When it comes to darker skin, pulse oximeters fall short

A pulse oximeter is worn by Brown University professor Kimani Toussaint. The devices have been shown in research to produce inaccurate results in dark-skinned people, and Toussaint's lab is developing technology that would be more accurate, regardless of skin tone. (Craig LeMoult)

Over the past two years, the pulse oximeter has become a crucial tool for tracking the health of COVID-19 patients.

The small device clips onto a finger and measures the amount of oxygen in a patient's blood. But a growing body of evidence shows the device can be inaccurate when measuring oxygen levels in people with dark skin tones.