Multifunctional Janus Microplates Arrays Actuated by Magnetic Fields for Water/Light Switches and Bio‐Inspired Assimilatory Coloration

: Smart dynamic regulation structured surfaces, inspired by nature, which can dynamically change their surface topographies under external stimuli for convertible fluidic and optical properties, have recently motivated significant interest for scientific research and industrial applications. However, there is still high demand for the development of multifunctional dynamically transformable surfaces using facile preparation strategies. In this work, a type of Janus high-aspect-ratio magnetically responsive microplates array (HAR-MMA) is readily fabricated by integrating a flexible laser scanning strategy, smart shape-memory-polymer-based soft transfer, and a simple surface treatment. By applying external magnetic field, instantaneous and reversible deformation of Janus HAR-MMA can be actuated, so surface wettability can be reversibly switched between superhydrophobic (158°) and hydrophilic (40°) states, based on which a novel magnetically responsive water droplet switch can be realized. Moreover, inspired by the biological assimilatory coloration of chameleons, dynamically color conversion can be skillfully realized by applying different colors on each side of the Janus HAR-MMA. Finally, as a proof-of-concept demonstration in light manipulation, a HAR-MMA is applied as an optical shutter actuated by external magnetic field with eximious controllability and repeatability. The developed multifunctional HAR-MMA provides a versatile platform for microfluidic, biomedical, and optical applications.