title: Size-dependent control of colloid transport via solute gradients in dead-end channels.
abstract: Transport of colloids in dead-end channels is involved in widespread applications including drug delivery and underground oil and gas recovery. In such geometries, Brownian motion may be considered as the sole mechanism that enables transport of colloidal particles into or out of the channels, but it is, unfortunately, an extremely inefficient transport mechanism for microscale particles. Here, we explore the possibility of diffusiophoresis as a means to control the colloid transport in dead-end channels by introducing a solute gradient. We demonstrate that the transport of colloidal particles into the dead-end channels can be either enhanced or completely prevented via diffusiophoresis. In addition, we show that size-dependent diffusiophoretic transport of particles can be achieved by considering a finite Debye layer thickness effect, which is commonly ignored. A combination of diffusiophoresis and Brownian motion leads to a strong size-dependent focusing effect such that the larger particles tend to concentrate more and reside deeper in the channel. Our findings have implications for all manners of controlled release processes, especially for site-specific delivery systems where localized targeting of particles with minimal dispersion to the nontarget area is essential.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544; sangwoos@princeton.edu.
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Shin
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544;
authors.forename: Eujin
authors.initials: E
authors.lastname: Um
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544;
authors.forename: Benedikt
authors.initials: B
authors.lastname: Sabass
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544;
authors.forename: Jesse T
authors.initials: JT
authors.lastname: Ault
authors.affiliation: Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544;
authors.forename: Mohammad
authors.initials: M
authors.lastname: Rahimi
authors.affiliation: Unilever R&D Port Sunlight, Bebington, Wirral CH63 3JW, United Kingdom.
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Warren
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544;
authors.forename: Howard A
authors.initials: HA
authors.lastname: Stone
keywords: colloid; dead-end channel; diffusiophoresis; size effect; solute gradient