An electrochemical sensor is disposed on a sensor substrate suitable for flip-chip mounting to another substrate. The electrochemical sensor can be fabricated in bulk by patterning sets of electrodes on a common substrate with vias that electrically couple each electrode to a conductive pad on the opposite side of the substrate. The substrate with electrodes thereon can then be diced and the individual electrochemical sensors can be flip-chip mounted in a body-mountable device in which the sensor can be used to obtain analyte concentrations. As a result, fabrication of the electrochemical sensor electrodes can be isolated from fabrication of the other electronics in the device, which can facilitate efficient fabrication of the sensor and allows for other electronics to be fabricated without restrictions associated with the electrode fabrication.