Researchers built a smartphone app that can check blood pressure by simply recording a short video of someone’s face, then analyzing the blood flow under the skin.
High blood pressure can lead to heart attack or stroke so making an easy at-home test for it could save huge numbers of lives.
The researchers from the University of Toronto in Canada and the Affiliated Hospital of Hangzhou Normal University in China created a proof-of-concept app that can accurately tell blood pressure without needing medical equipment. “We found, using a smartphone, we can accurately measure blood pressure within 30 seconds,” said lead researcher Kang Lee, Ph.D..
The study, Smartphone-Based Blood Pressure Measurement Using Transdermal Optical Imaging Technology, appears in Circulation: Cardiovascular Imaging.
Looking below the skin with transdermal optical imaging
The phone’s camera can see that light bounces off proteins under someone’s skin at different rates. That’s how this app sees hemoglobin in the blood. Tracking tiny changes in this protein allows the software to determine a surprising amount. “Once you know how blood concentration changes in different parts of your face, then we can learn a lot of things about your physiology, such as your heart rate, your stress and your blood pressure,” said Lee.
When compared with a stand “cuff” blood-pressure test, the researchers found that their transdermal optical imaging app running on an iPhone was able to accurately determine systolic blood pressure about 95% of the time, and diastolic pressure roughly 96% of the time.
A few caveats
It is still early days for this technology. The first round of testing was done under controlled lighting conditions, not someone’s kitchen, for example.
Also, the first test subjects didn’t have a full range of possible skin tones. And the temperature of the room might have an effect on this too.