Science -- July 29, 2022: Clinical staff can view a patient's internal organs in real time thanks to ultrasound imaging,
a safe and non-invasive window into the workings of the human body.

Trained technicians use ultrasound wands and probes to manipulate sound waves into the body in order to obtain these images. The heart, lungs, and other deep organs of the patient can be seen in high resolution because to the reflection of these waves.

At the moment, ultrasound imaging requires heavy, specialized equipment that is only found in medical facilities and clinics. The technology may soon be as wearable and accessible as buying Band-Aids at the drugstore thanks to a new design by MIT engineers.

The engineers describe their innovative ultrasound sticker design in a study that will be published in Science today. The ultrasound sticker is a stamp-sized gadget that adheres to the skin and can continuously image inside organs for 48 hours.

The devices yielded real-time, high-resolution photos of the deeper organs, including the heart, lungs, and stomach, when the researchers put the stickers to volunteers. The volunteers engaged in a variety of activities, such as sitting, standing, jogging, and biking, and the stickers remained firmly adhered and documented changes in the underlying organs.

The stickers must currently be connected to devices that convert the reflected sound waves into visuals. The researchers note that the stickers might be used right away even in their current form: To continually photograph internal organs without requiring a technician to hold a probe in place for extended periods of time, the devices could, for example, be affixed to hospital patients in a manner similar to heart-monitoring EKG stickers.

The ultrasound stickers might be turned into wearable imaging items that patients could take home from a doctor's office or even buy at a drugstore if the gadgets can be made to operate wirelessly, a goal the team is now working toward.

"We envision a few patches adhered to different locations on the body, and the patches would communicate with your cellphone, where AI algorithms would analyze the images on demand," says the study's senior author, Xuanhe Zhao, professor of mechanical engineering and civil and environmental engineering at MIT. "We believe we've opened a new era of wearable imaging: With a few patches on your body, you could see your internal organs."

Along with Hsiao-Chuan Liu of the Mayo Clinic in Rochester, Minnesota, the study's co-authors Liu Wang, Mitsutoshi Makihata, Tao Zhao, and main authors Chonghe Wang and Xiaoyu Chen also hail from MIT.

An ultrasound technician will first apply a liquid gel to the skin of the patient in order to transmit ultrasonic waves. Then, by pressing a probe into the gel, sound waves are sent into the body, resonating off of interior structures, and returning to the probe, where the echoed signals are converted into visual images.

Some hospitals have probes attached to robotic arms that can hold a transducer in place without tiring for patients who need prolonged imaging, but the liquid ultrasound gel eventually runs away and dries out, cutting off long-term imaging.

Stretchable ultrasonic probe designs have been studied recently in order to enable internal organ imaging that is portable and low-profile. These designs provided a stretchable array of tiny ultrasonic transducers with the intention that they would adapt to the shape of a patient's body.

But because of their stretch, these experimental designs have created low-resolution images: Transducers move relative to one another as the body does, causing an image distortion.

"Wearable ultrasound imaging tool would have huge potential in the future of clinical diagnosis. However, the resolution and imaging duration of existing ultrasound patches is relatively low, and they cannot image deep organs," says Chonghe Wang, who is an MIT graduate student.

The novel ultrasound sticker developed by the MIT team combines a stiff array of transducers with a stretchable adhesive layer to provide greater resolution images over a longer period of time. In order to provide sharper and more accurate images, the device can mold to the skin while maintaining the relative placement of the transducers. Wang opined.

The sticky layer of the device is constructed from two thin layers of elastomer that enclose a middle layer of solid hydrogel, a substance that is primarily water-based and effectively transmits sound waves. The hydrogel developed by the MIT team is elastic and stretchable, unlike conventional ultrasonic gels.

"The elastomer prevents dehydration of hydrogel," says Chen, an MIT postdoc. "Only when hydrogel is highly hydrated can acoustic waves penetrate effectively and give high-resolution imaging of internal organs."

The top layer attaches to a stiff array of transducers that the researchers also designed and made, while the bottom elastomer layer is intended to stick to skin. The complete ultrasound sticker is about the size of a postage stamp: 2 square centimeters wide and 3 millimeters thick.

With healthy participants wearing the stickers on various body areas, such as the neck, chest, belly, and arms, the researchers put the ultrasound sticker through a series of tests. For up to 48 hours, the stickers remained affixed to their skin and produced sharp photos of the underlying structures. Volunteers engaged in a range of activities in the lab during this period, including sitting and standing, jogging, biking, and lifting weights.

The team was able to see how the diameter of the main blood vessels changed between standing and sitting thanks to the images on the stickers. The stickers also recorded information about deeper organs, such as the way that exercise causes the heart to change shape. As subjects drank juice and then subsequently passed it out of their systems, the researchers were also able to observe the stomach expanding and then contracting. Additionally, the team could see colorful patterns in the muscles beneath some participants as they lifted weights, indicating transitory microdamage.

"With imaging, we might be able to capture the moment in a workout before overuse, and stop before muscles become sore," says Chen. "We do not know when that moment might be yet, but now we can provide imaging data that experts can interpret.

The group is attempting to make the stickers wirelessly functional. They are also creating artificial intelligence-based software algorithms that can more accurately decipher and diagnose the images of the stickers. Zhao then imagines that ultrasound stickers may be packed and bought by patients and customers, and used to not only monitor different internal organs but also the growth of malignancies and fetuses inside the womb.

"We imagine we could have a box of stickers, each designed to image a different location of the body," Zhao says. "We believe this represents a breakthrough in wearable devices and medical imaging."

Through MIT's Institute for Soldier Nanotechnologies, this research was supported in part by MIT, the Defense Advanced Research Projects Agency, the National Science Foundation, the National Institutes of Health, and the U.S. Army Research Office.

See the video at this link: here

Wnctimes by Marjorie Farrington

Materials provided by Massachusetts Institute of Technology. Original written by Jennifer Chu. 

Journal Reference:

Chonghe Wang, Xiaoyu Chen, Liu Wang, Mitsutoshi Makihata, Hsiao-Chuan Liu, Tao Zhou, Xuanhe Zhao. Bioadhesive ultrasound for long-term continuous imaging of diverse organs. Science, 2022; 377 (6605): 517 DOI: 10.1126/science.abo2542

Cite This Page:

Massachusetts Institute of Technology. "Engineers develop stickers that can see inside the body: New stamp-sized ultrasound adhesives produce clear images of heart, lungs, and other internal organs." ScienceDaily. ScienceDaily, 28 July 2022. .



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