Heterogeneous structured tough conductive gel fibres for stable and high-performance wearable strain sensors

Abstract

Wearable electronics have stimulated interest over the past few years due to their flexible and portable properties. Among them, hydrogel-based strain sensors demonstrate tremendous advantages because they exhibit attractive characteristics such as stretchability, skin-compliance, ion transport capability, and biocompatibility. However, their low strength compared to natural tissues, unstable sensing performance upon swelling, and a relatively low response rate arising from loose cross-linking networks still pose numerous challenges for their further applications. Here, tough hybrid hydrogel fibres with heterogeneous networks for stretchable, stable and high-performance wearable strain sensors are reported. In such gel fibres, a secondary polyaniline (PANI) hydrophobic nanostructured conductive polymer was constructed in clay/P(MEO₂MA-co-OEGMA-co-NIPAM) nanocomposite gel fibres to achieve tough hybrid gel fibres with high electrical conductivity (87.99 S m⁻¹) and good swelling resistance. Besides, multimolecular interactions among the heterogeneous structured gel fibres endowed them with high fracture energy (172.43 kJ m⁻²) and excellent tensile strength (7.21 MPa). Furthermore, such hybrid gel fibres allowed for integration into traditional fabrics to monitor human motions and physiological signals rapidly and sensitively in multiple environments (under air/wet conditions or underwater). It is believed that such hybrid gel fibres would create new opportunities in the design and manufacture of wearable and implantable sensors for health monitoring, innovative electronics and human–machine interactions.