The University of California San Diego engineers have created a wearable ultrasound patch that can continuously and non-invasively monitor blood flow in the brain. This stretchy and soft patch can be worn comfortably on the temple and provides three-dimensional data on cerebral blood flow, making it the first of its kind in wearable technology.
A research team led by Sheng Xu, a professor in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at the UC San Diego Jacobs School of Engineering, has developed a new technology that was published on May 22 in Nature.
The new wearable ultrasound patch is a major improvement from the current clinical standard, known as transcranial Doppler ultrasound. This method involves a trained technician holding an ultrasound probe against a patient’s head. However, this process has its drawbacks. It relies on the operator’s skill, so the accuracy of the measurement can vary based on the operator.The current method of monitoring cerebral blood flow is not practical for long-term use. Xu’s team has created a device that addresses this issue. Their wearable ultrasound patch offers a hands-free, consistent, and comfortable solution that can be worn continuously while a patient is in the hospital. Sai Zhou, a materials science and engineering Ph.D. candidate in Xu’s lab, explained that the patch’s continuous monitoring capability fills a critical gap in current clinical practices. Typically, cerebral blood flow is only monitored at specific times each day, which may not accurately reflect what happens during the rest of the day.There may be small changes in measurements that go unnoticed. This device could provide important information for timely intervention if a patient is about to have a stroke in the middle of the night.” Patients recovering from brain surgery could also benefit from this technology, according to Geonho Park, a co-author of the study and a Ph.D. student in chemical and nano engineering in Xu’s lab. The patch, about the size of a postage stamp, is made of silicone elastomer embedded with layers of stretchy electronics. One layer contains a group of small piezoelectric tra.The patch contains transducers that generate ultrasound waves when powered and detect ultrasound waves bounced back from the brain. It also includes a copper mesh layer, made of wire springs, to improve signal quality by reducing interference from the user’s body and surroundings. The remaining layers are made up of stretchable electrodes.
When in use, the patch is linked to a power source and computer through cables. In order to achieve 3D monitoring, the scientists integrated ultrafast ultrasound imaging into the system. This method differs from traditional ultrasound, which captures approximately 30 images per second., high-speed imaging technology is able to capture numerous images every second, allowing for the collection of reliable data from the piezoelectric transducers in the patch. This is crucial as the transducers would normally experience low signal intensity due to the strong reflection of the skull.
Afterwards, the collected data is processed using specialized algorithms to generate 3D details such as the dimensions, orientation, and location of the major arteries in the brain.
“The cerebral vasculature is a complex network of vessels that branch out in multiple directions. A device capable of capturing this three-dimensional information is necessary to gain a comprehensive understanding and to obtain more precise measurements.””Collaboration among disciplines is crucial for developing new medical advancements,” stated Xinyi Yang, a fellow co-first author and a materials science and engineering Ph.D. student in Xu’s lab. This study involved testing a patch on 36 healthy volunteers to assess its ability to measure blood flow velocities in the brain’s major arteries. Activities that affected blood flow, such as hand-gripping, breath-holding, and reading, were performed by the participants. The patch’s measurements were found to be in close agreement with those obtained using a traditional ultrasound probe. The next step for the researchers is to work with clinicians at UC San Diego School of Medicine to conduct further testing.Xu and his team have developed a patch for patients with neurological conditions that affect the flow of blood to the brain. The technology is being commercialized through a startup company called Softsonics, co-founded by Xu. The research and development of this patch were supported by the National Institutes of Health through various grants.
