Electrophoresis of a weakly charged dielectric fluid droplet in a cylindrical pore.
Journal
Electrophoresis
ISSN
1522-2683
Date Issued
2024-04-13
Author(s)
Lu, Shirley
Tseng, Jessica
Chuang, Lily
Chang, Nemo
Chen, Sunny
Hsu, Celia
Chien, Jean
Lin, Carol
DOI
10.1002/elps.202300276
Abstract
Electrophoresis of a weakly charged dielectric droplet with constant surface charge density in a chargeless cylindrical pore is investigated theoretically in this study, focusing on the boundary confinement effect of the double layer, which in turn determines the ultimate motion of the droplet. A patched pseudo-spectral method based on the Chebyshev polynomial is adopted to solve the resulting governing fundamental electrokinetic equations. Mobility reversal, among other interesting phenomena, is observed when the droplet is in a narrow cylindrical pore. No such observation was made in the corresponding motion of a rigid particle. The droplet with a thick double layer may even move against the prediction based on the Coulomb electrostatic law, for instance, a positively charged droplet may move against the electric field. The significant enhancement of the motion-deterring double layer polarization due to the severe steric boundary confinement within a narrow cylindrical pore is found to be responsible for this seemingly peculiar phenomenon. Moreover, smaller droplets may move in the opposite direction of the larger ones. The results are useful in capillary electrophoresis involving droplets in particular and migration of droplets through narrow channels in general.
Subjects
boundary confinement effect
cylindrical pore
dielectric droplet
electrophoresis
mobility reversal
Type
journal article