Researchers from the Center for Nanoparticle Research at the Institute for Basic Science have developed a wearable and implantable device that measures electrophysiological signals and stimulates as needed for pain relief, rehabilitation and prosthetic motor control.

The soft implantable recorded cardiac activity in multiple points of a swine heart in tests. The researchers on the study suggest that the prototype will contribute to the research and production of bioelectronics in the future.

Institute for Basic Science researchers have used the device on human skin to record electrical activity of heart and muscles, or electrocardiograms (ECG) and electromyograms (EMG). The device is soft and elastic, which means it can follow the contours of flexible joints. If it is worn on the forearm, it can monitor EMG signals and deliver electrical or thermal stimulations for therapeutic purposes.

The researchers created a customized large mesh that fit on the lower part of a swine heart. When wrapped around the heart, the implant could read signals from the heart and identify potential lesions and help with recovery. The device also registers ECG signal changes that are caused by an acute heart attack and stays stable during repetitive heart movements while not interfering with the pumping activity of the heart.

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

The device is a stretchable, conductive patch that is made with gold-coated silver nanowires mixed with a type of rubber, called polystyrene-butadiene-styrene (SBS). Silver wire-based conductive rubbers typically have limited biomedical applications since silver is toxic in the human body. The use of gold sheaths prevents silver leaching and corrosion that is caused by air and biological fluids like sweat.

“We took advantage of silver’s high conductivity, SBS’ stretchability and gold’s high biocompatibility,” Hyeon Taeghwan, corresponding co-author on the study, said. “Finding the right proportion of each material was the key to success.”

The researchers plan to include maximizing conductivity and stretchability to the device by designing non-toxic materials and studying the therapeutic effects of mesh in cardiac diseases.

The research was published in the journal Nature Nanotechnology.