Measuring rotational diffusion of colloidal spheres with confocal microscopy

Abstract

We report an experimental method to measure the translational and rotational dynamics of colloidal spheres in three dimensions with confocal microscopy and show that the experimental values reasonably agree with the theoretical values. This method can be extended to study rotational dynamics in concentrated colloidal systems and complex bio-systems.

Eppur si muove, and yet it moves: Patchy (phoretic) swimmers

“…Direct measurement of the rotational dynamics could be alternatively implemented following recent microscopy developments, e.g. confocal imaging [56] or differential dynamic microscopy (DDM), originally developed for translational diffusion [57], then bacterial motility [58] and recently adapted to probe rotational dynamics [59].…”

Colloidal Rings by Site‐Selective Growth on Patchy Colloidal Disc Templates

“…[11] In addition, SiO 2 allows for covalent incorporation of fluorescent dye molecules,which makes these rings visible under fluorescent light as can be seen using afluorescent microscope or alaser confocal scanning microscope.L abeling was done by following ar eported procedure. [12] As shown in Figure 4d,t hese labeled colloidal rings show strong fluorescent emission.…”

Contact angle as a powerful tool in anisotropic colloid synthesis

“…However, in recent years, several studies have appeared where researchers prepared spherically symmetric particles with an internal anisotropy. These include engulfed-spheres by Liu and Böker, [66] core-shell particles with a number of trace particles containing two differently labelled cores by Schütter et al, [67] and rough particles where a small number of the particles used to create the roughness is fluorescently labelled by Ilhan et al [68] Internal anisotropy provides a reference axis with which to track the rotation of spheres, without altering the particles' interaction with the medium. These studies have provided a wealth of new information on the rotational motion of spherical particles, for example that rotational motion reduces by a factor ~2.5 with volume fraction from freestanding particles to close-packing.…”