Relating rheotaxis and hydrodynamic actuation using asymmetric gold-platinum phoretic rods

Document Type

Article

Publication Date

10-25-2019

Abstract

We explore the behavior of micron-scale autophoretic Janus (Au/Pt) rods, having various Au/Pt length ratios, swimming near a wall in an imposed background flow. We find that their ability to robustly orient and move upstream, i.e., to rheotax, depends strongly on the Au/Pt ratio, which is easily tunable in synthesis. Numerical simulations of swimming rods actuated by a surface slip show a similar rheotactic tunability when varying the location of the surface slip versus surface drag. The slip location determines whether swimmers are pushers (rear actuated), pullers (front actuated), or in between. Our simulations and modeling show that pullers rheotax most robustly due to their larger tilt angle to the wall, which makes them responsive to flow gradients. Thus, rheotactic response infers the nature of difficult to measure flow fields of an active particle, establishes its dependence on swimmer type, and shows how Janus rods can be tuned for flow responsiveness.

Identifier

85074455594 (Scopus)

Publication Title

Physical Review Letters

External Full Text Location

https://doi.org/10.1103/PhysRevLett.123.178004

e-ISSN

10797114

ISSN

00319007

PubMed ID

31702241

Issue

17

Volume

123

Grant

1420073

Fund Ref

National Sleep Foundation

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