Active control of surface profile by magnetic micropillar arrays

Pillar arrays have been extensively used in science and engineering, with major applications at the micro or nano scale, requiring a control technique that can operate in a small, confined area. In this study, an active control method for the surface profile was developed using elastic micropillar arrays with magnetic tips. Single-, double-, and multiple-magnetic pillar arrays were fabricated from poly(dimethylsiloxane) and carbonyl iron particles using a mould prepared by laser drilling. The pillar behaviour was investigated in static and moving magnetic fields. In a static magnetic field, a single pillar is bent, double pillars are attached to a pair, and multiple pillars form pair and line patterns parallel to the magnetic field direction at a field strength of 55 mT and 85 mT, respectively, for a horizontal magnetic field. In a moving magnetic field, the propagating deformation of pillar arrays could successfully transport an 8 mm diameter plastic bead horizontally across the pillared surface at a speed of 4 mm s-1.