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Microfluidics Shrinks Fuel Cells

A Franco-Japanese consortium has just revealed that it is possible to make fuel cells the size of a microchip. The prototype fuel cell weighs less than 100 milligrams and has been developed by Steve Arscott's team at IEMN1 in Villeneuve d'Ascq, working in collaboration with the electronics company Sharp. With a power of 50 milliwatts per cubic centimeter, it is the smallest and most efficient fuel cell in the world. Its size would make it ideal for future portable electronics.



A silicon chip (5 mm x 3.6 mm) with microchannels through which methanol circulates in the micro fuel cell.

So far two patents have already been registered in Japan in partnership with CNRS for this technological marvel. Like all fuel cells of this type, a current is produced from an electrochemical reaction: the oxidation of a fuel. Specifically, in this case the reaction takes place between methanol and air. The device is based on a thin plastic membrane sandwiched between two silicon wafers etched with microchannels. Methanol from a reservoir outside the fuel cell circulates through these fine grooves, together with the air needed for the reaction. “The microchannels, which are no deeper than the diameter of a single hair, were etched using semi-conductor technology,” Arscott comments, “and they are the key to the fuel cell's performance.” The microchannels make it possible to precisely control the flow of methanol so as to obtain an optimal chemical reaction, leading to an efficiency of 75% at room temperature.
This new battery obviously has a promising future in the portable electronics sector. By stacking several cells, several hundreds of milliwatts of power and an infinite lifespan are envisaged (as long as it's refueled with methanol). The micro fuel cell could be used to power low-consumption devices, such as MEMS (Micro-Electro-Mechanical Systems)-type microsensors, currently developed all over the world. These could in particular be used as warning systems in the event of fire or chemical pollution. And in five to ten years' time, Arscott and his colleagues hope to combine several of these tiny fuel cells into one that could power more familiar electronic devices, such as mobile phones.2

Xavier Müller

Notes :

1. Institut d'électronique, de microélectronique et de nanotechnologie (CNRS / Université Lille-I / Université de Valenciennes / Isen Recherche).
2. A. Kamitani et al., “Improved fuel use efficiency in microchannel based DMFC using a hydrophilic macroporous layer.” J. Power Sources, 2009. 187: 148-55.

Contacts :

Steve Arscott,
IEMN, Villeneuve d'Ascq.


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