(5bz) Electrical Wiring of Enzymes and Living Cells for Bioelectrochemical Applications

Bio-based electrochemical devices such as biofuel cells, biosensors, MEMS actuation devices, bioelectronic chips, and micro-power systems integrate biotechnology, material science and electrochemistry. While amperometric biosensor is an established technology now, a closely similar biological fuel cell is still a budding area of research. Biofuel cells are a subset of fuel cells that employ biocatalysts. Biofuel cells offer a viable way for direct electricity production from organic compounds, biomass and biomass waste. Microbial biofuel cells employ living cells to catalyze the oxidation of the fuel, whereas enzymatic biofuel cells use enzymes and redox proteins for this purpose. The current advantage of microbial biofuel cells is that they typically have long lifetimes (up to five years) and are capable of completely oxidizing simple sugars to carbon dioxide. They are limited, however by low power densities. By contrast, enzymatic biofuel cells typically possess orders of magnitude higher power densities, but can only partially oxidize the fuel and have limited lifetimes owing to the fragile nature of the enzyme. Major advancement is needed in increasing enzyme lifetime, enhancing enzyme-electrode electron transfer, improving the kinetics of the bio-electrochemical reactions before this technology can be successfully commercialized. Promising near term applications of biological fuel cells include power sources for remote stand-alone equipments, portable electronic devices, implantable medical devices and biomass waste treatment.