Hydrodynamic coupling to the electrical response of fluid suspensions of non-Brownian conducting particles

We report on the electrical response of conducting non-Brownian suspensions to applied steady shear. We show using dc-conductivity measurements in a rheo-dielectric device that a shear-rate dependent conductivity increases both with the shear intensity and the particle volume fraction. The conductivity increases instantaneously upon flow start-up and returns instantaneously and reversibly to the quiescent value upon flow cessation. For volume fractions exceeding 30 vol% microspheres, the ratio of the conductivity under flow to that in the quiescent state can exceed a factor of 10⁵. We rationalize these results based on a simplistic scaling law that confirms the hydrodynamic forces couple to the interparticle electron transfer rate. These observations help to reconcile emerging experimental evidence for the role of particle mobility in determining electrical transport in colloidal fluids and suspensions and could prove a basis for new mechano-electric sensing modalities as well as improved electrochemical storage technologies.