An eye-mountable device includes an electrochemical sensor embedded in a polymeric material configured for mounting to a surface of an eye. The electrochemical sensor applies a stabilization voltage between a working electrode and a reference electrode to allow the amperometric current to stabilize before powering measurement electronics configured to measure the amperometric current and communicate the measured amperometric current. The electrochemical sensor consumes less power while applying the stabilization voltage than during the measurement. The measurement is initiated in response to receiving a measurement signal at an antenna in the eye-mountable device.