A Biofuel-Cell-based Energy Harvester with 91% Peak Efficiency and Inherent Biosensor

This paper presents a self-powered biosensing system based on biofuel cells (BFCs) for the simultaneous battery charging and inherent glucose/lactate sensing. The proposed boost converter performs maximum power point (MPP) tracking and power conversion from $0.15-0.6 \mathrm{~V}$ to $3.7-4.2 \mathrm{~V}$ (suitable for battery charging), while establishing a linear relationship between the BFC voltage at MPP and the conversion frequency. This enables the incorporation of the real-time sensing of glucose/lactate concentrations into the power converter, removing the need for separate sensing circuits and minimizing overheads. Simulated in 180 nm CMOS process, the system achieves the energy harvesting of $0.3-0.7 \mathrm{~mW}$ at $2.5-15 \mathrm{mM}$ lactate/glucose, while performing biosensing simultaneously. The boost converter peak efficiency is ${9 1 \%}$ for charging battery at 4V from a BFC MPP voltage of 0.29V.