Biosensor platform based on stress-improved piezoelectric membrane

A new design as piezoelectric membrane is introduced to improve the performance of a diaphragm based biosensor platform. In the design, stress is introduced into the diaphragm by a vacuum chamber and makes it work as membrane with a higher sensitivity and a higher Q factor. The mass sensitivity of stress-improved membrane was investigated and an effective mass approach is used to simulate the sensitivity of the device for a point mass load. Piezoelectric membranes with different sizes have been built using PVDF piezo-polymers. These devices were characterized in air and in water. The experimental results are consistent with the theoretical simulation and indicate that the device in liquid can have a higher Q factor than that in air. A theoretical model, which is a sphere executing translatory oscillations in viscous fluid, was used to analyze the Q factor in liquid environment. The results indicated that the large Q factor in liquid can be attributed to the relative large effective mass of membrane in liquid environment.