Low-voltage and high-performance electrothermal actuator based on multi-walled carbon nanotube/polymer composites

Multi-walled carbon nanotubes are used to fabricate a type of environment-friendly electrothermal bimetallic actuators with the matrix of waterborne polyurethane or silicone rubber. Even under a relatively low DC driven voltage of 7 V, the actuator can achieve a bending displacement up to 28 mm, or a curvature up to 0.29 cm−1, which are greater than most of other electrothermal actuators reported. The actuator has considerable controllability, large mechanical output and long life-time, and the working power can be reduced down to 25 mW/mm3 in the atmospheric environment. The actuation mechanisms owe not only to the mismatch in the coefficients of thermal expansion, but also to the unique negative temperature coefficient effect of nanotube composites. Furthermore, the bimetallic actuators based on various polymer matrices are supposed to provide revelations for electrothermal bimorph actuators.