MIT Engineers Develop Ultrasound Stickers That Can See Inside the Body

New stamp-sized ultrasound adhesives ship clear photographs of the coronary heart, lungs, and different inside organs.

When clinicians want dwell photographs of a affected person’s inside organs, they typically flip to ultrasound imaging for a secure and noninvasive window into the physique’s workings. In order to seize these insightful photographs, skilled technicians manipulate ultrasound wands and probes to direct sound waves into the physique. These waves replicate again out and are used to supply high-resolution photographs of a affected person’s coronary heart, lungs, and different deep organs.

Ultrasound imaging at the moment requires cumbersome and specialised gear obtainable solely in hospitals and physician’s places of work. However, a brand new design developed by MIT engineers might make the technology as wearable and accessible as buying Band-Aids at the drugstore.

The engineers presented the design for the new ultrasound sticker in a paper published on July 28 in the journal Science. The stamp-sized device sticks to skin and can provide continuous ultrasound imaging of internal organs for 48 hours.

To demonstrate the invention, the researchers applied the stickers to volunteers. They showed the devices produced live, high-resolution images of major blood vessels and deeper organs such as the heart, lungs, and stomach. As the volunteers performed various activities, including sitting, standing, jogging, and biking, the stickers maintained a strong adhesion and continued to capture changes in underlying organs.

In the current design, the stickers must be connected to instruments that translate the reflected sound waves into images. According to the researchers, the stickers could have immediate applications even in their current form. For example, the devices could be applied to patients in the hospital, similar to heart-monitoring EKG stickers, and could continuously image internal organs without requiring a technician to hold a probe in place for long periods of time.

Making the devices work wirelessly is a goal the team is currently working toward. If they are successful, the ultrasound stickers could be made into wearable imaging products that patients could take home from a doctor’s office or even buy at a pharmacy.

“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.”

The study also includes lead authors Chonghe Wang and Xiaoyu Chen, and co-authors Liu Wang, Mitsutoshi Makihata, and Tao Zhao at MIT, along with Hsiao-Chuan Liu of the Mayo Clinic in Rochester, Minnesota.

A sticky subject

To picture with ultrasound, a technician first applies a liquid gel to a affected person’s pores and skin, which acts to transmit ultrasound waves. A probe, or transducer, is then pressed towards the gel, sending sound waves into the physique that echo off inside buildings and again to the probe, the place the echoed indicators are translated into visible photographs.

For sufferers who require lengthy durations of imaging, some hospitals supply probes affixed to robotic arms that may maintain a transducer in place with out tiring, however the liquid ultrasound gel flows away and dries out over time, interrupting long-term imaging.

In latest years, scientists have explored designs for stretchable ultrasound probes that would offer moveable, low-profile imaging of inside organs. These designs gave a versatile array of tiny ultrasound transducers, the thought being that such a tool would stretch and conform to a affected person’s physique.

But these experimental designs have produced low-resolution photographs, partially as a result of their stretch: In transferring with the physique, transducers shift location relative to one another, distorting the ensuing picture.

“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’s an MIT graduate pupil.

An inside look

By pairing a stretchy adhesive layer with a inflexible array of transducers, the MIT staff’s new ultrasound sticker produces larger decision photographs over an extended length. “This combination enables the device to conform to the skin while maintaining the relative location of transducers to generate clearer and more precise images.” Wang says.

The machine’s adhesive layer is comprised of two skinny layers of elastomer that encapsulate a center layer of strong hydrogel, a largely water-based materials that simply transmits sound waves. Unlike conventional ultrasound gels, the MIT staff’s hydrogel is elastic and stretchy.

“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 backside elastomer layer is designed to stay to pores and skin, whereas the high layer adheres to a inflexible array of transducers that the staff additionally designed and fabricated. The complete ultrasound sticker measures about 2 sq. centimeters throughout, and three millimeters thick — about the space of a postage stamp.

The researchers ran the ultrasound sticker by a battery of exams with wholesome volunteers, who wore the stickers on varied components of their our bodies, together with the neck, chest, stomach, and arms. The stickers stayed connected to their pores and skin, and produced clear photographs of underlying buildings for as much as 48 hours. During this time, volunteers carried out quite a lot of actions in the lab, from sitting and standing, to jogging, biking, and lifting weights.

From the stickers’ photographs, the staff was in a position to observe the altering diameter of main blood vessels when seated versus standing. The stickers additionally captured particulars of deeper organs, akin to how the coronary heart adjustments form because it exerts throughout train. The researchers have been additionally in a position to watch the abdomen distend, then shrink again as volunteers drank then later handed juice out of their system. And as some volunteers lifted weights, the staff might detect shiny patterns in underlying muscular tissues, signaling non permanent 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 engineering staff is working to make the stickers perform wirelessly. They are additionally creating software program algorithms based mostly on synthetic intelligence that may higher interpret and diagnose the stickers’ photographs. Then, Zhao envisions ultrasound stickers might be packaged and bought by sufferers and shoppers, and used not solely to watch varied inside organs, but in addition the development of tumors, in addition to the growth of fetuses in 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.”

Reference: “Bioadhesive ultrasound for long-term continuous imaging of diverse organs” by Chonghe Wang, Xiaoyu Chen, Liu Wang, Mitsutoshi Makihata, Hsiao-Chuan Liu, Tao Zhou and Xuanhe Zhao, 28 July 2022, Science.
DOI: 10.1126/science.abo2542

This analysis was funded, partially, by MIT, the Defense Advanced Research Projects Agency, the National Science Foundation, the National Institutes of Health, and the U.S. Army Research Office by the Institute for Soldier Nanotechnologies at MIT.