Stretchable flexible fiber supercapacitors for wearable integrated devices

Abstract

Flexible fiber capacitors, renowned for their lightness, softness, and bendability, are prime candidates for wearable electronic devices. However, a significant challenge for their practical application in flexible wearable devices lies in the mismatch between the electrochemical and mechanical properties of their fibrous electrode materials. In this work, a thermoplastic polyurethane (TPU) film is prepared using electrostatic spinning and loaded with polyaniline (PANI) through in situ polymerization. By twisting the PANI-TPU fiber film a certain number of turns, a fiber supercapacitor capable of stabilizing under large tensile deformations is achieved. This PANI-TPU fiber demonstrates a remarkable tensile strain tolerance of 537.8%, while the entire supercapacitor device maintains stable and high specific capacitance characteristics (>45.12 F cm⁻³) even under large tensile strains. Furthermore, the PANI-TPU fiber excels not only in energy storage but also in sensing performance, enabling the monitoring of human pulse signals and movements across various body parts. Leveraging the versatility of the composite fiber, it can be flexibly integrated into a self-supplied integrated sensing system. This system can drive the PANI-TPU fiber sensors to identify and classify different movement gestures of the human body as well as diverse shapes of objects grasped by manipulators.