Robert Byer (Applied Physics)
Konstantin Vodopyanov (Applied Physics)
Niaz Banaei (Pathology)

Patients with pulmonary tuberculosis (TB) have unique volatile organic compounds (in trace amounts) in their exhaled breath that can be detected and used as biomarkers for TB. We develop laser spectroscopy tool for detection of TB volatiles with unprecedented capability for precise measurements of molecular traces in real time. The proposed setup, based on a robust, cost-efficient fiber laser with low power consumption, has the potential to be developed into a compact, easy-to use device for rapid TB diagnostics. As part of the laser development at Applied Physics Dept. at Stanford, an octave-spanning ‘frequency comb’ laser source operating in the molecular ‘fingerprint’ region of 2.5- 6 µm was developed and sensitive molecular detection with simultaneous identification of several biomarkers (carbon dioxide, isotopic carbon dioxide, carbon monoxide, water vapor, methane, formaldehyde) was demonstrated. This is a huge advancement in trace molecular detection: prior art semiconductor quantum cascade lasers used so far for molecular detection can detect only one biomarker at a time. We believe that with our technique, up to 100 biomarkers can be detected simultaneously.