Ultrasound stickers: A postage stamp-sized patch can continuously deliver ultrasound imaging for 48 hours, and it has been used to detect changes in the lungs, heart, and stomach of people who exercise and drink.

ultrasound stickers
A hydrogel ultrasound patch made from water Chonghe Wang, Xiaoyu Chen, Liu Wang, Mitsutoshi Makihata, Hsiao-Chuan Liu, Tao Zhou, and Xuanhe Zhao are among those who have contributed to this work.

Sticking a postage stamp-sized patch to your skin can provide continuous ultrasound imaging of internal organs for 48 hours. Details such as the human heart changing shape during exercise or the stomach expanding and contracting when a person eats or drinks can be revealed.

“Welcome to the era of ‘wearable imaging,'” Xuanhe Zhao of the Massachusetts Institute of Technology says.

Many researchers have been working on developing flexible ultrasound devices that can be worn. However, they have found it difficult to create flexible devices that stay attached to the skin for more than a few hours while also allowing for high-resolution ultrasound imaging.

Zhao and his colleagues solved this problem by combining a rigid transducer component capable of producing and detecting ultrasound waves with a soft, sticky patch. A layer of water-based hydrogel – used to transmit ultrasound waves – is sandwiched between two layers of flexible elastomer material to keep the hydrogel from dehydrating.

The ultrasound stickers were applied to the arms, necks, chests, and waists of 15 volunteers who drank juice, lifted weights, jogged, or biked in the lab. Ultrasound imaging from the stickers revealed changes in the size and shape of the lungs, diaphragm, heart, stomach, and major arteries and veins during these activities.

Before the ultrasound stickers can be used for medical monitoring anywhere, much more work needs to be done. The stickers are currently wired to a computer, which converts the ultrasound waves into images and collects data, limiting the system’s portability.

Nonetheless, “there are already point-of-care ultrasound devices with data acquisition systems the size of a cell phone,” according to Zhao. This gives him hope that the computing component can be miniaturized and eventually integrated with the ultrasound sticker to create a truly wireless and portable imaging system.

“It’s truly groundbreaking, and it’s really attempting to bring wearable ultrasound closer to the patient,” says Nanshu Lu, a researcher at the University of Texas at Austin.

According to Lu, this effort may benefit from medical companies that are already working to miniaturize the computing components used with handheld ultrasound probes.

The ultrasound stickers may offer hospitals a more flexible imaging option for monitoring patients without requiring human technicians to hold ultrasound probes, and they may be useful in situations where technicians are in short supply. “There is no need for a trained sonographer or a large ultrasound machine,” says Philip Tan of the University of Texas at Austin. “You could use it in low-resource communities.”

In the long run, such stickers could help covid-19 patients monitor their lungs at home, monitor people with cardiovascular disease, track a growing cancer tumor or even provide continuous monitoring for a fetus in the womb. The low-power ultrasound waves pose no known risks, but the researchers say they will investigate any potential long-term side effects.

Reference: Science, DOI: 10.1126/science.abo2542

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