Finite element simulation of one-port surface acoustic wave resonator with thick interdigital transducer for gas sensing

The paper presents finite element simulation of a surface acoustic wave (SAW) one-port resonator with thick interdigital transducers (IDT) made of nickel metal for sensing dimethyl methylphosphonate (DMMP) gas by placing fluoroalcoholpolysiloxane (SXFA) sensing film in the space between thick IDT fingers. The absorption of DMMP gas changes density and thickness of SXFA film and affect the SAW propagation velocity, hence resonance frequency of the device. The change in resonance frequency is measured as sensor response. In this paper individual effects of change in density and thickness of SXFA film due to absorption of DMMP gas on sensor response are simulated. The results show that the change in thickness of the SXFA film placed in the space between thick IDT fingers of proposed device is dominant in sensor response and the sensitivity of the proposed device (2.1 kHz/mg/m 3 ) is about 3.2 times greater than a conventional device using SXFA coated over the entire top surface of the device.