Humidity Effect on Transport Properties of Titanium Dioxide Nanoparticles

Rutile TiO2 nanoparticles were synthesized using co-precipitation method with an average diameter of ∼30 nm TiO2 nanoparticle device was then fabricated on glass substrate. Aluminum electrodes were defined using photolithography and vacuum evaporation. A suspension of TiO2 nanoparticles was prepared in isopropanol using ultrasonic agitation. The nanoparticles were deposited between the electrodes. The device was tested by AC electrical measurements at 40%–90% relative humidity (RH). The impedance of the TiO2 nanoparticles decreases by about 80 times with the increase in RH from 40% to 90% at 100 Hz. The response time and the recovery time were 4 s and 5 s, respectively between 40% and 90% RH. At 100 Hz, the sensitivity of the aluminum electrode TiO2 nanoparticle device in the range of 40%–90% RH was 17 MΩ/%RH. Complex modulus analysis also confirms the increase in DC conductivity of TiO2 nanoparticles as RH increases.