What are aluminium oxide capacitance dew-point sensors?
Aluminium oxide capacitance dew-point sensors measure moisture content (dew point) in gases. They are widely recognised for accuracy, reliability, and rapid response when detecting trace water vapour, making them essential across many industrial settings.

How do they work?
The operating principle is capacitance measurement:

• Sensor structure: A thin, porous aluminium oxide layer is deposited on a conductive substrate (typically aluminium) and sandwiched between two electrodes to form a capacitor.

• Moisture absorption: Water vapour molecules diffuse into the porous oxide layer when exposed to the gas.

• Capacitance change: Absorbed moisture alters the dielectric constant of the oxide. Because capacitance depends on the dielectric between the electrodes, changes in moisture produce a measurable shift in capacitance.

• Signal processing: Electronics detect this change and convert it to a dew-point value (or another engineering unit) for display or transmission to monitoring and control systems.

Key features

• High sensitivity: Detects very low moisture levels (down to parts per million).

• Fast response: Reacts quickly to changes in humidity.

• Long-term stability: Maintains accuracy with minimal drift over extended periods.

Why they matter in industry
These sensors help safeguard process integrity, safety, and product quality:

• Compressed air systems: Control moisture to prevent corrosion, equipment failures, and contamination of pneumatic processes.

• Natural gas processing: Ensure gas quality, avoid pipeline blockages, and reduce hydrate formation risk.

• Pharmaceutical and food: Support precise humidity control for consistency, shelf life, and regulatory compliance.

• Semiconductor manufacturing: Enable ultra-dry conditions to prevent defects and maintain yields.

• Power generation: Monitor moisture in turbines and generators to prevent insulation breakdown and electrical faults.

Advantages over other technologies

• Robust: Tolerant of contamination and harsh conditions.

• Low maintenance: Infrequent calibration and servicing.

• Wide measurement range: Suitable for both very dry and moderately humid environments.