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

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.