Related Experiment Video
Updated: Jun 22, 2026

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions
Published on: April 19, 2018
Two-dimensional to three-dimensional transition in soap films demonstrated by microrheology
1Department of Physics, Emory University, Atlanta, Georgia 30322, USA.
Abstract:
We follow the diffusive motion of colloidal particles of diameter d in soap films of varying thickness h with fluorescence microscopy. Diffusion constants are obtained both from one- and two-particle microrheological measurements of particle motion in these films. These diffusion constants are related to the surface viscosity of the interfaces comprising the soap films, by means of the Trapeznikov approximation and Saffman's equation for diffusion in a 2D fluid. Unphysical values of the surface viscosity are found for thick soap films (h/d>7+/-3), indicating a transition from 2D to 3D behavior.
Related Concept Videos
Colloids
Micelles
Fluid Mosaic Model

