A highly sensitive room temperature humidity sensor based on 2D-WS₂ nanosheets

Ambient humidity monitoring is of outmost importance in many technological fields. For this reason, there is still a substantial interest in the development of new simple humidity sensors with high performances. Here it is presented a study to the development of a sensitive, selective and reliable conductometric humidity sensor based on two-dimensional (2D) WS₂ nanosheets. The 2D nanomaterial was synthesized by exfoliation of a bulk WS₂ with tert–butyllithium, and then deposited onto the interdigitated electrodes of a conductometric ceramic platform. To evaluate the sensing performances, the sensor was exposed to different relative humidity (RH) levels, recording in real time the change of conductivity of the 2D-WS₂ layer. The sensor exhibited high sensitivity to humidity at room temperature, showing an increase of the current of about 3 orders of magnitude as RH value was varied between 8% and 85% with fast response and recovery times of 140 s and 30 s, respectively. Field tests, carried out to measure the environmental humidity, demonstrated the good performances of the developed sensor as a highly sensitive and reliable relative humidity probe for environmental applications.