A new wearable device called ChromaSense, developed by researchers, has demonstrated the ability to measure blood oxygen saturation, heart rate, and respiration across diverse skin tones with accuracy that meets FDA requirements. By measuring skin reflectance to adjust light emission and signal processing, the device eliminates the tone-dependent bias often found in traditional pulse oximeters, according to research from the lab of Valencia Koomson, an associate professor of electrical and computer engineering.
Addressing Racial Bias in Pulse Oximetry
Traditional pulse oximeters rely on light transmitted through the finger, a method that often fails to account for variations in skin pigmentation. Melanin in the skin absorbs and scatters light, which can weaken signals or distort the ratios used to calculate oxygen levels. This technical limitation gained significant attention during the COVID-19 pandemic. A 2020 study published in the New England Journal of Medicine found that nearly 17% of Black patients experienced “occult hypoxemia”—dangerously low blood oxygen that remained undetected by standard devices—at a rate three times higher than that of white patients.
Did you know?
Photoplethysmography (PPG) is the technology behind pulse oximetry. It measures changes in blood volume in the microvasculature, which pulse in time with the heartbeat. ChromaSense improves on this by first profiling a user’s skin reflectance before calculating vital signs.
Testing Accuracy Across Diverse Populations
The ChromaSense system operates as a watch-sized wrist-worn device. Rather than assuming a universal light setting, it calibrates itself to the individual user. Recent testing at the Hypoxia Research Laboratory at the University of California, San Francisco, subjected the device to rigorous conditions, lowering oxygen saturation levels between 70% and 100% in a cohort of Black, Asian, Hispanic, White, and multiethnic volunteers. According to the research, the device achieved an accuracy within 2.87% of a reference oximeter that reads directly from the blood. This result met FDA performance standards and showed no observable bias related to skin tone.
Technical Advantages of Wrist-Based Calibration
Previous testing of the device, conducted with 50 participants under normal oxygen saturation levels, showed an accuracy within 1.4% of standard reference equipment. Valencia Koomson notes that the data captured by PPG effectively measures how efficiently the heart pumps blood through the arteries. By shifting the measurement site to the wrist and implementing an adaptive light-adjustment process, the technology mitigates the distortions caused by skin pigment, ensuring that medical decisions—such as the need for hospitalization or supplemental oxygen—are based on accurate, equitable data.
Frequently Asked Questions
- How does ChromaSense differ from a standard pulse oximeter?
Standard oximeters pass light through the finger and use a “one-size-fits-all” light setting. ChromaSense is worn on the wrist and measures the user’s specific skin reflectance profile to adjust its light output and signal processing. - Is the device accurate for all skin tones?
Yes. Research conducted at the University of California, San Francisco, included a diverse group of participants and found no tone-dependent bias in measurements, even at lower oxygen levels. - Has the device met regulatory standards?
According to the research team, the device’s performance in hypoxia studies met FDA requirements for accuracy.
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