Finite element method (FEM) based simulation of the surface acoustic wave using carbon nanotubes as a sensing layer for the detection of dichloromethane

The paper presents the detection of Dichloromethane (DCM) using a surface acoustic wave (SAW) device. The performance of the device is examined through simulations employing the finite element method (FEM). The response of the device is investigated for five different types of piezoelectric substrates, including Lithium Tantalate ( LiTaO 3 / LT ), Lithium Niobate ( LiNbO 3 / LN ), Zinc Oxide (ZnO), Barium Sodium Niobate ( Ba 2 Na Nb 5 O 15 / BN ) , and Piezoelectric Ceramics Barium Titanate ( BaTiO 3 / BT ). The resonance frequency of 1.08 GHz for Lithium Niobate is the highest compared to the other substrates. A thin sensing layer of Carbon Nanotubes (CNT) is utilised to study the sensitivity effect of the active layer. The ZnO substrate is the least affected by the thickness of the CNT sensing layer. The device's reaction is further examined using DCM gas concentrations ranging from 10 ppm to 250 ppm, resulting in a corresponding frequency shift from 11.54 kHz to 291.835 kHz. The obtained resonance frequency shift is linearly proportional to the DCM concentration. Performance metrics such as frequency response, admittance, and displacement are evaluated for the five different types of substrates.