InGaZnO-Based Thin-Film Thermistors on PEEK Fabric for Green Smart Textiles

Electronic textiles (e-textiles) have recently achieved outstanding results, allowing fast and reliable systems to be directly integrated into fabrics and threads. However, based on the environmental impact of these systems, the improvement of their limited End-of-Life (EoL) strategies is nowadays a major challenge. For this reason, the development of a circular technology for the realization of e-textiles, aiming at waste reduction and support of materials recycling, is highly required. Herein, an innovative and fully recyclable integration of thin-film electronics on a biocompatible polyether ether ketone (PEEK) fabric is presented. Specifically, three different configuration of InGaZnO-based thin-film thermistors are investigated, comparing their capabilities and sustainability. The devices are characterized over a temperature range from 25 to $60{}^{\circ }\mathrm{C}$; besides their thermal response, reliable functionality under bending stress and for NO₂ gas detection are proven. To demonstrate a circular and yet green approach, the devices are dissolved in water and the textile substrate is reused for a 2^nd generation of thin-film sensors, achieving comparable performances with respect to the 1^st generation ones. This work represents a first comprehensive analysis of thin-film thermistors integrated with textiles for the realization of breathable, flexible, and recyclable e-textiles, with applications for daily routine, ranging from automotive to human health monitoring.