A proof-of-concept on Adaptive Control for High-Speed Atomic Force Microscopy

Master thesis (2022)

Authors

S.J.M. van der Maarel Mechanical Engineering

Contributors

G.J. Verbiest Dynamics of Micro and Nano Systems - Mechanical, Maritime and Materials Engineering (supervisor 1)
J. Noom Team Michel Verhaegen - Mechanical, Maritime and Materials Engineering (supervisor 1)
C.S. Smith Team Carlas Smith - Mechanical, Maritime and Materials Engineering (supervisor 1)
F. Alijani Dynamics of Micro and Nano Systems - Mechanical, Maritime and Materials Engineering (supervisor 2)
Faculty
Mechanical Engineering
Copyright: © 2022 Stefan van der Maarel
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Published Date

09-12-2022

Language

English

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Faculty

Mechanical Engineering

Abstract

High-Speed Atomic Force Microscopy is widely used for investigating biological architectures and the semiconductor industry. The main limitation comes from parachuting or the Wile E. Coyote effect. Parachuting is the phenomenon where the cantilever taps on the sample towards a steep decrease in height, but does not get adjusted for this decrease fast enough, resulting in poor imaging quality at higher scan speeds. A proof-of-concept has been modeled for an adaptive raster scanning methodology on the X and Y piezo actuators. There will be investigated how a variable scan speed can decrease the effect of parachuting and thereby improve the spatial resolution. A detection algorithm is designed to measure the parachuting and uphill events at high scanning speed as accurately and precisely as possible during the forward scan. This has been done by defining a mixed signal that multiplies the first and second derivatives of the filtered deflection signal. A variable scan speed will be applied for the backward scan. The detection algorithm turned out to have a very high repeatability of 97.1% for the uphill events, and 93.6% for the parachuting events. Its accuracy turned out to have a maximum deviation of one signal period, which has been accounted for within the controller. Implementing this for the adaptive controller results in an improvement in both resolution and time efficiency. The adaptive controller is up to 9.5 times more accurate and time efficient compared to conventional methods.