Large-strain, multiform movements from designable electrothermal actuators based on large highly anisotropic carbon nanotube sheets

Many electroactive polymer (EAP) actuators use diverse configurations of carbon nanotubes (CNTs) as pliable electrodes to realize discontinuous, agile movements, for CNTs are conductive and flexible. However, the reported CNT-based EAP actuators could only accomplish simple, monotonous actions. Few actuators were extended to complex devices because efficiently preparing a large-area CNT electrode was difficult, and complex electrode design has not been carried out. In this work, we successfully prepared large-area CNT paper (buckypaper, BP) through an efficient approach. The BP is highly anisotropic, strong, and suitable as flexible electrodes. By means of artful graphic design and processing on BP, we fabricated various functional BP electrodes and developed a series of BP-polymer electrothermal actuators (ETAs). The prepared ETAs can realize various controllable movements, such as large-stain bending (>180°), helical curling (∼630°), or even bionic actuations (imitating human-hand actions). These functional and interesting movements benefit from flexible electrode design and the anisotropy of BP material. Owing to the advantages of low driving voltage (20-200 V), electrolyte-free and long service life (over 10000 times), we think the ETAs will have great potential applications in the actuator field.