A process for fabricating a microelectrode is described that includes: a) providing a substrate comprising at least one polymer micro-ridge, where the polymer micro-ridge comprises an upper surface and two walls, and the two walls form an angle with a lower surface; b) depositing a metal thin film on the upper surface, the two walls, and the lower surface; and c) etching a predetermined amount of the deposited metal thin film on the lower surface to form the microelectrode.