AFM Cantilever Shape
Rectangular (diving board) AFM cantilevers are the most widely used as the approximate values of their spring constants and resonance frequencies can be easily calculated from their dimensions. Generally, any rectangular AFM cantilever can be produced with any required type of the AFM tip with a few exceptions.
|SEM image of AFM probe with three rectangular silicon AFM cantilevers.||Schematic drawing of the AFM probe chip.|
The rectangular shape is the best in terms of Q-factor, regularity of the resonance curve, and ease of use. The simplicity of the geometry allows making some approximate calculations of some important parameters of the AFM cantilever like torsional and flexural force constants. These AFM probes are suitable for both contact and oscillatory AFM modes.
The three cantilever AFM probes may be useful for material-sensitive contrast and phase-enhanced images of soft samples, whose stiffness is not known. The AFM cantilever with the most suitable stiffness can be chosen during the experiment. One should also take into account that the characteristics of the AFM cantilevers may vary slightly, and having three AFM cantilevers helps choosing the best match for the experiment.
The redundant two AFM cantilevers have to be broken off, otherwise they may cause a cross-talk in tapping mode, especially in liquid. In contact mode, the redundant AFM cantilevers may damage the sample, if not broken off.