Quantum cascade laser spectroscopic sensor for breath gas analysis

Breath analysis is an attractive method for disease diagnosis and therapeutic monitoring, due to its high potential for non-invasive medical diagnostics. Among numerous analysis techniques, tunable diode laser-based absorption spectroscopy (TDLAS) is an excellent method for detection of gas concentration, since it presents advantages of high sensitivity, good selectivity, fast response and high temporal resolution. In this study, state-of-the-art quantum cascade laser based gas sensor is demonstrated as a promising new tool for noninvasive, real-time identification and quantification of trace gases in human breath for clinical uses. Details of selection of spectroscopic parameters and primary lab studies conducted on CO, H2O and N2O molecules in exhaled breath are presented, together with suggestions on the future direction of this challenging analytical field.