Femtosecond laser-assisted printing of hard magnetic microrobots for swimming upstream in subcentimeter-per-second blood flow.

Journal: Science advances
Published Date: Jul 4, 2025

Abstract

Magnetic microrobots have garnered increasing attention in the biomedical field due to their wireless motion control and noninvasive therapeutic potential. However, current microrobots fabricated from soft magnetic materials exhibit critical limitations, including weak magnetic response and uncontrollable locomotion in high-rate blood flow, which hinder their practical applications. Here, we develop a fabrication method for three-dimensional (3D) hard magnetic microrobots (HM-microrobots) containing neodymium-iron-boron particles. HM-microrobots, featuring programmable 3D helical morphologies, are fabricated by integrating two-photon polymerization printing of molds in positive photoresist with subsequent vacuum infusion molding of hard magnetic slurries. The microrobots achieve a maximum swimming velocity of 22.6 body lengths per second (3 millimeters per second) in a weak rotating magnetic field of 2 millitesla, which represents a notable improvement over their soft magnetic counterparts. Furthermore, they demonstrate controllable upstream propulsion in subcentimeter-per-second blood flow, showing great potential for endovascular applications.

Authors

  • Dong Wu
  • Xiuwen Wang
    Department of Oncology, Qilu Hospital of Shandong University, Jinan, Shandong, China.
  • Rui Li
    Department of Oncology, Xiyuan Hospital, China Academy of Chinese Medical Science, Beijing, China.
  • Chaowei Wang
    CAS Key Laboratory of Mechanical Behavior and Design of Materials, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, 230027, China.
  • Zhongguo Ren
    Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China.
  • Deng Pan
    Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China.
  • Pinliang Ren
    CAS Key Laboratory of Mechanical Behavior and Design of Materials, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, China.
  • Yanlei Hu
    Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China.
  • Chen Xin
    Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China.
  • Li Zhang
    Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.

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