The Sensorex CS511 rugged, low-maintenance sensor consists of a self-polarising galvanic cell that generates a millivolt signal proportional to the amount of oxygen present in the measured medium (typically water).
Oxygen diffuses through its membrane onto a cathode that produces a chemical reaction. An electrical current is produced by this reaction, which is converted from microamps to millivolts by an inline resistor. An inline thermistor provides automatic temperature compensation.