Engineers at the University of California, San Diego developed a flexible, elastic ultrasonography patch that can be worn on the skin to follow blood flow through vital arteries and veins deep in a person’s body. To diagnose various heart diseases, such as blood clots, heart valve problems, poor circulation to organs, or blockages in arteries that can result in stroke or heart attack, doctors must be aware of how fast and how much blood is flowing. The patient’s blood vessels.
A new ultrasound patch developed at UC San Diego can monitor blood flow — as well as blood pressure and heart function — in real time. Wearing such a device makes it easier to identify heart problems quickly. A team led by Sheng Xu, a professor of nanoengineering at the UC San Diego Jacobs School of Engineering, reported the patch in a paper published July 16 in Nature Biomedical Engineering.
The patch can be worn on the neck or chest. What is special about the patch is that it can non-invasively sense and measure cardiovascular signals up to 14 cm deep inside the body. And it can do it with high accuracy. “This kind of wearable device can give you a more detailed, more accurate picture of what’s going on from the surface of the skin to deeper tissues and vital organs like the heart and brain,” Xu said.
“Sensing signals at such depths is extremely challenging for wearable electronics. However, this is where the body’s most important signals and central organs are buried,” said Chongye Wang, a former nanoengineering graduate student in Xu’s lab and co-first author. Study. “We have engineered a wearable device that can penetrate such deep tissue depths and sense those vital signals beneath the skin. This technology could provide new insights into the field of healthcare.”
Another innovative feature of the patch is that the ultrasound beam can be bent at different angles and steered to areas of the body that are not directly under the patch. This is a first in the field of wearables, Xu explained, because existing wearable sensors typically only monitor areas below them. “If you want to sense signals in a different position, you have to move the sensor to that position. With this patch, we can probe wider areas than the footprint of the device. This can open up a lot of opportunities.”
The patch is made of a thin sheet of flexible, stretchable polymer that adheres to the skin. Embedded in the patch is an array of millimeter-sized ultrasound transducers. Each is individually controlled by a computer — this type of array is called an ultrasound phased array. This is a key part of the technology because it gives the patch the ability to go deeper and wider.
A phased array offers two main modes of operation. In a single mode, all transducers can be synchronized to transmit ultrasound waves together, producing a high-intensity ultrasound beam that is focused as deep as 14 centimeters into the body. In another mode, the transducers can be programmed to send out of sync, producing ultrasound beams that can be steered at different angles.
“With phased array technology, we can manipulate the ultrasound beam in any way we want,” says nanoengineering Ph.D. Muyang Lin said. student at UC San Diego who is also co-first author of the study. “This gives our device several capabilities: monitoring central organs and blood flow with high resolution. This would not be possible using just one transducer.”
A phased array consists of a 12 by 12 grid of ultrasound transducers. When electricity flows through the transducers, they vibrate and emit ultrasound waves that travel deep into the skin and body. When ultrasound waves enter a major blood vessel, they encounter movement from red blood cells flowing in. This movement causes or changes how the ultrasound waves resonate in the patch – called a Doppler frequency shift. This change in reflected signals is picked up by the patch and used to create a visual recording of blood flow. This same mechanism can also be used to create dynamic images of the heart wall.
For most people, blood flow isn’t something that’s measured during a routine doctor’s visit. It is usually evaluated when the patient shows some signs of heart disease, or if the patient is at high risk. Standard blood flow tests themselves can be time consuming and labor intensive. A trained technician presses a handheld ultrasound probe against the patient’s skin and moves it from one area to another until it is directly over a major blood vessel. This may seem straightforward, but results can vary between tests and techniques.
Because the patch is easy to use, it can solve these problems, says Sai Zhou, a materials science and engineering Ph.D. student at UC San Diego and co-author of the study. “Just stick it on the skin, then read the signs. It’s not operator-dependent, and it doesn’t create any extra work or burden for technicians, physicians or patients,” he said. “In the future, patients could wear something like this for continuous monitoring at the point of care or at home.”
In the tests, the patch was performed as well as a commercial ultrasound probe used in the clinic. It accurately recorded blood flow in major blood vessels such as the carotid artery, which is an artery in the neck that supplies blood to the brain. The ability to monitor changes in this flow could, for example, help identify whether a person is at risk of stroke before symptoms begin.
The researchers point out that the patch still has a long way to go before it’s ready for the clinic. Currently, it needs to be connected to a power source and benchtop machine to work. Xu’s team is working on integrating all the electronics in the patch to make it wireless.
This story is published from the Wire Agency feed without modification to the text. Only the headline has been changed.