Abstract: A gas sensor comprises an electrically conductive housing including a shelf member and a chamber containing an electrolyte. A conductive cathode mounted on the shelf member has a plurality of holes therein and a conductive tail element. A gas permeable membrane overlying the cathode prevents electrolyte from escaping the chamber but allows gas to permeate the membrane. An anode within the chamber is in electrical contact with the electrolyte and the conductive housing. The tail element is adapted to be connected to the anode through an electrical circuit including the conductive housing.