Humidity Sensors

As-Salaam-Alaikum, Welcome to my blogger "World of Knowledge".Here we discuss the topic Humidity Sensors.

Points to be discuss in this Article are given below:

• Humidity Sensors
• Humidity Sensor in Industries
• Uses of Humidity Sensors
• Sensors based resistive effect
• Types of Humidity Sensors
• Application of Humidity Sensors are far and wide

HUMIDITY SENSORS:

Humidity is the presence of water in air. The amount of water vapour in air can affect human comfort as well as many manufacturing processes in industries. The presence of water vapor also influences various physical, chemical, and biological processes.

Humidity Sensor

Humidity sensors in industries:

Humidity measurement in industries is critical because it may affect the business cost of the product and the health and safety of the personnel.Hence, humidity sensing is very important, especially in the control systems for industrial processes and human comfort.

Uses of humidity sensors:

• Controlling or monitoring humidity is of paramount importance in many industrial & domestic applications.
• In semiconductor industry, humidity or moisture levels needs to be properly controlled & monitored during wafer processing.
• In medical applications, humidity control is required for respiratory equipments, sterilizers, incubators, pharmaceutical processing, and biological products.
• Humidity control is also necessary in chemical gas purification, dryers, ovens, film desiccation, paper and textile production, and food processing.
• In agriculture, measurement of humidity is important for plantation protection (dew prevention), soil moisture monitoring, etc.
• For domestic applications, humidity control is required for living environment in buildings, cooking control for microwave ovens, etc. 

Types of Humidity Sensors:

There are three basic types of humidity sensors:

• Capacitive
• Resistive
• Thermal

Capacitive:

A capacitive humidity sensor measures relative humidity by placing a thin strip of metal oxide between two electrodes. The metal oxide’s electrical capacity changes with the atmosphere’s relative humidity. Weather, commercial and industries are the major application areas.The capacitive type sensors are linear and can measure relative humidity from 0% to 100%. The catch here is a complex circuit and regular calibration. However, for designers this a lesser hassle over precise measurement and hence these dominate atmospheric and process measurements. These are the only types of full-range relative humidity measuring devices down to 0% relative humidity. This low-temperature effect often leads to them being used over wide temperature ranges without active temperature compensation.

Resistive:

Resistive humidity sensors utilize ions in salts to measure the electrical impedance of atoms. As humidity changes, so do the resistance of the electrodes on either side of the salt medium.

Thermal:

Two thermal sensors conduct electricity based upon the humidity of the surrounding air. One sensor is encased in dry nitrogen while the other measures ambient air. The difference between the two measures the humidity.

Applications of humidity sensors are far and wide:

The applications of humidity sensor range far and wide. People with illnesses affected by humidity, monitoring and preventive measure in homes employ humidity sensors. A humidity sensor is also found as part of home heating, ventilating and air conditioning systems (HVAC systems). These are also used in offices, cars, humidors, museums, industrial spaces and greenhouses and are also used in meteorology stations to report and predict the weather.