Fig. 2. The MEW-printed LCE microfiber actuators.

(A) The LCE microfiber array with the same diameter of 30 μm was fabricated by MEW. Scale bar, 300 μm. (B) LCE microfiber array with diameters of 30, 40, and 50 μm. Scale bar, 200 μm. (C) LCE microfiber diameter versus printing speed at five printing temperatures. (D) Actuation strain test and the dynamic thermal contraction process of a single LCE microfiber. Scale bar, 50 μm. The LCE microfiber was directly printed onto two adjustable glass slides. The gap distance between the slides was increased until the microfiber was straightened, and then the original length (L₀) of the microfibers was measured. By decreasing the gap distance, the LCE microfiber was bent. Next, the LCE microfiber was heated at a temperature of approximately 120°C, and the gap distance was adjusted until the microfiber was straightened again, and then its contracted length (L₁) was measured. (E) Actuation strain of the LCE microfiber printed at five different printing temperatures versus the printing speed. (F) Actuation strain versus the temperature of single-LCE microfibers printed at different printing temperatures. (G) Actuation stress measurement method of LCE microfibers. The UV-curable adhesive droplet was used as a load. The LCE microfiber with the adhesive droplet was placed inside an oven and heat up to 120°C for actuation stress testing. (H) Actuation strain of the LCE microfibers as a function of the applied actuation stress. (I) Rapid response capability testing of the LCE microfiber actuators at various frequencies. Scale bar, 5 mm. (J) Actuation strain of the LCE microfiber actuator that drives a slider that is 3500 times heavier than it, continuously lifting it up and down under thermal airflow stimuli at frequencies of up to 15 Hz.