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Proceedings Paper

Trapping-force calibration in biological applications of optical tweezers
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Paper Abstract

In this work we analyzed the calibration of optical trapping forces. One calibration technique utilizes the controlled motion of a trapped object in a fluid with known viscosity where the trapping force is calculated from the Stokes’ Law based on inertia-free assumptions (i.e., neglecting velocity and acceleration of the trapped object). In our study, we calculated the displacement of the trapped object from the trapping center using Fourier analysis of the equation of motion. Waveforms of different frequencies were used both in theoretical modeling and experiments to control the motion of the trapped object in an aqueous solution. Calibration data obtained experimentally were compared to theoretical results. The dynamic analysis of the trapped object showed that trapping force can significantly differ from theoretically predicted values under inertia-free assumptions. Various factors including type of the waveform used to control the motion of a trapped object during calibration, its frequency, viscosity of the calibration fluid, mass and dimensions of the trapped object, stiffness of the optical trap and frequency response of the equipment used to control the motion of the trapped object contribute to the differences.

Paper Details

Date Published: 19 June 2003
PDF: 9 pages
Proc. SPIE 4962, Manipulation and Analysis of Biomolecules, Cells, and Tissues, (19 June 2003); doi: 10.1117/12.477849
Show Author Affiliations
Sergey A. Ermilov, Rice Univ. (United States)
Bahman Anvari, Rice Univ. (United States)

Published in SPIE Proceedings Vol. 4962:
Manipulation and Analysis of Biomolecules, Cells, and Tissues
Dan V. Nicolau; Joerg Enderlein; Robert C. Leif; Daniel L. Farkas, Editor(s)

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