The Polymer Society of Korea

Abstract

High-fidelity capture of physiological vibrations over a broad frequency range remains challenging due to the trade-off between sensitivity, bandwidth, and power stability in soft sensors. Here, we present a piezoelectric-powered capacitive vibration sensor in which a piezoelectric diaphragm functions as a self-sustained bias source while simultaneously modulating the capacitive signal. This non-contact driving scheme enables stable, low-power operation without external bias circuitry. To further improve signal fidelity, an optimized device architecture incorporating in-plane air ventilation and a high-density sensor array is introduced. The resulting sensor exhibits linear sensitivity of 626 mV g⁻¹, a flat frequency response spanning 80–5,000 Hz, and a detection limit of 0.01 g. Owing to its hyperpacked array configuration and self-powered operation, the platform enables accurate detection of subtle vibrations associated with music, speech, and respiratory activity.