posted on 2021-03-02, 14:11authored byYing Hu, Lulu Yang, Qiuyang Yan, Qixiao Ji, Longfei Chang, Chenchu Zhang, Jian Yan, Ranran Wang, Lei Zhang, Guan Wu, Jing Sun, Bin Zi, Wei Chen, Yucheng Wu
Soft
actuators and microrobots that can move spontaneously and
continuously without artificial energy supply and intervention have
great potential in industrial, environmental, and military applications,
but still remain a challenge. Here, a bioinspired MXene-based bimorph
actuator with an asymmetric layered microstructure is reported, which
can harness natural sunlight to achieve directional self-locomotion.
We fabricate a freestanding MXene film with an increased and asymmetric
layered microstructure through the graft of coupling agents into the
MXene nanosheets. Owing to the excellent photothermal effect of MXene
nanosheets, increased interlayer spacing favoring intercalation/deintercalation
of water molecules and its caused reversible volume change, and the
asymmetric microstructure, this film exhibits light-driven deformation
with a macroscopic and fast response. Based on it, a soft bimorph
actuator with ultrahigh response to solar energy is fabricated, showing
natural sunlight-driven actuation with ultralarge amplitude and fast
response (346° in 1 s). By utilizing continuous bending deformation
of the bimorph actuator in response to the change of natural sunlight
intensity and biomimetic design of an inchworm to rectify the repeated
bending deformation, an inchwormlike soft robot is constructed, achieving
directional self-locomotion without any artificial energy and control.
Moreover, soft arms for lifting objects driven by natural sunlight
and wearable smart ornaments that are combined with clothing and produce
three-dimensional deformation under natural sunlight are also developed.
These results provide a strategy for developing natural sunlight-driven
soft actuators and reveal great application prospects of this photoactuator
in sunlight-driven soft biomimetic robots, intelligent solar-energy-driven
devices in space, and wearable clothing.