The Holy Grail for wearable technology may well be a reliable way to measure blood pressure without using a pressure cuff or similar device. A dependable and accurate system would be valuable for constant remote patient monitoring, both in clinical settings and at home. Many researchers are working toward optical solutions, but some experts are skeptical that this can be made to work reliably or without a cuff measurement to calibrate the readings.

Researchers at the Jacobs School of Engineering at the University of California San Diego are developing a wearable ultrasound patch that measures central blood pressure beneath the skin. This non-invasive technology could potentially replace current invasive methods that utilize catheters or probes to read central artery blood pressure. Central blood pressure measurement has greater significance for predicting heart disease than peripheral blood pressure readings with inflatable cuffs or any other method that reads data from the skin surface. According to the UCSD team, their wearable ultrasound patch can return continuous, accurate central blood pressure readings in major arteries as deep as four centimeters beneath the skin (more than an inch and a half deep).

The patch has an island-bridge pattern structure on a thin sheet of silicone elastomer. The “islands” are tiny piezoelectric transducers and electrodes. Spring-like copper wires act as “bridges” to connect the electronics. The pattern allows the patch to conform to body shapes without interfering with the device’s function. In a study published in Nature Biomedical Engineering, the team reports the wearable ultrasound patch was as accurate as some clinical central blood pressure measurement methods.

The UCSD researchers aren’t close to releasing the ultrasound patch. Next development steps include the development of power sources, data processing units, and wireless communication. The initial results offer hope that in the future, we may be able to monitor blood pressure simply by applying a smart patch.