DermaGlow: Objective Quantification of Melanin, Erythema and Skin-tone Using Wearable Optical Spectroscopy

Accurate characterization of the skin is essential for optimizing diagnostic and therapeutic dermatological tools, as well as technologies like pulse oximetry that rely on skin perfusion. Traditionally, optical spectroscopy has been used for skin assessments through devices like commercial colorimeters, which are high-cost instruments that, while precise, only provide single measurements rather than continuous data. Additionally, medical wearable devices that use this technology often show variable accuracy based on skin tone. The limitations of existing devices demonstrate the need for a solution that can provide low-cost, accurate, and continuous skin monitoring across varying skin tones in a wearable form-factor. This paper introduces DermaGlow, a novel wearable optical spectroscopy framework designed for low-cost, non-invasive monitoring of melanin, erythema, and skin tone. DermaGlow utilizes an off-the-shelf multi-spectrum wearable device available in various configurations to enable real-time, personalized assessments across diverse skin conditions and skin tones. We assess the performance of the DermaGlow algorithm against a state-of-the-art colorimeter in a comprehensive user study involving a diverse group of 77 subjects, demonstrating a normalized mean absolute error (NMAE) of 5.33% (melanin) and 4.18% (erythema), and ΔE values less than 2.5 for CIE LAB measurements. Furthermore, we present an algorithm that utilizes DermaGlow outputs to correct for pulse oximeter inaccuracies typically found in those with darker skin pigmentation, resulting in an up to 75% decrease in mean absolute error (MAE) in hypoxic readings across skin tones relative to arterial blood measurements. Our findings highlight DermaGlow's potential for short and long-term skin monitoring and as a significant enhancement to existing wearable devices, particularly in improving the accuracy of pulse oximeter readings across different skin tones.