Modelling Of The Response Of Bulk Acoustic Wave Based Devices In Bio Sensor Applications

Bulk acoustic wave device are considered now as a high resolution analytical tools for the real time monitoring of small amount of surface attached mass of bio molecules. Among various mass sensor, acoustic sensors are playing a pivotal role due to their high sensitivity to mass change, easier in packing and potentially low manufacturing cost. Piezoelectric biosensor is a kind of BAW device that utilize longitudinal wave, known as thickness shear mode that propagates in the bulk of materials. The gravimetrical measurement performed with the piezoelectric biosensor provides the high precise experimental data. This experimental data is used for quantification of surface mass of the piezoelectric crystal substrate and additional mass applied to the oscillating surface. The theoretical modelling is important for the quantative analysis and interpretation of the experimental data. For BAW device, a linear relationship is sustained between the shift in resonance frequency and surface mass which cause this shift. But for liquid medium, viscoelastic effect is introduced with the linear relation. Through the formulation of the theoretical modelling it is possible to show the necessary correction factors of surface mass deduced from BAW device measurement in liquid. Theoretically obtained result must be compared with the experimental value for the liquid phase measurement.