Humidity Sensor – What is it and how does it work?

Humidity sensors are modern age equipment for ensuring a comfortable environment in your house. Its job is to sense, measure, and report the percentage and change in the air’s water vapor level. Many would debate the necessity of the very machine. But it is scientifically proven that the humidity sensor detects the slightest change in the humid level in seconds just for your convenience. A healthy home and workplace is something we all desire and a humidity sensor works on that purpose only.

What is a humidity sensor?

Before knowing how this particular machine works, we should know what it actually is. So, what is the most important factor when determining the comfort of your home? Well, it is relative humidity. The humidity sensor is what measures relative humidity. It is also called a hygrometer—this a device to determine moisture to air percentage in a specific area. In short, the percentage of water vapor present in the environment around the device. It has two or several electrical conductors which catch the relative humidity. Then it converts the electronic reading to a digital output for the user to understand easily. Next, the advantage of a dehumidifier comes in to control the humidity. Now let’s see how the humidity sensor works exactly.

How does the humidity sensor work?

Once we are known about what a humidity sensor is, let us see how it works to keep the room humidity controlled. There are different types of humidity sensors but their working mechanism is more it less identical. There are electrode layers that reaction in contact with moister in the room in present of other necessary substance.

Different Types of humidity sensors Work in Different Ways:

It is essential to consider three types of humidity sensors and each of them works differently-

  1. Capacitive humidity sensors
  2. Resistive humidity sensors
  3. Thermal Conductivity humidity sensors

The Way Capacitive humidity sensors Work:

Apparent from the name, these sensors are made of two electrode layers and they have a dielectric material between them, which is hygroscopic. This is what absorbs the moisture around the air. A polymer film is a widely-used dielectric for capacitive humidity sensors. It has a range of dielectric constants from 2-15.

The geometry of the capacitor and the permittivity of the dialectic material determines the capacitance. When the dielectric material soaks in water vapor from the air, the constant goes high, resulting in increasing your sensor’s capacitance.

The amount of humidity in the air and the moisture existing in the dielectric material directly link with the sensor’s capacitance. When there is a change in the dielectric constant, the value of relative humidity changes as well. This is where it all happens. The difference in the dielectric constant and the relative humidity level can point out the humidity level.

These sensors are well-known for their accurate reading and the capacity to detect a wide range of humidity.

The Way Resistive Humidity Sensors Work:

Also known as a hygristor or an electrical conductivity sensor, the resistive humidity sensor reads the difference in the resistivity measured between two electrodes and gives the final result of the value of humidity. It has a hygroscopic conductive layer as a polymer humidity sensing film that is attached to a substrate. With time, it absorbs more water vapor, the conductive material’s conductivity levels up and decreases in resistivity.

The plus point of this humidity sensor is that it is budget-friendly and you can interchange the device. The difference between capacitive and resistive humidity sensors is that it works fine when the sensor and signaling circuit have a long distance between themselves.

They Way Thermal Conductivity Humidity Sensors Work:

The thermal conductivity humidity sensors read the humidity regardless of the temperature, which is also known as absolute humidity. They detect the contrast between the thermal conductivity of dry and humid air.

In the device, two NTC thermistors are dangled by thin wires. One of them is put on a chamber open to air using ventilation holes. And the second one is set in a chamber within the sensor sealed in dry nitrogen. The difference between the readings of the two thermistors indicates the absolute humidity.

These sensors are perfect for extremely heated environments and can provide a more accurate reading than the others.

The benefit of having a humidity sensor switch:

Just like the advantages of a motion sensor, the humidity sensor switch has many of them as well. The humidity sensor switch is a must for a healthy, comfortable and energy-saving environment for monitoring applications. Industries like HVAC, food processing, agriculture and biomedical depend on the humidity sensor to keep their work going. The humidity in the air can make manufacturing processes inconvenient. The humidity can affect the health of the personnel as well. To avoid such a disaster, it is a must to control humidity in the air. Once your sensor detects the humidity level, you can use a dehumidifier to control the moisture to keep your work going safely.

Parameters of Judgement: Once you got one, you must keep an eye on the performance. There are few factors that could work as a standard to help you judge your humidity sensor’s performance.

Accuracy: The sensor itself has a standard curve. It will pitch the pros against the cons in the chart.

Linearity: It will read out the distinguished value from the BFSL and the measured one and give relative humidity.

Reliability: The sensor must provide reliable measurements.

Response time: Usually, the rise time is 66% and the fall time is 33% of the maximum voltage output, which is known as response time.

Bottom line

Now that you know different types of humidity sensors and how they work, you can easily pick out the best one of them that suits your needs the most. The detection of excess moisture in your industry can be deadly for your production and your personnel. No one would want that for sure. Check out some top-rated humidity sensors in the market and go through their pros and cons. Finally, get the best one that suits your budget and have a safe, healthy and productive environment. The concept is clear now, what is Humidity Sensor and how does it work?