A micromachined surface acoustic wave sensor for detecting inert gases

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:432889

Ahuja, S; Hersam, M; Ross, C; Chien, H T; Raptis, A C ^[1]

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1. Argonne National Lab., IL (United States). Energy Technology Div.

Surface acoustic wave (SAW) sensors must be specifically designed for each application because many variables directly affect the acoustic wave velocity. In the present work, the authors have designed, fabricated, and tested an SAW sensor for detection of metastable states of He. The sensor consists of two sets of micromachined interdigitated transducers (IDTs) and delay lines fabricated by photolithography on a single Y-cut LiNbO{sub 3} substrate oriented for Z-propagation of the SAWs. One set is used as a reference and the other set employs a delay line coated with a titanium-based thin film sensitive to electrical conductivity changes when exposed to metastable states of He. The reference sensor is used to obtain a true frequency translation in relation to a voltage controlled oscillator. An operating frequency of 109 MHz has been used, and the IDT finger width is 8 {micro}m. Variation in electrical conductivity of the thin film at the delay line due to exposure to He is detected as a frequency shift in the assembly, which is then used as a measure of the amount of metastable He exposed to the sensing film on the SAW delay line. A variation in the He pressure versus frequency shifts indicates the extent of the metastable He interaction.

• Research Organization: Argonne National Lab., IL (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 432889
• Report Number(s): ANL/ET/CP--90372; CONF-9611113--2; ON: DE97000928
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
ACOUSTIC MEASUREMENTS
DESIGN
ELECTRIC CONDUCTIVITY
FABRICATION
HELIUM
LITHIUM OXIDES
METASTABLE STATES
MICROELECTRONIC CIRCUITS
NIOBIUM OXIDES
PERFORMANCE
SOUND WAVES
WAVE PROPAGATION