A Light-Driven Microgel Rotor

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

Abstract

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.

Citation

Zhang, H., Koens, L., Lauga, E., Mourran, A., & Möller, M. (2019). A Light-Driven Microgel Rotor. Small, 15(46), Article 1903379. https://doi.org/10.1002/smll.201903379

• Journal Article Type: Article
• Acceptance Date: Nov 25, 2019
• Online Publication Date: Sep 25, 2019
• Publication Date: Nov 13, 2019
• Deposit Date: Jan 25, 2022
• Publicly Available Date: Jan 31, 2022
• Journal: Small
• Print ISSN: 1613-6810
• Electronic ISSN: 1613-6829
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 15
• Issue: 46
• Article Number: 1903379
• DOI: https://doi.org/10.1002/smll.201903379
• Keywords: Microgels; Microswimmers; Out-of-equilibrium; Photothermal actuation; Rotational motion; Stokes flow
• Public URL: https://hull-repository.worktribe.com/output/3916627