Ozone monitoring by micro-machined sensors with WO3 sensing films

Tungsten trioxide sensing films were deposited by rf sputtering onto silicon micro-machined substrates. The sensor substrate consisted of four-element integrated micro-hotplate arrays constructed using micro-systems technology. The sensing films were deposited using two sputtering technologies. The first one was a standard deposition without interruption of film deposition process. The second one included three interruptions of the process. It is shown that the sensor response to ozone is enhanced by the use of the second approach. Moreover, the features of sensor response to ozone demonstrate that fast responses and good sensor stability at low ozone concentrations are achieved using the micro-sensors.