What is a Humidity / Dew Sensor?
A humidity sensor (or hygrometer) senses, measures and reports the relative humidity in the air. It therefore measures both moisture and air temperature. Relative humidity is the ratio of actual moisture in the air to the highest amount of moisture that can be held at that air temperature. The warmer the air temperature is, the more moisture it can hold.
How does Humidity sensor or hygrometer works ?
Humidity / dew sensors use capacitive measurement, which relies on electrical capacitance. Electrical capacity is the ability of two nearby electrical conductors to create an electrical field between them. The sensor is composed of two metal plates and contains a non-conductive polymer film between them. This film collects moisture from the air, which causes the voltage between the two plates to change. These voltage changes are converted into digital readings showing the level of moisture in the air.
This type of measurement relies on two electrical conductors with a non-conductive polymer film laying between them to create an electrical field between them. Moisture from the air collects on the film and causes changes in the voltage levels between the two plates. This change is then converted into a digital measurement of the air’s relative humidity after taking the air temperature into account.
Applications for Humidity / Dew Sensors:
Humidity sensors can be used as a monitoring and preventive measure in homes for people with illnesses that are affected by humidity. They are also found as part of home heating, ventilating, and air conditioning systems (HVAC systems). They can also be found in offices, cars, humidors, museums, industrial spaces and greenhouses and can be used in meteorology stations to report and predict weather. Dew sensors are used in the coating industry because the application of paint and other coatings may be extremely sensitive to dew point.
Private consumers typically use humidity sensors when they suffer from allergies or a respiratory illness that low humidity exacerbates. Conversely, high humidity can encourage mold, fungus, or bacteria growth. Humidity sensors are also used in wine cellars and humidors to help keep the air at a consistent humidity level to prolong wine and cigar storage. Museums, storage facilities, and commercial HVAC systems use the sensors to ensure a consistent level of moisture and air quality in the building(s). Automobiles now use humidity sensors as part of their defogging or defrosting systems to automatically adjust the amount and type of air used for the vehicle’s air conditioning system. Finally, humidity sensors are also used when collecting weather or oceanographic information while researching or measuring weather effects over time to help predict and analyze weather patterns.
Example of Humidity sensor
DHT11 and DHT22 are the most popular types of humidity sensor . They can measure relative humidity in percentage and temperature in degree celcius , it can measure temperature range of 0 to 50 °C and relative humidity 20% to 90% .This sensor is normal type of sensor which has three leg in which two pins are used for ground and vcc and from one pin data can be observed .Data are normally digital in nature so we do not need to convert it into another form . we can direct measure the output value digitally . If you want to make a project using humidity sensor please check our project section of microcontrollers there you will find some material for it .