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Proceedings Paper

Optical trapping meets atomic force microscopy: a precision force microscope for biophysics
Author(s): Gavin M. King; Allison B. Churnside; Thomas T. Perkins
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Paper Abstract

Mechanical drift between an atomic force microscope (AFM) tip and sample is a longstanding problem that limits tipsample stability, registration, and the signal-to-noise ratio during imaging. We demonstrate a robust solution to drift that enables novel precision measurements, especially of biological macromolecules in physiologically relevant conditions. Our strategy - inspired by precision optical trapping microscopy - is to actively stabilize both the tip and the sample using locally generated optical signals. In particular, we scatter a laser off the apex of commercial AFM tips and use the scattered light to locally measure and thereby actively control the tip's three-dimensional position above a sample surface with atomic precision in ambient conditions. With this enhanced stability, we overcome the traditional need to scan rapidly while imaging and achieve a 5-fold increase in the image signal-to-noise ratio. Finally, we demonstrate atomic-scale (~ 100 pm) tip-sample stability and registration over tens of minutes with a series of AFM images. The stabilization technique requires low laser power (<1 mW), imparts a minimal perturbation upon the cantilever, and is independent of the tip-sample interaction. This work extends atomic-scale tip-sample control, previously restricted to cryogenic temperatures and ultrahigh vacuum, to a wide range of perturbative operating environments.

Paper Details

Date Published: 27 August 2010
PDF: 7 pages
Proc. SPIE 7762, Optical Trapping and Optical Micromanipulation VII, 77620D (27 August 2010); doi: 10.1117/12.862745
Show Author Affiliations
Gavin M. King, National Institute of Standards and Technology (United States)
Univ. of Colorado, Boulder (United States)
Allison B. Churnside, National Institute of Standards and Technology (United States)
Univ. of Colorado, Boulder (United States)
Thomas T. Perkins, National Institute of Standards and Technology (United States)
Univ. of Colorado, Boulder (United States)


Published in SPIE Proceedings Vol. 7762:
Optical Trapping and Optical Micromanipulation VII
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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