The movement and behaviour of particles suspended in aqueous solutions subjected to non-uniform ac electric fields is examined. induce polarizable particles, a phenomenon known as dielectrophoresis. high strength that are often used separation systems can give rise fluid motion, which turn results viscous drag on the particle. field generates heat, leading volume forces liquid. Gradients conductivity permittivity electrothermal gradients mass density buoyancy. In addition, produce induced...

Under the influence of an ac electric field, electrolytes on planar microelectrodes exhibit fluid flow. The nonuniform field generated by electrodes interacts with suspending through a number mechanisms, giving rise to body forces and This paper presents detailed experimental measurements velocity flow at frequencies below charge relaxation frequency electrolyte. latex tracer particles was measured as function applied signal potential, electrolyte conductivity, position electrode surface....

The application of a nonuniform ac electric field to an electrolyte using coplanar microelectrodes results in steady fluid flow. flow has its origin the interaction tangential component with induced charge electrical double layer on electrode surfaces. Termed electro-osmosis, been studied experimentally and theoretically linear analysis. This paper presents experimental observations profile obtained by superimposing images particle movement plane normal surface. These streamlines demonstrate...

Frequency-dependent fluid flow in electrolytes on microelectrodes subjected to ac voltages has recently been reported. The is predominant at frequencies of the order relaxation frequency electrode-electrolyte system. mechanism responsible for this motion termed electro-osmosis: a continuous driven by interaction oscillating electric field and charge diffuse double layer electrodes. This paper develops basis theoretical approach problem using linear analysis. results are compared with...

The net flow of electrolyte induced by an ac electric potential applied to array asymmetric pairs microelectrodes has recently been reported. interaction between the oscillating field and charge at diffuse double layer on electrodes results in a steady electro-osmotic velocity distribution top electrodes. This slip is anisotropic produces fluid. paper presents theoretical analysis pumping phenomena based upon model fields. electrical equations are solved numerically using simulation method....

Particles suspended in fluid exhibit motion when subjected to ac electric fields. The applied field results forces on both the particles and fluid, study of which is referred as electrokinetics. electrokinetic techniques can be used for controlled manipulation characterization particles, separation mixtures. For sub-micrometre Brownian important strong fields are required overcome these effects. Planar micro-electrode arrays, fabricated using semiconductor manufacturing processes, generate...

In alternating current electrokinetics, electric fields are used to generate forces on particles. Techniques have been applied for the manipulation of particles and measurement their dielectric properties. The typically generated by microelectrode structures fabricated planar surfaces. One particular design, using interdigitated bar electrodes, is both in dielectrophoretic field flow fractionation travelling wave dielectrophoresis. This paper presents a Fourier series analysis force particle...

Net flow of electrolyte induced by a traveling-wave electric potential applied to an array microelectrodes is reported. Two fluid regimes have been observed: at small-voltage amplitudes the follows direction traveling wave, and higher-voltage reversed. In both cases, seems be driven level electrodes. The experiments analyzed with linear electroosmotic model based upon Debye–Huckel theory double layer. electrical problem for experimental interdigitated electrode solved numerically using...

Electrothermal motion in an aqueous solution arises from the action of electric field on inhomogeneities liquid induced by temperature gradients. The can be produced applied through Joule heating, or caused external sources, such as strong illumination. flows microsystems are usually observed at signal frequencies around 1 MHz and voltages 10 V. In this work, we present self-similar solutions for a constant gradient placed top of: (a) two coplanar electrodes subjected to a.c. potential...

We present dielectrophoresis (DEP) and electrorotation (ROT) measurements of gold-coated polystyrene microspheres as a function frequency for several electrolyte conductivities. Particle rotation was counterfield with maximum rate observed at single characteristic frequency. Negative DEP frequencies lower than this positive signal higher this. These experimental observations are in agreement predictions the force torque on induced dipole perfectly polarizable metal sphere. theoretical model...

We describe a novel particle separation technique that combines deterministic lateral displacement (DLD) with orthogonal electrokinetic forces to separate particles below the critical diameter.

Granular materials exhibit several regimes of behavior: plastic, inertial, fluidized, and entrained flow, but not all can pass through these states. Our concern is with the criteria that determine transition from one regime to another boundaries various flow define. Experimentally we have focused on fine, cohesive powders, where interparticle force dominates over gravitational air cause moving powder become fluidized.

The electrokinetic manipulation of particles suspended in a fluid medium is accomplished using microelectrodes that generate non-uniform fields significant strength from low applied potentials. high produce not only forces on the but also used for suspension. This paper presents qualitative and semi-quantitative observations movement at field frequencies order 1MHz higher. importance illumination generating flow described, depending both intensity electric field. theory electrothermally...

Mixing within sessile drops can be enhanced by generating internal flow patterns using ac electrowetting. While for low frequencies, the have been attributed to oscillations of drop surface, we provide here driving mechanism hitherto unexplained high-frequency flows. We show that: (1) electric field in liquid bulk becomes important, leading energy dissipation due Joule heating and a temperature increase several degrees Celsius, (2) fluid at these frequencies is generated electrothermal...

Net fluid flow induced by AC potentials applied to arrays of co-planar interdigitated microelectrodes is reported. Two types microelectrode structures have been employed: unequal width electrodes subjected a single signal, and identical traveling-wave potential. A square glass chamber was constructed around the electrode filled with concentration KCl in water conductivity 1 mS/m. map velocity as function voltage (0-8 Vpp) frequency (0.1-100 kHz) presented for array. In both microstructures,...