Testing novel miniature NIR spectrometers for wearable broadband NIRS devices

The feasibility of new-generation miniature spectrometers for use in portable broadband NIRS (bNIRS) devices was explored in this investigation. The study outlines tests of varying integration time between 1000 ms, 500 ms and 250 ms and source-detector separations between 2 cm, 3cm and 4 cm, and their effect on the received signal through MEDPHOT tissue-mimicking phantoms, A2, B2, B3 and D7, using the Oceans Optics HL-2000-HP tungsten halogen lamp as a broadband light source. The spectra and SNR were then compared to two gold-standard bNIRS systems. It is found that two of the spectrometers give respectable SNR values for the detection range of 600 - 1000 nm in all regimes except when saturated or using phantom D7. It is demonstrated that these two devices can appropriately be used for source-detector separations of 3 cm and 4 cm at 500 ms and 1000 ms integration times, to determine absorption changes in tissue and thus chromophore concentrations. To use them for 2 cm separations, an additional attenuation component will be required.