Note: Guaranteed collocated multimode control of an atomic force microscope cantilever using on-chip piezoelectric actuation and sensing

Abstract

The quality (Q) factor is an important parameter of the resonance of the microcantilever as it determines both imaging bandwidth and force sensitivity. The ability to control the Q factor of multiple modes is believed to be of great benefit for atomic force microscopy techniques involving multiple eigenmodes. In this paper, we propose a novel cantilever design employing multiple piezoelectric transducers which are used for separated actuation and sensing, leading to guaranteed collocation of the first eight eigenmodes up to 3 MHz. The design minimizes the feedthrough usually observed with these systems by incorporating a guard trace on the cantilever chip. As a result, a multimode Q controller is demonstrated to be able to modify the quality factor of the first two eigenmodes over up to four orders of magnitude without sacrificing robust stability.

Multimodal atomic force microscopy with optimized higher eigenmode sensitivity using on-chip piezoelectric actuation and sensing

“…The wire-bonding pads labeled A and S are used for actuation and sensing. The ground trace is run between the signal traces and piezoelectric areas in order to minimize the actuator-sensor feedthrough [38].…”

“…Another indicator for a low actuator/sensor feedthrough is the location of the complex zero pair leading up to the first eigenmode. This effect is explained by a small amount of parasitic capacitance between actuator and sensor causing a residual amount of feedthrough charge with opposite sign to the motional charge [38].…”

All-optical dynamic analysis of the photothermal and photoacoustic response of a microcantilever by laser Doppler vibrometry

“…Till now, a wide spectrum of actuation approaches has been developed to characterize the dynamic response of CBs. Piezoelectric actuation [ 34 , 35 ] is the most used method, in which a cantilever is attached to a piezoelectric transducer or film. The involved mechanical contact has been reported [ 36 ] to affect the dynamic behavior of CBs, deteriorating the representativeness of the measured response.…”

Tuneable Q-Factor of MEMS Cantilevers with Integrated Piezoelectric Thin Films

“…A tailored differential sensing approach is used to cancel out manufacturing tolerances. By adding various active layers for actuation and sensing purposes, a positive position feedback (PPF) controller and a field-programmable analogue array (FPAA) are implemented as a multimode Q-controller that adjusts the Q-factor within three to four orders of magnitude [ 23 ].…”