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arXiv · 2509.07959

Comparison of the propulsion of helical microrobots based on hard- and soft-magnetic elements under rotating external magnetic fieldsv

Joost Wijnmalen·Leon Abelmann·Iulian Apachitei
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Abstract

This study compares the propulsion of helical microrobots based on hard- and soft-magnetic elements under rotating magnetic fields. Results show that hard-magnetic microrobots achieved step-out frequencies and maximum propulsion speeds 4.5 times higher than soft-magnetic microrobots. Below saturation magnetization, soft-magnetic micro-robots demonstrated similar performance irrespective of magnetic susceptibility, high-lighting that torque generation in these materials is purely geometry-dependent. Employing a tapered ribbon design increased propulsion speed by a factor of 3.5 compared to regular helical designs. These results provide a quantitative basis for selecting materials and designs, enabling designers to weigh the propulsion benefits of hard magnets against the biocompatibility of soft-magnetic microrobots.

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Joost Wijnmalen, Leon Abelmann, Iulian Apachitei. 2025-09-09. Comparison of the propulsion of helical microrobots based on hard- and soft-magnetic elements under rotating external magnetic fieldsv. https://arxiv.org/abs/2509.07959

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