Blood pressure readings at your fingertips

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You’ll soon be able to measure your blood pressure at home using just your smartphone, thanks to Vibro, an app from Billion Labs, a spinoff company founded by electrical engineers at the University of California San Diego. Designed by Edward Wang, an assistant professor of electrical and computer engineering at the Jacobs School of Engineering and Design Lab, and graduate student Colin Barry, Vibro uses your phone’s native camera, a vibration motor, and a motion sensor.

Unlike other devices currently on the market, Vibro does not rely on a separate blood pressure cuff: when a patient’s finger is pressed against the screen of a vibrating phone, the finger pressure dampens the vibrations. The phone senses how much dampening there is and uses that value to calculate the force on the screen. Through the relatively thin tissue of the finger, the camera can see both the pulse and the point at which the finger pressure cuts off blood flow. Oscillometric blood pressure is then determined using a standard calculation based on the time elapsed since blood flow was cut off.

Competing blood pressure monitoring solutions in development use a method called pulse wave analysis. Because pulse wave analysis is affected by factors such as body length, arterial stiffness and body position, it is less reliable, even though it includes calibration from a blood pressure cuff. “The literature is starting to show that pulse wave analysis of blood pressure is very unstable,” Wang says.

The development of the Vibro app was supported by the National Institutes of Health (NIH) through multiple programs—including the Year 3 NIH MassAITC Pilot Awardees cohort, a $4.3 million effort, and the NIH POCTRN program under the CAPCaT mechanism. Initial research by Billion Labs at UC San Diego was funded by Wang’s Google Research Scholar Award.

The attention to user-centric design was recently awarded a Special Recognition Award by the Don Norman Design Awards. Users who press too hard will cut off the blood supply before a pulse reading appears; those who press too lightly on the smartphone screen to cut off the blood supply will not receive a blood pressure reading. In addition, it takes several seconds of steady pressure to determine blood pressure.