MIT engineers develop stickers to see inside | MIT News

Ultrasound imaging is a safe, non-invasive window to the work of the body, providing clinicians with live images of the patient’s internal organs. To capture these images, a trained technician operates an ultrasonic wand and probe to direct sound waves into the body. These waves are reflected back and produce high-resolution images of the patient’s heart, lungs, and other deep organs.

Currently, ultrasound imaging requires bulky special equipment that can only be used in hospitals and clinics. However, the new design by MIT engineers could make the technology as wearable and accessible as buying a band-aid at a pharmacy.

of paper Appeared today Chemistry, Engineers announce new ultrasonic sticker design. This is a stamp-sized device that adheres to the skin and can provide continuous ultrasound images of internal organs for 48 hours.

Researchers put stickers on volunteers and showed that the device produces live high-resolution images of major blood vessels and deeper organs such as the heart, lungs, and stomach. The sticker maintained strong adhesion and captured changes in the underlying organs when volunteers performed various activities such as sitting, standing, jogging, and biking.

The current design requires a sticker to be connected to a device that converts the reflected sound waves into an image. Researchers have pointed out that even in the current format, stickers may be immediately applicable. For example, the device can be applied to hospital patients, similar to a cardiac monitoring EKG sticker, and can continuously image internal organs without the need for a technician. Hold the probe in place for an extended period of time.

If the team can operate the device wirelessly, which is the goal they are currently working on, the ultrasound sticker can be a wearable imaging product that patients can take home from the clinic or buy at the pharmacy.

“We envision several patches that are applied to different parts of the body. The patches communicate with mobile phones and AI algorithms analyze images on demand,” said the lead researcher. The author, Xuanhe Zhao, said. Environmental engineering at MIT. “We believe we have opened up a new era of wearable imaging. With a few patches on our body, we can see the internal organs.”

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

Wicked problem

For ultrasound imaging, the technician first applies a liquid gel to the patient’s skin. It works like sending ultrasonic waves. The probe or transducer is then pressed against the gel, sending sound waves into the body, echoing from the internal structure and back into the probe. Here, the echoed signal is transformed into a visual image.

For patients who require long-term imaging, some hospitals offer robotic arm-mounted probes that can hold the transducer in place without fatigue, but liquid ultrasound. The gel will flow out and dry over time, interrupting long-term imaging.

In recent years, researchers have sought to design elastic ultrasound probes that provide portable, thin imaging of internal organs. These designs provided a flexible array of small ultrasonic transducers. The idea is that such a device will stretch and adapt to the patient’s body.

However, these designs produced low-resolution images, in part due to their growth. When moving with the body, the transducers shift their positions relative to each other, distorting the resulting image.

“Wearable ultrasound imaging tools have great potential for future clinical diagnostics, although existing ultrasound patches have relatively low resolution and imaging duration and cannot image deep organs,” MIT said. Said Chonghe Wang, a graduate student at.

Interior appearance

The MIT team’s new ultrasound stickers combine a stretchy adhesive layer with a rigid array of transducers to produce higher resolution images over longer periods of time. “This combination allows the device to fit the skin while maintaining the relative position of the transducer, producing a clearer, more accurate image,” says Wang.

The device’s adhesive layer is made up of two thin layers of elastomer that encapsulate an intermediate layer of solid hydrogel, which is mostly water-based material that easily transmits sound waves. Unlike traditional ultrasonic gels, the MIT team’s hydrogels are elastic and stretchy.

“Elastomers prevent the dehydration of hydrogels,” says Chen, a MIT postdoc. “Only when the hydrogel is highly hydrated can the sound waves penetrate effectively and provide high resolution imaging of the internal organs.”

The lower elastomer layer is designed to adhere to the skin, and the upper layer adheres to the rigid array of transducers designed and manufactured by the team. The overall size of the ultrasonic sticker is about 2 square centimeters wide and 3 millimeters thick, about the same as the area of ​​a stamp.

Researchers performed ultrasound stickers in a series of tests with healthy volunteers who put stickers on various parts of the body, such as the neck, chest, abdomen, and arms. The sticker remained on the skin, producing a clear image of the underlying structure for up to 48 hours. During this time, volunteers performed a variety of activities in the lab, including sitting and standing, jogging, cycling and weightlifting.

From the image on the sticker, the team was able to observe changes in the diameter of the major blood vessels when sitting and standing. The sticker also details deeper organs, such as how the heart changes shape during exercise. Researchers were also able to observe the stomach swell, contract when the volunteers drank, and then drain the juice from the system. Also, when some volunteers lifted the weights, the team was able to detect a bright pattern of the underlying muscles, indicating temporary microinjuries.

“Using imaging, we may be able to capture the moment of training before overuse and stop before the muscles hurt,” says Chen. “I don’t know when that moment will be, but we are now able to provide image data that can be interpreted by experts.”

The team is working on making the stickers work wirelessly. They are also developing artificial intelligence-based software algorithms that can better interpret and diagnose stickers images. Next, Zhao believes that ultrasound stickers can be packaged and purchased by patients and consumers to monitor the progression of tumors and the development of the fetus in utero, as well as various internal organs.

“We imagine that each can have a box of stickers designed to image different parts of the body,” says Zhao. “We believe this represents a breakthrough in wearable devices and medical imaging.”

This study was partially funded by the US Army Institute through MIT, the Department of Defense Advanced Research Planning, the National Science Foundation, the National Institutes of Health, and MIT’s Soldier Nanotechnology Institute.