Triboelectric Nanogenerator Modeling and Triboelectric Nanogenerator-Based Pressure-Sensor Interface for Implantable Total Knee Replacement

Abstract

Total knee replacement (TKR) surgeries are increasing worldwide due to the aging population and the growing activity levels of middle-aged patients. Continuous monitoring of knee-joint loading is crucial for enhancing implant design, facilitating early failure detection, and informing personalized rehabilitation. Triboelectric nanogenerators (TENGs), which convert mechanical energy into electrical energy through contact electrification and electrostatic induction, are attractive for wearable and implantable electronics owing to their high energy density and mechanical flexibility. However, implantable TENGs are often limited by small surface areas and low internal capacitance, which makes energy harvesting challenging. To address this limitation, this work employs TENGs as pressure sensors rather than energy harvesters. We present a TENG model suitable for integration into TKR implants and propose a lowpower sensor interface that rectifies and digitizes the signal using a dual-output rectifier (DOR) and a 10-bit SAR ADC. Under a 1-Hz gait-like excitation, the system measured forcedependent voltage responses and monotonic ADC outputs. These results show that the proposed TENG model and TENG sensor interface enable pressure/load monitoring in TKR implants.