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Author: Zhang, Hang × Subject: microgels ×

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Now showing 1 - 2 of 2
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    Soft Microrobots Employing Nonequilibrium Actuation via Plasmonic Heating
    (Weinheim : Wiley-VCH, 2017) Mourran, Ahmed; Zhang, Hang; Vinokur, Rostislav; Möller, Martin
    A soft microrobot composed of a microgel and driven by the light-controlled nonequilibrium dynamics of volume changes is presented. The photothermal response of the microgel, containing plasmonic gold nanorods, enables fast heating/cooling dynamics. Mastering the nonequilibrium response provides control of the complex motion, which goes beyond what has been so far reported for hydrophilic microgels.
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    A Light-Driven Microgel Rotor
    (Weinheim : Wiley-VCH, 2019) Zhang, Hang; Koens, Lyndon; Lauga, Eric; Mourran, Ahmed; Möller, Martin
    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.