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Single-Use paPER-based fuel CELLs

Periodic Reporting for period 4 - SUPERCELL (Single-Use paPER-based fuel CELLs)

Reporting period: 2020-01-01 to 2021-06-30

SUPERCELL proposed to develop single use fuel cells as a key component of smart and single use point-of-care devices. These microfuel cells are inspired in the lateral flow devices in terms of design, manufacturing processes and materials and take advantage of paper capillarity to keep a continuous flow of reactants. At the same time, they are conceived to follow the same life-cycle than the test strips to be powered so they can be disposed of with minimal environmental impact. These fuel cells generate energy directly from the fluid to be tested in the point-of-care device by oxidizing the molecules present in the samples. This makes possible to deliver power on-board that can be used to enable both measuring and result communicating functions. Along the project, it has been shown that it is possible to develop stand-alone paper-based power sources that operate by generating and consuming hydrogen in-situ or to extract sufficient power from blood to enable HIV detection. Besides, as the amount of power generated by the fuel cell depends on the concentration of the molecules to be oxidized, the project has also explored the viability of developing self-powered point-of-care sensors, in which the fuel cell acts both as a sensor and a power source. In particular, a glucometer that performs glucose quantification with the energy generated by a drop of serum has been successfully demonstrated. The concept has been implemented with a novel and radical minimization of electronic components that paves the way towards a new generation of devices with minimalistic electronic waste generation. The solution has the potential of being applicable to a wide variety of amperometric sensors, which will lead towards PoC digitalization at low cost as well as environmental impact. Finally, the self-powered concept has also been extended to fluid-activated paper-based batteries. The batteries have been turned into very simple ionic sensors, with promising application in wearable applications. As a demonstration, the battery has been integrated into a single use patch able to measure sweat conductivity on artificial samples. SUPERCELL has demonstrated that it is possible to break the paradigm “sensor – electronics – power source” typically used to develop a PoC device and develop a new generation of sustainable, intelligent, cost-effective and REASSURED (i.e. real-time connecte, environmentally friendly, affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free and delivered to those who need it) devices.
SUPERCELL project has successfully achieved the major technical challenges that needed to be tackled to accomplish the vision of “self-powered sensors”. During the initial phase of the project, we developed a battery-like fuel cell able to produce as much power density as a button cell. This prototype is a stand-alone power source that integrates a paper-based hydrogen fuel cell with a customized chemical heater that produces hydrogen in-situ upon the addition of a liquid. The device operates by capillary action and takes advantage of the hydrogen released as a by-product of an exothermic reaction used in point-of-care diagnostics. The paper-based fuel cell is suitable for powering a diversity of electrical devices such as commercially available digital pregnancy tests. Later on, the project opened an unforeseen avenue by presenting a new method for conductivity measurement of biological samples with the use of a liquid-activated paper battery as a sensor. This kind of battery starts to function upon the addition of a fluid, which acts as the battery electrolyte. This means that the battery can be used as a conductivity sensor, whose generated power depends on the conductivity of the sample used to activate it. Taking in advantage the change this new approach, a paper battery as the core of the self-powered device has been optimized to perform a conductivity measurement of sweat samples in order to perform easy screening of Cystic Fibrosis disease in children. Moreover, the project has developed a glucometer that quantifies the amount of glucose contained in a drop of serum using the energy of glucose molecules to perform quantification. The project explored different chemistries that operating as cathode, boosted the open circuit of the fuel cell up to 0.8V and provided us with a wider dynamic range and the possibility of operating discrete commercial electronic components. Then, we tackled glucose quantification with an innovative strategy allowed for a radical simplification of the electronic circuit required for glucose quantification, which could be implemented with a very low number of discrete components (i.e. transistors, resistors and diodes). With this strategy, we developed a single-use card demonstrator able to perform screening of gestational diabetes. Results achieved during the execution of the grant have been disseminated in International Scientific Conferences, Industrials Forums and Spanish Media. The results of the project also provided leverage to the credibility of the PI, who has been also involved in promoting her figure as Woman in Tech. The project has generated 4 different patent applications with that aim to protect the different technological approaches developed in SUPERCELL. One of them has already been awarded in Europe and has generated a spin-off company whereas another one has been submitted to National Phases and has raised interested of some companies of the diagnostic sector.
The self-powered and minimalistic approaches developed in this project suppose a radical change in the field of diagnostic devices in terms of simplification. Developed world regions like Europe are starting to consider the environmental impact of healthcare technologies and goods as a global concerning issue. Several initiatives are currently active such as the European Healthcare Climate Council and the Healthcare Without Harm organisation. Whereas plans to modify unhealthy practices — such as poor waste management, the use of toxic chemicals and reliance on polluting technologies — are underway in rich areas, healthcare facilities in Low-Medium Income Countries still rely heavily on low-cost medical waste incinerators that emit significant levels of toxic chemicals and pollute the soil. Therefore, the deployment of millions of devices for point-of-care testing systems and the batteries needed for their operation can be an important source of pollution if recycling routes are not well-stablished and therefore, more sustainable alternatives need to be developed. In SUPERCELL, we have made a big step towards the new way of concieving such devices. Both in publications and conferences where the project results have been disseminated, we send a new message to the electronics community: electronic devices make use of too complex modules that are on-the-shelf components, most of the time overdimensioned for some applications. In SUPERCELL we present a radical simplification by merging power source and sensor into a single element and show that devices can be conceive to operate with a minimal number of components and make use of less material and therefore generate a minimal amount of waste.
Picture of self-powered conductivity patch for cystic fibrosis screening
Picture of Battery-like fuel cell (prototype 1)