Electro-rheological fluids:

Esto va, esto va que explotaaaa !!!!

    We study the structure of electrorheological (ER) fluids(ER Bibliography).

    • ER fluids are colloidal suspensions of particles of size 1-100 microns in non-conducting solvents

    • The viscosity of ER suspensions can increase 2-3 orders of magnitude when electric fields ~1kV/mm are applied across them. The response takes ~ 1ms. This increase in viscosity is attributed to the energy required to disassociate the electric field induced structures.

    As shown in the diagram below, an external electric field induces a dipole oriented parallel to the field in a dielectric particles (a sphere here), and dipoles interact such that they align themselves along the field direction.


    (below) Schematic of a ER suspension forming chains across electrodes and undergoing shear:The force required to break apart the electric-field induced structures manifests itself in an increase in viscosity.

    Chains from Klingenberg and Zukoski, Langmuir 1990, 6, 15-24

    Because of the large increase in viscosity, and the rapid, reversible viscous response, technological applications have been proposed for ER fluids, in devices such as shock absorbers, clutches and valves.