Polyisobutylene and carbon nanotube based heterostructure SAW sensor for detection of TCM gas

The paper presents a study on surface acoustic wave (SAW) one-port resonating sensor device using 2-D modelling based on finite element method (FEM). The proposed SAW resonator structure was modeled with aluminum inter-digitated transducer (IDT) metallic electrodes over 128°YX-cut Lithium Niobate piezoelectric substrate. The SAW sensor model was designed with the carbon nanotube with a sensing polymer layer polyisobutylene, which helps in the detection of the various properties of the target gas i.e., Trichloromethane (TCM) at room temperature. The sensing characteristics was compared with other volatile organic compounds at 100 ppm of gas concentration. The eigen frequencies were measured either by exposure of target gas or without over the sensing layer. The model shows the significant shift in resonant frequencies
$(\Delta f)$
for 100 ppm gas concentrations. Sensor admittance
$(\mathrm{Y}_{11})$
parameter, change in CNT thickness and electric potential distribution for the TCM SAW sensor were investigated. The outcome of various response for multilayered SAW sensor shows better performance in terms of sensitivity, and found to be the most suitable for sensing TCM.