Minimizing probe loss in tapping mode Atomic Force Microscopy using a switched gain resonant controller

When imaging samples containing large steep drops in topography at high speed, with an Atomic Force Microscope (AFM) operating in tapping mode, it is common for the sensing cantilever probe to lose contact with the sample. This leads to significant artifacts in the resulting image. In this work a switched gain resonant controller is developed to increase the effective quality (Q) factor of the AFM micro-cantilever when the tip loses contact with the sample. This technique is shown to considerably reduce the time that the probe is detached from the sample resulting in reduced image artifacts. This method of Q factor switching is designed to be compact and easily integrable into existing AFMs.