Fast Large‐Stroke Sheath‐Driven Electrothermal Artificial Muscles with High Power Densities

Electrothermal carbon nanotube (CNT) yarn muscles can provide large strokes during thermal cycling. However, the slow cooling rate of limits their applications, since diameter prior-art cannot be rapidly cycled. Herein, a fast thermally powered sheath-driven muscle that uses hybrid CNT sheath and an inexpensive polymer core, is reported. The stroke recovery for much lower at all frequencies than about same muscle, which means full cycle contractile mechanical power higher comparable muscle. More specifically, coiled contracts 14.3% 1 Hz 7.3% 8 in air when by square-wave electrical voltage input, 2.9- 11.4-times these respective frequencies. An average density 12 kW kg−1 obtained 42-times human skeletal These high-performance results heating drives actuation cycles are largely restricted to sheath, this direct contact with ambient temperature air.