Wavelength modulation spectrometer using interband cascade laser for exhaled breath carbon monoxide measurement

Exhaled breath analysis has attract growing attention as a promising noninvasive medical detection method. Carbon monoxide in human exhaled breath is of great value in the diagnosis of diseases, such as hematolysis and neonatal jaundice. However, conventional methods for the detection of CO was limited in practical application. In view of this, we have developed a highly sensitive system based on wavelength modulation spectroscopy by using an interband cascade laser at the optical wavelength of 4.71 μm. The temperature and pressure of gas example are extremely controlled by the proportional-integral-derivative control algorithm. As a proof of concept, the spectrometer was utilized to detect standard samples and real breath samples. The results show that the spectrometer has a good sensitivity with a detection limit of 3 ppb, and the concentration of CO in exhaled breath of non-smoking health people is flutuated little and not influenced significantly by the normal diet.