title: Engineering particle trajectories in microfluidic flows using particle shape.
abstract: Recent advances in microfluidic technologies have created a demand for techniques to control the motion of flowing microparticles. Here we consider how the shape and geometric confinement of a rigid microparticle can be tailored for 'self-steering' under external flow. We find that an asymmetric particle, weakly confined in one direction and strongly confined in another, will align with the flow and focus to the channel centreline. Experimentally and theoretically, we isolate three viscous hydrodynamic mechanisms that contribute to particle dynamics. Through their combined effects, a particle is stably attracted to the channel centreline, effectively behaving as a damped oscillator. We demonstrate the use of self-steering particles for microfluidic device applications, eliminating the need for external forces or sheath flows.
authors.affiliation: 1] Department of Physics, Massachusetts Institute of Technology, Room 4-304, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA [2].
authors.forename: William E
authors.initials: WE
authors.lastname: Uspal
authors.forename: H
authors.initials: H
authors.lastname: Burak Eral
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Doyle
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry; D057446:Hydrodynamics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000706:statistics & numerical data*; D008856:Microscopy, Fluorescence; D015233:Models, Statistical; D009038:Motion; D010316:Particle Size; D012235:Rhodamines / Q000737:chemistry
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines