The details of the wearable device – called Glabella – have been published by the Microsoft Research designers. In addition, the company has been granted a patent for the “Head-Mounted Device for Capturing Pulse Data.”
The wearable glasses prototype integrates optical sensors, processing, storage, and communication components into the frame to passively collect physiological data about the user without the need for any interaction. It continuously records the stream of reflected light intensities from blood flow as well as inertial measurements of the user’s head.
From the temporal differences in pulse events across the sensors, the prototype derives the wearer’s pulse transit time on a beat-to-beat basis. Given a significant correlation between a person’s pulse transit time and their systolic blood pressure, the device is able to continuously observes pulse transit time as a proxy for the behavior of systolic blood pressure levels — at a far greater convenience and higher rate than traditional blood pressure monitors.
“This enables our cuff-less prototype to model the beat-to-beat fluctuations in the user’s blood pressure over the course of the day,” say the researchers. “And [to] record its short-term responses to events, such as postural changes, exercise, eating and drinking, resting, medication intake, location changes, or time of day.”
Testing of the prototype device showed a high correlation between the pulse transit times computed with the device with participants’ heart rates and systolic blood pressure values measured using oscillometric cuffs. The results, say the researchers, indicate that Glabella has the potential to serve as a socially-acceptable capture device, requiring no user input or behavior changes during regular activities, and whose continuous measurements may prove informative to physicians as well as users’ self-tracking activities.
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