title: Directed Motion of Metallodielectric Particles by Contact Charge Electrophoresis.
abstract: We investigate the dynamics of metallodielectric Janus particles moving via contact charge electrophoresis (CCEP) between two parallel electrodes. CCEP uses a constant voltage to repeatedly charge and actuate conductive particles within a dielectric fluid, resulting in rapid oscillatory motion between the electrodes. In addition to particle oscillations, we find that micrometer-scale Janus particles move perpendicular to the field at high speeds (up to 600 μm/s) and over large distances. We characterize particle motions and propose a mechanism based on the rotation-induced translation of the particle following charge transfer at the electrode surface. The propulsion mechanism is supported both by experiments with fluorescent particles that reveal their rotational motions and by simulations of CCEP dynamics that capture the relevant electrostatics and hydrodynamics. We also show that interactions among multiple particles can lead to repulsion, attraction, and/or cooperative motions depending on the position and phase of the respective particle oscillators. Our results demonstrate how particle asymmetries can be used to direct the motions of active colloids powered by CCEP.
authors.affiliation: Department of Chemical Engineering, Columbia University , New York, New York 10027, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Dou
authors.affiliation: Department of Chemical Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Cartier
authors.affiliation: Department of Chemical Engineering, Columbia University , New York, New York 10027, United States.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Fei
authors.affiliation: Department of Chemical Engineering, Columbia University , New York, New York 10027, United States.
authors.forename: Shashank
authors.initials: S
authors.lastname: Pandey
authors.affiliation: Department of Chemical Engineering, City College of the City University of New York , New York, New York 10031, United States.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Razavi
authors.affiliation: Department of Chemical Engineering, City College of the City University of New York , New York, New York 10031, United States.
authors.forename: Ilona
authors.initials: I
authors.lastname: Kretzschmar
authors.affiliation: Department of Chemical Engineering, Columbia University , New York, New York 10027, United States.
authors.forename: Kyle J M
authors.initials: KJ
authors.lastname: Bishop