Scientists have developed a soft mesh that can record signals from the heart and muscles, paving the way for a new generation of flexible wearable health monitoring devices. The implantable device, provides information on muscle and cardiac dysfunctions, and thus could be implemented for pain relief, rehabilitation, and prosthetic motor control. It is the first soft implant that can record the cardiac activity in multiple points of a swine heart, according to a study published in the journal Nature Nanotechnology.
Researchers from the Institute for Basic Science (IBS) in South Korea used the device on human skin to record the electrical activity of heart and muscles, that is electrocardiogram (ECG) and electromyogram (EMG) respectively. Its softness, elasticity and stretchability, allows the device to follow the contours of flexible joints, such as the wrist. Worn on a forearm, it simultaneously monitored EMG signals, and delivered electrical and/or thermal stimulations that could be employed in therapeutic applications.
The research team has also produced a customised large mesh that fits 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 of ECG signal caused by an acute heart attack. The mesh is stable during repetitive heart movements and does 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 Suji, from IBS. “We aim to study heart diseases, and stimulate the heart more effectively by synchronizing cardiac pumping activity,” said Suji.
This stretchable and conductive patch is created by 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. The gold sheath prevents both silver’s leaching, and corrosion caused by air and biological fluids, such as sweat.
“We took advantage of silver’s high conductivity, SBS’ stretchability, and gold’s high biocompatibility,” said Hyeon Taeghwan, from IBS. “Finding the right proportion of each material was the key to success,” Taeghwan said.