Carbon Nanofiber-Based Wearable Patches for Bio-Potential Monitoring

Purpose We fabricated a wearable patch including a novel patch-type flexible dry electrode based on carbon nanofibers (CNFs) and biocompatible PDMS (MED-6215) for long-term bio-potential monitoring. Methods The patch comprises dry electrode parts for recording bio signals and sticky parts for skin mounting. To evaluate electrical characteristics and electrocardiograph (ECG) recording, the CNF concentrations and dry electrode thickness were varied. The electromechanical properties of the dry electrode were tested under cyclic load conditions. Cytotoxicity tests and long-term wearing tests were conducted to prove biocompatibility. Results The fabricated wearable patch is flexible, stretchable, easily skin mountable, and directly connectable with the measuring system. CNF concentrations is the most important variable compared with diameter, thickness for obtaining high-quality ECG signals. The electromechanical tests revealed excellent recovery performances in resistivity and durability. Cytotoxicity tests showed no effects on cells and long-term wearing tests showed no skin reactions. Conclusions The fabricated patch can be utilized for long-term bio-potential monitoring such as electromyography and electroencephalograms. The proposed dry electrode has flexibility, conductivity, and biocompatibility and is widely applicable to wearable sensors.