Porous silicon based orientation independent, self-priming micro direct ethanol fuel cell

The design, fabrication and testing of an orientation independent, self-priming micro direct ethanol fuel cell (DEFC) is presented. The electrodes of the fuel cell are fabricated using macro-porous silicon technology. The capillary force generated by the pores has the ability of “wicking” the fuel towards the electrode irrespective of the orientation of the cell, resulting in a uniform and regulated supply of the fuel (ethanol/water mixture). The porous silicon structure also serves as a built-in fuel storage reservoir. The porous silicon substrate is platinized to create the electrodes and integrated with Nafion® 115 membrane to build the micro fuel cell stack. The cell performance tests indicate an open circuit voltage (OCV) of 260 mV and a maximum power density of 8.1 mW/cm2 at room temperature (23 °C), with a fuel supply of 5 μL, 8.5 M ethanol solution. Unlike most micro-electro-mechanical systems (MEMS) DEFCs, changes in orientation of this cell have minimal effect on the output voltage/power thus eliminating the need for an active fuel pump.