Another kind of fitness tracker?

Unfortunately, with today’s technology these wearable watches would squeeze your wrist every few minutes like the cuffs at a doctor’s office, making them annoying – especially if you’re trying to sleep. A better way might measure the tiny changes in pressure on your wrist with each heartbeat.

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. To help them, scientists at NIST are working with doctors to create a basic model of a human arm.

The model arm is made of a squishy pad of see-through silicone, the stand-in for skin, muscle, and fat. This silicone sits on top of a metal plate, which acts like bone. Buried inside the silicone is a soft plastic tube. Scientists pump water through this tube to mimic the flow of blood through an artery. They also put sensors inside the model arm, to measure the pressure around the fake artery and throughout the silicone.

The model arm is designed to be simple, so that scientists can understand it completely. Right now NIST is helping to design the arm and test how their sensors respond. When they have finished their tests, they will send the arm to medical researchers – who can use it to make BP watches for you.