title: Influence of electrostatic forces on particle propulsion in the evanescent field of silver ion-exchanged waveguides.
abstract: The effect of electrostatic interaction between carboxylate- and amino-functionalized polystyrene particles and a charged waveguide surface on the propulsion speed in optical tweezers is considered to be a function of the pH and ionic strength. It was shown that with the variation of the pH of the aqueous solution in which the particles were immersed, a systematic change in propulsion speed with a maximum speed could be achieved. The appearance of a maximum speed was ascribed to changes in the particle-waveguide separation as a result of the combination of two forces: Coulomb repulsion/attraction and induced dipole forces. The highest maximum speed at low ionic strength was around 12 μm/s. Changes in the ionic strength of the solution influenced the gradient of the dielectric constant near the involved surfaces and also led to a slightly reduced hydrodynamic radius of the particles. The combination of these effects subsequently increased the maximum speed to about 23 μm/s.
authors: Department of Physics and Astronomy, The University of Western Ontario (Western University), London, Ontario N6A 3K7, Canada.
authors: Dmytro
authors: D
authors: Gebennikov
authors: Silvia
authors: S
authors: Mittler
mesh_terms: D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D010316:Particle Size; D012834:Silver / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D007477:Ions; D012834:Silver