High temperature SAW gas sensor on langasite

Novel Surface Acoustic Wave (SAW) devices using the new langasite (LGS) family of crystals have been designed, fabricated, and tested for high temperature (up to 750/spl deg/C) gas sensor applications. The devices were fabricated using platinum (Pt) and palladium (Pd) thin film technology and were mounted in a high temperature sealed stainless steel chamber for gas testing. The high temperature SAW sensors have been exposed to temperatures from 250/spl deg/C to 750/spl deg/C and cycled more than ten times in that temperature range over periods from two to six weeks. Gas sensing of C/sub 2/H/sub 4/ in N/sub 2/ and H/sub 2/ in N/sub 2/ with baselines of O/sub 2/ and N/sub 2/ on the LGS SAW devices has been performed from 250/spl deg/C to 550/spl deg/C and is reported for the first time in this paper.