A Resistive Type Humidity Sensor Based on ZnO-SnO2 Nanocomposite

Paper reports a resistive type humidity sensing studies of ZnO-SnO2 nanocomposite powder pellets prepared through solid-state reaction route. When exposed to humidity, resistance of pellets decreases with increase in relative humidity from 10 to 90%. Sensing element with 25 weight% of SnO2 in ZnO shows best results with maximum sensitivity of 1.25 M Omega/% RH in 10-90% relative humidity range. This sensing element manifests smallest crystallite size of 60 nm as measured from XRD and lowest grain size of 92 nm calculated from SEM micrograph. This sensing element manifests low hysteresis, less effect of ageing and good reproducibility. The response and recovery time of sensing element SZ-25 is found to be 92 and 480 seconds respectively.