Devices capable of operating up to 1000°C are in high demand as harsh environment temperature, pressure, strain and gas sensors. Potential applications include: (i) aerospace vehicle health management of military and civil aircraft; (ii) monitoring of jet fuel combustion targeting economy for increased flight range, and pollution reduction; (iii) detection of gas leaks for both operational and safety purposes in the space shuttle program and space exploration; (iv) early detection and mitigation of hazardous fire situations; and (v) gas and oil well exploration.             Semiconductor, magnetic, fiber optic and acoustic wave (AW) technologies have been used for high temperature applications with limited success in terms of reliability and life span, mostly due to temperature limitations in electronic performance or structural properties of the materials available. Recent work by several groups around the world on AW devices using gallium orthophosphate (GaPO4) and the langasite family of crystals (LGX) have indicated that these materials can be used in high temperature sensor applications.
           This work reports on recent progress by the author’s group on the design, fabrication, test, and packaging of high temperature langasite (LGS) surface acoustic wave (SAW) sensors using platinum (Pt) and palladium (Pd) thin film technology. The reported temperature and gas sensors have been tested between 250°C and 750°C over periods up to six weeks, with device degradation smaller than 7 dB in the magnitude of the transmission coefficient, |S₂₁|, with respect to room temperature. Single and dual configurations have been used as frequency control elements in oscillator circuitry. Present work is targeting tests up to 1000 ºC and package improvements for Air Force applications. The results obtained so far and that will be presented in this conference qualify Pt and Pd LGS SAW sensors for consideration for the above listed harsh environment applications.Devices capable of operating up to 1000°C are in high demand as harsh environment temperature, pressure, strain and gas sensors. Potential applications include: (i) aerospace vehicle health management of military and civil aircraft; (ii) monitoring of jet fuel combustion targeting economy for increased flight range, and pollution reduction; (iii) detection of gas leaks for both operational and safety purposes in the space shuttle program and space exploration; (iv) early detection and mitigation of hazardous fire situations; and (v) gas and oil well exploration.             Semiconductor, magnetic, fiber optic and acoustic wave (AW) technologies have been used for high temperature applications with limited success in terms of reliability and life span, mostly due to temperature limitations in electronic performance or structural properties of the materials available. Recent work by several groups around the world on AW devices using gallium orthophosphate (GaPO4) and the langasite family of crystals (LGX) have indicated that these materials can be used in high temperature sensor applications.
           This work reports on recent progress by the author’s group on the design, fabrication, test, and packaging of high temperature langasite (LGS) surface acoustic wave (SAW) sensors using platinum (Pt) and palladium (Pd) thin film technology. The reported temperature and gas sensors have been tested between 250°C and 750°C over periods up to six weeks, with device degradation smaller than 7 dB in the magnitude of the transmission coefficient, |S₂₁|, with respect to room temperature. Single and dual configurations have been used as frequency control elements in oscillator circuitry. Present work is targeting tests up to 1000 ºC and package improvements for Air Force applications. The results obtained so far and that will be presented in this conference qualify Pt and Pd LGS SAW sensors for consideration for the above listed harsh environment applications.Devices capable of operating up to 1000°C are in high demand as harsh environment temperature, pressure, strain and gas sensors. Potential applications include: (i) aerospace vehicle health management of military and civil aircraft; (ii) monitoring of jet fuel combustion targeting economy for increased flight range, and pollution reduction; (iii) detection of gas leaks for both operational and safety purposes in the space shuttle program and space exploration; (iv) early detection and mitigation of hazardous fire situations; and (v) gas and oil well exploration.             Semiconductor, magnetic, fiber optic and acoustic wave (AW) technologies have been used for high temperature applications with limited success in terms of reliability and life span, mostly due to temperature limitations in electronic performance or structural properties of the materials available. Recent work by several groups around the world on AW devices using gallium orthophosphate (GaPO4) and the langasite family of crystals (LGX) have indicated that these materials can be used in high temperature sensor applications.
           This work reports on recent progress by the author’s group on the design, fabrication, test, and packaging of high temperature langasite (LGS) surface acoustic wave (SAW) sensors using platinum (Pt) and palladium (Pd) thin film technology. The reported temperature and gas sensors have been tested between 250°C and 750°C over periods up to six weeks, with device degradation smaller than 7 dB in the magnitude of the transmission coefficient, |S₂₁|, with respect to room temperature. Single and dual configurations have been used as frequency control elements in oscillator circuitry. Present work is targeting tests up to 1000 ºC and package improvements for Air Force applications. The results obtained so far and that will be presented in this conference qualify Pt and Pd LGS SAW sensors for consideration for the above listed harsh environment applications.