Low‐Temperature Demulsification‐Induced Gelation Coupled With Gel‐Confined Freeze Casting for Highly Elastic Conductive Aerogels in Wireless Gait Monitoring

Abstract

ABSTRACT Polymer‐based conductive aerogels are promising for flexible piezoresistive sensors but suffer from skeleton deformation and conductive filler detachment under high‐strain and long‐term compression. Here, an aminopropyltriethoxysilane/carboxylated carbon nanotubes/waterborne polyurethane (APTS/CNTs/WPU) aerogel featuring a semi‐interpenetrating network is developed through a strategy combining low‐temperature demulsification‐induced gelation with gel‐confined freeze‐casting and simultaneously possesses a highly elastic skeleton, continuous conductive pathways, and reinforced filler/matrix interfaces. The low‐temperature condition retards the electrostatic demulsification rate between anionic WPU and protonated APTS, transforming the otherwise rapidly destabilizing emulsion into a controllable gelation process. Accompanied by the gradual occurrence of electrostatic interactions, hydrogen bonding, and hydrolysis–condensation reactions of silane, a semi‐interpenetrating gel network is established within minutes. The formed gel network prevents re‐agglomeration of CNTs and ensures their stable immobilization within the skeleton during freeze‐casting. The aerogel exhibits 99.1% elastic recovery after 10 cycles at 80% strain and 5.1% plastic deformation after 10 000 cycles. The piezoresistive sensor achieves a detection range of 0–408 kPa, a maximum sensitivity of 12.33 kPa −1 , and stable response over 10 000 cycles. Furthermore, a sensing array integrated with a wireless/wired signal acquisition system is constructed for monitoring gait pressure distribution, fully demonstrating its substantial application potential in human motion perception and wearable electronics.