Laser Micromachining of Magnetoactive Elastomers as Enabling Technology for Magnetoresponsive Surfaces

Abstract

A simple method for structuring of the surface of a magnetoactive elastomer (MAE) on the tens of micrometers scale, which capabilities extend beyond conventional mold‐based polymer casting, is reported. The method relies on the ablation of the material by absorption of nanosecond infrared pulses from a commercial laser. It is shown that it is possible to fabricate parallel lamellar structures with a high aspect ratio (up to 6:1) as well as structures with complex scanning trajectories. The method is fast (fabrication time for the 7 × 7 mm2 is about 60 s), and the results are highly reproducible. To illustrate the capabilities of the fabrication method, both orthogonal to the MAE surface and tilted lamellar structures are fabricated. These magnetosensitive lamellae can be easily bent by ±45° using an external magnetic field of about 230 mT. It is demonstrated that this bending allows one to control the sliding angle of water droplets in a great range between a sticky (>90°) and a sliding state (<20°). Perspectives on employing this fabrication technology for magnetosensitive smart surfaces in microfluidic devices and soft robotics are discussed.

Underwater Directional and Continuous Manipulation of Gas Bubbles on Superaerophobic Magnetically Responsive Microcilia Array

“…[9] On the other hand, the tunability and control of magnetically active elastomers have proven to be particularly advantageous in different external stimuli and possible material systems. [10] Thus, herein, inspired by G. viridula's feet setae and pigeons' migration behaviors, we bionically constructed a superaerophobic flexible magnetic microcilia array (FMMA) surface for gas bubbles controllable transport. Under the action of external magnetic field, the flexible cilia can bend toward the center of the magnet to form a tiny concave.…”

In Situ Observation of the Movement of Magnetic Particles in Polyurethane Elastomer Densely Packed Magnetic Particles Using Synchrotron Radiation X-ray Computed Tomography

“…The physical properties of magnetic-responsive soft materials, which are composites of magnetic particles and gels or elastomers, change in response to magnetic fields, e.g., macroscopic expansion and contraction due to nonuniform magnetic fields, magnetostriction, rotational motion due to rotating magnetic fields, magnetorheological grease, multiferroic cantilevers, magnetically switchable adhesion and friction, and microstructural changes on the surface. , The viscoelastic properties of magnetic soft materials also change in response to magnetic fields, − which is called the magnetorheological effect (MR effect). The variable viscoelasticity is a very important property industrially, such as in tactile-sense displays or active vibration-control devices.…”

Natural Cilia and Pine Needles Combinedly Inspired Asymmetric Pillar Actuators for All-Space Liquid Transport and Self-Regulated Robotic Locomotion

“…However, constrained by the unchangeable structure of plant-inspired surfaces, liquid transport can only occur in specific orientations, highly reducing their flexibility and controllability in practical applications. Although scientists have proposed some magnetic-response surfaces to enrich the forms of surface structures, − it is still challenging to design intelligent surfaces with flexible transport in all directions and controllable transport speeds. By contrast, magnetic artificial cilia systems, with the ability of active liquid transport, − stand out from various driving principles (light-driven, , electric-driven, , ultrasound-driven, and fluidic-driven , ) due to their convenient control, rapid response, and cross-scale applicability.…”