Developing stimuli-responsive agents that can trigger mechanical responses is key to improving the design and functionality of soft actuators used in medical robots, artificial muscles, smart sensors, and more. Light is often utilized as a stimulus, however, light-responsive actuators typically respond to a single actuation mode determined by the light intensity. This prevents performance of multiple tasks under constant illumination, such as sunlight or ambient light, and energy input cannot be easily tuned. Current tunable actuation methods include chemical processing, self-oscillating, and reconfigurable patterning, but these often require prolonged processing.
Researchers at the University of California, Santa Barbara, have developed a visible light-responsive bilayer actuator enhanced by the tunable actuation performance of donor-acceptor Stenhouse adduct (DASA). This invention leverages negative photochromism and photothermal properties of DASA to enable load-bearing actuation capable of producing mechanical work. The bilayer actuators are tunable under a constant light intensity using broadband light sources to trigger responses. The DASA-polymer enables the use of visible and infrared light that does not damage living cells – a critical feature for in vivo applications. This technology is demonstrated by a visible light-powered cantilever capable of lifting up to 13 times its own weight against gravity, as well as a centimeter-scale remote-controlled crawler powered by robust light-activated bending. Applications for this technology are vast, including medical robots, soft surgical devices, soft exoskeletons, artificial muscle, smart sensors, adaptive optics devices and even photo-responsive artificial skin.
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