Using Pt Dopant and Sol Gel Technology for Sensitivity Enhancement of TiO2/SnO2Humidity Sensors

The sensitivity of the humidity sensor based on hybrid thin films of nanostructure TiO₂/SnO₂ with Pt dopant was successfully increased. The humidity-sensitive materials, TiO₂/SnO₂, were prepared by sol gel technology. The microstructure of the sensing film after calcination was investigated by the field emission gun scanning electron microscopy (FESEM) and revealed that the metal oxide hybrid had about 10 nm grain size. For studying the effect of Pt dopant on the humidity-sensitive responses, 1 ml to 10 ml of Pt standard solution was added into the colloidal solution. To compare the humidity sensor of Pt dopant with that of no Pt dopant, operational frequencies and electrode spacing were set under the relative humidity from 30% to 95% at the ambient temperature of 22degC. We demonstrated that adding Pt dopant remarkably enhanced the sensitivity of TiO₂/SnO₂ humidity sensor, and further decreased the TiO₂/SnO₂ resistance, which was 3.3 times lower than that without Pt dopant at the high humidity