Multi Gas Detection

Reference

Peng, Jie, et al. "Multigas Nonresonant Photoacoustic Spectroscopy Sensor Based on a Broadband Radiation Source." Microwave and Optical Technology Letters, vol. 66, 2024, doi:10.1002/mop.33989.

Use Case

The article describes the development of a multi-gas detection sensor using a technique called nonresonant photoacoustic spectroscopy, which is particularly useful for environmental and industrial monitoring. This sensor can identify and measure the presence of six different gases—carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6)—with high sensitivity and selectivity.

Here's a simplified explanation suitable for someone with a non-expert background:

Imagine you have a room where various gases might be present due to leaks or emissions from machines. Detecting and measuring these gases accurately is crucial for safety and environmental monitoring. The sensor discussed in the article shines a broad range of light (a broadband radiation source) through the air in the room. When this light encounters molecules of these gases, they absorb specific wavelengths of the light, and this absorption process generates a tiny amount of heat.

The sensor then detects this heat in the form of sound waves generated by the expanding gases (hence "photoacoustic"). By analyzing these sound waves, the sensor can determine which gases are present and in what quantities. What's clever about this sensor is its ability to use different filters to focus on the specific light waves absorbed by different gases, making it very precise in identifying and measuring multiple gases simultaneously.

This technology offers a quick and effective way to monitor air quality, detect leaks, and even diagnose issues in electrical equipment without the need for direct contact with the gases or complicated setups.

Bandpass Filter Selection

Here are the filters and their associated gases:

1. Carbon Monoxide (CO) - Filter centered at 4600 nm with a bandwidth of 150 nm.
2. Carbon Dioxide (CO2) - Filter centered at 4250 nm with a bandwidth of 128 nm.
3. Methane (CH4) - Filter centered at 3320 nm with a bandwidth of 180 nm.
4. Acetylene (C2H2) - Filter centered at 3030 nm with a bandwidth of 100 nm.
5. Ethylene (C2H4) - Filter centered at 10520 nm with a bandwidth of 240 nm.
6. Ethane (C2H6) - Filter centered at 3350 nm with a bandwidth of 140 nm.