GE Panametrics Moisture Probe This moisture probe is also known as ALUMINIUM OXIDE MOISTURE SENSOR . An Aluminium   probe is chemically treated to form a thin porous coating of aluminium oxide. The aluminium oxide is then coated with a thin, permeable layer of gold. . The gold layer and the aluminium probe form the anode and cathode. The gold layer is permeable to moisture and conductive. This forms the second electrode of a capacitor. The pores in the aluminum oxide layer absorb moisture from the gas stream in amounts directly proportional to the moisture content of the gas stream. The absorption of water molecules changes the capacitance of the sensor. The capacitance of the sensor is measured which is then converted to the moisture value. The radiuses of the pores in aluminium oxide layer make the sensor specific to water molecules. Types of  Panametr ics moisture probes 1. M Series     - Moisture and Temperature measurement 2. TF S