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A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor
Department of Mechanical Engineering, University of Alberta, Edmonton, AB, T6G 2G8, Canada
* Author to whom correspondence should be addressed.
Received: 15 December 2009; in revised form: 31 December 2009 / Accepted: 23 January 2010 / Published: 2 February 2010
Abstract: Hydrogen plays a significant role in various industrial applications, but careful handling and continuous monitoring are crucial since it is explosive when mixed with air. Surface Acoustic Wave (SAW) sensors provide desirable characteristics for hydrogen detection due to their small size, low fabrication cost, ease of integration and high sensitivity. In this paper a finite element model of a Surface Acoustic Wave sensor is developed using ANSYS12© and tested for hydrogen detection. The sensor consists of a YZ-lithium niobate substrate with interdigital electrodes (IDT) patterned on the surface. A thin palladium (Pd) film is added on the surface of the sensor due to its high affinity for hydrogen. With increased hydrogen absorption the palladium hydride structure undergoes a phase change due to the formation of the β-phase, which deteriorates the crystal structure. Therefore with increasing hydrogen concentration the stiffness and the density are significantly reduced. The values of the modulus of elasticity and the density at different hydrogen concentrations in palladium are utilized in the finite element model to determine the corresponding SAW sensor response. Results indicate that with increasing the hydrogen concentration the wave velocity decreases and the attenuation of the wave is reduced.
Keywords: finite element analysis; Surface Acoustic Waves (SAW); hydrogen; piezoelectricity; MEMS; palladium
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EL Gowini, M.M.; Moussa, W.A. A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor. Sensors 2010, 10, 1232-1250.
EL Gowini MM, Moussa WA. A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor. Sensors. 2010; 10(2):1232-1250.
EL Gowini, Mohamed M.; Moussa, Walied A. 2010. "A Finite Element Model of a MEMS-based Surface Acoustic Wave Hydrogen Sensor." Sensors 10, no. 2: 1232-1250.