1. A method of fabricating an electrode sensor, comprising:
providing a substrate with a first electrode;
forming a resist layer on the substrate to cover the first electrode;
patterning the resist layer to expose a portion of the first electrode;
forming an insulating layer on the substrate;
removing the insulating layer on the resist layer and the resist layer to form a well in the insulating layer; and
forming a second electrode in the well to be electrically connected to the first electrode.