Rheology and Microrheology

What is the difffrence between rheology and microrheology ?

For a basic description of rheology look here.Microrheology is a very specific form of rheology. In classic / traditional rheology we have to apply a force or movement to the sample in order to perform any test.That implies that this movement or force we apply might change the sample (especially very delicate or "weakly structured" samples). Microrheology measures the samples at rest . Gravitation forces still apply to the sample but otherwise the sample simply sits in a container. We measure the movement or vibration of particles in the sample using light . The proper name is Multi-Speckle Diffusing Wave Spectroscopy or MS-DWS in short.

We can learn a number of interesting parameters from microrheology and the MS-DWS technique.

Solid Liquid Balance: the ratio between the solid-like and the liquid-like behavior of the studied sample. Monitor properties such as adhesion, spreadability, gel point, shape stability, physical stability, etc...
Elasticity Index: Elasticity strength in the studied sample. Monitor properties such as mesh/pore size, hardness, recovery, gelation, etc...
Macroscopic Viscosity Index: quantify and compare the macroscopic viscosity at zero-shear. Monitor properties such as the effect of a thickening agent, texture, flowability, long-term stability, etc..

 Microrheology instruments : RHEOLASER Master
                                             RHEOLASER Crystal