What if you could get an ultrasound of your body without visiting the doctor’s office? That was the idea behind the creation of a new wearable sticker the size of a postage stamp that MIT researchers believe could one day revolutionize ultrasound procedures if brought to the market.
When researchers attached these stickers to the human body, they discovered that “you can have long-term, continuous images of diverse, deep internal organs over hours, even days,” says Xuanhe Zhao, an MIT mechanical engineering professor who is part of a team that designed a new wearable that attaches to the human body like a Band-Aid and provides continuous ultrasound imaging of internal organs for 48 hours and published research about it in the journal Science.
A year and a half in the making, each ultrasound sticker contains an adhesive layer compiled of two thin layers of elastomer, which Zhao likens to plastic wrap. Inside these two layers is a middle layer of hydrogel, which is a water-based material that transmits sound waves.
Unlike traditional ultrasound gels, however, the team’s hydrogel is super hydrated, so it doesn’t dry out as easily and can produce a high-resolution image. The sticker’s bottom elastomer layer sticks to your skin, while the top layer adheres to tiny transducers, which send the sound wave through the body. The stickers peel off easily and can be re-used unless they become dirty.
In the current design iteration, the stickers are connected to wires that run to a data acquisition box. However, the researchers hope to make the design more consumer-friendly and develop a wireless version someday, which would make it easy for people to use them at home. A price for the wireless device—not yet in operation—has not been established.
You can have long-term, continuous images of diverse, deep internal organs over hours, even days.
—Xuanhe Zhao, an MIT mechanical engineering professor.
During a traditional ultrasound procedure, a technician uses an ultrasound wand covered in transducers (which convert energy from one form to another) to create sound waves that produce high-resolution images of a patient’s internal organs. This equipment is only available in hospitals and doctor’s offices, but Zhao’s design could one day make the technology easily accessible at local drug stores. The applications are really only limited by one’s imagination and provide real-time updates on a patient’s condition. Take heart disease, for example. Sometimes a patient’s chest pain disappears by the time they arrive at the doctor’s office or hospital.
“Once that moment has passed, the patient may go to the hospital but may have already missed all the symptoms,” Zhao says. “With this ultrasound sticker, you can take an image or video right at the moment and then send those to clinicians for early diagnosis of diverse heart disease. The best scenario is that whenever someone feels chest pain or uncomfortable somewhere in the body, you take an image right at the moment.”
A wearable device with huge potential in healthcare
To test the sticker, the MIT team had volunteers perform different activities, such as jogging, biking and lifting weights, and were able to see the changing diameter of blood vessels and how the heart changes shape during exercise. During weight-lifting exercises, the team could detect patterns in muscles that pointed to temporary microdamage. One day, this information could be used to help people from overexercising and injuring themselves by “observing the microstructure evolution of the muscles so that in the future those ultrasound patches may tell you, ‘Now you should stop exercising—you already achieved an ideal workout,'” explains Zhao.
Zhao says that the stickers could be helpful in fighting COVID-19 if applied to the chest to monitor lung function. “If a lung infection sets in and gets severe, then the system will send the patient a warning that the patient should go to the hospital for treatment,” he says.
Hypertension is another application. “There is no way to continuously measure the blood pressure waveform,” he says. “We know how cumbersome the cuff is. But now with a sticker on the neck, potentially we can continuously measure one’s blood pressure in a waveform, then if the blood pressure gets high, or if you see an early symptom, you can take some medicine or do early mitigation.”
Other possible uses are evaluating the progression of liver disease, observing a tumor’s growth and monitoring the bladder to see whether it is empty or full. Pregnant women could also apply a sticker to provide an image of their baby. “These are just a small fraction of possible applications,” he says.
Monitoring internal organs using smartphones
Zhao says that the ultrasound stickers—funded by MIT, the Defense Advanced Research Projects Agency, the National Science Foundation, the National Institutes of Health and the U.S. Army Research Office—could be used immediately in healthcare settings, similar to heart-monitoring EKG stickers. Doing so would give healthcare providers the ability to image a patient’s internal organs without requiring a technician to hold a probe in place for long periods of time.
That said, the team hopes to update the devices so that they can operate wirelessly, without needing a connection to a data acquisition box, which functions like a computer that reads the information coming in. “Our current goal is to really miniaturize everything, to make it all integrated into the patch,” Zhao says.
Doing so would make it easier for the stickers to be taken home from a doctor’s office or the pharmacy. A person could attach a sticker on their body, which could communicate with their cell phone. Artificial intelligence algorithms could then analyze the images.
“We hope in a couple years we can do that,” he says. “Eventually, on your phone, you’ll see your different organs inside your body.”
Even though that’s not yet possible, the creation of these stickers is still an achievement because the stickers provide real-time, continuous monitoring of human organs. That’s why the researchers are focusing on rolling out the wired version to healthcare facilities. Doing so can minimize the need for expensive sonogram machines and help create more flexibility in the event of a staffing shortage, given that there wouldn’t be a need for a trained technician to manipulate an ultrasound wand to get the perfect image. Says Zhao, “Even the wired versions will have immediate application in hospitals.”
Lead image of a bioadhesive ultrasound device adhered to the skin. Photo courtesy of Chonghe Wang, Xiaoyu Chen, Liu Wang, Mitsutoshi Makihata, Hsiao-Chuan Liu, Tao Zhou and Xuanhe Zhao.