Miniaturized enzymatic biofuel cells (EBFCs) that convert biological energy into electrical energy by using enzymemodified electrodes are considered as one of the promising candidates to power the implantable medical devices and portable electronics. However, their low power density and insufficient cell lifetime are two big obstacles to need to be tackled before EBFCs become viable for practical application. In this study, the theoretical simulation of this EBFC system is conducted using finite element analysis from COMSOL 4.3a in terms of cell performance, efficiency and optimum cell configurations. We optimized the electrodes design in steady state based on a three dimensional EBFC chip and studied the effect of orientation of the microelectrode arrays in blood artery. In the experimental part, we demonstrated an EBFC system that used 3D micropillar arrays integrated with graphene/enzyme composites. The fabrication process of this system combined top-down carbon microelectromechanical system (CMEMS) technology to fabricate the 3D micropillar arrays platform and bottom-up electrophoretic deposition (EPD) to deposit graphene/enzyme composite onto the 3D micropillar arrays. The amperometric response of the graphene based bioelectrodes exhibited excellent electrochemical performance and the 3D graphene/enzyme based EBFC generated a maximum power density of 136.3 μWcm-2 at 0.59 V, which is about 7 times of the maximum power density of the bare 3D carbon based EBFC.
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