A Light-Driven Microgel Rotor

Hang Zhang, Lyndon Koens, Eric Lauga, Ahmed Mourran*, Martin Möller

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

34 Citations (Scopus)


The current understanding of motility through body shape deformation of micro-organisms and the knowledge of fluid flows at the microscale provides ample examples for mimicry and design of soft microrobots. In this work, a 2D spiral is presented that is capable of rotating by non-reciprocal curling deformations. The body of the microswimmer is a ribbon consisting of a thermoresponsive hydrogel bilayer with embedded plasmonic gold nanorods. Such a system allows fast local photothermal heating and nonreciprocal bending deformation of the hydrogel bilayer under nonequilibrium conditions. It is shown that the spiral acts as a spring capable of large deformations thanks to its low stiffness, which is tunable by the swelling degree of the hydrogel and the temperature. Tethering the ribbon to a freely rotating microsphere enables rotational motion of the spiral by stroboscopic irradiation. The efficiency of the rotor is estimated using resistive force theory for Stokes flow. This research demonstrates microscopic locomotion by the shape change of a spiral and may find applications in the field of microfluidics, or soft microrobotics.

Original languageEnglish
Article number1903379
Issue number46
Publication statusPublished - 1 Nov 2019
MoE publication typeA1 Journal article-refereed


  • microgels
  • microswimmers
  • out-of-equilibrium
  • photothermal actuation
  • rotational motion
  • Stokes flow


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