Human breath analysis employing DFG laser spectroscopy

In this paper, our project aims at developing a non-invasive diagnosis tool based on the quantification of certain compounds or rather mixtures of compounds in exhaled air. Our goal is to develop an IR laser spectroscopy trace gas analyser in order to monitor simultaneously the breath concentration of a selection of gases relevant to some hepatic (cirrhosis, hepatitis) or renal (haemodialysis patients) diseases. diseases. The simultaneous monitoring of several specific gases will increase both the specificity and the reliability of the diagnosis in comparison to current clinical breath tests that usually sense one gas only. For this purpose we based our trace gas analyser upon a difference frequency generation (DFG) source.