An investigation of response time of TiO2 thin-film oxygen sensors

TiO2 thin-film oxygen sensors have been made by a sol-gel process. The TiO2 thin film is formed on an alumina rod by dip-coating of a titania sol derived from titanium butanol alkoxide solution in ethanol. The dependence of the resistance (R) of the TiO2 film on the oxygen partial pressure (P-O2) and temperature (T) has been determined. The TiO2 thin-film oxygen sensor possesses linear relations between lg(R) and lg(P-O2) with temperature-dependent slopes. The response time of the TiO2 thin-film sensor is shorter for an atmosphere change from oxygen rich to lean than that from oxygen lean to rich. The response time decreases with increasing temperature. A platinum coating on the TiO2 surface reduces the response time.