title: Single nanoparticle collisions at microfluidic microband electrodes: the effect of electrode material and mass transfer.
abstract: We report on the effect of convection on electrochemically active collisions between individual Pt nanoparticles (PtNPs) and Hg and Au electrodes. Compared to standard electrochemical cells utilizing Hg and Au ultramicroelectrodes (UMEs) used in previous studies of electrocatalytic amplification, microelectrochemical devices offer two major advantages. First, the PtNP limit of detection (0.084 pM) is ∼8 times lower than the lowest concentration measured using UMEs. Second, convection enhances the mass transfer of PtNPs to the electrode surface, which enhances the collision frequency from ∼0.02 pM(-1) s(-1) on UMEs to ∼0.07 pM(-1) s(-1) in microelectrochemical devices. We also show that the size of PtNPs can be measured in flowing systems using data from collision experiments and then validate this finding using multiphysics simulations.
authors.affiliation: Department of Chemistry and Center for Nano- and Molecular Science and Technology, The University of Texas at Austin , 105 East 24th Street, Stop A5300, Austin, Texas 78712-0165, United States.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Alligrant
authors.forename: Morgan J
authors.initials: MJ
authors.lastname: Anderson
authors.forename: Radhika
authors.initials: R
authors.lastname: Dasari
authors.forename: Keith J
authors.initials: KJ
authors.lastname: Stevenson
authors.forename: Richard M
authors.initials: RM
authors.lastname: Crooks