Non-spherical osmotic motor: chemical sailing

Abstract The behaviour of a non-spherical osmotic motor – an axisymmetric catalytic particle self-propelling in a dilute dispersion of reactant particles – is considered. In contrast to a conventional osmotic motor that creates differences in concentration, and hence in osmotic pressure, due to asymmetry in reaction rate along its surface (e.g. a Janus particle with reactive and non-reactive patches), a non-spherical particle is able to move even with uniform chemical activity on its surface. For small departures from a sphere the velocity of self-propulsion is proportional to the square of the non-sphericity or distortion of the particle shape. It is shown that the inclusion of hydrodynamic interactions (HI) may drastically change the self-propulsion. Except for very slow chemical reactions, even the direction of self-propulsion changes with and without HI. Numerical calculations at finite non-sphericity suggest that the maximum velocity of self-propulsion is obtained by a sail-like motor shape, leading to the name ‘chemical sailing’. Moreover, no saturation in the speed of propulsion is found; the motor velocity increases as the area of this ‘sail’ grows and its thickness decreases. The self-propulsion of a non-spherical particle releasing products of a chemical reaction – a constant flux motor – is also considered.

[1]  Wentao Duan,et al.  Depolymerization-powered autonomous motors using biocompatible fuel. , 2013, Journal of the American Chemical Society.

[2]  J. Brady,et al.  Osmotic propulsion of colloidal particles via constant surface flux , 2013 .

[3]  J. Koplik,et al.  Diffusiophoretic self-propulsion of colloids driven by a surface reaction: The sub-micron particle regime for exponential and van der Waals interactions , 2013 .

[4]  N. Hoh Effects of Particle Size Ratio on Single Particle Motion in Colloidal Dispersions , 2013 .

[5]  Ayusman Sen,et al.  Fantastic voyage: designing self-powered nanorobots. , 2012, Angewandte Chemie.

[6]  Eric Lauga,et al.  Viscous Marangoni propulsion , 2011, Journal of Fluid Mechanics.

[7]  S. Dietrich,et al.  Pulling and pushing a cargo with a catalytically active carrier , 2011, 1106.0066.

[8]  J. Brady Particle motion driven by solute gradients with application to autonomous motion: continuum and colloidal perspectives , 2010, Journal of Fluid Mechanics.

[9]  R. Kapral,et al.  Self-propelled nanodimer bound state pairs. , 2010, The Journal of chemical physics.

[10]  Hsien-Hung Wei,et al.  Self-propulsion and dispersion of reactive colloids due to entropic anisotropy , 2010, Journal of Fluid Mechanics.

[11]  Aditya S. Khair,et al.  On the hydrodynamics of ‘slip–stick’ spheres , 2008, Journal of Fluid Mechanics.

[12]  J. Brady,et al.  Osmotic propulsion: the osmotic motor. , 2008, Physical review letters.

[13]  Ramin Golestanian,et al.  Self-motile colloidal particles: from directed propulsion to random walk. , 2007, Physical review letters.

[14]  Raymond Kapral,et al.  Chemically powered nanodimers. , 2007, Physical review letters.

[15]  R. Golestanian,et al.  Designing phoretic micro- and nano-swimmers , 2007, cond-mat/0701168.

[16]  Walter F Paxton,et al.  Chemical locomotion. , 2006, Angewandte Chemie.

[17]  R. Golestanian,et al.  Propulsion of a molecular machine by asymmetric distribution of reaction products. , 2005, Physical review letters.

[18]  G. Whitesides,et al.  Autonomous Movement and Self‐Assembly , 2002 .

[19]  John T. Katsikadelis,et al.  Boundary Elements: Theory and Applications , 2002 .

[20]  John L. Anderson,et al.  Colloid Transport by Interfacial Forces , 1989 .

[21]  John L. Ande,et al.  COLLOID TRANSPORT BY INTERFACIAL FORCES , 1989 .

[22]  D. A. Saville,et al.  Colloidal Dispersions: ACKNOWLEDGEMENTS , 1989 .

[23]  D. Owen Handbook of Mathematical Functions with Formulas , 1965 .

[24]  J. Happel,et al.  Low Reynolds number hydrodynamics , 1965 .

[25]  David M. Miller,et al.  Handbook of Mathematical Functions With Formulas, Graphs and Mathematical Tables (National Bureau of Standards Applied Mathematics Series No. 55) , 1965 .

[26]  L. Payne,et al.  The Stokes flow problem for a class of axially symmetric bodies , 1960, Journal of Fluid Mechanics.

[27]  R. A. Sampson,et al.  On Stokes's Current Function , 1891 .