High-linearity flexible sensor for real-time pressure monitoring across wide frequency range by integrating piezoelectric and piezoresistive effects

Flexible sensors capable of real-time monitoring pressure across wide frequency range have garnered significant interest in line with the explosive exploitation of wearable technology and the Internet of Things (IoT). However, it remains a challenge to enable high yet linearized sensitivity over broad pressure range across full-spectrum frequency for the practical application of flexible pressure sensors. Herein, a novel flexible pressure sensor, featured with both high sensitivity and linearity over wide pressure range across full-spectrum frequency, is proposed by assembling micro-structured polyurethane (PU) based piezoresistive layer and poly(vinylidene fluoride) (PVDF) based piezoelectric layer. By synergizing the nanocomposites and topological structure approaches, notably amplified yet linearized sensing performances can be obtained in piezoresistive and piezoelectric layers, respectively. The subsequent coupling of laminated layers permits highly linearized (R-2 > 0.982) piezoelectric sensitivity of 0.0346 V/kPa over 0-1300 kPa for dynamic pressures monitoring while a piezoresistive sensitivity of 0.0098 kPa(-1) (R-2 = 0.960) over 0-100 kPa for static and low frequency (< 4.0 Hz) pressures detecting. Furthermore, the extraordinary sensing capability of sensor permits its viability in real-time capturing physiological signals and aircraft wings motion, highlighting its great applicability in diverse applications.