Superparamagnetic microrobots: fabrication by two-photon polymerization and biocompatibility

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This work presents the fabrication and controlled actuation of swimming microrobots made of a magnetic polymer composite (MPC) consisting of 11-nm-diameter magnetite (Fe3O4) nanoparticles and photocurable resin (SU-8). Two-photon polymerization (TPP) is used to fabricate the magnetic microstructures. The material properties and the cytotoxicity of the MPC with different nanoparticle concentrations are characterized. The live/dead staining tests indicate that MPC samples with varied concentrations, up to 10 vol.%, have negligible cytotoxicity after 24 h incubation. Fabrication parameters of MPC with up to 4 vol.% were investigated. We demonstrate that the helical microdevices made of 2 vol.% MPC were capable of performing corkscrew motion in water applying weak uniform rotating magnetic fields.

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The authors thank Eszter Barthazy and Elisabeth Müller (EMEZ at ETH Zurich) for the TEM-images, the technical support from the FIRST lab at ETH Zurich. Funding for this research is provided by Swiss National Science Foundation (SNSF), project number 130069 and the ETH Zurich (TH-28 06–3).

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Correspondence to Li Zhang.

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Suter, M., Zhang, L., Siringil, E.C. et al. Superparamagnetic microrobots: fabrication by two-photon polymerization and biocompatibility. Biomed Microdevices 15, 997–1003 (2013).

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  • Superparamagnetic nanocomposite
  • Microrobots
  • Magnetic actuation
  • Cytotoxicity