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Soft, Stretchable Health Monitor Eyed for Long-Term Use

One of the key challenges researchers aim to overcome with wearable technology to is to make it more comfortable for the user while still being able to perform and transmit data effectively.

A team at the Georgia Institute of Technology (Georgia Tech) has made strides in this area with the development of a wireless, stretchable device they said allows for long-term health monitoring without creating discomfort for users, particularly allergic reactions or injuries that are associated with conventional adhesive sensors that use conductive gels.

health monitor, wearable tech, wearable monitor, stretchable electronics, Georgia Tech
A wireless, wearable monitor built with stretchable electronics could allow comfortable, long-term health monitoring of adults, babies, and small children. (Image source: John Toon, Georgia Institute of Technology)

A team led by Woon-Hong Yeo, an assistant professor in Georgia Tech’s departments of mechanical engineering and biomedical engineering, designed the monitor--on which electronics are mounted on a stretchable substrate and connected to gold, skin-like electrodes through printed connectors. The connectors can stretch with the medical film in which they are embedded, giving flexibility to the device that can accommodate user movement better than such devices typically do.

The monitor—which can send electrocardiogram (ECG), heart rate, respiratory rate, and motion-activity data to a mobile device—is especially well-suited to young children, who are more active than adults, Yeo said.

“This health monitor has a key advantage for young children who are always moving, since the soft conformal device can accommodate that activity with a gentle integration onto the skin,” he said in a press statement. “This is designed to meet the electronic health-monitoring needs of people whose sensitive skin may be harmed by conventional monitors.”

Made for Conformity and Flexibility

A comfortable and useful way to attach sensors to human skin has been a challenge for those designing health-monitoring devices, especially for long-term use. Often movement from sitting up or walking has interrupted signals from typical metal-gel electrodes on the skin to monitoring equipment, limiting a user’s range of motion or ability to wear devices for a long period of time.

The device Yeo’s team developed—which already has been tested on both animal and human subjects--helps solve this problem with its flexibility and conformity, giving users a wider range of movement without interrupting the device’s ability to collect and transmit data, he said. The device can even obtain accurate signals from a person who is walking, running, or climbing stairs, Yeo said.

“Because our device is soft and conformal, it moves with the skin and provides information that cannot be seen with the motion artifacts of conventional sensors,” he said in a press statement.

Researchers designed the monitor—which is three inches in diameter--by embedding three gold electrodes in a film that also contains the electronic-processing equipment. The team is planning a more sophisticated version of the technology that will be half that size.

In the current version, a small rechargeable battery powers the wireless motor; however, researchers want to improve this feature in future versions by replacing the battery with an external radio frequency-based charging system.

To develop the monitor’s circuitry, researchers used a thin-film, mesh-like pattern of copper that can flex with the soft substrate. In fact, the only part of the system that isn’t flexible is its chips, but researchers found a way around this by mounting them on the strain-isolated soft substrate instead of a traditional plastic circuit board, Yeo said.

The team published a paper describing the monitor’s design and use in the journal Advanced Science.

Good Solution for Kids

Researchers are particularly eyeing pediatric patients with their technology, who have been particularly difficult to monitor and assess due to their general restlessness and movement tendencies, researchers said. Using a device that’s more comfortable can help facilitate health intervention early in health situations that demand attention, researchers said.

The team envisions that children could wear the monitor in the home to evaluate changes that might not be evident externally. In a clinical environment, such devices would make it easier to test children who might otherwise feel uncomfortable using typical monitoring equipment, researchers said.

In addition to its usefulness in children, adults also can benefit from the monitor, especially if they have sensitive skin and gels typically used with monitor electrodes irritate it, Yeo said.

“The monitor could be worn for multiple days, perhaps for as long as two weeks,” he said in the press statement. “The membrane is waterproof, so an adult could take a shower while wearing it. After use, the electronic components can be recycled.”

Currently, two versions of the monitor exist--one based on medical tape and designed for short-term use in a hospital or care facility, and a soft elastomer medical film that can be used in wound care and remain on the skin longer.

“The devices are completely dry and do not require a gel to pick up signals from the skin,” Yeo explained in the press release. “There is nothing between the skin and the ultrathin sensor, so it is comfortable to wear.”

Researchers plan to continue to work on the monitor to make further improvements, including reducing the size of the device and adding features to measure other health-related parameters such as temperature, blood oxygen, and blood pressure.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

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