Analysis of the detection of organophosphate pesticides in aqueous solutions using polymer-coated SH-SAW sensor arrays

There is a need for on-site and real time detection of organophosphate pesticides in aqueous environments. This work proposes the use of polymer coated shear horizontal surface acoustic wave (SH-SAW) sensors as a sensing platform for detection of organophosphate pesticides in aqueous environments. The chemically sensitive polymer coatings BPA-HMTS and BPA-PDMS, synthesized in-house, and the commercially available polymer PECH, were chosen as sensor coatings for organophosphate detection. The polymers are characterized at various thicknesses (0.25μm and 0.50μm) for their selectivity and sensitivity towards parathion, parathion-methyl, and paraoxon. A sensor array is designed for analyte identification and quantification using both steady-state and transient response information. Analyte identification is performed using a visual pattern recognition technique based on radial plots for the analytes at concentrations from 0.5mg/L to 3.0mg/L. It is shown that using the absorption time constant, which is unique to a given analyte-coating pair, in conjunction with steady-state frequency shifts permits direct identification and quantification of organophosphate pesticides in liquid-phase at low-ppm and sub-ppm concentrations.