Researchers have developed a new type of wearable sensor that could greatly improve the accuracy and practicality of heart monitoring. Developed by Zhenan Bao, a professor of chemical engineering at Stanford University, the paper-thin, stamp-sized sensor is made with flexible organic materials and can be worn under an adhesive bandage on the wrist to monitor the pulse.

To achieve this combination of reduced scale and high sensitivity, the researchers used a thin middle layer of compressible rubber covered with tiny pyramid-shaped bumps only a few microns wide. When pressure is applied the pyramids deform slightly, which results in a measurable change in the electromagnetic field and the current flow in the device.

The degree of sensitivity achieved by the monitor means that when placed on a patient’s wrist it can measure the two distinct peaks of the pulse wave as well as fluctuations within the wave, opening up the possibility for extremely detailed diagnostics.

"You can use the ratio of the two peaks to determine the stiffness of the artery, for example," said Gregor Schwartz, a post-doctoral fellow and a physicist for the project.

The device offers obvious advantages in situations where the pulse needs to be measured constantly, such as monitoring patients during surgery or athletes during sporting activity.

"For some patients with a potential heart disease, wearing a bandage would allow them to constantly measure their heart's condition," Bao said. "This could be done without interfering with their daily life at all, since it really just requires wearing a small bandage."

This accuracy of the prototype device also means that once it has been calibrated, the signals of the pulse can be used as an alternative to intravascular catheters for calculating blood pressure.

In addition, a number of these sensors on a prosthetic limb could be used as a kind of electronic skin with an artificial sense of touch.

The team’s next goal is to fit the device with wireless connection that would allow doctors to receive continuous updates about a patient’s heart via cell phone.

Details of the device appeared in the May 12 edition of Nature Communications.

In the video below members of the Stanford research team discuss new sensor.