Abstract: The system includes a wash source configured to concurrently generate a plurality of streams that are each incident on a sensor structure configured to detect a presence and/or amount of a compound on the sensor structure. The sensor structure has electrodes on a substrate. The wash source generates the streams such that each one of the streams is incident on a different one of the electrodes. Each of the streams is incident on one of the electrodes at an angle that is non-perpendicular to the sensor.