BROWNIAN-MOTION AND FLUID-MECHANICS OF LIPID MONOLAYER DOMAINS

Lipid monolayers at the air-water interface show a variety of coexisting phases. Frequently, small, disklike solid domains are interspersed in a matrix of fluid lipid. These solid domains show strong electrostatic interaction as well as Brownian motion. A method is used to isolate single solid domains in a large, drift-free background of fluid lipid. The Brownian motion of these domains is then undisturbed and can be analyzed to a high degree of precision. This method allows one to perform a crucial test for theoretical calculations of the drag on a moving lipid domain.