Breath-Analysis Using Mid-Infrared Tunable Laser Spectroscopy

Breath analysis is becoming an attractive technique for the noninvasive monitoring of various molecular constituents in exhaled breath. Nitric oxide (NO) is a widely studied biomarker in breath and is known to indicate the lower airway inflammation associated with asthma. A mid-IR laser-based spectroscopic sensor and associated electronics were designed to measure exhaled NO simultaneously with CO₂. To evaluate the sensor performance, a large observational clinical field study consisting of more than 2200 volunteers was performed over a period of two years. The generated distributions of the measured exhaled NO and CO₂ levels were found to be log-normal and Gaussian, respectively. In addition, preliminary results of measuring exhaled nitrous oxide (N₂O) are given as well as suggestions for future applications in infectious disease.