Ultrasensitive Piezoelectric Sensor based on Polyimide Foam for Sound Recognition and Motion Monitoring

The ultrasensitive piezoelectric sensors with the capability of sound recognition have attracted extensive attention due to their unique characteristics. However, the fabrication of acoustic sensors with favorable flexibility and sensitivity via simple and controllable methods remains a significant challenge. Herein, an ultrasensitive and adaptive acoustic sensor based on piezoelectric polyimide (PI) composite foams containing fluorine groups is developed. The uniform porous morphology endows the composite foam-based sensors with remarkable sensitivity of 0.9536 V/N over a broad pressure range (2.5–12.5 N), rapid response and recovery times (18 and 15 ms, respectively), and outstanding durability (over 19,000 cycles). Moreover, the sensors are capable of effectively monitoring human motions, and the generated piezoelectric output voltages reached ∼30 V for practical applications as intelligent household devices. In particular, the sensors exhibit excellent capability of detecting a wide range of acoustic sounds, indicating exceptional sensitivity. This work offers promising opportunities for the design and development of high-performance piezoelectric sensors for sound recognition, motion monitoring, and self-powered wearable devices in extreme environments.