Shear mode FBARs as highly sensitive liquid biosensors

Thin film bulk acoustic resonators (FBARs) operating in shear mode have been investigated for biosensing applications. Dynamic measurements in liquid were carried out and the adsorption of an antibody–antigen system was observed. Although this is the very first FBAR biosensor system operating in liquid environment it was found that the sensor performance ruled by the smallest detectable mass attachment, is already better (2.3 ng/cm 2) than that of QCMs. The ability of easy integration onto wafers together with readout-circuitry as well as the possibility of making up large arrays comprising pixels with different functionalities make these devices interesting for future acoustic biosensors.