A pure shear mode ZnO film resonator for the detection of organophosphorous pesticides

A pure shear mode ZnO film resonator has been developed for the detection of organophosphorous pesticides. The resonator works at near 1.47 GHz with Q-factors of 411 in air and 298 in dimethylformamide liquid. Acetylcholinesterase enzyme is immobilized on one of the faces of the resonator by cross-link method as sensitive coating. The enzymatic reaction can be followed by measuring the frequency shift associated with the mass loading induced by accumulation of the reaction product precipitated on the surface of resonator. Based on the inhibitory effect of organophosphorous compound on the enzymatic activity, the presence of chlorpyrifos (a typical organophosphorous pesticide) is detected by following the diminution of frequency shift from the level found in its absence. The proposed sensor has a remarkably low detection limit of 4.1 × 10−11 M and the advantages including small size, simpler operation and IC-compatibility, which make it very promising in the applications of food safety analysis.