Apparatus and methods employing contact lenses having electrochemical sensors that have adjustable analyte-sensing sensitivity are provided. In some aspects, level of the analyte or biological substance is detected and a number of sub-electrodes of the sensor are turned on or off based on the level of the analyte or biological substance. The sensitivity of the sensor is adjusted based on the number of sub-electrodes that are turned on or off. In some aspects, the current level from the sensor is employed in determining the number of sub-electrodes to turn on or off. In one aspect, a contact lens includes: a substrate a power component a circuit and an adjustment circuit. The circuit can include a potentiostat and a sensor electrically coupled to the potentiostat, and configured to sense a level of an analyte. The sensitivity of the sensor can be adjustable by the adjustment circuit.
