Fast response flexible humidity sensors based on Ti3C2Tx MXene-heterostructures for multifunctional applications

Abstract

High-performance humidity sensors with fast response and recovery capabilities are still a significant requirement in wearable digital healthcare applications. Herein, multifunctional humidity sensors based on heterostructured Ti₃C₂T_x MXenes have been designed, and are endowed with greatly improved sensing performance compared with the Ti₃C₂T_x sensors. The Ti₃C₂T_x/SnO₂ sensor displays a high response of 13.4 and rapid response time (2 s) to 59% relative humidity (RH), good repeatability, a wide detection range for 11–97% RH, and high selectivity to water. Complex impedance spectroscopy and the synergistic effects of heterojunctions are employed to explain the mechanisms of the enhanced sensing performance of the Ti₃C₂T_x/SnO₂ sensors. Such exceptional performance makes this Ti₃C₂T_x/SnO₂-based humidity sensor much more applicable for applications of real-time respiratory monitoring and non-contact measurements. This work provides effective strategies for humidity sensors for collecting biomedical signals and realizing non-contact human–machine interaction.