Engineers develop ultrasound patch to monitor blood flow

Engineers at the University of California San Diego have developed an ultrasound patch that can be worn on the skin. It monitors the blood flow through major arteries and veins deep within the body.

It is hoped that it could help clinicians diagnose cardiovascular conditions faster.

The ultrasound patch continuously monitors blood flow as well as blood pressure and heart function in real-time. Assessing how much blood flows through a patient’s blood vessels could help diagnose blood clots, heart valve problems, poor circulation in the limbs, blockages in the arteries which could lead to strokes or heart attacks.

For many patients, blood flow is not measured during a regular visit to their doctors. It is usually assessed after a patient shows signs of cardiovascular problems. The patch can be worn on the neck or chest and can measure cardiovascular signals up to 14 centimetres inside the body non invasively with high accuracy.

How the patch works:

The patch is made of a thin, flexible polymer that sticks to the skin. There is an array of millimetre-sized ultrasound transducers on the patch known as an ultrasound phased array. These are individually controlled by a computer.

Another feature is that the ultrasound beam can be tilted at different angles to areas in the body that are not directly below the patch.

It can operate in two modes. In one, all of the transducers can be synched together to transmit ultrasound waves which produce a high-intensity beam that focuses on one spot. This can be up to 14cm deep in the body.

The other mode allows the transducers to be programmed to transmit out of sync producing beams at different angles. In being able to manipulate the beams, it gives the device multiple capacities for monitoring central organs as well as blood flow with high resolution.

When the electricity flows through the transducers, they vibrate while emitting ultrasound waves that travel through the skin into the body. When they penetrate a blood vessel, they encounter the movement of red blood cells flowing inside.

The cell movement changes how the waves are transmitted back to the patch. This change is recorded by the patch and creates a visual recording of the blood flow. It can also be used to create moving images of the heart’s walls.

The benefits

Sheng Xu, professor of nanoengineering at the UC San Diego Jacobs School of Engineering said: “This type of wearable device can give you a more comprehensive, more accurate picture of what’s going on in deep tissues and critical organs like the heart and the brain, all from the surface of the skin.”

Xu added: “This is a first in the field of wearables, because existing wearable sensors typically only monitor areas right below them. “If you want to sense signals at a different position, you have to move the sensor to that location.

“With this patch, we can probe areas that are wider than the device’s footprint. This can open up a lot of opportunities.”

The researchers say that the easy to use patch could allow patients to wear the patch and monitor the results themselves. It doesn’t depend on a technician to read the results

The next stage

The patch is not yet ready for clinical use. The researchers are currently working on a way to make the electronics wireless as it currently needs a power source and benchtop machine.

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Image credit: Nature Biomedical Engineering