A novel NDIR CO2 sensor using a mid-IR hollow fiber as a gas cell

A novel CO
₂
non-dispersive infrared (NDIR) sensor using the mid-infrared (mid-IR) hollow fiber as a gas cell has been demonstrated. The mid-IR hollow fiber is chosen for its optimum transmission band (bandgap) overlap with CO
₂
fundamental absorption spectrum around 4.26 μm to serve as a filter. A comparison with the system using a smooth metal cell is presented. The signal noise suggests that a measurement resolution better than 5 ppm concentration is achievable using this mid-IR hollow fiber. The response time of the system using hollow fiber can be in the order of shorter than 10s with the sensitivity of 1.82 mv/ppm.