Flexible Self-Powered Ionic Gel Pressure Sensors from Polyacrylonitrile for Wearable Motion and Physiological Monitoring

Flexible self-powered pressure sensors have attracted attention for wearable electronics, particularly in real-time monitoring of human motion and physiological signals. Here, we present a high-performance pressure sensor based on a composite membrane consisting of polyacrylonitrile/multiwalled carbon nanotubes (PAN/MWCNTs) and an ionic gel layer. The integration of electrospun PAN/MWCNTs nanofibers with the ionic gel matrix synergistically enhances piezoelectric output, pressure sensitivity, and detection range. At an optimal MWCNT content of 2 wt %, the device achieves a maximum output voltage of 14 V and current of 40 μA, along with a 96% relative resistance change under 100 kPa. The composite structure facilitates improved interfacial contact, molecular orientation, and charge transport, leading to significantly enhanced piezoresistive performance compared to single-component configurations. Importantly, the device operates in a self-powered mode by directly converting mechanical stimuli into electrical signals, exhibiting excellent sensitivity (7.20 kPa–1 for pressures <10 kPa), a wide detection range up to 100 kPa, and long-term operational stability (maintaining output over 5700 s). The sensor effectively detects subtle physiological signals and complex motion patterns. A 5 × 5 sensor array enables high-resolution spatial pressure mapping and even recognition of Chinese characters formed by applied loads. This work provides a simple yet effective strategy for designing high-performance self-powered flexible sensors, with promising applications in health monitoring, gesture recognition, and intelligent robotics.