Remote actuation based on magnetically responsive pillar arrays

Abstract

Smart actuators, integrated with high aspect-ratio structures and stimuli-responsive materials, can take more diverse tasks skillfully. Although great advances have been achieved over the past few years, it is still difficult in manipulating the small objects such as the transporting and grasping them under the remote untethered condition. Inspired by the ciliary structures on biological organs, a magnetically responsive actuator with hierarchical pillars on the surface of the film is designed and proposed, which allows active, fast, and dynamic manipulation over the force and speed of a small object by taking an external magnetic field. Magnetic pillars of different morphologies were fabricated by a modified soft lithographic method involving inking and imprinting processes. The magnetic-force conversion unit was constructed by magnetically responsive pillar arrays. Upon applying an external magnetic field, these pillars can rhythmically bend and recover in a controlled manner, and the generated force can be used to drive the small object to move or capture the small object. All these was further addressed from experimental and theoretical perspectives. This magnetically responsive actuator demonstrates reliable actuating performance with instant field responses. No complex mechanical and electrical control systems are required. Thus, the combined use of high aspect-ratio structures and stimuli-responsive materials will facilitate many other applications such as surface engineering, soft actuators and robotics in the future.

Recent Progress on the Development of Magnetically‐Responsive Micropillars: Actuation, Fabrication, and Applications

“…Besides the traditional manipulation of the particle and droplet on a plane, magnetic micropillars can also serve as a tweezer to grip microscale targets. [144] As mentioned before, a micropillar array containing two types of micropillars with two different nanoparticle distributions (i.e., tip-replete or base-replete) was fabricated. [42] Thus, for a tweezer composed of the tip-replete and base-replete micropillars, a microscale particle could be grasped because the interpillar distance decreased when a magnetic field was applied (Figure 9D(iv)).…”

Droplet Manipulation on Bioinspired Slippery Surfaces: From Design Principle to Biomedical Applications

“…In recent years, more and more magnetic responsive slippery surfaces using micropillars were reported for droplet manipulation. [94][95][96][97] However, micropillar-based magnetic actuation methods are challenged regarding long-range and fast transportation control, precise droplet location, and efficient droplet mixing. In addition to micropillars, it is also possible to make Isotropic/Anisotropic surface morphology for guided droplet movement.…”