Biosensor utilizing a resonator having a functionalized surface

A method for detecting target molecules comprising:

• providing a film bulk acoustic resonator (FBAR) comprising a first FBAR, wherein the first FBAR has a first surface functionalized with a first type of biomolecules, wherein the presence of target molecules causes the first type of biomolecules to change the frequency response of the first FBAR;
• exposing the first surface of the first FBAR to a test fluid;
• determining a frequency response of the first FBAR after the first surface has been exposed to the test fluid;
• and
• determining, based upon the frequency response of the first FBAR, whether the test fluid contained target molecules,
• said FBAR being mounted on an insulator comprising a semiconductive layer and first and second, spaced apart insulating layers, said FBAR having a first edge contacting said first insulating layer and a second edge contacting said second insulating layer, wherein said semiconductive layer, said spaced apart insulating layers, and said FBAR define a void region, therebetween.