Composite materials

A sensor capable of detecting the direction of shear forces comprises electrical contacts 1 and a body including a composite material, responsive to force, pressure, mechanical and/or electrical stress, connected to the body. The composite material 2 comprises at least one substantially non-conductive elastic binder and at least a first electrically conductive filler. The binder forms a layer around each electrically conductive filler particle, filling interstices between the electrically conductive filler particles and insulating adjacent particles from each other. The conductivity of the composite material in an unstressed state is related to the conductivity of the at least one substantially nonconductive binder and in a stressed state to the conductivity resulting from the presence of the at least first electrically conductive filler in the composition. The binder includes an oil, a gel, a wax a gel-wax, gel-ink or mixtures thereof and the filler is comprised of magnetite particles which allows the electrical resistance of the composite material to change anisotropically with the pressure applied between the quiescent state and the electrically conducting state when the composition is subject to applied pressure. The electrical contacts comprise a base electrode 1b and at least one peripheral electrode 1c-1f.