University of California San Diego (UCSD) engineers have developed a smart skin patch that can detect blood clots and other concerning cardiovascular conditions. The soft patch uses ultrasound nanotechnology to provide a comprehensive picture of how blood flows through deep arteries and veins.

The new patch, worn on the neck or chest, continuously monitors blood flow, blood pressure, and heart function. It detects cardiovascular signals in blood vessels as deep as 14 centimeters (five and a half inches) inside the body in real-time with high accuracy. Analyzing those signals could help providers diagnose heart valve or circulation issues, as well as blockages that could cause strokes or heart attacks.

Improving on the limitations of existing wearables, the UCSD team embedded a phased array of ultrasound transducers within a stretchable polymer similar to a bandaid. A computer controls each individual 1-millimeter transducer separately. In one mode, the computer synchronizes all transducers to produce a high-intensity ultrasound beam that focuses deeply on a single spot. 

The second mode involves an asynchronized program in which the transducers transmit individually. In this mode, the ultrasound beam can be tilted to measure from multiple angles. Most wearable biosensors can’t monitor deep structures, nor can they detect signals anywhere except directly beneath them. The UCSD patch offers a much broader monitoring range that results in high-acuity moving images of blood as it flows through vessels or an inside view of the heart’s wall as it pumps blood through the circulatory system.

Tests showed that the patch performed with the same accuracy as the gold standard for measuring blood flow: a handheld ultrasound probe. Currently, a provider only orders an in-clinic ultrasound for at-risk patients or who already have cardiovascular symptoms. The new patch could identify signs that an individual is at risk for dangerous events such as stroke much earlier, potentially preventing adverse patient events. 

However, further development is needed before it can be used during standard office visits or for at-home monitoring. At the moment, bulky wires connect the device to the computer and power source, so a priority for the engineering team is to make the patch fully wireless. The UCSD team published their findings in the journal nature biomedical engineering.