Intermittent Contact Dynamics of a Micro-Cantilever in High Speed Contact Mode Scanning Probe Microscopy
The intermittent contact dynamics of a scanning probe microscopy (SPM) micro-cantilever are investigated in the context of high speed imaging in contact mode. At high scan speeds the cantilever can completely detach from the sample surface, and this lowers the achievable image resolution and limits the imaging speed. An analysis is performed, modeling the micro-cantilever as an Euler-Bernoulli beam and approximating the effect of the tip’s contact with the surface by an attached spring with an end mass that is subjected to attractive/repulsive interaction force. At low scan speeds, the cantilever follows the surface profile, while the frequency spectra exhibit a number of side-bands, while at higher speeds, the contact is intermittent. The sensitivity of the cantilever’s deflection varies along the length and hence the image resolution strongly depends on the point selected for optical laser deflection.