Active piezoelectric shunt control of an Atomic Force Microscope micro-cantilever

The benefits of decreasing the quality (Q) factor of an Atomic Force Microscope (AFM) micro-cantilever, when operating in tapping mode, using passive piezoelectric shunt control have been previously demonstrated. A passive electrical impedance is placed in series with the cantilever oscillation voltage to control the Q factor of the cantilever. The amount of Q factor reduction obtainable using this method is limited due to the passive nature of the shunt impedance. This work demonstrates that further decreases in the cantilever Q factor may be obtained through the use of an active impedance. The active impedance is designed in such a way that the piezoelectric shunt controller emulates a PPF controller in a displacement feedback loop. The damping obtained with this controller is compared with the maximum damping obtainable with a passive impedance.