Flexible, Piezoresistive, and Triboelectric Self-Powered Sensors Based on Ultralight Electrospun Cross-Linked Gelatin Nanofibers

Abstract

With the rapid development of wearable electronics, most flexible devices are made of nondegradable materials, which cannot be processed after use and thus impose significant environmental pressure. To address this, gelatin extracted from porcine skin was selected as the research material. By modifying gelatin with methacrylic anhydride, carbon–carbon double bonds were successfully introduced into the gelatin molecular chain, producing vinyl gelatin suitable as an electrospinning solution. A gelatin nanofiber material with a three-dimensional network structure was then prepared via electrospinning and ultraviolet radiation cross-linking. The ultralight gelatin nanofibers were combined with silver nanowires to serve as the pressure-sensitive material for piezoresistive strain sensors and as the positive material for triboelectric self-powered sensors. The optimal electrospinning conditions were determined to be 8 wt % solution concentration, 20 kV voltage, and 0.8 mL/h feeding rate, yielding a gelatin-based nanofiber membrane with enhanced mechanical strength and thermal stability. When the AgNWs were sprayed six times at a distance of 4 cm, the resulting GelMA/AgNW piezoresistive sensor exhibited strong mechanical performance, stable current output, multidimensional recognition, excellent cycle stability, and reliable responsiveness to different pressures and bending angles. The assembled GelMA/AgNWs-TENG demonstrated outstanding durability and electrical performance, maintaining stability over 10,000 cycles and achieving a peak-to-peak voltage of approximately 634 V. Furthermore, the device successfully harvested energy to power various light-emitting diodes (LEDs) and small electronic devices, while also serving as a self-powered sensor for human motion monitoring. These results underscore its potential for diverse applications and its contribution to environmentally sustainable wearable technologies.