Prototype of the device.Paper electronics goes forward steadily. In the future, many of the biomedical diagnostic kits –the ones based on reactive paper- will be printed on paper. These devices will need a compatible energy source. Scientists at the CSIC's Instituto de Microelectrónica de Barcelona (IMB-CNM) have developed and patented a microfluidic fuel cell on paper.
The results of their work have been published in the magazine Environment and Energy, in an article that has counted with the collaboration of the Instituto de Catálisis y Petroquímica (ICP-CSIC).
Neus Sabaté, scientists at the Instituto de Microelectrónica de Barcelona (IMB-CNM) explains: “In the future, the biomedical test strips that nowadays offer only a positive or negative outcome, will be more precise. For instance, in the case of colorimetric tests, the outcome measure will correspond with a different intensity of colour, and for that an optical reader and an energy source is necessary.”
As a general rule, in these cases a button battery is used. But the issue of printed electronics is to replace the button battery for integrated sources of energy, which can be printed together with the other components and have a minimal environmental impact.
The fuel cell developed by the scientists fits all these requirements. Printed on paper, it uses the capacity of paper to flow fluents by capillarity, so there is no need of external pumping. It has an electrolite and stored fuel (methanol) on the paper strip. When water is added, the fuel cell starts to produce energy, which is enough for the test.
The team at the IMB-CNM: from left to right, Neus Sabaté, Javier del Campo and Juan Pablo Esquivel. As a matter of fact, the current biomedical tests with button battery only use 1 per cent of the energy stored. After use, these batteries have to be disposed of and recycled. From this point of view, the fuel cell means energy savings, as well as less environmental impact and fewer economical costs.
Until now, the essays have been done with methanol, but the team is working to improve the device in order to get energy from molecules which are present in biological fluids, such as glucose in blood or urea in urine.
Applicattions are not limited to the biomedical sector. There are other fields where single-use strip tests are used, such as the environmental, veterinary, agro-food and security sectors.
This research team is working to integrate fuel cells into organic printed electronics. Therefore, all the components (sensors, source of energy, electronics) could be simultaneously produced through a print process which is similar to reprography. This processing technology, known as ‘roll-to-roll’, allows the deposition of different layers of materials which will form the different electronics components on flexible supports.
J. P. Esquivel, F. J. Del Campo, J. L. Gómez de la Fuente S. Rojas y N. Sabaté. Microfluidic fuel cells on paper: meeting the power needs of next generation lateral flow devices. Energy and Environmental Science. DOI: 10.1039/ C3EE44044C
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