Controlled partial carbonization of polyimide nanofiber network: Structural-conductive integration for high-temperature flexible piezoresistive sensors

The development of wearable electronics for use in extreme high-temperature environments, such as fire rescue operations and aerospace explorations, has created an urgent demand for flexible pressure sensors that exhibit both high sensitivity and high-temperature stability. Herein, a high-temperature flexible piezoresistive sensor was fabricated via controlled partial carbonization of a three-dimensional polyimide nanofiber network (PCPN). This sensor maintains high sensitivity up to 350 °C while preserving mechanical flexibility, representing the highest operational temperature ever achieved in polymer-based flexible sensors. The PCPN serves dual functions as both a structural flexible substrate component and a conductive sensing element, eliminating the necessity for additional conductive elements or complex composite architectures compared with traditional flexible pressure sensors. The PCPN-based pressure sensor with optimal carbonization degree demonstrates high sensitivity over a wide temperature range from ambient temperature (255.1 kPa −1 ) to 350 °C (94.8 kPa −1 ), fast response time (86 ms), and outstanding durability (9000 cycles at ambient temperature, 4500 cycles at 200 °C and 1000 cycles at 350 °C). As a proof of concept, the PCPN pressure sensor can be applied to not only real-time monitoring of human physiological activities but also to pressure identification in high-temperature environments, showcasing its potential for applications across a range of demanding conditions.