dissipates only 38nW of power at 600mV supply voltage.

Right from the start of this RIA project, three exploitation and commercialization cases were investigated; ticketing, payment and board game industries.
This is the first time capacitive communication tags are attempted using a thin-film transistor technology. Preliminary estimates concluded the need for a significant reduction of the power of integrated circuits made of such thin-film transistors, about 100x lower compared to the state-of-the-art. Technology and design work on low-power building blocks in the first year of the project has already yielded a 30x reduction. Co-optimization of power harvesting and power consumption will continue in the second part of the project, setting a target of battery-free demonstrators in the end of the third year.
The project aims for a seamless integration of electronics into paper cards. From a look and feel point of view the products with and without chips should be nearly identical. The achieved thickness, stiffness and components are a quality beyond the state-of-the-art. Big focus will lay on scaling the lab parameters for CAPID integration up to industrial standards. A low additional cost is an important requirement. The chosen manufacturing method will fit current paper converting lines allowing the fastest supply chain possible.
The 3 applications represent a broad spectrum of technical requirements. The board game demonstrator will focus on identification, location and angular tracking with a very low cost taken into account. The ticketing demo will put an emphasis on a vast number of different tags and fast data throughputs whereas a payment concept will require high security standards and bi-directional communication.
The tags will allow traditional product to be blended with immersive content such as video, sound, security and other multi-media. CAPID can be a game changer for paper products with embedded electronics.