RAMOS REYES , Antonio

No description

European Regional Development Fund PGC2018-099217-B-I00

No description

Dispositivo y procedimiento para medir la cohesión de medios granulares finos. El objeto de la presente invención es un dispositivo automatizado para la medida de la cohesión de medios granulares finos (polvos). El aparato se basa en un procedimiento que

We study experimentally the electrorotation (ROT) of semiconducting microspheres. ZnO microspheres obtained by a hydrothermal synthesis method are dispersed in KCl aqueous solutions and subjected to rotating electric fields. Two ROT peaks are found in experiments: a counterfield peak and a cofield peak at somewhat higher frequencies. These...

The stability spectrum for a jet of perfectly insulating, viscous liquid subjected to a longitudinal electric field is obtained for axisymmetric perturbations. Both dielectric forces at the interface and viscous dissipation produce lower growth factors for all the range of unstable wavelengths. If the imposed field is time varying, parametric...

Net flow of electrolyte induced by a traveling-wave electric potential applied to an array of microelectrodes is reported. Two fluid flow regimes have been observed: at small-voltage amplitudes the fluid flow follows the direction of the traveling wave, and at higher-voltage amplitudes the fluid flow is reversed. In both cases, the flow seems...

We have investigated the onset of avalanches in fine, cohesive granular materials. In our experiments shear stress is generated by tilting an initialized bed of powder and increasing the angle of tilt until the powder avalanches. We find that the angle a of the avalanche decreases with increasing bed width. The avalanche depth increases with...

Deterministic Lateral Displacement (DLD) is a microfluidic technique where arrays of micropillars within a microchannel deflect particles leading to size-based segregation. We recently demonstrated that applying AC electric fields orthogonal to the fluid flow increases the separation capabilities of these devices with a deflection angle that...

We study theoretically the dielectrophoresis and electrorotation of a semiconducting microsphere immersed in an aqueous electrolyte. To this end, the particle polarizability is calculated from first principles for arbitrary thickness of the Debye layers in liquid and semiconductor. We show that the polarizability dispersion arises from the...

We study theoretically and numerically the electrokinetic behavior of metal microparticles immersed in aqueous electrolytes. We consider small particles subjected to non-homogeneous ac electric fields and we describe their motion as arising from the combination of electrical forces (dielectrophoresis) and the electroosmotic flows on the...

We consider the scattering of metal colloids in aqueous solutions by an insulating circular post under the action of an AC electric field. We analyze the effects on the particle of several forces of electrical origin: the repulsion between the induced dipole of the particle and its image dipole in the post, the hydrodynamic interaction with the...

This paper describes the behavior of particles in a deterministic lateral displacement (DLD) separation device with DC and AC electric fields applied orthogonal to the fluid flow. As proof of principle, we demonstrate tunable microparticle and nanoparticle separation and fractionation depending on both particle size and zeta potential. DLD is a...

Slender axisymmetric dielectric liquid bridges are made stable by the action of an axial electric field. In this paper, the subsequent dynamics of a slender liquid bridge after turning off the electric field is considered. The evolution in time of the bridge profile is investigated both theoretically and experimentally. A one-dimensional model...

We experimentally study the repulsion of charged microscopic particles with the channel walls during electrophoresis in microfluidic devices. For low frequencies of the electric fields (< 10 kHz), this repulsion is mainly due to the hydrodynamic interaction caused by the flow vortices that arise from the slip velocity induced by the electric...

Net fluid flow of electrolytes driven on an array of microelectrodes subjected to a travelling-wave potential is presented. Two sizes of platinum microelectrodes have been studied. In both arrays, at low voltages the liquid flows according to the prediction given by ac electroosmotic theory. At voltages above a threshold the fluid flow is...

This paper presents an experimental and theoretical study of the dynamics of a conducting ball in a poorly conducting liquid subjected to an electric field. When the applied voltage is constant the ball bounces regularly on the lower electrode. If an AC voltage is superimposed, with a period equal to the unperturbed time between impacts, the...

No description

This paper presents a numerical study of DC-biased AC-electrokinetic (DC-biased ACEK) flow over a pair of symmetrical electrodes. The flow mechanism is based on a transverse conductivity gradient created through incipient Faradaic reactions occurring at the electrodes when a DC-bias is applied. The DC biased AC electric field acting on this...