Enhanced dispersion in an oscillating array of harmonic traps
Abstract
Experiment, theory, and simulation are employed to understand the dispersion of colloidal particles in a periodic array of oscillating harmonic traps generated by optical tweezers. In the presence of trap oscillation, a non-monotonic and anisotropic dispersion is observed. Surprisingly, the stiffest traps produce the largest dispersion at a critical frequency, and the particles diffuse significantly faster in the direction of oscillation than those undergoing passive Stokes-Einstein-Sutherland diffusion. Theoretical predictions for the effective diffusivity of the particles as a function of trap stiffness and oscillation frequency are developed using generalized Taylor dispersion theory and Brownian dynamics simulations. Both theory and simulation demonstrate excellent agreement with the experiments, and reveal a new ``slingshot'' mechanism that predicts a significant enhancement of colloidal diffusion in dynamic external fields.
Cite
@article{arxiv.2209.12399,
title = {Enhanced dispersion in an oscillating array of harmonic traps},
author = {Joseph M. Barakat and Sho C. Takatori},
journal= {arXiv preprint arXiv:2209.12399},
year = {2023}
}
Comments
5 pages, 4 figures, 15 pages supplemental material