Humidity Sensor (or Rh Sensor) for all applicationsA humidity sensor measures the amount of water vapour in the air. Humidity affects how we feel and how well specific machines work. That's why this sensor can be a valuable tool everywhere.

These sensors vary in size and how they work. You can find them in everything from smartphones to a building's air control mechanism. 

Humidity sensors are helpful for agriculture, medical science, and the automobile industry. They're also valuable for the home and small offices. 

How Accurate Are Humidity Sensors?

Different businesses can have varying standards. The accuracy advertised on a product's package is valid at the time of production. This accuracy won't always be the same.   

A sensor may not produce accurate results over time. This is especially true when a chemical or water has entered it. Some producers offer easy ways to recalibrate your device. That way, you can be sure that the results are accurate. 

Types of Humidity‌

There are three different types of humidity. They are absolute, relative, and specific humidity. 


Absolute Humidity

Absolute humidity is also known as the humidity ratio. It shows the amount of water vapour in the air, measured in grams. If the level of moisture is low, absolute humidity is low. When it's high, absolute humidity is high. 

Relative Humidity

The relative humidity is the level of water vapour in an area compared to its maximum level. Specifically, it is the level of water saturation that the air may hold. Interestingly, Meteorologists use this for weather reports. 

Specific Humidity

Specific humidity is the sum of water vapour in a unit amount of wet air.  

Types of Humidity Sensors

Humidity sensors identify fluctuations that affect the temperature or electrical currents in the air. An example is the DHT-22, which can interface with an Arduino Uno. Others include SHT71, DHT11, DHT22, and AM2302. 

There are different types, and they all work slightly differently. Here are the main types available and how best you can use them. 

Capacitive Humidity Sensors

These sensors use capacitors consisting of two electrodes separated by a dielectric or non-conductive polymer film. The film draws moisture from the air to give a voltage charge. 

An analog dial captures and displays the voltage reading and sends it to another system. It then translates the amount of air moisture into digital information. Capacitive sensors calculate relative humidity from 0% to 100%. An example is a hygrometer. 

These sensors are low-cost, compact, and durable. They are suitable for residential, commercial, and industrial use.


Resistive Humidity Sensors

Also known as hygristors, resistive humidity sensors work like capacitive sensors. The sensor calculates electrical changes to determine relative humidity. They also make use of hygroscopic moisture. 

However, they do this with slightly different sensors. There's an inverse relationship in the way resistive humidity sensors function. They absorb more moisture. This leads to an increase in conductivity and a decrease in resistivity. 

Resistive sensors are used in residential and commercial environments. They're famous for intelligent food packaging, automotive, and remote monitoring networks.

Thermal Humidity Sensors

Thermal sensors use a dual sensor system to calculate absolute humidity. While liquid nitrogen seals one sensor, the other sits in an exposure chamber to measure ambient air. The difference between the two findings determines the humidity level.

Thermal conductivity humidity sensors are valuable in corrosive or high-temperature environments. They supply higher resolution than other categories. 

Digital Humidity Sensors

Digital humidity sensors report changes in conductivity and resistivity. They produce digital values and are easy to use with microcontrollers like Raspberry Pi boards and Arduino. 


Mechanical Humidity Sensors

Mechanical humidity sensors trigger a switch in reaction to humidity. They show the increased difference between two fibres — one that's sensitive to humidity, another that isn't.

Electrolytic Humidity Sensors

Electrolytic humidity sensors translate relative humidity values into electronic measurements. They're often embedded in:

  • air dryers,
  • household appliances,
  • office equipment,
  • climate monitors,
  • humidifiers,
  • refrigerators,
  • air conditioners, and
  • building management systems. 


Resistive Dew Sensors

Resistive dew sensors detect emerging condensation and dew formation. They use thermal contact to identify the surface moisture of cooled objects. These sensors are usually attached to metallic materials. 

Resistive dew sensors help with ventilation control. They can also serve as leakage monitors for waterproof housing. They're found in various cameras and appliances as well.

Electronic Humidity Sensors

Electronic humidity sensors calculate the capacitance or resistance of air samples.


How To Calibrate Humidity Sensors

Using your humidity sensor consistently, you need to calibrate it to get the most accurate readings. All you need is a humidity generator or some moist salts.


Humidity Generator or Calibrator

A humidity generator or calibrator allows you to create and determine humidity at several temperatures and humidity levels. It also lets you evaluate its result against your equipment. 

Moist Salts

You can also perform a two-point calibration using two moist salts. Do this by preparing a solution in a sealed jar. The seal prevents air from going in and creates relative humidity. Then, place the connected sensor in the sealed jar. 

Repeat this procedure with different salts and record the results. Observe the reading deviations to verify the sensor's accuracy. 

Where Can You Use Humidity Sensors? 

Humidity sensors are used across major industries. These include medicine, agriculture, and facilities management. Options like the Google Nest humidity sensor, Ecobee humidity sensor, and Leviton humidity sensor are versatile. They can be used on the job or at home.

Humidity Sensors in IoT 

There are various sensor systems available on the market today. They range from SmartThings systems to WiFi humidity sensors that allow you to review real-time data. You'll access readings on your smartphone or computer through texts and emails.

You can further pair them with home appliances and interior temperature controls. For example, a home sensor can spot high humidity levels in the laundry room. When this happens, it can automatically turn on the bathroom exhaust fan with a humidity sensor switch. 

A home sensor can also notify those with severe sinus issues or asthma. When relative humidity levels drop, it may trigger symptoms. 

Humidity Sensors for Industrial Applications

Many industries need humidity sensors, including metal, chemical, paper, food processing, and refineries and other companies that use furnaces. These sensors help indicate when high humidity decreases oxygen in the air. 

Humidity Sensors for Agriculture

In agriculture, sensors calculate moisture content in the soil, which plays a significant role in plant growth. Farmers can also use humidity sensors for drip irrigation techniques. This is important to achieve precise moisture content for plants. Indoor vegetation also requires this type of sensor.

Humidity Sensors for Small Businesses

Office managers can monitor and adjust humidity to provide the best comfort and productive working conditions. 


Where To Buy Humidity Sensors

These sensors are helpful for both personal and commercial purposes. You can buy them from any leading distributor of Machine-to-Machine (M2M) and Internet of Things (IoT) hardware and solutions. 

Novotech supplies high-quality humidity sensor solutions. They are used in enterprise, industrial, residential, and commercial applications. Most of our sensors are wireless and use cloud-based mobile and web applications. This allows you to view accurate humidity sensor data from anywhere.