Ti3C2Tx MXene-based all-resistive dual-mode sensor with near-zero temperature coefficient of resistance for crosstalk-free pressure and temperature detections

Abstract

All-resistive pressure and temperature dual-mode sensors are always a focus of attention in the field of flexible tactile sensing due to the lack of need for complex readout systems. However, the intrinsic temperature coefficient of resistance (TCR) of the active material greatly limits crosstalk-free detection of pressure. Herein, a near-zero TCR of −2.1 × 10−3% °C−1 has been achieved from a simple sandwich structure with a Ti3C2Tx MXene film printed on a polyethylene terephthalate substrate and encapsulated by a polydimethylsiloxane (PDMS) film. The mechanism is explained by the combination of PDMS thermal expansion and the negative TCR of MXene, which is certified by the simulations of their mechanical, thermal and electrical properties. In addition, a silver film is printed on the PDMS surface in contact with MXene film to form a temperature-independent pressure sensor based on two-phase contact mechanism with different conductivities. Moreover, a pressure-independent temperature sensor is constructed by opening a square hole in the PDMS encapsulated above another MXene film. Given their independent structures, the dual-mode sensing units are flexibly expandable on the same substrate to suit various application scenarios. For example, they are integrated into a glove to detect pressure and temperature without crosstalk in multiple states. Owing to the exceptional crosstalk-free detection and expandability, the sensor developed in this work hold immense promise for multifunctional tactile sensing.