Developing a wearable fitness device to monitor Blood Pressure (BP) continuously 24/7 is important. The problem is that blood pressure measurements currently require the use of a cuff that temporarily stops blood flow. So a wearable BP watch using today’s technology would squeeze your wrists every few minutes, making it impracticable to use—not to mention annoying.
A better method might gauge subtle pressure changes at the surface of your skin above one of the main wrist arteries called the radial artery without regularly cutting off the circulation. But before scientists can create this new technology, they need to understand what the pressure inside a blood vessel looks like on the surface of the skin. However, to do this, a physical model must be made that could be used to test wearable devices in the laboratory.
To proceed, the National Institute of Standards and Technology’s (NIST) Physical Measurement Laboratory (PML)www.nist.gov/pm is collaborating with Tufts University’s School of Medicine http://medicine.tufts.edu to develop the model blood pressure wrist phantom. The blood pressure phantom is essentially a fake arm that mimics the mechanical properties of blood pulsing through an artery surrounded by human tissue.
The NIST-Tufts blood pressure phantom consists of a slab of squishy silicone which stands in for human tissue, sitting on top of a metal plate. A pliable tube runs through the silicone to mimic an artery through which fluid flows via a mechanical heart pump.
The materials used in the blood pressure phantom were selected to match the properties of skin, soft tissues, bone, and artery walls. But unlike actual live human tissue, the phantom can easily have sensors running through it to measure the pressure changes that occur each time water is pumped through the tube.
The NIST team is conducting preliminary tests to gauge the performance of their sensors using a prototype. So far, they have found that their sensors are able to detect pressures. The team is currently preparing to test the sensors’ ability to measure pressures that change over time using a universal testing machine. If all goes well, the collaboration could potentially have a working prototype sometime in 2017.