A multiwavelength ring platform for assessing and mitigating the impact of melanin on pulse oximetry accuracy

Pulse oximeters are critical vital sign monitors in clinical settings but are prone to skin-tone-related bias that substantially worsens patient outcomes. Consequently, darker skin tone patients are frequently at higher risk of undetected or occult hypoxemia when using pulse oximeters. To address this, we propose a wireless spectral ring designed to mitigate the impact of melanin on pulse oximetry estimations. To capture real-time optical data, a miniaturized spectrometer was applied in both reflective and transmissive formats to perform spectroscopy and pulse oximetry respectively. Device capabilities were assessed via a standardized desaturation protocol with humans (n=12) to quantify melanin and calculate oxygen saturation. We identified a good correlation between our estimated melanin metric and an external reference (Pearson’s R = 0.5701). Additionally, we observed a reduced bias (ΔSpO2 = 1.00%) compared to an external reference (ΔSpO2 = 2.23%) at the finger pads between individuals considered medium and light skin tones by exploiting the palmar side of the finger. Our novel approach of combining light path engineering and on-skin spectroscopy reduces this bias by 35%. We demonstrate that our method can perform melanin quantification comparable to external references and apply this method in real-time to mitigate the impact of skin tone bias in pulse oximetry in a unified wearable device.