US Patent 7622844 Metal fiber brush interface conditioning

An electrical brush having at least one conductive element and at least one conditioning material coated on the at least one conductive element wherein the conditioning material has a composition and thickness on the conductive element such that, as deposited on a moving contact surface in the course of brush operation, the conditioning material can have an average film thickness S<˜1 μm so that current can be conducted by means of electron tunneling through a film thickness of the deposited conditioning material of Si≦12 nm thickness over a fractional area fC, greater than 0.01 of a foot print of the conductive element in a current conductive area.