A postage-stamp-sized patch applied to the skin can provide continuous ultrasound imaging of internal organs for up to 48 hours. This can reveal details such as changes in the shape of the human heart during exercise, or the expansion and contraction of a person’s stomach when they eat or drink. A related paper was published in Science.
Ultrasonic patch made of water-based hydrogel Image credit: Mitsutoshi Makihata /Xuanhe Zhao
Welcome to the era of ‘wearable imaging,'” says Xuanhe Zhao (phonetic) of the Massachusetts Institute of Technology.
Many researchers have been working to develop wearable ultrasound devices made of flexible materials. But they have found it challenging to create flexible devices that can both stick to the skin for more than a few hours and also enable high-resolution ultrasound imaging.
Xuanhe Zhao and colleagues solved this problem by combining a rigid transducer assembly that generates and detects ultrasound waves with a soft, sticky patch. The patch consists of a layer of water-based hydrogel used to transmit ultrasound, sandwiched between two layers of elastomeric material to prevent the hydrogel from dehydrating.
The research team applied ultrasound patches to the arms, neck, chest and lower back of 15 volunteers who drank juice, lifted weights, jogged or rode bicycles in the lab. During these activities, ultrasound imaging on the stickers showed changes in the size and shape of their lungs, diaphragm, heart, stomach and large arteries and veins.
There is still much work to be done before ultrasound stickers can be used anywhere for medical monitoring. Currently, the stickers must be connected by wire to a computer that converts the ultrasound into an image and collects data, meaning it’s not a fully portable system.
Nonetheless, “there is already an instant ultrasound device with a data collection system the size of a cell phone.” This has led Xuanhe Zhao to believe that the computing components could be miniaturized and eventually integrated with ultrasound stickers to become a truly wireless and fully portable imaging system.
Nanshu Lu (phonetic) of the University of Texas at Austin said, “This is a truly groundbreaking study to bring wearable ultrasound closer to the patient.”
Ultrasound stickers could provide hospitals with more flexible imaging options to monitor patients without requiring technicians to hold ultrasound probes, and they could be useful in situations where there is a shortage of technicians. “You don’t need a trained sonographer and you don’t need a huge ultrasound machine.” Philip Tan of the University of Texas at Austin says, “It can be deployed to communities with very few resources.”
In the long run, the stickers could help monitor the lungs of newly crowned pneumonia patients at home, monitor and manage patients with cardiovascular disease, track growing cancerous tumors, and even continuously monitor fetuses in the womb. There are no known risks associated with low-power ultrasound, but the team said they will study any potential side effects of prolonged exposure to ultrasound in the future.