Non-Dispersive Infrared Gas Sensing Technology: A Review

Non-dispersive infrared gas sensing (NDIR) is a unique optical sensing technique where IR radiation interacts with the targeted analyte and in the process, it is absorbed. This absorption is unique for every gas and hence, based on the absorption characteristics, gas molecules can be fingerprinted and distinctively identified. A simple NDIR gas sensor consists of an IR emitter, detector, optical filter, gas cell, and circuit elements for signal processing. Further, these components also offer choice for selection for example a microelectromechanical system (MEMS) based membrane heater, a light-emitting diode (LED), and IR lamp all have the capability of generating IR spectra. Similarly, a pyroelectric detector, photodiode, bolometer, as well as thermopile has the ability to detect IR rays. The choice of the selection of components carries advantages and disadvantages associated with them, and thus it is very important to choose them correctly for the targeted applications. This article reviews the evolution of non-dispersive infrared gas sensing techniques and the basic components of these sensors are discussed one-by-one. Finally, the shortcomings of the NDIR gas sensor have been summarized and the efforts made in recent times to cope with these are also discussed.