Infrared NDIR Gas Sensor:Working,Advantages,disadvantages,Manufacturers

Introduction : An Infrared Gas Sensor, also known as an NDIR (Non-Dispersive Infrared) sensor, is a widely used technology for detecting gases such as carbon dioxide (CO₂), methane (CH₄), and other hydrocarbons. NDIR sensors work on the principle that gas molecules absorb infrared light at specific wavelengths

NDIR gas sensors are popular in industrial safety, environmental monitoring, HVAC systems, automotive applications, and smart IoT devices because of their high accuracy, long-term stability, and low maintenance requirements.

Infrared NDIR Sensor Working principle

It works based on the principle of infrared absorption spectroscopy in which methane molecules absorb IR light at specific wavelength of about 3.3 μm. The sensor consists of following.

1. Infrared light source : Usually IR lamp or LED.
2. Optical path : Gas chamber through which IR signal passes.
3. Detector is used with optical filters tuned to methane’s absorption band.

Let us understand working of Infrared gas sensor.

• IR source emits light which passes through the gas sample.
• If methane is present, it absrobs infrared signal at its characteristic wavelength.
• The detector at the opposite side measures reduction in infrared signal intensity compared to reference channel.
• The drop in signal measured is proportional to the methane gas concentration. It is measured in %LEL (Lower Explosive Limit) or ppm.

Advantages of Infrared NDIR Sensor

Following are some of the benefits of Infrared NDIR Sensor.

1. It is highly selective.
2. It does not need oxygen.
3. It is immune to poisoning unlike catalytic bead sensor.
4. It offers long life time; typically >10 years.
5. It requires less frequent re-calibration.
6. MEMS based IR sensors offer low power consumption.
7. Offers fast response.

Disadvantages of Infrared NDIR Sensor

Following are some of the drawbacks of Infrared NDIR Sensor.

1. Higher in cost compared to catalytic & MOS sensor types.
2. It is sensitive to dust, humidity and optical contamination. This requires protective windows/filters.
3. It works only for IR active gases.
4. It has slightly larger form factor compared to simple pellistor sensors.
5. It’s output result varies due to variation in temperature and hence it requires compensation.

Manufacturers

Conclusion: Unlike catalytic or electrochemical sensors, they are non consumptive and highly selective, making them suitable for continuous monitoring in both indoor and outdoor environments. With advantages such as fast response, long lifespan and resistance to poisoning, NDIR gas sensors have become a preferred choice for modern gas detection systems, especially where precision and reliability are critical.