MIT Engineers Develop Stamp-Sized Stickers That Can Perform Ultrasounds
(Photo: Felice Frankel/MIT)What if you could monitor a serious health concern by purchasing a box of stickers from your local pharmacy, then wearing those stickers on your body for up to two days at a time? That’s what a group of engineers at MIT asked themselves as they developed wearable ultrasound devices the size of a postage stamp.
At two centimeters across and three millimeters thick, the tiny ultrasound devices can be worn for up to 48 hours. They adhere to the body using a sort of elastomer sandwich; while one layer clings to the skin, the other attaches to an array of transducers MIT custom-designed for the project. Between the elastomer layers sits a thin spread of hydrogel—the same cold jelly spread on the skin during a traditional ultrasound—which acts as a medium for acoustic waves.
These acoustic waves are what form an ultrasound image, the applications of which are endless. While many associate ultrasounds with distinguishing the sex of a baby in utero, the technology is frequently used to find gallstones, guide biopsies, monitor tumor progression, and diagnose conditions from blood flow obstructions to kidney disease. Some of these applications are relatively quick and can be performed in a few minutes, while others require longer, steadier internal monitoring. That’s where the stickers come in.
It isn’t practical to require an ultrasound technician to hold a transducer over a patient’s body for hours at a time, between technician discomfort and staffing concerns. Longer ultrasounds like this also allow the hydrogel on a patient’s body to dry out, which interrupts the imaging process. Some hospitals have the privilege of attaching transducers to robotic arms for extended periods of time, but this doesn’t fix the hydrogel issue. Meanwhile, the two layers of elastomer in MIT’s ultrasound stickers keep the hydrogel contained, which prevents dehydration. It also frees ultrasound technicians to focus on patients for whom long-term monitoring isn’t required.
The engineers tested the stickers on a number of healthy volunteers, who wore the devices on the neck, chest, abdomen, and arms. Despite performing activities like biking, jogging, and weightlifting (as well as sitting and standing), the stickers remained attached to the volunteers’ bodies and continued to provide clear internal images. The team was able to use the stickers to monitor the volunteers’ blood vessel dilation and heart exertion during exercise, as well as watch their stomachs digest juice. They were even able to use the tiny ultrasound devices to detect microdamage in volunteers’ muscle tissue as they lifted weights.
The team at MIT is still working to make the devices 100 percent wireless, meaning it’ll be a long while before the public gets to try sticker ultrasounds for themselves. But the engineers have high hopes for their invention. “We envision a few patches adhered to different locations on the body, and the patches would communicate with your cell phone, where AI algorithms would analyze the images on demand,” the study’s senior author, mechanical engineering professor Xuanhe Zhao, told 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.”