Micro-machined WO3-based sensors selective to oxidizing gases

Tungsten trioxide sensing films were deposited with interruptions by rf sputtering onto silicon micro-machined substrates. The use of a deposition process with several interruptions allowed decreasing grain size in the WO3 films. The decrease in grain size is a result of the thin film formation features. It is shown that the gas sensing properties observed for the WO3 films deposited with three interruptions are highly enhanced to oxidizing gases in comparison with those sensing films prepared without interruptions. For instance, the response of the fabricated micro-sensors to nitrogen dioxide and ozone is up to four times higher than that of the micro-sensors prepared using the basic technology.