Developed by professor Zhenan Bao of Stanford University, the monitor is thinner than a dollar bill and about as wide as a postage stamp. The middle layer of the device is made of rubber covered with tiny, pyramid-shaped bumps a few microns across. When the device is subjected to pressure (such as the beating of a pulse) the bumps deform slightly and alter the size of the gap between the device’s two halves, resulting in a measurable change in the current flow in the device.

The device is also sensitive enough to detect the main peak of the pulse as well as its recoil pressure, providing medical staff with a way to monitor heart health details like the patient's degree of artery stiffness.