It's not the first time researchers have tried to create wearable ultrasound patches, but previous efforts have always run into problems. That’s because of their design: they have so far mostly relied on a flexible array of tiny ultrasound transducers, allowing the patches to stretch and move with the patient’s body.
But that has meant that these transducers move relative to each other, too – and that distorts the resulting image. “The resolution and imaging duration of existing ultrasound patches is relatively low, and they cannot image deep organs,” explained Chonghe Wang, a graduate student in MIT’s Department of Mechanical Engineering and a study lead author.
The new design fixes both those issues. In this patch, the transducer array is rigid, but it’s paired with a stretchy adhesive layer that’s a sort of elastomer-hydrogel-elastomer sandwich. “This combination enables the device to conform to the skin while maintaining the relative location of transducers to generate clearer and more precise images,” said Wang.
The team hopes that the devices will ultimately be wireless – and indeed they’re already working on that goal – but for now, the patches need to be connected to medical instruments that can translate the reflected sound waves into images. But in tests, the devices have already performed well: in trials on healthy volunteers, the stickers stayed on the skin for up to 48 hours at a time, producing clear images from inside participants’ bodies.
With just their sticky stamp-sized sonograph, the team was able to see the changing diameter of major blood vessels when seated versus standing, and watch the stomach distend then shrink back as volunteers drank then later passed juice out of their system. When participants lifted weights, the patches recorded the temporary microdamage happening in their muscles, and they could even pick up details of deeper organs, such as how the heart changes shape as it exerts during exercise.
“With imaging, we might be able to capture the moment in a workout before overuse, and stop before muscles become sore,” said lead author Xiaoyu Chen. “We do not know when that moment might be yet, but now we can provide imaging data that experts can interpret.”
While the teamwork to make the patches wireless, they’re also developing AI to better interpret and diagnose the images they pick up. And the ultimate goal? A giant leap forward in user accessibility: Zhao believes that eventually, the ultrasound stickers could be bought over the counter at pharmacies, and used by consumers to monitor medical conditions, internal organs, or that mainstay of ultrasound imaging, 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,” he said. “We believe this represents a breakthrough in wearable devices and medical imaging.”