A Flexible Device To Monitor Heart Health

Scientists in South Korea have developed an elastic, conductive mesh that can be used to monitor electrophysiological signals as well as deliver thermal and electrical stimulations.

AsianScientist (Aug. 28, 2018) – Silver, gold and a special type of rubber have been used by researchers at the Institute for Basic Science (IBS) in South Korea to develop a device that can both measure electrophysiological signals and stimulate the heart. Their findings are published in Nature Nanotechnology.

Wearable electronics have the potential to be useful diagnostics, such as in the monitoring of physical activity and cardiac function. To perform optimally, these wearables have to be flexible and sensitive to either motion or bioelectric signals.

In the present study, researchers led by Dr. Choi Suji at IBS have invented a wearable device that can be used to record the electrical activity of the heart and muscles, that is, to produce an electrocardiogram (ECG) and electromyogram (EMG), respectively. The stretchable and conductive patch was created using gold-coated silver nanowires mixed with a type of rubber, called polystyrene-butadiene-styrene (SBS).

Conventional silver wire-based conductive rubbers have had limited biomedical applications because silver is toxic to the body. However, because the researchers coated the silver nanowires in an inert gold sheath, the silver was prevented from leaching and protected from corrosion by air and biological fluids such as sweat.

“We took advantage of silver’s high conductivity, SBS’ stretchability and gold’s high biocompatibility,” explained Professor Hyeon Taeghwan, director of the Center for Nanoparticle Research at IBS and an author on the paper. “Finding the right proportion of each material was the key to success.”

The elasticity and stretchability of the device allowed it to follow the contours of flexible joints, such as the wrist. Worn on the forearm, it simultaneously monitored EMG signals and delivered electrical and thermal stimulations that could be employed in therapeutic applications.

The research team has also produced a customized large mesh that fits onto the lower part of a swine heart. Wrapped around the heart, the implant can read signals from the entire organ to identify possible lesions and help recovery. For example, it was able to register the change in ECG signal caused by an acute heart attack. The mesh was shown to be stable during repetitive heart movements and did not interfere with the heart’s pumping activity.

“Although various soft cardiac devices have been reported for the rat heart, this study on pigs can approximate human physiology more accurately,” said Choi. “We aim to study heart diseases and stimulate the heart more effectively by synchronizing cardiac pumping activity.”

Going forward, the researchers intend to maximize the conductivity and stretchability of their device even further by designing novel, non-toxic materials and studying the therapeutic effect of the mesh in cardiac diseases.


The article can be found at: Choi et al. (2018) Highly Conductive, Stretchable and Biocompatible Ag–Au Core–sheath Nanowire Composite for Wearable and Implantable Bioelectronics.

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Source: Institute for Basic Science; Photo: Shutterstock.
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