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Structured light enables biomimetic swimming and versatile locomotion of photoresponsive soft microrobots

Nature Materials volume 15, pages 647–653 (2016)Cite this article

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Abstract

Microorganisms move in challenging environments by periodic changes in body shape. In contrast, current artificial microrobots cannot actively deform, exhibiting at best passive bending under external fields. Here, by taking advantage of the wireless, scalable and spatiotemporally selective capabilities that light allows, we show that soft microrobots consisting of photoactive liquid-crystal elastomers can be driven by structured monochromatic light to perform sophisticated biomimetic motions. We realize continuum yet selectively addressable artificial microswimmers that generate travelling-wave motions to self-propel without external forces or torques, as well as microrobots capable of versatile locomotion behaviours on demand. Both theoretical predictions and experimental results confirm that multiple gaits, mimicking either symplectic or antiplectic metachrony of ciliate protozoa, can be achieved with single microswimmers. The principle of using structured light can be extended to other applications that require microscale actuation with sophisticated spatiotemporal coordination for advanced microrobotic technologies.

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Figure 1: Locomotion based on travelling-wave features, from nature to technology.
Figure 2: Deformation of microrobots made of soft active materials wirelessly controlled by dynamic light fields.
Figure 3: Force- and torque-free swimming of a cylindrical microrobot driven by light-controlled travelling-wave deformations.
Figure 4: In-plane controlled locomotion of disc-shaped microrobots.

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Acknowledgements

This work was in part supported by the European Research Council under the ERC Grant agreements 278213 and 291349, and the DFG as part of the project SPP 1726 (microswimmers, FI 1966/1-1). S.P. acknowledges support by the Max Planck ETH Center for Learning Systems. We thank A. Posada for help with the movies and figures.

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Authors and Affiliations

  1. Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany

    Stefano Palagi, Andrew G. Mark, Kai Melde, Tian Qiu, Alberto Sanchez-Castillo & Peer Fischer

  2. Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Cambridge CB3 0WA, UK

    Shang Yik Reigh & Eric Lauga

  3. Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

    Tian Qiu

  4. European Laboratory for Non Linear Spectroscopy (LENS), University of Florence, 50019 Sesto Fiorentino, Italy

    Hao Zeng, Camilla Parmeggiani, Daniele Martella & Diederik S. Wiersma

  5. CNR-INO, 50019 Sesto Fiorentino, Italy

    Camilla Parmeggiani

  6. Institut für Physikalische Chemie, Universität Stuttgart, 70569 Stuttgart, Germany

    Nadia Kapernaum, Frank Giesselmann & Peer Fischer

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  1. Stefano Palagi
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Contributions

S.P., A.G.M. and P.F. proposed the experiment; S.P., A.G.M. and K.M. built the structured light set-up; H.Z., C.P., D.M. and D.S.W. synthesized the LCE and formed the cylindrical samples; S.P. performed the experiments and numerical simulations; S.P. and T.Q. fabricated the disc by photolithography; S.P., A.G.M., A.S.-C., N.K. and F.G. characterized the LCE material by SAXS; S.Y.R. and E.L. developed the analytical theory model; S.P., A.G.M. and P.F. wrote the manuscript with contributions from all authors.

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Correspondence to Peer Fischer.

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Palagi, S., Mark, A., Reigh, S. et al. Structured light enables biomimetic swimming and versatile locomotion of photoresponsive soft microrobots. Nature Mater 15, 647–653 (2016). https://doi.org/10.1038/nmat4569

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