6
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Gravitaxis in Spherical Janus Swimming Devices

      research-article
      ,
      Langmuir
      American Chemical Society

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          In this work, we show that the asymmetrical distribution of mass at the surface of catalytic Janus swimmers results in the devices preferentially propelling themselves upward in a gravitational field. We demonstrate the existence of this gravitaxis phenomenon by observing the trajectories of fueled Janus swimmers, which generate thrust along a vector pointing away from their metallically coated half. We report that as the size of the spherical swimmer increases, the propulsive trajectories are no longer isotropic with respect to gravity, and they start to show a pronounced tendency to move in an upward direction. We suggest that this effect is due to the platinum caps asymmetric mass exerting an increasing influence on the azimuthal angle of the Janus sphere with size, biasing its orientation toward a configuration where the heavier propulsion generating surface faces down. This argument is supported by the good agreement we find between the experimentally observed azimuthal angle distribution for the Janus swimmers and predictions made by simple Boltzmann statistics. This gravitaxis phenomenon provides a mechanism to autonomously control and direct the motion of catalytic swimming devices and so enable a route to make autonomous transport devices and develop new separation, sensing, and controlled release applications.

          Related collections

          Most cited references13

          • Record: found
          • Abstract: found
          • Article: not found

          Catalytic Janus motors on microfluidic chip: deterministic motion for targeted cargo delivery.

          We fabricated self-powered colloidal Janus motors combining catalytic and magnetic cap structures, and demonstrated their performance for manipulation (uploading, transportation, delivery) and sorting of microobjects on microfluidic chips. The specific magnetic properties of the Janus motors are provided by ultrathin multilayer films that are designed to align the magnetic moment along the main symmetry axis of the cap. This unique property allows a deterministic motion of the Janus particles at a large scale when guided in an external magnetic field. The observed directional control of the motion combined with extensive functionality of the colloidal Janus motors conceptually opens a straightforward route for targeted delivery of species, which are relevant in the field of chemistry, biology, and medicine.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Rolled-up magnetic microdrillers: towards remotely controlled minimally invasive surgery.

            Self-folded magnetic microtools with sharp ends are directed at enabling drilling and related incision operations of tissues, ex vivo, in a fluid with a viscosity similar to that of blood. These microtools change their rotation from a horizontal to a vertical one when they are immersed into a rotational magnetic field. Novel self-assembly paradigms with magnetic materials can enable the creation of remotely controlled and mass-produced tools for potential applications in minimally invasive surgery.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Magnetically actuated propulsion at low Reynolds numbers: towards nanoscale control.

              Significant progress has been made in the fabrication of micron and sub-micron structures whose motion can be controlled in liquids under ambient conditions. The aim of many of these engineering endeavors is to be able to build and propel an artificial micro-structure that rivals the versatility of biological swimmers of similar size, e.g. motile bacterial cells. Applications for such artificial "micro-bots" are envisioned to range from microrheology to targeted drug delivery and microsurgery, and require full motion-control under ambient conditions. In this Mini-Review we discuss the construction, actuation, and operation of several devices that have recently been reported, especially systems that can be controlled by and propelled with homogenous magnetic fields. We describe the fabrication and associated experimental challenges and discuss potential applications.
                Bookmark

                Author and article information

                Journal
                Langmuir
                Langmuir
                la
                langd5
                Langmuir
                American Chemical Society
                0743-7463
                1520-5827
                17 October 2013
                19 November 2013
                : 29
                : 46
                : 14066-14073
                Affiliations
                [1]Department of Chemical and Biological Engineering, The University of Sheffield , Mappin Street, Sheffield S1 3JD, U.K..
                Author notes
                Article
                10.1021/la403450j
                3901380
                24134682
                5a66254d-7fb8-4b24-a48a-507d8e381879
                Copyright © 2013 American Chemical Society
                History
                : 10 September 2013
                : 16 October 2013
                Categories
                Article
                Custom metadata
                la403450j
                la-2013-03450j

                Physical chemistry
                Physical chemistry

                Comments

                Comment on this article