Infrared quantum cascade laser spectroscopy as non-invasive diagnostic tests for human diseases

In this work, infrared (IR) experimental setup for exhaled breath analysis (BA-setup) and experimental setup for biological fluids analysis (FA-setup) based on quantum cascade laser was demonstrated. For breath analysis, we use the absorption spectroscopy with astigmatic multipass gas cells for biomarkers identification in human breath. The expected sensitivity of BA-setup was estimated. Mathematical methods for processing the human breath IR spectra were proposed. FA-setup uses spectral analysis of diffuse reflected radiation for identification of liquid and solid substances. Examples of the obtained experimental data were provided. Using FA-setup, several solid organic components and liquid substances were successfully indicated.