High-performance capacitive humidity sensor based on flower-like SnS2/Ti3C2 MXene for respiration monitoring and non-contact sensing

Abstract

Flexible humidity sensors with high sensitivity, fast response time, and excellent reliability have wide application potential in electronic skins, healthcare, and noncontact detection. In this study, novel 3D flower-like SnS2/Ti3C2 MXene nanocomposites are fabricated via an in-situ hydrothermal synthesis strategy. The nanostructural, morphological and compositional properties of the SnS2/Ti3C2 MXene composites illustrate the doping of Ti3C2 MXene nanosheets on the surface of SnS2 nanoflowers, which increases the adsorption sites for water molecules. The results of the humidity sensing experiments reveal that the capacitive response of SnS2/Ti3C2 MXene is optimal when the mass ratio of Ti3C2 MXene is 20 %. Moreover, the SnS2/Ti3C2 MXene composite film sensor has an ultrahigh capacitance response with an amplitude increase of three orders of magnitude compared with the pure SnS2 sensor, and a wide detection range of 7–93 % relative humidity. Complex impedance spectroscopy, bode diagrams and Schottky junction theory are employed to understand the potential sensing mechanisms of the SnS2/Ti3C2 MXene composite under various humidity conditions. With the highly sensitive and rapid humidity sensing capability, the prepared respiratory detection system could effectively monitor respiratory patterns, confirming its potential application in the field of medical health. Moreover, the non-contact sensing system prepared based on a 4 × 4 humidity sensor array can effectively monitor moisture distribution in the external environment.