A stretchable, wireless, wearable health monitor

By Dr. Ananya Mandal, MDJul 31 2019

Researchers have developed wearable wireless monitors that contain stretchable electronics and would provide long term health data about the adults, babies and children. These sensors are an advantage over the presently used devices because they are free from the risk of skin allergic reactions and injuries that are associated with conventional adhesive sensors containing conductive gel formulations.

The researchers reported the preliminary experiments with their monitor in the July 24th issue of the journal Advanced Science. The study is titled, “All-in-One, Wireless, Stretchable Hybrid Electronics for Smart, Connected, and Ambulatory Physiological Monitoring.” The development of the device was supported by the Imlay Innovation Fund at Children's Healthcare of Atlanta, NextFlex (Flexible Hybrid Electronics Manufacturing Institute) as well as from the Institute for Electronics and Nanotechnology at Georgia Tech.

A wireless, wearable monitor built with stretchable electronics could allow comfortable, long-term health monitoring of adults, babies and children. Image Credit: John Toon, Georgia Tech

The team of researchers developing this new monitor used it successfully in animal studies as well as on human subjects and declared it to be effective and safe. Their new soft monitor could be used to record electrocardiogram (ECG), heart rate, respiratory rate along with the motion activity data. The maximum distance to which the device could transfer its information was found to be 15 metres. This transferring device could not only be a computer, or a laptop but also could be a smart phone or a tablet explain the researchers.

The Monitor is mounted upon a stretchable substrate. This is connected with gold, skin-like electrodes that are placed over printed connectors that allow the device to stretch over a medical fil in which it is embedded. There are three gold electrodes in the monitor. These are embedded in a film that contains an electronic processing equipment. The circuitry is made up for a thin mesh of copper, the team explains. There is no use of the traditional plastic circuit board but instead a “strain-isolated soft substrate” is being used. The three inch long monitor is slated to become even smaller as researchers are trying to make it more acceptable. There is a small rechargeable battery in the wireless monitor the power it up. The researchers explain that they are trying to develop the monitor so that it could be charged externally by a radio-frequency charging system.

Woon-Hong Yeo, an assistant professor in the George W. Woodruff School of Mechanical Engineering and Wallace H. Coulter Department of Biomedical Engineering at the Georgia Institute of Technology explained, “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. This is designed to meet the electronic health monitoring needs of people whose sensitive skin may be harmed by conventional monitors.”

The team explains that unlike metal or gel electrodes on the skin, this monitor is adaptable to the skin and there are significantly less problems with delivering the signals to the device paired with it. A mobile person who is walking, running or climbing stairs or a child who is moving about can also use this device and the signals would be accurately relayed, they add. Woon-Hong Yeo said, “When you put a conventional electrode on the chest, movement from sitting up or walking creates motion artefacts that are challenging to separate from the signals you want to measure. Because our device is soft and conformal, it moves with the skin and provides information that cannot be seen with the motion artefacts of conventional sensors.”

Dr. Kevin Maher, a pediatric cardiologist at Children's Healthcare of Atlanta said this device could be a boon for situations where continuous monitoring is necessary. He added that in children who need continuous cardiac monitoring, this could help diagnose conditions where single or serial reports are not adequate to make a diagnosis. Further early detection of disease could be possible he said. He added, “The generation of continuous data from the respiratory and cardiovascular systems could allow for the application of advanced diagnostics to detect changes in clinical status, response to therapies and implementation of early intervention. A device to literally follow every breath a child takes could allow for early recognition and intervention prior to a more severe presentation of a disease.” He added that thus device is wireless and allows the child to be free from being “tethered” to a place for continuous monitoring. He said, “I see this device as a significant change in pediatric health care and am excited to partner with Georgia Tech on the project.” The first author of the study is postdoctoral fellow Yun-Soung Kim. Both Yeo and Kim are at present looking at the application of this monitor in children. They explain that ambulatory monitoring is essential in paediatrics. Older adults with sensitive skin could also benefit from it they add.

Yeo added, “The monitor could be worn for multiple days, perhaps for as long as two weeks. The membrane is waterproof, so an adult could take a shower while wearing it. After use, the electronic components can be recycled.” He explained that they have developed two versions of the monitor. One of them is based over a medical tape and could be used over a short term during the hospital stay for example. The other uses a soft elastomer medical film that is commonly used for wound dressing. This is longer lasting explain the developers of the monitor.

Yeo explained, “The devices are completely dry and do not require a gel to pick up signals from the skin. There is nothing between the skin and the ultrathin sensor, so it is comfortable to wear.” He added, “We use deep learning to monitor the signals while comparing them to data from a larger group of patients. If an abnormality is detected, it can be reported wirelessly through a smartphone or other connected device.” He added that they are planning on making the device capture other data as well including blood oxygen, blood pressure and temperature of the wearer.

Yeo said, “It will be a dream come true for me to see something we have developed be helpful to someone who is suffering. We all want to see developments in science and engineering translated into improved patient care.”