When you think of radar, you might well think of the dishes that scan the skies to locate aircraft, sending out radio waves and detecting them when they bounce off a target object. But radar can do more than determine an object’s location; it can also determine the direction and speed of its movement. If you’re a baseball fan, you’re probably familiar with the handheld radar used to measure the speed of pitches during a game. The speed is determined by the Doppler effect; if the object is moving toward you, the radio waves get compressed slightly and the higher frequency can yield the velocity. This is the same effect that makes a train’s horn sound at a higher pitch as it approaches you, then drops to a lower pitch as it passes and moves away from you.
Fascinating, right? But what the heck does this have to do with wearable Health Tech? Researchers in Belgium have studied the use of radar as a way to detect heartbeats in subjects. Unlike other electrical or optical systems that require contact with the skin, this technique works without touching the subject’s body. While it can be incorporated into a wearable pinned to a subject’s clothing, it can even be implemented using base stations located within the user’s environment. Tiny radio signals are projected onto the body and then the minute changes in the reflected frequency can be used to determine heartbeats. The heart contractions result in nearly imperceptible movement at the surface of the body. The researchers have even developed algorithms that can separate the motion due to heartbeats from those caused by walking or even breathing.
It is possible to create the required radar antennas using conductive textile material, so it may be possible to create clothing that would incorporate this sort of sensor. The device can be used for other functions as well, such as fall detection for the elderly. Using this technology, a wearable device or a system of radar beacons around the home could simultaneously monitor a subject for their location, fall-detection, and the collection of vital sign biometric data using the one set of non-contact sensors.
