Enzymatic biofuel cells (EBFCs) that oxidize biological fuels using enzyme-modified electrodes are considered a
promising candidate for implantable power sources. However, there are still challenges to overcome before biofuel cells
become competitive in any practical applications. Currently, the short lifespan of the catalytic enzymes and poor power
density are the most critical issues in developing EBFCs. In this paper, we will review the recent development of biofuel
cells and highlight the progress in Carbon-microelectromechanical system (C-MEMS) based micro biofuel cells by both
computational modeling and experimental work. Also, our effort on utilizing a covalent immobilization technique for the
attachment of enzymes onto the substrate which is expected to increase the enzyme loading efficiency and the power
density of devices is discussed in this paper.