Abstract: An electrochemical sensor includes a ceramic substrate, a capillary disposed through the ceramic substrate, a plurality of electrodes disposed on a first surface of the ceramic substrate, an electrolyte disposed over at least a portion of each electrode of the plurality of electrodes, a coating disposed over the plurality of electrodes and the electrolyte, and control and detection circuitry coupled to the substrate. The coating sealingly couples to the substrate over the plurality of electrodes and the electrolyte, and the plurality of electrodes are electrically coupled to the control and detection circuitry.