Electric fields are commonly used for manipulating particles and liquids in microfluidic systems. In this work, we report stationary electro-osmotic flow vortices around dielectric micropillars induced by ac electric electrolytes. The characteristics theoretically predicted based on the well-known phenomena of surface conductance concentration polarization a charged object. flows arise from two distinct contributions working together: an oscillating nonuniform zeta potential pillar rectified...

Electrophoresis describes the motion of charged particles suspended in electrolytes when subjected to an external electric field. Previous experiments have shown that undergoing electrophoresis are repelled from nearby channel walls, contrary standard description predicts no hydrodynamic repulsion. Dielectrophoretic (DEP) repulsive forces been commonly invoked as cause this wall We show DEP can only account for repulsion at high frequencies applied In presence a low-frequency field,...

We demonstrate vesicle and nanoparticle fractionation in an optimised DLD array with micron-sized structures. When combined orthogonal AC electric field, these devices enable high-throughput high-conductivity electrolytes.

Abstract

Concentration-polarization electroosmosis (CPEO) refers to steady-state electroosmotic flows around charged dielectric micro-particles induced by low-frequency AC electric fields. Recently, these were shown cause repulsion of colloidal particles from the wall a microfluidic channel when an field is applied along length channel. In this work, we exploit mechanism demonstrate fractionation micron-sized polystyrene and bacteria in flow-focusing device. The results are agreement with predictions...

We experimentally study the repulsion of charged microscopic particles with channel walls during electrophoresis in microfluidic devices. For low frequencies electric fields (<10 kHz), this is mainly due to hydrodynamic interaction caused by flow vortices that arise from slip velocity induced field on particle surface, as shown a recent publication [Fernandez-Mateo et al., Phys. Rev. Lett. 128, 074501 (2022)]. The maximum surface inferred measurements wall-particle separation....

Deterministic Lateral Displacement (DLD) exploits periodic arrays of pillars inside microfluidic channels for high-precision sorting micro- and nano-particles. Previously we demonstrated how DLD separation can be significantly improved by the addition AC electrokinetic forces, increasing tunability technique expanding range applications. At high frequencies electric field (>1 kHz) behaviour such systems is dominated Dielectrophoresis (DEP), whereas at low particle much richer more complex....

We compute the electric force between a dielectric sphere and plane in presence of an external field. Laplace's equation is solved bispherical coordinates Maxwell's stress tensor used to calculate force. The result given as series expansion that evaluated numerically. Asymptotic expressions for case large small distances are obtained compared with well-known analytical solutions. use COMSOL commercial software validate semi-analytical results.

Electric fields are commonly used to trap and separate micro- nanoparticles near channel constrictions in microfluidic devices. The trapping mechanism is attributed the electrical forces arising from nonhomogeneous electric field caused by constrictions, phenomenon known as insulator-based-dielectrophoresis (iDEP). In this paper, we describe stationary electroosmotic flows of electrolytes around insulating induced low frequency AC (below 10 kHz). Experimental characterization described for...

Vertically oscillating fluid surfaces have been a subject extensively studied in the past, as well surface instabilities produced by electrohydrodynamic waves similar configurations. In present work, unification of both effects and their consequences on stability surface. Given versatility electromagnetic fields, application to phenomenon walking droplets is suggested; dispersion relation bouncing regimes force are revisited, feasible experimental configurations proposed.

Abstract We describe a user-friendly, open source software for single-particle detection/counting in continuous-flow. The tool automatically processes video images of particles, including pre-conditioning, followed by size-based discrimination independent detection fluorescent and non-fluorescent particles different sizes. This is done interactive tuning reduced set parameters that can be checked with robust, real-time quality control the original files. provides concentration distribution...

We describe an improved method for determining the electroosmotic mobility and zeta potential of surfaces based on a current-monitoring method. This technique eliminates requirement measurements channel dimensions sample conductivities, leading to simple high precision measurement. The PDMS is measured native treated with nonionic surfactant in low-conductivity electrolytes.

The dispersion relation of vertically oscillating fluid surfaces has been a subject extensively studied in the past, as well surface instabilities produced by electrohydrodynamic (EHD) waves similar configurations. In present work it is unification both effects and its consequences to instability surface. Given versatility electromagnetic fields, possible application phenomenon walking droplets suggested.

Deterministic Lateral Displacement (DLD) exploits periodic arrays of pillars inside microfluidic channels for high-precision sorting micro- and nano-particles. Previously we demonstrated how DLD separation can be significantly improved by the addition AC electrokinetic forces, increasing tunability technique expanding range applications. At high frequencies electric field (f > 1 kHz) behaviour such systems is dominated Dielectrophoresis (DEP), whereas at low particle much richer more...

Traveling-wave electrophoresis (TWE) is a method for transporting charged colloidal particles used in many microfluidic techniques particle manipulation and fractionation. This exploits the traveling-wave components of electric field generated by an array electrodes subjected to ac voltages with phase delay between neighboring electrodes. In this article, we propose alternative way generating fields microchannels. We apply rotating around cylindrical insulating micropillar resulting modes...

We compute the electric force between a sphere and plane as function of their separation distance under influence an external field. Laplace's equation is solved in bispherical coordinates by variables method. The then obtained integrating Maxwell's stress tensor on plane. result given series expansion that computed numerically. focus asymptotic limit for small distances dielectric constant. It shown diverges tends to zero, but functional form this divergency relies heavily value