The Efficiency of Self-Phoretic Propulsion Mechanisms with Surface Reaction Heterogeneity

Abstract

We consider the efficiency of self-phoretic colloidal particles (swimmers) as a function of the heterogeneity in the surface reaction rate. The set of fluid, species, and electrostatic continuity equations is solved analytically using a linearization and numerically using a finite-element method. To compare spherical swimmers of different size and with heterogeneous catalytic conversion rates, a 'swimmer efficiency' functional $\eta$ is introduced. It is proven, that in order to obtain maximum swimmer efficiency the reactivity has to be localized at the pole(s). Our results also shed light on the sensitivity of the propulsion speed to details of the surface reactivity, a property that is notoriously hard to measure. This insight can be utilized in the design of new self-phoretic swimmers.

arXiv comment10 pages, 4 figures

References in corpus (16)

• Self-motile colloidal particles: from directed propulsion to random walk
• The Mechanics and Statistics of Active Matter
• Motility-Induced Phase Separation
• Dynamical clustering and phase separation in suspensions of self-propelled colloidal particles
• Designing phoretic micro- and nano-swimmers
• Diffusive transport without detailed balance in motile bacteria: Does microbiology need statistical physics?
• Electrokinetic Effects in Catalytic Pt-Insulator Janus Swimmers
• Phoretic Motion of Spheroidal Particles Due To Self-Generated Solute Gradients
• Locomotion of Electrocatalytic Nanomotors due to Reaction Induced Charge Auto-Electrophoresis
• Dynamics and efficiency of a self-propelled, diffusiophoretic swimmer
• Autophoretic locomotion from geometric asymmetry
• Fluid mixing by curved trajectories of microswimmers
• Nonlinear, electrocatalytic swimming in the presence of salt
• Efficiency of surface-driven motion: nano-swimmers beat micro-swimmers
• Swimmer-tracer scattering at low Reynolds number
• Efficacy of self-phoretic colloids and microswimmers

Cited by in corpus (8)

• Experimental Observation of Flow Fields Around Active Janus Spheres
• Which Interactions Dominate in Active Colloids?
• Microfluidic Pumping by Micromolar Salt Concentrations
• Moving Charged Particles in Lattice Boltzmann-Based Electrokinetics
• Limiting Spurious Flow in Simulations of Electrokinetic Phenomena
• Auto-electrophoresis in non-Newtonian media: interaction of rheology and electrocatalytic parameters
• A Predictive Model for Convective Flows Induced by Surface Reactivity Contrast
• Janus microswimmers are poor hydrodynamic mixers