Engineers at the Massachusetts Institute of Technology (MIT) have designed a tiny sticker that can provide continuous ultrasound images of internal organs for up to 48 hours. The innovation is a step toward a future in which stickers can wirelessly track muscle health during exercise or fetal development during pregnancy.
Ultrasound imaging is probably the safest and most commonly used form of medical imaging. However, it still requires trips to the doctor’s office and bulky equipment.
Everyone who has had an ultrasound will be familiar with the thick, cold gel that is sprayed on their skin before the probe is used. This gel is necessary for the clear transmission of ultrasound from the probe to a person’s internal organs and back again. Over time, this gel may dry out or run off the skin, thus requiring constant reapplication during longer ultrasound sessions.
One of the biggest new innovations in this development at MIT is the creation of a hydrogel that is encased within a thin elastic membrane. This creates a perfectly elastic material that can be placed on the skin while efficiently transmitting ultrasound.
“The elastomer prevents the hydrogel from dehydrating,” explained co-lead author Xiaoyu Chen. “Only when the hydrogel is highly hydrated can the sound waves effectively penetrate and image internal organs at high resolution.”
The other part of the device contains a rigid array of hundreds of tiny ultrasonic sensors. This dense array of transducers paired with an elastic mix of elastomer and hydrogel allows the stickers to continuously image internal organs over long periods of time, said co-first author Chonghe Wang.
“This combination allows the device to conform to the skin while maintaining the relative position of the transducers to produce clearer and more accurate images,” said Chonghe Wang.
A new study published in the journal Science describes tests of the device in a variety of applications, from jogging to weight lifting. It demonstrates the extraordinary potential of the new device to provide ultrasound imaging of human activity in an unprecedented way.
Using the device, the researchers were able to observe the expansion and contraction of a volunteer’s stomach as he drank a glass of juice. Other tests have shown how the device can monitor muscles as a person lifts weights, potentially notifying the wearer when they should stop exercising to avoid injury.
With imaging, we may be able to capture the moment of exercise before overuse and stop before the muscle becomes sore,” Chen speculated. We don’t yet know when that moment might be, but now we can provide imaging data that experts can interpret.”
For now, the device is not wireless, but even in its current form, the researchers suggest there are direct real-world applications. For example, hospitals can currently use it to monitor heart patients in real-time.
But the future potential of this device is even more exciting. The team is currently working to make the device work wirelessly, so it could hypothetically communicate with a smartphone app. The ultrasound stickers could be used for any number of purposes, from exercise tracking to long-term monitoring of suspicious tumors. Pregnancy can even be tracked in real-time from home.
Senior author Xuanhe Zhao says, “We envision putting some stickers on different parts of the body, and the stickers will communicate with your phone and the AI algorithm will analyze the images as needed. We believe we have opened a new era of wearable imaging. With a few patches on your body, you can see your internal organs.”
The new study was published in the journal Science.
