Highly sensitive and wearable bionic piezoelectric sensor for human respiratory monitoring

Flexible piezoelectric sensors hold great promising for applications in electronic skin (E-skin), wearable devices, and biomedical devices. However, it is still challenging to apply flexible piezoelectric sensors to respiratory health monitoring which requires an extremely low detection limit. To address this challenge, a flexible bionic piezoelectric sensor inspired by the lateral line structure of fish is proposed in this study. Benefited from the excellent piezoelectric effect of polyvinylidene fluoride (PVDF) and the bionic structural design, the proposed sensor has a low detection limit of 0.0005 N and can be conformal with a cylindrical surface. In addition, the sensor can accurately sense the pressure at a high sensitivity of 0.24 V N-1 with a fast response time of 4 ms and long-term repeatability of 4000 cycles. Through the design of back-end circuitry, the bionic sensor is capable of accurately monitoring of various respiratory states, such as apnea, coughing, and deep breathing. These results show that our sensor has great potential as a wearable device in the field of respiratory health monitoring, and is also highly inspiring for designing other types of flexible sensors.