Manipulation and control of droplets on surfaces in a homogeneous electric field

A method to manipulate and control droplets on a surface is presented. The method is based on inducing electric dipoles inside the droplets using a homogeneous external electric field. It is shown that the repulsive dipole force efficiently suppresses the coalescence of droplets moving on a liquid-infused surface (LIS). Using a combination of experiments, numerical computations and semi-analytical models, the dependence of the repulsion force on the droplet volumes, the distance between the droplets and the electric field strength is revealed. The method allows to suppress coalescence in complex multi-droplet flows and is real-time adaptive. When the electric field strength exceeds a critical value, tip streaming from the droplets sets in. Based on that, it becomes possible to withdraw minute samples from an array of droplets in a parallel process.

Effects of channel size, wall wettability, and electric field strength on ion removal from water in nanochannels

Molecular dynamics simulations are employed to estimate the effect of nanopore size, wall wettability, and the external field strength on successful ion removal from water solutions. It is demonstrated that the presence of ions, along with the additive effect of an external electric field, constitute a multivariate environment that affect fluidic interactions and facilitate, or block, ion drift to the walls. The potential energy is calculated across every channel case investigated, indicating possible ion localization, while electric field lines are presented, to reveal ion routing throughout the channel. The electric field strength is the dominant ion separation factor, while wall wettability strength, which characterizes if the walls are hydrophobic or hydrophilic has not been found to affect ion movement significantly at the scale studied here. Moreover, the diffusion coefficient values along the three dimensions are reported. Diffusion coefficients have shown a decreasing tendency as the external electric field increases, and do not seem to be affected by the degree of wall wettability at the scale investigated here.

Out-of-plane faradaic ion concentration polarization: stable focusing of charged analytes at a three-dimensional porous electrode

Ion concentration polarization (ICP) accomplishes preconcentration for bioanalysis by localized depletion of electrolyte ions, thereby generating a gradient in electric field strength that facilitates electrokinetic focusing of charged analytes by...

Investigation of the dielectric fatigue on the example of lead titanate films PbTiO3

The phenomenon of dielectric fatigue of active dielectrics, which consists in a decrease in the residual polarization depending on the number of switching cycles, is researched. A model of the dependence of the residual polarization of ferroelectric materials on the number of switching cycles is proposed. The model is based on piecewise - linear approximation of the results of measurements of the hysteresis loops of thin films PbTiO3 at a temperature T = 470 (°C), the electric field strength E = 100 (kV/cm). The developed model was used in the development of a technique for studying dielectric fatigue, depending on different modes of material switching.

Mathematical model of colostrum defrosting in super-high-frequency generator equipped

The paper is devoted to development and parameters studying of two-resonator super-high-frequency (SHF) generator based on continuous flow principle of action. It is equipped with two quasi-stationary toroidal resonators; so it allows to separate such processes of cattle colostral milk treatnent as defrosting and heating and thus to ensure both the electromagnetic safety and the high electric field strength. In order to improve efficiency of the cattle colostrum defrosting/heating performed by its exposure to the super-high frequency electromagnetic field, the methodology was developed for the SHF generator designing. It includes, firstly, development & studying of mathematical models based on due consideration of the phase transitions and, secondly, the structural designing of the SHF generator working chamber with examination of its effective operating modes. The mathematical model is proposed of the electromagnetic waves interaction with the raw material (colostral milk) being in different physical states. With aid of the electric field strength control (by the generators power changing) and the gap adjustment in the capacitor part of the resonators (by smooth movement of the common perforated base), it is possible to achieve the equipment capacity up to 170… 200 L/h. The energy expenses are 0.025 (kWh)/kg.

Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions

In this review, the research conducted by the authors on anodic oxide films on aluminum is described, paying particular attention to how the electric field strength, as a factor other than voltage, controls the nanostructures and properties of the films. It will also be indicated what factors contribute to the formation of defects, which, in contrast to the ideal or model film structure, contains a significant number of defects in the film. In addition to electrochemical measurements, the films were examined with a variety of advanced instruments, including electron microscopes, to confirm the “reality of film nanostructure” from a slightly different angle than the conventional view. The following topics on anodic films formed in four types of major anodizing electrolytes are discussed: pore initiation process, steady-state porous structure, sealing mechanism, the relationship between cell parameters and voltage/electric field strength, amount and depth of anion incorporation, electrolyte types, radial branching of pores, atypical pore structures, defect formation mechanism, self-ordering, Al coordination number, and the creation of α-alumina membranes.

DUAL SPHERICAL ELECTRIC FIELD VOLTAGE SENSOR

Мы живем в мире высоких энергетических технологий, способных передавать электрическую энергию на большие расстояния. Эту энергию невозможно сосредоточить только внутри передающих энергетических систем. Она выплескивается наружу в виде электрических полей. Эти электрические поля неблагоприятно воздействуют на окружающую среду, технические и биологические объекты. В связи с этим необходимо контролировать уровни электрических полей, важной характеристикой которых является напряженность электрического поля. Для восприятия электрического поля необходимы датчики напряженности электрического поля. Существующие датчики неудобны в эксплуатации и имеют высокую погрешность восприятия напряженности электрического поля, достигающую ± 20%. Bыдвигается идея создания универсального датчика нового вида, относящeгося к виду сдвоенных датчиков. Его универсальность заключается в том, что он воплощает в себе все виды известных датчиков - одинарные, сдвоенные и теперь еще двойные. Погрешность восприятия напряженности неоднородного электрического поля сдвоенных датчиков не превышает +5 % во всем пространственном диапазоне измерения 0£ a £1. При этом расстояние d до источника поля ограничено только радиусом сферического основания датчика, т.е. d » R , в то время как для датчиков, входящих в состав сдвоенного датчика, в том же пространственном диапазоне измерение погрешности составляет ± 35 %. Используя сдвоенный датчик, можно добиться значительного повышения точности измерения напряженности неоднородных электрических полей в широком пространственном диапазоне измерений по сравнению с известными датчиками We live in a world of high energy technologies capable of transmitting electrical energy over long distances. This energy cannot be concentrated only within the transmitting energy systems. It spills out in the form of electric fields. These electric fields adversely affect the environment, technical and biological objects. In this regard, it is necessary to control the levels of electric fields, an important characteristic of which is the strength of the electric field. Sensors of the electric field strength are required to sense the electric field. The existing sensors are inconvenient in operation and have a high error in the perception of the electric field strength, reaching ± 20%. In the work under consideration, the idea of creating a universal sensor of a new type, related to the type of dual sensors, is put forward. Its versatility lies in the fact that it embodies all types of known sensors - single, twin, and now dual. The error in the perception of the intensity of the inhomogeneous electric field of the dual sensors does not exceed + 5% in the entire spatial measurement range 0£ a £1. In this case, the distance d to the field source is limited only by the radius of the spherical base of the sensor, i.e. d » R . At the same time, for sensors that are part of a dual sensor in the same spatial measurement range, the error is ± 35%. Using a dual sensor, it is possible to achieve a significant increase in the accuracy of measuring the strength of inhomogeneous electric fields in a wide spatial measurement range in comparison with known sensors.

Electric field strength in a discharge with a liquid electrolyte cathode in air at atmospheric pressure

The electric field strength in the channel of a discharge with a liquid electrolyte cathode at atmospheric pressure in air with the current in range of 20–90 mA is measured. The dependences of the electric field strength on the value of the discharge current are found for aqueous solutions with different compositions and with different pH values, but with the same specific conductivity of 300 μS/cm. It is shown that these dependences don’t differ by much from eachother. The dependence of the electric field strength in a discharge with a liquid cathode on the discharge current, averaged over the composition of the solution, is obtained.