Improvement of the mass sensitivity in flexural plate wave biosensor based on PZT thin film

This paper presents the fabrication and characterization of microfabricated FPW device based on the piezoelectric PZT (Zr/Ti = 52/48) thin films for biological sensor applications. And we investigated the improvement of mass sensitivity in the FPW devices by etching the PZT on the delay-line. For biosensor application, when we bind bio-molecules directly on the delay-line to the device, the mass of the sensing plate is increased and a decrease in wave velocity, or resonant frequency, of the device is observed. The sensitivity of flexural plate wave device is nano gram level in milliliter by measuring resonant frequency shift. This is characterized by Au deposition method which has the mass loading effect similar to adsorption of protein. In the case of biotin-streptavidin binding, the device shows the good frequency response to streptavidin addition on the biotin coated Au of membrane. The FITC (Fluorescein Isothiocyanate) is labeled on streptavidin to check the binding between biotin and streptavidin. This is verified by using a fluorescent microscopy.