A Self-Powered Pressure Sensor System Based on Triboelectric Energy Harvesting for Knee Implants

This work presents a compact, self-powered pressure sensor based on a triboelectric nanogenerator (TENG), which is developed for total knee replacement (TKR) implants. Unlike conventional bulky and inefficient systems with separate attenuators and signal processing units, this design seamlessly integrates a pressure sensor within an energy-efficient energy harvesting (EH) circuit. The system features a bidirectional, high-voltage (HV) four-input buck converter with a newly proposed HV protector, enhancing EH efficiency across four different input voltages. The converter achieves a maximum end-to-end efficiency of 79.21%. Additionally, the pressure-sensing circuits offer accurate readouts by sampling the HV open-circuit voltages (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</inf>) from TENGs using a V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OC</inf> sampler without the need for an attenuator. Compared to state-of-the-art solutions, this work not only achieves competitive energy harvesting performance but also introduces, for the first time, a fully integrated pressure-sensing function.