Design of a Flexible Poly(L‐Lactic Acid) Piezoelectric Sensor with Bionic Fish‐Scale Microstructure for Detecting Human Swallowing Function

Abstract Flexible pressure sensors have broad application prospects in the field of human vital sign monitoring. However, the challenge of achieving excellent performance while maintaining low cost and energy consumption remains a bottleneck in further expanding their application. This study endeavors to tackle the challenge by improving the performance of flexible poly(L‐lactic acid) (PLLA) piezoelectric sensors and fabricating the encapsulation layer with a fish‐scale microstructure (FSm) via the Digital Light Processing (DLP) technique. The FSm sensor presented herein exhibits a high sensitivity of 24.54 mV·kPa −1 and excellent linearity (R 2 > 0.99) in the low‐pressure range (<20 kPa), with an optimal parameter design (200 µm distance and 400 µm height) of the microstructure. As a result, a 477% increase in sensitivity is obtained compared to conventional PLLA sensors. Simulation analyses are conducted to evaluate the impact of fish‐scale orientation on the detection of human swallowing signals. The physiological pressure signals associated with the swallowing process are recorded using the FSm sensor in a wearable format. Moreover, the interference (additional) of vibration signals is effectively eliminated through further voice tests. The results indicated that FSm sensors hold promise for human swallowing health monitoring and action recognition, offering a novel approach to the treatment of swallowing disorders.