Aluminum Oxide - The key solution for moisture and dew point measurements

Aluminum Oxide (Al₂O₃) sensors work by measuring the capacitance between the aluminum core and a gold film deposited on the oxide layer. The capacitance varies according to the water vapor content in the pores of the oxide layer.

The ultra-thin Al₂O₃ sensors have three innovative structural improvements that offer better performance than traditional Al₂O₃ sensors, with advantages for sensitivity and stability.

1. A much thinner oxide layer: This results in higher capacitance, since this is inversely proportional to the distance of the capacitor’s plates from each other. Higher capacitance results in a more sensitive measurement. The thinner layer also allows water molecules to travel in and out of the pores more quickly, ensuring a faster response.

2. A better-defined barrier layer: The sharply defined barrier means that the sensor’s wet to dry capacitance ratio is very high, reducing the effects of any drift due to undesirable factors. It also reduces metal migration, one of the major causes of drift in conventional Al₂O₃ sensors.

3. Unique pore geometry: Holding more water than conventional sensors, the ordered pore geometry increases the change in capacitance for a given change in dew point. This means greater accuracy and a quicker response. It is also more stable, so only annual calibration checks are needed when the sensor is used in clean, non-corrosive gases.