Label-free immunosensor based on micromachined bulk acoustic resonator for the detection of trace pesticide residues

A highly sensitive label-free immunosensor based on film bulk acoustic resonator has been developed for the detection of pesticide residues. The film bulk acoustic resonator works at 2 GHz as a mass-sensitive transducer for bio-sensing. Artificial antigens were immobilized on the sensing surface of the resonator through self-assembled method to employ a competitive format for the immunoassays. The competitive immunoreactions are observed in real time by measuring the frequency changes of the resonator. The presence of pesticides can be detected according to the diminution of the frequency shift compared with the level without pesticides. The obtained ultra low limit of detection for parathion was as low as 0.08 μg/L. The fabricated device was further used to detect trace pesticide residues in vegetable samples. The results show that the proposed immunosensor is a rapid and convenient detection method with a high accuracy comparable to gas chromatography.