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 (R) 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/cm(2) at room temperature (23 degrees C), with a fuel supply of 5 mu L, 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. (C) 2005 Elsevier B.V. All rights reserved.