Resistance Based Humidity Sensing Properties of TiO2

Abstract

The present paper reports pellets of TiO2 powder used as humidity sensor. Pellet of about 9 mm diameter and 5 mm thickness has been made by hydraulic pressing machine under a load of 4 tons and annealed in an electric furnace up to 100 °C, 200 °C, 300 °C and 400 °C for 3 hour. After each and every time of annealing this pellet has then been exposed to humidity in specially designed humidity chamber. It is observed that as Relative Humidity (% RH) increases, there is a decrease in the resistance for the entire range of humidity i.e. from 5 % to 95 %. Relative humidity (% RH) has been measured by using standard hygrometer and variations in the resistance have been noted by using Sinometer. Porosity of the samples decreases on increasing the annealing temperature. Temperature variation of chamber throughout the experiment is 1°C. Surface morphology of sensing element has also been studied. This material has a very good scope for developing a resistance type humidity sensor for entire range of humidity. Sensitivity of the sample annealed at 400°C is found better than other sensing elements reported in this paper.