Smart fabrics with liquid metal reinforced PU/CNT/MXene multilayer structures for constructing multifunctional sensors and wearable electronics

Abstract

Smart fibers as interfaces for sensing environmental information are expected to accelerate sustainable development in the wearable era. However, challenges remain in terms of fiber versatility, low power consumption and the ability to discriminate between different mechanics. Herein, we propose a novel three-layer core–shell manufacturing strategy: the combination of coaxial spinning and spraying technology, using pure elastomers (polyurethane) as a base layer to increase the tensile range; mixing a liquid metal (LM) and carbon nanotubes (CNTs) doped into a polyurethane (PU) matrix as a durable electrode layer to reduce the power used and enhance the electron transfer pathway; spraying pleated MXene coatings to enrich the gas sensing sites. Finally, the strain sensor has an impressive gauge factor (GF) of 1.1367 ± 0.08643 (in the sensing range of 0–200%, R² = 0.99425), a low strain detection limit of 1% and a fast response time of 0.12 s. Meanwhile, the single fibers, which are warp and weft braided, can also accurately sense changes in spatial pressure. In addition, these fibers exhibit superior electrothermal performance, with the capability to heat from room temperature to 65.7 °C at a 10 V voltage just in 50 s. Furthermore, with the strong hydrogen bonds formed between the MXene outer coating and organic gas molecules, it is highly selective for acetone, and with the excellent electrical conductivity of liquid metals, it can also be used as an electrical heating device. These results provide effective tools for building multifunctional sensing platforms for strain, pressure, temperature, and gases, which can be applied in fields such as wearable health and environmental monitoring.