Photoresponsive hydrogel microcrawlers exploit friction hysteresis to crawl by reciprocal actuation

Rehor, Ivan and Maslen, Charlie and Moerman, Pepijn G. and van Ravensteijn, Bas G.P. and van Alst, Renee and Groenewold, Jan and Eral, Huseyin Burak and Kegel, Willem K. (2021) Photoresponsive hydrogel microcrawlers exploit friction hysteresis to crawl by reciprocal actuation. Soft Robotics, 8 (1). pp. 10-18. (https://doi.org/10.1089/soro.2019.0169)

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Abstract

Mimicking the locomotive abilities of living organisms on the microscale, where the downsizing of rigid parts and circuitry presents inherent problems, is a complex feat. In nature, many soft-bodied organisms (inchworm, leech) have evolved simple, yet efficient locomotion strategies in which reciprocal actuation cycles synchronize with spatiotemporal modulation of friction between their bodies and environment. We developed microscopic (∼100 μm) hydrogel crawlers that move in aqueous environment through spatiotemporal modulation of the friction between their bodies and the substrate. Thermo-responsive poly-n-isopropyl acrylamide hydrogels loaded with gold nanoparticles shrink locally and reversibly when heated photothermally with laser light. The out-of-equilibrium collapse and reswelling of the hydrogel is responsible for asymmetric changes in the friction between the actuating section of the crawler and the substrate. This friction hysteresis, together with off-centered irradiation, results in directional motion of the crawler. We developed a model that predicts the order of magnitude of the crawler motion (within 50%) and agrees with the observed experimental trends. Crawler trajectories can be controlled enabling applications of the crawler as micromanipulator that can push small cargo along a surface.

ORCID iDs

Rehor, Ivan, Maslen, Charlie ORCID logoORCID: https://orcid.org/0000-0003-2995-0918, Moerman, Pepijn G., van Ravensteijn, Bas G.P., van Alst, Renee, Groenewold, Jan, Eral, Huseyin Burak and Kegel, Willem K.;
  • Item type:Article
    ID code:90893
    Dates:
    Date
    Event
    15 February 2021
    Published
    22 April 2020
    Published Online
    1 January 2020
    Accepted
    Notes:This is the accepted version of the following article: Rehor et al., 2021, 'Photoresponsive hydrogel microcrawlers exploit friction hysteresis to crawl by reciprocal actuation', Soft Robotics, vol. 8, no. 1, pp. 10-18. It has now been formally published in final form at Soft Robotics at https://doi.org/10.1089/soro.2019.0169. This original submission version of the article may be used for non-commercial purposes in accordance with the Mary Ann Liebert, Inc., publishers’ self-archiving terms and conditions.
    Subjects:Technology > Chemical engineering
    Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:17 Oct 2024 15:18
    Last modified:11 Nov 2024 14:22
    URI:https://strathprints.strath.ac.uk/id/eprint/90893
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