A microstructure enhancement method for hard magnetic particle chains based on magnetic field oscillation sieve

Magnetic actuation has emerged as a prominent method in soft robots due to its charming advantages on diverse magnetization designs, which heavily rely on the microstructures formed by hard magnetic particles (NdFeB) inside the robot. However, the contradiction between the need for multiple orientations of the particles and the issue of particle agglomeration caused by repeated orientation during fabrication has not been effectively resolved. This limitation prevents additive manufacturing of high-performance magnetic soft robots and hinders further diversification of robot magnetization structures. In this study, we proposed a method that utilizes a dynamic magnetic field to re-disperse agglomerated particles. This method is able to effectively disperse the agglomerates uniformly and enhance the re-oriented particle chains in multiple aspects, including compactness, orientation (similar to 200 %), and maintenance time (>120 min). Furthermore, this method was utilized to improve the magneto-induced deformation (from 7.71 to 13.89) of the Magneto-Rheological Elastomer (MRE) samples, which were fabricated with repeatedly orientated magnetizations using magnetic field-assisted Stereo-lithography (SLA). Overall, the proposed method lays the groundwork for the structural complexity of magnetic soft robots and holds significant potential for broadening the fabrication methods of magnetic soft robots.