Tunable Photothermal Actuators Based on a Pre-programmed Aligned Nanostructure

For various applications, it is challenging
but essential to obtain
complex tunable mechanical actuations in response to environmental
stimuli. Here, a general and effective strategy is developed to produce
multiple types of photomechanical actuation (from phototropic/apheliotropic
bending to three-dimensional helical buckling) by manipulating the
orientation of one-dimensional nanomaterials. These materials are
manipulated to mimic plants that generate diverse mechanical motions
through the orientation of cellulose fibrils. The photomechanical
actuations can be completed in milliseconds and can be performed reversibly
without detectable fatigue after 100 000 cycles. This capacity
to produce multiple types of photomechanical actuation is further
developed to produce complex integrated movements, as demonstrated
by a light-manipulated robotic arm and a solar energy harvesting system.