Humidity hysteresis and temperature property of MWNT-SiO2 thin film humidity sensor at AC testing

Multiwall carbon nanotubes(MWNTs)-SiO2 composite thin film humidity sensors are fabricated and humidity hysteresis and temperature property for different MWNTs contents at AC testing are investigated in this paper. Shapes diversity for humidity hysteresis curves of different MWNTs proportion sensors are analyzed by capillary condensation effect. Sensors temperature property at 200 kHz frequency are based on the dielectric relaxation theory in dielectric physics. Sensor conductance increases as temperature rises because relaxation time is greatly infected by temperature. Sensitivity of sensors is also improved with the increasing temperature.

I. Introduction

As carbon nanotubes (CNTs) came into view of scientific researchers in 1990s [1], it has become the investigation hotspot in various fields, such as biology chemistry, material chemistry, micro/nano electronics and mechanics [2], because of their fantastic structure and outstanding performance. Multiwall carbon nanotubes (MWNTs) are extremely attractive as humidity sensing material because of the unique porous network and great surface area of MWNTs entanglement. However, this has not received adequate attention and few profound investigations are reported on their property and application.