Date of Award
Level of Access Assigned by Author
Master of Science (MS)
Electrical and Computer Engineering
Mauricio Pereira da Cunha
Second Committee Member
John F. Vetelino
Third Committee Member
M. Clayton Wheeler
There is a pressing need for the research and development of sensors to operate as pressure, temperature, and gas sensors, frequency control elements, and signal processing filters, in harsh environments, at elevated temperature and pressure conditions. The applications range from gas and oil wells, automobile and aerospace combustion engines, and high power duplexers in communication systems. Surface acoustic wave (SAW) devices have been recently reconsidered for harsh environment sensing upon the introduction of the langasite (LGS) family of crystals, which can operate up to 1470°C. This thesis reports on the investigation of LGS as a high temperature (up to 750°C) SAW device and gas sensor. The investigations carried out in this research work included: high temperature LGS SAW devices design, fabrication, and test; interdigital transducer (IDT) electrode materials analysis and deposition; high temperature test chambers design and fabrication; dual oscillator sensing configuration design and implementation; and the realization of the appropriate high temperature gas sensing experimental set up. High temperature LGS SAW Pt electrode devices, WOs film devices, and original all-Pd electrode devices, which use Pd as both electrode and sensing layer, have been fabricated in this work. These SAW components have been used to sense ethylene (C2H4) and hydrogen (Hz) as a proof-of-concept effort at temperatures ranging from 250°C to 450°C.
Thiele, Jeremy Allan, "High Temperature LGX Acoustic Wave Devices and Application for Gas Sensors" (2005). Electronic Theses and Dissertations. 967.