Novel SAW CWA Detector Using Temperature Programmed Desorption

In this article a temperature programmed desorption (TPD) on an uncoated surface acoustic wave (SAW) device has been explored for selectivity studies of chemical warfare agents (CWA). High sensitivity to mass change on SAW device surface was exploited to study desorption patterns in a novel way. CWA Simulants 2-chloroethyl ethyl sulfide (CEES), Methyl Salicylate (MS) and Dimethyl Methyl phosphonate (DMMP) were investigated at different concentrations. SAW device was cooled and exposed to simulant vapours resulting in physical adsorption of gas molecules on device surface and subsequently by ramp heating the device, vapours were desorbed. The change in SAW oscillation frequency, due to desorption, was monitored during the temperature ramping and desorption spectrum was obtained. Desorption spectra were statistically analyzed using Principal Component Analysis (PCA) and our results indicate that all the three compounds investigated produced distinct desorption patterns independent of concentrations. Through this work we aim to develop a reliable methodology for subsequent development of a hand held TDP-SAW detector for field applications.