A Corrugated PVDF-Based Flexible Piezoelectric Sensor for Physiological Signal Detection

Continuous monitoring of heart rate and respiration is vital for disease diagnosis and health management. Flexible polyvinylidene fluoride (PVDF) piezoelectric sensors can accurately acquire these signals, thereby providing critical data support for health management. Current high-performance PVDF sensors typically enhance properties by doping functional materials but suffer from complex fabrication procedures and difficulties in composition control. In this study, we propose a flexible piezoelectric sensor based on a corrugated polyvinylidene fluoride (PVDF) film for contactless physiological signal monitoring. By using a simple template molding method, the corrugated PVDF film (CPF) is shaped into a uniform wavy configuration and encapsulated in a soft elastomer to preserve its geometry. The wave design enhances the spatial freedom of PVDF deformation, and the elastic encapsulation layer facilitates rapid shape recovery. The two effects synergistically improve the piezoelectric output and dynamic response of the sensor. The CPF-based sensor exhibits a sensitivity of 0.36 V/N, a minimum detectable force of 98 mg, and a fast response/recovery time of less than 0.1 ms. By integrating with a soft cushion, the sensor is capable of detecting subtle vibrations caused by thoracic and cardiac movements once people lie or sit on the smart cushion. Moreover, it reliably captures pulse waveforms at multiple body locations, demonstrating its promising potential for noncontact physiological signal monitoring.