A Scalable, Incoherent-Light-Powered, Omnidirectional Self-Oscillator

Light-fueled self-oscillators based on stimuli-responsive soft materials have been explored toward the realization of a myriad of nonequilibrium robotic functions, such as adaptation, autonomous locomotion, and energy conversion. However, the high energy density and unidirectionality of the light field, together with the unscalable design of the existing demonstrations, hinder their further implementation. Herein, a light-responsive lampshade-like smart material assembly as a new self-oscillator model that is unfettered by the abovementioned challenges, is introduced. Liquid crystal elastomer with low phase transition temperature is used as the photomechanical component to provide twisting movement under low-intensity incoherent light field. A spiral lampshade frame ensures an equal amount of light being shadowed as negative feedback to sustain the oscillation upon constant light field from omnidirectional excitation (0 degrees-360 degrees azimuth and 20 degrees-90 degrees zenith). Different-sized oscillators with 6, 15, and 50 mm in diameter are fabricated to prove the possibility of scaling up and down the concept. The results provide a viewpoint on the fast-growing topic of self-oscillation in soft matter and new implications for self-sustained soft robots.