When clinicians need live images of a patient’s internal organs, they often turn to ultrasound imaging for a safe and noninvasive window into the body’s workings. In order to capture these insightful images, trained technicians manipulate ultrasound wands and probes to direct sound waves into the body. These waves reflect back out and are used to produce high-resolution images of a patient’s heart, lungs, and other deep organs.
Ultrasound imaging currently requires bulky and specialized equipment available only in hospitals and doctor’s offices. However, a 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 issue
To image with ultrasound, a technician first applies a liquid gel to a patient’s skin, which acts to transmit ultrasound waves. A probe, or transducer, is then pressed against the gel, sending sound waves into the body that echo off internal structures and back to the probe, where the echoed signals are translated into visual images
For patients who require long periods of imaging, some hospitals offer probes affixed to robotic arms that can hold a transducer in place without tiring, but the liquid ultrasound gel flows away and dries out over time, interrupting long-term imaging.
In recent years, scientists have explored designs for stretchable ultrasound probes that would provide portable, low-profile imaging of internal organs. These designs gave a flexible array of tiny ultrasound transducers, the idea being that such a device would stretch and conform to a patient’s body.
But these experimental designs have produced low-resolution images, in part due to their stretch: In moving with the body, transducers shift location relative to each other, distorting the resulting image.
“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.
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