A high-sensitivity MoS2/graphene oxide nanocomposite humidity sensor based on surface acoustic wave

We herein propose a surface acoustic wave (SAW) sensor coating with a MoS2/graphene oxide (GO) nanocomposite. MoS2 nanosheets were prepared using the liquid stripping method, and the MoS2/GO nanoflakes were characterized by scanning electron microscopy. Subsequently, the surface acoustic sensor was prepared using a standard photolithographic technique and the MoS2/GO layers were deposited via drop-casting on the sensor surfaces. The performance of the sensor was then tested from 20% relative humidity (RH) to 95% RH. The sensor exhibits good performance with a sensitivity of 114 ppm/%RH at low humidity (at 20–70% RH) and a sensitivity of 766.8 ppm/%RH at high humidity (at 70–95% RH). The recovery and response time of the sensor were 6.6 s and 3.5 s. Moreover, the sensor exhibited good repeatability and long-term stability. The influence of temperature on sensor response at different values of humidity was also tested, and the relationship between temperature and frequency was almost linear from 25° to 70°C at different humidity levels. Finally, the humidity-sensitive mechanism was analyzed at different humidity values. The humidity sensor has great application potential in medical care, environmental monitoring, and cultural relic preservation.