Tonometer with glasses
Microsoft glasses track blood pressure
Vyacheslav Golovanov, Habrahabr
Hardly anyone feels stylish without taking off the pressure measurement bracelet all day – even when their health and, possibly, life depend on constant monitoring. One alternative to this could be Microsoft glasses, which can unobtrusively monitor blood pressure while the bespectacled go about their daily business.
Smart glasses developed as part of the Glabella Project, a division of Microsoft Research, use optical pulse sensors to track blood flow through various sections of the arteries in a person's head. Measuring the passage of the pulse – the time interval during which, after each heartbeat, a pressure wave passes between two sections of the artery – provides a way to indirectly measure blood pressure without any effort or inconvenience on the part of the carrier. Ease of use may appeal to people suffering from health problems such as hypertension, who require constant measurement of blood pressure outside hospital walls.
"The code name of the research project was given in honor of the glabella, the approximate location of one of the sensors in our device, built into the nose stops of ordinary glasses," says Christian Holtz is a researcher at Microsoft Research, located in Redmond, Washington. "This allows the sensor to imperceptibly merge with a wearable device acceptable in society, while constantly polling the wearer's pulse at a key location."
The company's researchers applied for a patent for a "head-mounted device for taking pulse readings" in June 2017, but the application was published online only last month. They also described the operation scheme of Glabella glasses and the results of trial tests in a report published in the September 2017 issue of the journal Proceedings of the ACM Journal of Interactive, Mobile, Wearable and Ubiquitous Technologies.
Such hidden tracking, which the Glabella Project promises, does not require the carrier to perform any actions manually - for example, do not forget to put a measurement bracelet on your hand at a certain time of the day. It is also more convenient and not as noticeable as a semi-automatic pressure measuring bracelet, which periodically self-inflates. The wearer is not even required to make any gestures or movements, as is necessary in the case of a smartwatch that measures the pulse by a similar method.
The current prototypes of the glasses cannot be called supermodel, but they seem comfortable enough for everyday wear, and weigh only 45 grams; typical glasses weigh 37 grams. Holtz and his colleague from Warby Parker, Edward Vaughn, created a special printed circuit board located in the frame of ordinary glasses. The glasses are able to work all day on a fully charged small tablet battery.
They also created special pulse sensors configured to recognize reflected signals from arterial blood in special places of the wearer's head. Current prototypes of the glasses were tested on two different combinations of sensor locations: nasal stops and the superficial temporal artery (located in front of the ear) or occipital artery (behind the ear). In the first case, the signal turns out to be of higher quality, and in the second, the device "could potentially become completely invisible" in the glasses form factor, Holtz explains.
For a trial run of points, the researchers recruited relatively young Microsoft employees aged from their early 20s to early 40s. The four subjects were doing their usual chores in the office, talking while the glasses recorded their blood pressure. They also manually measured the pressure at certain times of the day using a standard device with a cuff to indicate the baseline values with which data from the wearable device could be compared.
Although the test was successful, you should not hurry up and look for Glabella glasses in stores yet. One of the problems that researchers still need to solve is related to choosing the most practical approach to calibrating the measurements obtained for each individual without the need for constant pressure checks using classical devices. They plan to try the glasses in a clinical setting, comparing them with very accurate invasive pressure measurements using needles – patients of a university hospital can participate in this study.
The research team is also developing a new version of glasses with a reduced frame, more efficient energy consumption and improved signal recognition. Ideally, they tend to reduce the device to the size of a clothespin that can fit on any glasses.
Whether Microsoft's Glabella glasses become a breakthrough, or some other wearable device, convenient and constant monitoring of blood pressure can help to more closely link pressure and factors such as walking or jogging, eating certain foods and taking medications. Continuous data collection on a large scale may even someday lead to improvements in the medical understanding of various diseases thanks to pressure data collected during the day from hundreds or thousands of people.
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