Types of gas sensors

Types of gas sensors

Interestingly, the human nose can sense over one trillion types of different odors, but it still can not identify the amount of gas in the air.

Gas sensors are used to identify the concentration of a specific gas in the air. It has a measurement set in its memory which it uses to compare the concentration in the air to compare it with and give an accurate reading of the gas.

There are many different types of sensors;

· MEMS Pellistors

· Metal Oxide Gas Sensors

· Electrochemical Gas Sensors

· Evaluation Kits

· Indoor Air Quality sensors

· Infrared Gas Sensors

· Catalytic Pellistors

· Thermal Conductivity Gas Sensors

In this article, we will go over these different types of sensors briefly.

Electrochemical gas sensors

Starting off our list are the electrochemical gas sensors. Electrochemical (EC) sensors measure the concentration of a target gas by oxidizing or reducing reactions of target gas and the electrode, measuring the resulting electrical current output. These types of gas sensors are used for detecting oxygen and toxic gases in an external circuit.

Manufactures customize electrochemical gas detectors by changing the porous barrier to detect a certain gas concentration range. These sensors work on the principle of diffusion. The diffusion barrier is mechanical, so it lasts over a longer period and requires less maintenance.

These sensors are susceptible to corrosion, so they last 1-3 years before they need to be replaced.

Catalytic bead sensors

Catalytic bead sensors oxidize (burn) a combustible gas and convert the temperature changes into an electric signal. It is the most common type of sensor used to measure the concentration of gases like methane, propane, etc.

These sensors measure the hazardous gases between two ranges, i.e., LEL (Lower explosion limit) and UEL (Upper explosion limit).

These sensors are mostly cheap and effective, but they require a small amount of oxygen to be present in the environment.

These sensors can be inhibited, and their working can be compromised by compounds such as silicones and mineral acids.

Infrared gas sensors

Low-powered infrared (IR) gas sensors are an alternative to combustible gas measurement equipment. These sensors can work without oxygen. These sensors work on the principle of absorption of light. The change in the absorbed light intensity is measured relative to the intensity of light at a reference wavelength. The sensor then calculates the difference in absorbed light and measures the gas concentration.

These sensors can be used for remote testing since they don't have to be placed inside the gas. These sensors are used to detect hydrocarbons, water vapors, carbon dioxide, or other infrared active gases.

Holographic gas sensors

Holographic gas sensors use light reflection to detect changes in a polymer film matrix containing a hologram. These work on the principle of reflection. Since different holograms reflect light at different and certain wavelengths, the hologram sensor can identify a change in the gas composition since it can generate a colorful reflection indicating the presence of a gas molecule.

Holographic sensors require illumination sources to work.

These are some of the major types of gas sensors based on their working principles. Each type has its uses and benefits and is used to detect different types of gases differently.