Designing an Ultrasound Sticker that can Image your Internal Organs

Interview conducted by Emily Henderson, B.Sc.Oct 25 2022

Thought LeadersProfessor Xuanhe ZhaoProfessor of Mechanical EngineeringMassachusetts Institute of Technology (MIT)

In this interview, we speak to researchers from the Zhao lab at MIT about their new ultrasound sticker that can provide non-invasive imaging of internal organs for up to 48 hours.

Please can you introduce yourself and tell us what inspired your latest research?

We are a team of engineers from MIT Zhao lab (http://zhao.mit.edu/)

Current medical diagnosis heavily relies on clinical radiology tools for imaging organs to reach a decision. However, those are usually infrequent clinical approaches and will highly likely miss the disease patterns. To address this challenge, we wish to develop a wearable device that could provide long-term imaging capabilities to both clinicians and patients, tracking their disease or health status.

In healthcare settings, clinicians often need to image a patient’s internal organs. To do this, ultrasound imaging is frequently used. Can you tell us more about how ultrasound imaging works?

Ultrasound imaging is a safe and noninvasive window into the body’s workings, providing clinicians with live images of a patient’s internal organs. To capture these images, trained technicians manipulate ultrasound wands and probes to direct sound waves into the body. These waves reflect back out to produce high-resolution images of a patient’s heart, lungs, and other deep organs.

Image Credit: HOMONSTOCK/Shutterstock.com

Despite ultrasound imaging being commonplace within healthcare settings, it has many disadvantages. What are some of these disadvantages, and how does your new technology help to overcome them?

Conventionally, to image with ultrasound, a technician first applies a liquid gel to a patient’s skin, transmitting ultrasound waves. A probe, or transducer, is then pressed against the gel, sending sound waves into the body that echo off internal structures and back to the probe, where the echoed signals are translated into visual images.

For patients who require long periods of imaging, some hospitals offer probes affixed to robotic arms that can hold a transducer in place without tiring, but the liquid ultrasound gel flows away and dries out over time, interrupting long-term imaging.

To solve this problem, we designed an ultrasound sticker that produces higher-resolution images over a longer duration by pairing a stretchy adhesive layer with a rigid array of transducers. This combination enables the device to conform to the skin while maintaining the relative location of transducers to generate clearer and more precise images.

In your latest research, you have designed a new ultrasound sticker. How did you design this sticker, and how does it work?

We designed a new ultrasound sticker that produces high-resolution images over a longer duration by pairing a stretchy adhesive layer with a rigid array of transducers. This combination enables the device to conform to the skin while maintaining the relative location of transducers to generate clearer and more precise images.

The device’s adhesive layer is made from two thin layers of elastomer that encapsulate a middle layer of solid hydrogel, a mostly water-based material that easily transmits sound waves. The MIT team’s hydrogel is elastic and stretchy, unlike traditional ultrasound gels. The elastomer prevents dehydration of hydrogel. When hydrogel is highly hydrated, acoustic waves can 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 transducers that the team also designed and fabricated. The entire ultrasound sticker measures about 2 square centimeters across and 3 millimeters thick — about the area of a postage stamp.

To test our design, we put the ultrasound sticker through a battery of tests with healthy volunteers, who wore the stickers on various parts of their bodies, including the neck, chest, abdomen, and arms. The stickers stayed attached to their skin and produced clear images of underlying structures for up to 48 hours.Ultrasound Sticker