A breathable and reliable thermoplastic polyurethane/Ag@K2Ti4O9 composite film with an asymmetrical porous structure for wearable piezoresistive sensors

Abstract

High sensitivity and long-term comfort are of extreme significance to wearable tactile sensors. However, balancing their trade-offs is still a challenge. The management of electronic waste has received considerable attention for the avoidance of the environmental burden. Thus, a breathable and reliable piezoresistive sensor based on a hierarchical porous thermoplastic polyurethane (TPU)/Ag@K₂Ti₄O₉ (AKT) hybrid membrane was successfully fabricated using water as a non-solvent to induce phase separation. Unlike widely reported studies, the prepared porous membrane presents an interesting asymmetric structure with graded pore size distribution due to the anchoring effect of AKT whiskers. Benefiting from these, the resultant micro-porous membrane exhibits high air permeability and enhanced sensitivity (0.127 kPa⁻¹) along with a wide working range (5 Pa–100 kPa). Conceptual experiments have demonstrated potential applications in human motion monitoring, real-time fluid height detection and spatial pressure resolution. Moreover, due to the one-step process without cross-linking, the obtained sensors can be facilely dissolved, molded, and reused. Overall, all these results provide new insights for the design and popularization of renewable human-computer interaction components.