Mass sensing device for liquid environment

1. A device for sensing a mass in a liquid environment comprising:

a resonator comprising a piezo layer disposed between a top electrode and a bottom electrode;

a sensing surface located adjacent the top electrode;

a gap formed between the top electrode and the sensing surface, the gap structured and operable to provide acoustic energy loss isolation; and

at least one post disposed between the top electrode and the sensing surface to support the sensing surface and provide the gap.

2. The device of claim 1 wherein the at least one post comprises a plurality of posts.

3. The device of claim 1 wherein the gap is filled with air or a gas.

4. The device of claim 1 wherein the gap is a vacuum gap.

5. The device of claim 1 wherein the resonator is a film bulk acoustic resonator.

6. The device of claim 1 wherein the electrodes are made from a material selected from the group consisting of molybdenum, ruthenium, aluminum (Al), platinum (Pt), and tungsten (W).

7. The device of claim 6 wherein the electrodes are molybdenum or ruthenium.

8. The device of claim 1 wherein the shape of the electrodes are selected from the groups of shapes consisting of a rectangle, a circle, an ellipse and a pillow shape.

9. The device of claim 8 wherein the electrodes are elliptical or pillow shape.

10. The device of claim 1 wherein the sensing surface includes a binding layer for binding a target chemical or biological analyte.

11. The device of claim 1 wherein the gap is sealed by a binding diaphragm.

12. The device of claim 11 wherein the binding diaphragm is made from a low stress silicon nitride.

13. The device of claim 11 wherein the binding diaphragm is between about 0.5 microns and about 1.0 micron thick.