Environment‐Adaptable Rotational Energy Harvesters Based on Nylon‐core Coiled Carbon Nanotube Yarns

Abstract Owing to increasing amount of research on energy harvesting, studies on harvesters for practical application and their performance are attracting attention. Therefore, studies on the use of continuous energy as an energy source for energy‐harvesting devices are being conducted, and fluid flows, e.g., wind, river flow, and sea wave, are widely used as input energy sources for continuous energy harvesting. A new energy‐harvesting technology has emerged based on the mechanical stretch and release of coiled carbon nanotube (CNT) yarns, which generate energy based on the change in the electrochemical double‐layer capacitance. First, this CNT yarn–based mechanical energy harvester is demonstrated, which is applicable to various environments where fluid flow exists. This environment‐adaptable harvester uses rotational energy as the mechanical energy source and is tested in river and ocean environments. Moreover, an attachable‐type harvester for the application of the existing rotational system is devised. In the case of a slow rotational environment, a square‐wave strain‐applying harvester has been implemented, which can convert sinusoidal strain motion into square‐wave strain motion for high output voltages. To achieve high performance of practical harvesting applications, a scale‐up method for powering signal‐transmitting devices has been implemented.