title: Boundaries can steer active Janus spheres.
abstract: The advent of autonomous self-propulsion has instigated research towards making colloidal machines that can deliver mechanical work in the form of transport, and other functions such as sensing and cleaning. While much progress has been made in the last 10 years on various mechanisms to generate self-propulsion, the ability to steer self-propelled colloidal devices has so far been much more limited. A critical barrier in increasing the impact of such motors is in directing their motion against the Brownian rotation, which randomizes particle orientations. In this context, here we report directed motion of a specific class of catalytic motors when moving in close proximity to solid surfaces. This is achieved through active quenching of their Brownian rotation by constraining it in a rotational well, caused not by equilibrium, but by hydrodynamic effects. We demonstrate how combining these geometric constraints can be utilized to steer these active colloids along arbitrary trajectories.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Sambeeta
authors.initials: S
authors.lastname: Das
authors.affiliation: Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Astha
authors.initials: A
authors.lastname: Garg
authors.affiliation: Department of Chemical &Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK.
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Campbell
authors.affiliation: Department of Chemical &Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Howse
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Ayusman
authors.initials: A
authors.lastname: Sen
authors.affiliation: Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Darrell
authors.initials: D
authors.lastname: Velegol
authors.affiliation: Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, UK.
authors.forename: Ramin
authors.initials: R
authors.lastname: Golestanian
authors.affiliation: Department of Chemical &Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ebbens