ABSTRACT
The opportunity to develop the cantilever as a highly sensitive biosensor, however, had to wait the invention and widespread adoption of the atomic force microscope (AFM).4 An AFM measures the forces between the tip of a cantilever and the sample surface by recording the tip deflection of a static cantilever (contact mode AFM) or changes in the resonance frequency of a vibrating cantilever (dynamic mode AFM). As we will see in Section 15.2, nanocantilever based biosensors operate on a closely related principle, where interaction with biological molecules changes the bending (static mode) or resonance frequency (dynamic mode) of the cantilever.5 Note that these mechanical sensors offer an advantage of detecting both charged and neutral bio-molecules. In contrast, their electronic counterpart, e.g., ion-sensitive fieldeffect transistors (ISFETs)6 can only detect charged molecules.
