Terminology » Measurements » Humidity Sensor Advantages and Disadvantages: Capacitive, Psychrometric, Hygrometric

Humidity Sensor Advantages and Disadvantages: Capacitive, Psychrometric, Hygrometric

humidity sensor sensor technology capacitive sensor hygrometry psychrometry

This article explores the pros and cons of different types of humidity sensors, covering capacitive, psychrometric, and hygrometric measurement methods.

Definition:

A humidity sensor measures the amount of moisture in the air. While “moisture” refers to water content in liquids and solids, “humidity” specifically describes the water vapor content in gases.

Capacitive Humidity Sensor Capacitive Humidity Sensor

Different methods exist for measuring humidity, each with its own accuracy and suitability for long-term use. The primary methods include:

  • Capacitive air humidity measurement
  • Psychrometric air humidity measurement
  • Hygrometric air humidity measurement

The figure above illustrates a capacitive humidity sensor. For more in-depth information, refer to the basics of humidity sensor types.

The advantages and disadvantages of each humidity sensor type are directly linked to the mechanisms employed in their construction. Let’s delve into a detailed comparison.

Advantages and Disadvantages of Humidity Sensors

The following table summarizes the advantages and disadvantages of different humidity sensor types:

Humidity sensing methodAdvantagesDisadvantages
Capacitive- Can withstand temperatures below 0°C
- Requires minimal maintenance over long periods
- Offers flexibility in application
- Independent of atmospheric pressure; functions even under pressure		- Exhibits limited long-term stability
- Sensitive to dewing and certain aggressive substances
Psychrometric- High accuracy
- High quality
- Usable up to 100% relative humidity (RH) in all substances
- No aging effect except when the wick is contaminated		- Difficult to use at temperatures below 0°C and in low humidity environments
- Long-term measurement is limited by the required water reserve and wick maintenance
Hygrometric- Easy to clean
- Simple construction
- Low cost
- Usable in contaminated environments		- Limited accuracy
- Limited measurement range
- Slow measurement speed