Compact mid-IR Breath Analysis System

Daylight Solutions is developing broadly tunable, external cavity quantum cascade lasers (EC-QCLs) for gas sensing instrumentation for numerous markets including medical breath analysis. Progress in two specific areas of development will be discussed: (i) miniaturization of a fast tunable, moderate resolution, pulsed EC-QCL and (ii) demonstration of a EC-QCL acetone sensor capable of breath acetone detection at the required low levels. Recent efforts at Daylight Solutions yielded the world´s first miniature room temperature EC-QCLs comprising of a 15 mm long optical cavity, custom collimating optics, miniature grating tuning mechanism and integrated current and temperature controls. The laser can operate anywhere in the 4.5 -10.5 micron spectral region with a scanning range of over 100 wavenumbers. The spectral resolution is better than 1 wave number and the scanning rate is faster than 1 second. In addition to the relative simplicity and ruggedness of the optomechanical design, the laser also features low average power consumption, does not require precise current and temperature control, and can operate at room temperature with convective cooling. The prototype EC-QCL acetone sensor operating in 8 micron spectral range combined with Daylight Solutions´ optimized IR detector together with a custom data acquisition system have shown a sensitivity of <100 PPB level of acetone, an important breath biomarker using single breath resolved absorption spectroscopy. The measurement approach, sensitivity, and selectivity in presence of other breath constituents will be discussed.