Interdigitated microelectrode and a process for producing the interdigitated microelectrode

A process for producing an interdigitated microelectrode, which process comprises providing a substrate, providing a first layer of a first metal on the substrate, and providing a second layer of a second metal on the substrate, and the process being such that the first layer comprises a plurality of line microelectrodes which are connected at a first end and are not connected at a second end, the second layer comprises a plurality of line microelectrodes which are connected at a first end and are not connected at a second end, the line microelectrodes of the first layer and the line microelectrodes of the second layer extend into each other but do not touch each other thereby to form an interdigitated microelectrode array, the first layer of the first metal is a thick film printed first layer, the second layer of the second metal is a thick film printed second layer, the line width of the line microelectrodes of the second layer is such that the line width has been reduced after deposition of the second layer on the substrate, the line width has been reduced by thin film photolithography and etching, the line width has been reduced to less than 25 microns wide, the first metal is different from the second metal, and the second metal is gold.