Developing a device for monitoring O2 saturation in blood

We present a single-channel device for monitoring oxygen saturation in blood using near infrared light (NIR). This device measures the differential absorption of both oxi-hemoglobin (HbO2) and deoxi-hemoglobin (HHb) concentrations using wavelengths within the biophotonic window (700 nm – 1100 nm). Our device works with two wavelengths: the first source (λ1 = 632 nm) operates in continuous wave (CW) and the second (λ2 = 940 nm) operates in pulsed mode. The pulsed signal at λ2 operates in a 20% fill factor. The CW signal provides information related to the arterial pulse, whereas both CW and pulsed signal provide information about blood oxygenation. Light emitted from the sources travels through the tissue and are collected on the detector by transmission. Measurements of blood oxygenation measured in transmission on fingers tips are presented which are comparable to commercial devices. The values obtained are above 90.0% blood oxygenation in healthy tests subjects with 0.1% accuracy in the measurements.