Abstract : The objective of the project was the design of glucose electrooxidizing anodes and oxygen electroreducing cathodes for a miniature compartment-less and case-less biofuel cell powering sensor-transmitter and receiver-actuator systems implanted in animas. It resulted in the smallest (smaller by a factor of 180 than previously reported) and highest power density (higher by a factor of 5) biofuel cell ever built. The results were obtained in a pH 5 solution in absence of chloride at 37 deg C and formed the basis for their subsequent extension to physiological conditions after the project ended on Dec 1, 2001. The anodes were based on the electrical 'wiring' of glucose oxidase with redox polymers of low (reducing) redox potentials that connected their redox centers to carbon electrodes. The cathodes were based on the electrical 'wiring' of copper enzymes (laccases and bilirubin oxidases) with high (oxidizing) redox potential redox polymers to carbon cathodes. The anodic current densities near 0.1 V (Ag/AgCl) were of ^ 1 mA/sq cm and the cathodic current densities were of ^ 3 mA/sq cm at ^ 0.5 V (Ag/AgCl). The smallest biofuel cell built consisted of two 7 micrometers diameter 2 cm long carbon fibers. It's output at 37 deg C was ^ 1 Micro-W.