Blood pressure is typically measured via a cuff that’s designed to temporarily half blood flow. Whilst there may be benefits, therefore of being able to monitor blood pressure more frequently, it is both impractical and rather annoying to do so using this technology.
A better alternative may exist however, with researchers from NIST developing a device that is capable of detecting subtle pressure changes in the skin above our radial artery, without needing to cut off the circulation.
To support this project, the researchers are developing a physical ‘phantom’ model to mimic the mechanics of blood as it makes its way around the body. This can then be used to test various wearable blood pressure devices.
Constant pressure
The device consists of a piece of squishy silicone sitting on top of a metal plate. A pliable tube then runs through the silicone to replicate the artery, and fluid is pumped through it via a mechanical heart pump.
“One of the things we want to understand is, if a sensor is sitting up here on top of the silicone, what is it really seeing?” the team say. “Is it just seeing the primary wave from a pulse of fluid going through? Is it seeing a lot of reflection waves, when the primary wave bounces off the metal plate? How does the pressure change over the time it takes for each pulse of water to pass through the artificial artery?”
They are currently using Bragg gratings to sense changes in the fluid as it flows through the ‘artery’, with the system designed to change color as the pressure changes.
The team are conducting preliminary tests to measure the performance of the system, with these tests suggesting the system can currently detect pressures from 170 millimeters of mercury down to 60 mmHG, with a resolution of 2 mmHG.
Also of note is that the results achieved thus far are easily reproducible, and with the device robust enough to sustain the rigors of daily use, it shows considerable promise. The hope is that if further testing proves successful over a longer timeframe, a prototype could be developed later this year.
Check out the video below to see the device in action.
