In the comfort of a patient’s home, wearable ultrasound patches can revolutionize healthcare by easing the remote monitoring of vital physiological functions.
A view of the ultrasound probe and the interior of the circuit. Image Credit: National Institute of Biomedical Imaging and Bioengineering
However, the majority of the patches in development have a significant limitation: they need cables to power the device and further transmit the ultrasound data, thereby physically tying the wearer to a control system.
A completely wireless ultrasound patch that can constantly track essential vital signals like blood pressure and heart rate was recently reported in Nature Biotechnology.
The patch, which has the potential to capture elaborate medical information and wirelessly send the data to a smart device (like a smartphone or laptop), could depict a significant step forward in at-home healthcare technology.
The true impact of wearable ultrasound patches has yet to be fully realized, as previously described iterations aren’t wireless and limit the users’ ability to go about their daily lives.
Randy King, Ph.D., Program Director, Division of Applied Science & Technology, National Institute of Biomedical Imaging and Bioengineering
King added, “The technology described here represents necessary and essential progress in the wearable ultrasound space, potentially unlocking the promise of remote ultrasound monitoring for any number of health conditions.”
Ultrasound, which makes use of sound waves and their consequent echoes to image tissues within the body, has conventionally been restricted to the clinic.
In this study, the ultrasound patch technology was pioneered by Sheng Xu, Ph.D., an associate professor and Jacobs Faculty Scholar at the University of California San Diego (UC San Diego). Earlier, his team reported wearable ultrasound patches with comparable transducers. The real progress in this latest study is the patch’s wireless capability.
The key element of this study is the design of the ultrasound circuit. In our previous patches, the ultrasound probe was connected to a flexible cable for power and data transmission. In this patch, the cables are replaced with a wearable circuit, which can pre-process and wirelessly transmit the ultrasound data to a back-end station for further analysis.
Sheng Xu, Ph.D., Associate Professor and Jacobs Faculty Scholar, the University of California San Diego
The ultrasound system is made of a circuit, probe, and also battery. Since the present system was developed with a focus on cardiovascular health, the ultrasound probe was placed normally on the carotid artery in this study.
The probe has been fixed to a flexible circuit, which triggers the ultrasound transducers, gathers the ultrasound echoes, amplifies and filters such echoes, and further sends the digitized signal to a terminal device. The complete system is powered by a commercial rechargeable lithium polymer battery.
“We developed a machine learning algorithm to coordinate with the circuit to automatically process the ultrasound signals and continuously track the carotid artery, which allows us to obtain ultrasound information even when the wearer of the patch is moving. This automatic tracking algorithm provides unprecedented opportunities for medical ultrasonography and exercise physiology,” explained first author Muyang Lin, a Ph.D. candidate in the Xu laboratory.
For its generalizability to be evaluated, the scientists cross-validated their machine learning model among ten healthy subjects constituting three distinct racial groups. With the help of a machine learning method known as domain adaptation, the scientists discovered that a model trained on data from one participant wearing the patch could be adapted successfully for the other participants.
Having the least model retraining, the patch can track the pulsations of the carotid artery with high precision, thereby enabling measurements like arterial stiffness, blood pressure, and cardiac output. Constant tracking of such measurements among high-risk populations could offer progressive warning of heart failure.
Lin stated, “Validating our patch in a larger population is a crucial next step. We are working on validating our sensor against existing medical devices.”
While the device was primarily assessed on its potential to track cardiovascular functions, the scientists also illustrated that the patch could be employed in the limbs for peripheral artery monitoring or the abdomen for diaphragm monitoring.
The system holds the potential to perform measurements at multiple spots in the body, and we can easily tailor the probe design to fit diverse tissue monitoring requirements.
Sheng Xu, Ph.D., Associate Professor and Jacobs Faculty Scholar, the University of California San Diego
Lin added, “With this kind of device, we hope to blur the boundary between at-home care and in-hospital diagnosis. We foresee a future where diagnoses can occur anytime and anywhere, enabled by wireless devices like these.”
This study was financially supported by a grant from NIBIB (R01EB033464).
Journal Reference
Lin, M., et al. (2023) A fully integrated wearable ultrasound system to monitor deep tissues in moving subjects. Nature Biotechnology. doi.org/10.1038/s41587-023-01800-0.