MIT engineers designed an adhesive patch that produces ultrasound images of the body. The stamp-sized device sticks to skin and can provide continuous ultrasound imaging of internal organs for 48 hours. (Image: Felice Frankel)

Ultrasound imaging, as it currently stands, requires specialized, bulky equipment typically only available in medical centers. However, MIT engineers are working to make such technology as wearable and accessible as lotion at a drug store.

The design for the new ultrasound sticker is stamp-sized technology that sticks to the skin and can provide ultrasound imaging of internal organs for up to 48 hours — much more convenient than having a technician hold a probe in place for extended periods of time.

The team applied the stickers to volunteers and the devices produced live, high-resolution images of major blood vessels and organs such as the heart, lungs, and stomach. The stickers stuck and captured changes in underlying organs even as the volunteers performed various exercises.

The design requires connecting the stickers to instruments that translate the reflected sound waves into images. However, the team is working to make the technology operate wirelessly.

“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,” said 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.”

“[A] 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,” said Chonghe Wang, an MIT graduate student.

The new technology produces higher-resolution images over a longer duration by pairing a stretchy adhesive layer with a rigid array of transducers, the combination of which enables the device to conform to the skin while maintaining the relative location of transducers for a clearer and more precise images, the team said.

The device’s adhesive layer is made up of two thin layers of elastomer that encapsulate a middle layer of solid hydrogel, a largely water-based, elastic, stretchy material — unlike current ultrasound gels — that transmits sound waves.

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

The bottom elastomer layer is designed to stick to the skin, while the top layer adheres to a rigid array of team-designed transducers, a press release says. The entire sticker measures about 2 square centimeters across, and 3 millimeters thick — about the size of a postage stamp.

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

The team is also developing software algorithms based on AI that can better interpret and diagnose the stickers’ images. Then, they hope the stickers can be packaged and sold — and even used to monitor the progression of tumors and the development 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 said. “We believe this represents a breakthrough in wearable devices and medical imaging.”

Tech Briefs’ Q&A with the study’s Senior Author Xuanhe Zhao.

TB: When will this technology be available?

XZ: In a few years, probably about 5-10 [years].

TB: Will there be a large market for it? Will it catch on?

XZ: Yes, it may potentially revolutionize two fields (and the corresponding markets): medical imaging and wearable devices. Current medical imaging is usually taken in hospitals for short term, such as a few seconds. Current wearable devices only give linear data such as body temperature, heart rate, and ECG.

BAUS (bioadhesive ultrasound) provides long-term, continuous, wearable imaging of diverse internal organs such as the heart, lung, blood vessels, and muscles. It will add a “time” dimension (e.g., over a few days) to medical imaging; it will add an “imaging” dimension to wearable technology.

TB: How will this change the ultrasound game?

XZ: It will allow long-term continuous wearable ultrasound imaging of patients in dynamic motions. It may represent a new era of wearable ultrasound imaging.

We are developing the wireless version of the devices. We are developing algorithms for real-time image analysis and diagnosis.

Zhao added that the team is also working on other medical advances, such as a joystick-operated robot that aims to help surgeons  treat stroke patients remotely, surgical “duct tape” as an alternative to sutures , and an inflatable robotic hand to give amputees  real-time tactile control.