Laser Micromachining of Magnetoactive Elastomers as Enabling Technology for Magneto-Responsive Surfaces

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 x 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 magneto-sensitive smart surfaces in microfluidic devices and soft robotics are discussed.

Movie files show measurements of the sliding angle of water droplets. Their names include the following information:
MAE_<structure type>_B<magnetic field amplitude in mT>_<angle of magnetic field>.avi

DOI of article: 10.1002/admt.202101045