Programmable Soft Actuators Enabled by Wavelength‐Selective Liquid‐Gas Phase Transition

ABSTRACT Soft actuators that operate wirelessly with high spatial and functional programmability are central to the development of next‐generation soft robotic and microfluidic systems. Liquid‐gas phase transition‐driven actuation offers large and rapid deformations, yet its practical implementation remains limited by a lack of spatial selectivity and programmable control. Here, we introduce a wavelength‐selective soft actuation strategy that couples photothermal heating with liquid‐gas phase transitions in hexafluoroisopropanol (HFIP)‐loaded Ecoflex architectures. By incorporating color‐specific acrylic dyes, we engineer spectral matching between the illumination wavelength and the optical absorption spectrum, enabling localized vaporization and efficient pressure generation. The actuation behavior is systematically tuned through dye concentration, solvent loading, and illumination wavelength, achieving reversible elongations exceeding 250% without compromising mechanical integrity. Beyond fundamental actuation, we demonstrate light‐controlled liquid pumping, sequential fluid release, cargo transport, and on‐demand organic solvent adsorption, all achieved without the need for external pumps, valves, or wiring. This work establishes wavelength‐selective phase‐transition‐driven actuation as a versatile, programmable platform for remotely controlled soft robotics, adaptive microfluidics, and chemical handling systems.