Optimisation of a nano-positioning stage for a Transverse Dynamic Force Microscope

G De Silva,S.C Burgess,T Hatano,S.G Khan,K Zhang,T Nguyen,G Herrmann,C Edwards,M Miles

doi:10.1016/j.precisioneng.2017.05.005

G De Silva, S.C Burgess + Show 7 more

Open Access

https://doi.org/10.1016/j.precisioneng.2017.05.005

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Abstract

This paper describes the optimisation of a nano-positioning stage for a Transverse Dynamic Force Microscope (TDFM). The nano-precision stage is required to move a specimen dish within a horizontal region of 1μm×1μm and with a resolution of 0.3nm. The design objective was to maximise positional accuracy during high speed actuation. This was achieved by minimising out-of-plane distortions and vibrations during actuation. Optimal performance was achieved through maximising out-of-plane stiffness through shape and material selection as well optimisation of the anchoring system. Several shape parameters were optimised including the shape of flexural beams and the shape of the dish holder. Physical prototype testing was an essential part of the design process to confirm the accuracy of modelling and also to reveal issues with manufacturing tolerances. An overall resonant frequency of 6kHz was achieved allowing for a closed loop-control frequency of 1.73kHz for precise horizontal motion control. This resonance represented a 12-fold increase from the original 500Hz of a commercially available positioning stage. Experimental maximum out-of-plane distortions below the first resonance frequency were reduced from 0.3μm for the first prototype to less than 0.05μm for the final practical prototype.

Highlights

Since its invention in 1986 [1], atomic force microscopes (AFMs) have become one of the most important tools to measure the 3D topography of nano-scale objects including both biological and non-biological specimens [2,3,4]
AFMs are widely used for biomedical analysis in cancer research [6], cell biology research [7] and material science [8]
AFMs have a number of advantages over scanning electron microscopes (SEMs) such as the ability to carry out 3D scanning, the ability to scan untreated specimens and the ability to scan without the need for a vacuum

Summary

Introduction

The need for design optimisation of atomic force microscopes. Since its invention in 1986 [1], atomic force microscopes (AFMs) have become one of the most important tools to measure the 3D topography of nano-scale objects including both biological and non-biological specimens [2,3,4]. AFMs have a number of advantages over scanning electron microscopes (SEMs) such as the ability to carry out 3D scanning, the ability to scan untreated specimens and the ability to scan without the need for a vacuum. One of the key disadvantages of AFMs is relatively slow scanning rates.

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