A ceramic thick film humidity sensor based on MnZn ferrite

A ceramic thick film humidity sensor, produced from MnZn ferrite, is presented. The proposed sensing mechanism is a combination of proton hopping, hydronium diffusion, and vacancy donor traps releasing electrons into the conduction band. The sensor structure comprises a two-layer device; the first layer is an interdigitated conductor and the second layer is a 30 mum thick sensing layer. The effects of sintering the sensing pastes in air and vacuum have been reported. The air-fired sample exhibits the highest humidity sensitivity (1.54%/RH%) and the lowest temperature sensitivity ( 0.37%/degreesC). The vacuum-fired sample has the lowest humidity sensitivity ( 0.043%/ RH) and the highest temperature sensitivity (0.77%/degreesC). The sensitivity results indicate that the air-fired sample has the best potential for use in humidity sensing applications.