Microsoft’s Glasses to Monitor Blood Pressure
A number of approaches have been tried in the past to accurately measure blood pressure, but the upper-arm cuff remains the standard used in hospitals, clinics, and by patients at home. People that require frequent daily checks of their blood pressure know that it can often be inconvenient to have to have a cuff-based pressure monitor always on hand. Researchers at Microsoft have been working on a wearable set of glasses that can measure the blood pressure using a combination of three optical sensors and a three-axis accelerometer.
The optical sensors detect heartbeat pulses in three spots on the head, while the accelerometer detects the movement of the head. By keenly discerning the time differences between when the pulses are detected at the three sites, the glasses are able to calculate the so-called “pulse transit time,” essentially the speed at which longitudinal waves travel through the blood vessels. This measure, combined with a bit of other data, can be extrapolated into a fairly accurate blood pressure estimate. Because Microsoft’s device, called Glabella, can perform these measurements thousands of times a day, it has the potential to identify the activities, diet, drugs, and other factors that influence an individual’s blood pressure. Microsoft has already tried the Glabella with four volunteers continuously using it for five days, and the device has shown a pretty good correlation at estimating systolic blood pressure compared to a standard cuff.