Underpants-tonometer
Underpants have been developed and patented to help hypertensive patients monitor their blood pressure, NewScientist reports.
As you know, the procedure for measuring blood pressure is not complicated, but requires a relatively bulky device, which is difficult to have with you all the time. At the same time, blood pressure monitoring can significantly reduce the risk of hypertension complications.
The principle of operation of the underpants-tonometer is based on the recently discovered relationship between the pulse wave velocity and blood pressure. A pulse wave is an expansion of their walls propagating along the arteries under the influence of blood pressure ejected into these vessels by a contraction of the heart.
As the pulse wave moves through the arteries, the electrical resistance of the tissues changes. Therefore, the pulse wave velocity, and hence blood pressure, can be calculated by the time the wave passes between the two resistance sensors.
(If you are also wondering why underpants and not a bracelet, take a closer look at the drawing from the patent. It is not difficult to guess that the larger the arteries and the less interference from sudden movements, the fewer errors there will be when measuring signals – VM).
Note that in 2003 Philips developed underpants that allow recording an electrocardiogram.