MWCNTs/WS2 nanocomposite sensor realized by LC wireless method for humidity monitoring

Abstract

In this work, we demonstrate an LC (inductor-capacitor) wireless passive humidity sensor based on MWCNTs(tungsten disulfide-multiwalled carbon nanotubes)/WS2 nanocomposites. We optimized the sensor structure and subsequently investigated the transmitting distance effect on the sensing performance of the sensor via the HFSS software. Subsequently, we observed the MWCNTs/WS2 nanocomposites by a scanning electron microscope, and the as-designed humidity sensor was fabricated via screen printing technology. In the experiments, we proved that the detectable transmitting distance of the sensor was up to 28 mm, and originally validated the transmitting distance effect on the sensitivity of the as-fabricated humidity. Based on the results, the transmitting distance of 6 mm was chosen to be the desired transmitting distance for further investigation of the humidity sensor. Consequently, the sensing test at the transmitting distance of 6 mm indicates that the resonance frequency of the proposed humidity sensor shifts by approximately 2.562 MHz in 15–95%RH(RT) with a sensitivity of 2201.25Hz/%RH at a low humidity range (15–55%RH) and a sensitivity of up to 70684Hz/%RH at a high humidity range (55–95%RH). The sensor has a response and recovery time of 7.8 s and 19.6 s, respectively, in 15–95%RH, and the repeatability and stability tests indicate the MWCNTs/WS2 nanocomposites applied for humidity sensors are reusable and stable in 15–95%RH. Eventually, the sensing mechanism of the proposed sensor at different transmitting distances is analyzed. Our results show that the humidity sensor is applicable for fast humidity detection in both sealed and open environments.