The next big sensor challenge for health-focused wearables is measuring blood pressure, ideally without a cuff inflating on your arm a few times an hour.
A new Microsoft patent application has just been published explaining how this could be done using a set of wearable sensors mounted on eyeglasses.
The device would incorporate optical sensors to continuously measure and store the user’s pulse waves at three different sites on their face. It would additionally comprise inertial sensors and a processing unit that compares the continuously recorded pulse waves to extract the user’s pulse transit time—the delay between the moments at which the blood ejected from the heart reaches the three sites. Pulse transit time functions as a proxy measurement to monitor the short-term behaviour of the user’s systolic blood pressure, which Microsoft’s evaluation found shows a significant correlation with your actual blood pressure.
Despite the bulk of the device as demonstrated in the images above, Microsoft believes the sensor has the potential to serve as a socially-acceptable capture device which would require no user input or behaviour changes during regular activities, and whose continuous measurements may prove informative to physicians as well as users’ self-tracking activities.
The chief inventors of the device, Christian Holz and Edward Wang, have posted a paper on the prototype called “GLABELLA: CONTINUOUSLY SENSING BLOOD PRESSURE BEHAVIOR USING AN UNOBTRUSIVE WEARABLE DEVICE” which can be read at Holz’s site here. The full patent can be read here.