Enhanced magneto-mechanical actuation of micropillar arrays via anisotopic stress-distribution

초록

Shape-reconfigurable magnetic response of micropillar arrays was manifested by arranging magnetic particles within the elastomeric polymer matrix. Magnetic actuation was programmed by chain-like arranged particles as two types of twisting or bending. Herein, the particle alignment axis is harmonized to the external linear magnetic field axis. Previous studies have intensively documented the cylindrical micropillars where the stiffness distribution is radially balanced within the microcylinders, resulting in attenuated actuation degrees because of unfocused momentum. Alternatively, we demonstrate the influences of anisotropic polygonal geometry on magnetic actuation. As the fundamental quadrangular polygon has only four edges, the rectangular forms factor is profitable to compare theoretically calculated stress distribution with experimentally measured actuation degree. Long axis of the rectangular cross-section has larger bending stiffness than short axis of that, resulting in concentrated magnetic momentum on actuation along long axis of micropillars. When the aqueous polymeric solution was cast on micropillar arrays, the liquid spreading and wetting shape are dynamically tunable by varying pinning and depinning conditions according to the mode of magnetic actuation. We will discuss the relationships between geometry factors of micropillars and magnetic actuation as well as wetting properties.