A Microfabricated PDMS Microbial Fuel Cell

This paper presents a microfabricated polydimethylsiloxane (PDMS) microbial fuel cell (MFC) with embedded micropillar electrodes. This MFC is characterized by a flexible and biocompatible structure suitable for body implantation as a potential power source for implanted bioMEMS devices. The MFC is biocatalyzed by a microorganism, Saccharomyces cerevisiae, which converts chemical energy stored in glucose in the blood stream to electrical energy. The MFC is a laminate design, consisting of 0.2-mu m-thick gold-evaporated PDMS anode and cathode separated by a Nafion 117 proton exchange membrane. These electrode surfaces feature more than 70000 8-mu m-high micropillar structures in a 1.2-cm x 1.0-cm geometric area. The MFC is encapsulated by PDMS and has an overall size of 1.7 cm x 1.7 cm x 0.2 cm and a net weight of less than 0.5 g. Compared with recent silicon micromachined MFCs working in a phosphate buffer medium, the presented MFC with its micropillar structure showed a 4.9 times increase in average current density and a 40.5 times increase in average power density when operated at identical conditions. Using 15-mu L droplet of human plasma, containing 4.2-mM blood glucose, the PDMS MFC demonstrated a maximum open circuit potential (OCP) of 488.1 mV, maximum current density of 30.2 mu A/cm(2), and a maximum power density of 401.2 nW/cm(2). When the MFC operated continuously for 60 min, it showed an average OCP of 297.4 mV, average current density at 4.3 mu A/cm(2), and average power density of 42.4 nW/cm(2) at 1-k Omega load. The coulombic efficiency of electron conversion from blood glucose was 14.7%.