There are two types of methods to extract the forces acting on colloids: equilibrium-
distribution and drift-diffusion methods [1,2,3]. While the former can only be used when the
system is in thermodynamic equilibrium, drift-diffusion methods relying on displacement
measurements do not require this condition. Alas, because of the solvent agitation,
deterministic displacements caused by the for...
There are two types of methods to extract the forces acting on colloids: equilibrium-
distribution and drift-diffusion methods [1,2,3]. While the former can only be used when the
system is in thermodynamic equilibrium, drift-diffusion methods relying on displacement
measurements do not require this condition. Alas, because of the solvent agitation,
deterministic displacements caused by the forces are tangled with Brownian motion and when
this thermal noise is heterogeneous, particles are subject to a noise-induced spurious force that
adds another layer of complexity [4,5].
Recently, a novel method based on information and communication theory was
introduced to infer force-fields and diffusion from high dimensional stochastic trajectories [6].
Within this approach, we develop a framework for the analysis of trajectories of invidual
colloids: we first validate our approach with molecular dynamics simulations and we then
successfully apply it to three-dimensional trajectories of individual colloids measured using a
modified version of 3D-phase contrast holographic microscopy [7]. Within this framework we
are able to infer the one-body and two-body interactions as well as the diffusion and spurious
force in different solvents. Our method also allows to investigate the measurement error to
optimize the acquisition protocol.
References
[1]T. Brettschneider, G. Volpe, L. Helden, J. Wehr, C. Bechinger, Phys. Rev. E, 83, 041113 (2011)
[2]A. Stones, R. Dullens, D. Aarts, Phys. Rev. Lett., 123, 098002 (2019)
[3]I. Jenkins, J. Crocker, T. Sinno, Soft Matter, 11, 6948-6956 (2015)
[4]A. Serov, F. Laurent, C. Floderer, K. Perronet, C. Favard, D. Muriaux, N. Westbrook, C. Vestergaard, J. Masson, Sci. Rep., 10, 3783 (2020)
[5]G. Volpe, J. Wehr, Rep. Prog. Phys., 79, 053901 (2016)
[6]A. Frishman, P. Ronceray, Phys. Rev. X, 10, 021009 (2020)
[7]F. Cheong, C. Wong, Y. Gao, M. Nai, Y. Cui, S. Park, L. Kenney, C. Lim, Biophysical Journal, 108, 1248-1256 (2015)