Biocompatible and breathable all-fiber-based piezoresistive sensor with high sensitivity for human physiological movements monitoring

Flexible pressure sensors have attracted tremendous attention for their various potential applications in wearable electronics, personal health monitoring, disease diagnosis, and smart electronic skin (E-skin). However, the preparation of pressure sensors with high flexibility, lightweight, breathability, favorable biocompatibility, and excellent sensing performance for comfortable and comprehensive human physiological movement monitoring is still a great challenge and highly desired. Herein, we present a biocompatible and breathable all-fiber-based piezoresistive sensor with high sensitivity. The device is elaborately assembled from a porous polyvinylidene fluoride (PVDF) nanofiber film impregnated with conductive MXene nanosheets (MXene/PVDF) as the sensitive layer, and a porous PVDF nanofiber film with magnetron sputtered Ag interdigital electrode (Ag/PVDF) as the electrode layer, with polyimide (PI) introduced in between as the insulation layer. The all-PVDF nanofiber structure enables the sensor to demonstrate excellent flexibility, reliable breathability, and favorable biocompatibility. Remarkably, benefitting from the insulation layer, the sensitivity of the sensor is further enhanced (up to 1970.65 kPa(-1)), which is about 13 times that without the insulation layer. Moreover, the sensor also exhibits other excellent characteristics such as rapid response/recovery time (10/20 ms) and excellent cycling stability (10000 cycles). These superior performances lay a foundation for the application of comprehensive human motion monitoring and pressure spatial distribution detection. Our study provides an effective strategy for fabricating flexible pressure sensors with good comprehensive properties in the field of intelligent wearable electronics.