Electrical properties of electrorheological particle clusters

The electrical conductivity of static clusters of ∼220-μm diameter humidified glass beads in silicone oil arranged in a rectangular or cubic lattice was determined under d.c. electric field. The current density flowing through the cluster increased with field strength. It was independent of the number of glass spheres forming a chain in the cluster but increased with the number of chains comprising the cluster. The conductivity of a single chain was about twice the saturation conductivity of the silicone oil. Some possible reasons for the enhanced current density of a cluster of particles compared to an equal number of single-row chains are proposed.