Micromachined microbial and photosynthetic fuel cells

This paper presents two types of fuel cells: a miniature microbial fuel cell (μMFC) and a miniature photosynthetic electrochemical cell (μPEC). A bulk micromachining process is used to fabricate the fuel cells, and the prototype has an active proton exchange membrane area of 1 cm2. Two different micro-organisms are used as biocatalysts in the anode: (1) Saccharomyces cerevisiae (baker’s yeast) is used to catalyze glucose and (2) Phylum Cyanophyta (blue-green algae) is used to produce electrons by a photosynthetic reaction under light. In the dark, the μPEC continues to generate power using the glucose produced under light. In the cathode, potassium ferricyanide is used to accept electrons and electric power is produced by the overall redox reactions. The bio-electrical responses of μMFCs and μPECs are characterized with the open-circuit potential measured at an average value of 300–500 mV. Under a 10 ohm load, the power density is measured as 2.3 nW cm−2 and 0.04 nW cm−2 for μMFCs and μPECs, respectively. (Some figures in this article are in colour only in the electronic version)