Microviscosity

Microviscosity is the friction experienced by a single particle undergoing diffusion because of its interaction with its environment at the micrometer length scale. The concept of microviscosity is intimately related to the concept of single particle diffusion and can be measured using microrheology. Microviscosity is also referred to as microscopic viscosity.

Understanding microviscosity requires an understanding of viscosity and diffusion i.e. macroscopic viscosity and bulk diffusion and where their assumptions break down at the micro to nanometer scale where physicists are still trying to replace phenomenological laws with physical laws governing the behavior of single particle mobility.

In the field of biophysics, a typical microviscosity problem is understanding how a biomolecule undergoes movement within a cellular compartment which will depend upon many factors such as the size, shape, charge, quantity and density of both the diffusing particle and all members of its environment.

A comprehensive explanation of single protein diffusion and microviscosity and its relation to established viscosity and diffusion theory and polymer phenomenology and how it can be measured using the microrheological technique of fluorescence correlation spectroscopy can be found in the Thesis of Aron Benjamin Goins

Quotations

• "The friction experienced by a single particle can be thought of as a microscopic viscosity (microviscosity) and should not necessarily agree with the bulk viscosity since it is a measure of the probe's local friction whereas bulk viscosity analogously would be the measure of an infinitely large probe." Aron Benjamin Goins