Fabrication of magnetic field-responsive flexible pillar arrays and its application to droplet manipulation

Abstract

The manipulation of droplets is of significant interest for a broad range of applications. To manipulate a droplet, patterned surfaces, chemical gradients or electrowetting have been suggested as a passive approach. Due to inherent limitations of existing techniques, magnetically actuatable structures became considerable for the active droplet manipulation due to their reversible structural tunability in response to a remote magnetic field. To this end, we report a novel technique that enables dynamic control over the position and motion of a pure droplet by utilizing a magnetically responsive flexible film. comprising reversibly actuating hierarchical pillars on the surface (Fig. 1). The droplet can be rapidly manipulated to arbitrary targets with only the use of a permanent magnet. This surface exhibits reliable actuating capabilities with immediate field responses and maximum tilting angles of ~90° with superhydrophobicity.