Thick films of copper-titanate resistive humidity sensor

The humidity-sensitive TiO2-Cu2O-Na2O thick films were prepared by screen printing on alumina substrates and subsequent firing. Pastes for screen printing were obtained by adding an organic vehicle and binder to TiO2-Cu2O-Na2CO3 powders. The microstructure of the films changed with the content of the sodium oxide and the firing temperatures. When the resistance characteristics of the sensors obtained from TiO2-Cu2O-Na2O, 10-2-1 were measured, the resistance changed linearly in its semi-logarithmic graph. The resistance varied from 107 to 104 Ω between 20 and 95%RH, which was required for a common humidity sensor. Temperature dependence, frequency dependence and response time were also measured and estimated.