Electrically conductive composition

A sensor comprising two layers of semi-conductor separated by a layer of a composition comprising a quantity of electrically conductive particles including first electrically conductive particles, and an electrically insulating binder, wherein the first electrically conductive particles are magnetite particles, and the quantity of magnetite particles includes a distribution of particle sizes between sub-micron and tens of microns, and 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 wherein the magnetite particles are irregular in shape, the electrically conductive particles contained in the binder, wherein the binder forms a layer around each electrically conductive particle, and wherein the composition is electrically anisotropic and pressure sensitive, the electrical resistance of the composition changing immediately and only around the point of exertion of pressure on the composition, the change in resistance being anisotropic and in accordance with the pressure exerted thereon, the resistance reducing with increased applied pressure and increasing with reduced applied pressure, between a quiescent state in the absence of pressure and an electrically conducting state when the composition is subject to an applied pressure, each layer of semi-conductor having at least one electrode attached thereto and wherein the at least one electrode of one layer of semi-conductor is arranged orthogonal to the at least one electrodes of the other semi-conducting layer.

A method of manufacturing a composition comprising a quantity of electrically conductive particles including first electrically conductive particles, and an electrically insulating binder, wherein the first electrically conductive particles are magnetite particles, and the quantity of magnetite particles includes a distribution of particle sizes between sub-micron and tens of microns, and 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 wherein the magnetite particles are irregular in shape, the electrically conductive particles contained in the binder, wherein the binder forms a layer around each electrically conductive particle, and wherein the composition is electrically anisotropic and pressure sensitive, the electrical resistance of the composition changing immediately and only around the point of exertion of pressure on the composition, the change in resistance being anisotropic and in accordance with the pressure exerted thereon, the resistance reducing with increased applied pressure and increasing with reduced applied pressure, between a quiescent state in the absence of pressure and an electrically conducting state when the composition is subject to an applied pressure, the method comprising the step of:

• providing the electrically conductive particles and the binder;
• and
• mixing the electrically conductive particles with the binder until the mixture thereof is homogeneous.