Patent ID: 7735379

Claim:
A fluid flow sensor for sensing a flow of a fluid through a region, the sensor comprising a magnetic circuit for applying a magnetic field to at least a part of the region, and a configuration of electrodes for sensing a potential generated in operation between the electrodes in response to the fluid flowing through the magnetic field wherein each of the electrodes is formed by a succession of a metal element, a metal halide element, and an at least partially electrically conductive porous element located in contact with said metal halide element and, in use, with said fluid, said porous element being operable to at least partially hinder progressive loss of the metal halide element to the flow of the fluid and to provide an electrically conductive path between the flow of the fluid and the metal halide element and thereby to the metal element; wherein said porous element is less electro-chemically active than the metal employed for the metal element.