fig5
Figure 5. Light and heat actuation of 4D-printed soft microbots. (A) Light actuation mechanism. Reproduced with permission from Ref.[110]. Copyright 2021, MDPI; (B) DIW TiNC/LCE photochromic actuator with near infrared photothermal bending, for reprogrammable barcode and origami/kirigami forms. Reproduced with permission from Ref.[111]. Copyright 2024, Wiley-VCH; (C) Azobenzene-ink LCE swimmer with UV/green light photochemical propulsion without laser tracking. Reproduced with permission from Ref.[29]. Copyright 2024, Wiley-VCH; (D) DIW supramolecular LCE light actuators with reversible morphing in air and water. The scale bars are 5, 5, and 2.5 mm, respectively. Reproduced with permission from Ref.[112]. Copyright 2023, Wiley-VCH; (E) Heat actuation mechanism. Reproduced with permission from Ref.[30]. Copyright 2025, American Chemical Society; Reproduced with permission from Ref.[115]. Copyright 2022, American Association for the Advancement of Science; Reproduced with permission from Ref.[114]. Copyright 2020, American Chemical Society; (F) Thermally actuated 4D printed soft robot with eccentric hinges for tunable crawling, rolling, oscillating, and passive energy harvesting. Reproduced with permission from Ref.[116]. Copyright 2024, Wiley-VCH; (G) Electrothermal LCE bimorph with patterned silver nanowire heaters for programmable bidirectional crawling and confined obstacle traversal. Reproduced with permission from Ref.[117]. Copyright 2023, American Association for the Advancement of Science; (H) Ambient heat powered LCE self-rolling robot with twisted and helical ends for autonomous maze navigation on granular terrain. Reproduced with permission from Ref.[118]. Copyright 2023, American Association for the Advancement of Science. 4D: Four-dimensional; DIW: direct ink writing; LCE: liquid crystal elastomer; UV: ultraviolet; NIR: near infrared; PDMS: polydimethylsiloxane; RGO: reduced graphene oxide; LMs: liquid metals.
