Composite materials

A composite material responsive to stress selected from the group of mechanical and electrical stress, the composite material comprising at least one non-conductive binder and at least a first electrically conductive filler, wherein the conductivity of the composite material in an unstressed state is related to the conductivity of the at least one non-conductive binder and in a stressed state to the conductivity resulting from the presence of the at least first electrically conductive filler in the composition, wherein the first electrically conductive filler is comprised of magnetite particles in a particle size distribution, and the at least one binder is inelastic and selected from the group comprising an oil, a gel, a wax, a gel-wax, a gel-ink and mixtures thereof, wherein the magnetite particles have a plurality of planar faces, adjacent planar faces connected at a vertex, the particles each having a plurality of vertices, and the binder fills interstices between the electrically conductive filler particles, forming a layer around each electrically conductive particle and insulating adjacent particles from each other.