Abstract
Peripheral oxygen saturation (SpO₂) measured by small wearable devices has garnered significant attention as a tool for detecting vital signs in acute and chronic diseases. However, the accuracy of such devices, particularly smart rings measuring SpO₂ at the finger base, remains underexplored. This study aimed to validate the accuracy of SpO₂ measurements obtained from a smart ring by comparing them with a clinical pulse oximeter in a controlled hypoxic environment. A total of 10 active males and females lay in the supine position at rest in a hypoxic environment, where oxygen saturation was maintained between 80% and 100% (normoxic levels). The participants wore a smart ring with photoplethysmography at the base of the second and third fingers of the dominant hand and a clinical pulse oximeter on their fingertips. To validate the accuracy of SpO₂ measured by a smart ring, leave-one-out cross-validation was performed, comparing root-mean-square error (RMSE) for 6793 data samples. The mean SpO₂ was 88.3 ± 7.2% for the smart ring and 88.3 ± 8.0% for the clinical-grade pulse oximeter, with a RMSE of 3.55%. These findings suggest that the smart ring provides reasonably accurate SpO₂ readings at rest, supporting its potential utility for health monitoring.
