It is shown that in an electrokinetic acoustoelectric transducer, when a constant DC electric field (pump voltage) is applied during reception of an acoustic signal, it becomes possible to retransmit the initial external acoustic field. This is due to the presence of simultaneously reverse electrokinetic phenomena in the transducer: electroosmosis and flow potential. The necessary theoretical substantiation of this phenomenon is presented. The data of a full-scale experiment confirming the theory are presented. Keywords: acoustoelectric conversion, electrokinetic phenomena, current potential, energy pumping, electrokinetic repeater.

A mathematical model of an acoustoelectric transducer based on the use of the electrokinetic phenomenon of the flow potential is proposed. It is shown theoretically that the flow potential increases in proportion to the strength of the constant electric pumping field, which is confirmed experimentally. The described converter has variable sensitivity. Rather large values of the sensitivity of an electrokinetic microphone have been obtained experimentally. The results of the work can be used in the design of acoustoelectric transducers. Keywords: Acoustoelectric conversion, Electrokinetic phenomena, Current potential, Flow potential hydrodynamics, Energy pumping. Electrokinetic microphone sensitivity.

The features of the flow potential in the electrolyte that are significant for implementing a liquid acousto-electric converter are presented. The electrochemistry of the flow potential in electrolytes is considered. The peculiarities of the process in the electrolyte solutions associated with the influence of the ion strength of the electrolyte and its dependence on the electrokinetic radius are noted. It is shown that at small values of the electrokinetic radius, the effect of overlapping the electric double layer occurs, leading to a sharp decrease in the absolute values of the flow potential and, consequently, to the practical impossibility of implementing the acoustoelectric transformation. The results obtained can find wide practical application.

A mathematical model of operation of an acoustoelectric converter, based on the electrokinetic phenomenon of flow potential, is proposed. It is shown theoretically that the flow potential increases in proportion to the strength of the pumping dc electric field. This is also confirmed experimentally. It is shown that the described converter exhibits variable sensitivity. The presence of saturation in this process, caused by the physics of the process (its nonlinearity and occurrence of turbulent liquid motion in the converter body), is revealed experimentally. The acoustoelectric-converter theory, based on the electrokinetic phenomenon of flow potential, is identical to the electroacoustic transformation theory, based on the electrokinetic phenomenon of electro-osmosis, which is inverse to the flow potential. The measured converter sensitivity exceeds those of analogs. The results can be used in theory and in practice in designing reversible electroacoustic and acoustoelectric converters.

Показано, что в электрокинетическом акустоэлектрическом преобразователе при приложении постоянного электрического поля (напряжения накачки) в процессе приема акустического сигнала возникает возможность ретрансляции исходного внешнего акустического поля. Это происходит вследствие наличия в преобразователе одновременно обратных электрокинетических явлений: электроосмоса и потенциала течения. Приведены необходимые теоретические обоснования этого явления. Представлены данные натурного эксперимента, подтверждающие теорию. Ключевые слова: акустоэлектрическое преобразование, электрокинетические явления, потенциал течения, накачка энергии, электрокинетический ретранслятор.

In the approximation of a thin double layer, simple dependences of the acoustic fields excited in an electrokinetic electroacoustic transducer on the velocity of the Helmholtz—Smolukhovsky osmotic movement are obtained. From the dependencies it follows that in the absence of losses, when the nonlinearity of the fluid motion equation does not yet affect and there is no turbulent mode of fluid motion in the transducer body, the magnitudes of the amplitudes of the acoustic velocity and pressure linearly depend on the magnitude of the Helmholtz—Smolukhovsky electroosmotic motion velocity.

A new type of microphone is proposed, one of the distinguishing features of which is a variable sensitivity, which depends on the magnitude of the constant electric pumping voltage. In addition, a matching device (mediator) has been created that allows to significantly increase the sensitivity of the microphone. In the course of experiments, a significant increase in sensitivity was confirmed, both due to a charge pump and the use of a mediator. In the course of the experiments, the microphone sensitivity was obtained equal to 1990.5 mV / Pa at 1000 V pumping.

Basing on the analysis of the physical features of the operation of the microphone on electrokinetic phenomena, it has been experimentally confirmed that this microphone works on a functional principle different from the principle of operation of a condenser microphone. It is shown that a microphone based on electrokinetic phenomena can increase its sensitivity by up to about 40 dB due to pumping. Comparison of two experimental studies shows that the sensitivity of an electrokinetic microphone can strongly depend on the size of the porosity of the dielectric placed between the electrodes of the microphone.

A mathematical model of an acoustoelectric transducer based on the use of the electrokinetic phenomenon of the flow potential is proposed. It is shown theoretically that the flow potential increases in proportion to the strength of the constant electric pumping field, which is confirmed experimentally. The described converter has variable sensitivity. Rather large values of the sensitivity of an electrokinetic microphone have been obtained experimentally. The results of the work can be used in the design of acoustoelectric transducers.

The hydrodynamics of electrophoresis under the simultaneous impact of constant and alternating electric fields is considered. It has been shown that when the constant and alternating external fields are combined, the energy of the constant electric field is transferred into the alternating hydrodynamic field. An example is given of a dispersed medium in which a giant dispersion of the dielectric constant can arise, which in turn can contribute to an increase in the total electrophoresis rate. Analogies of the behavior of the considered dispersed medium with the action of an electroacoustic transducer based on the use of electrokinetic phenomena are given.

О МЕХАНИЗМЕ ФОРМИРОВАНИЯ КАПЕЛЬ В Х-ОБРАЗНОМ МИКРОФЛЮИДНОМ УСТРОЙСТВЕВ работе описаны результаты экспериментального исследования генерирования микроэмульсий в микрофлюидном устройстве собственного производства, оснащенном X-образным смесителем.Представленные карты режимов показали значительное влияние концентрации поверхностно-активных веществ на режим течения в канале и на размер формируемых капель.Получено универсальное уравнение для расчета критических капиллярных чисел, определяющих переход между режимами течения

The paper considers equations describing the motion of a fluid in a porous medium under the action of an electric field in conditions of the formed turbulent mode of motion. Equations are given that describe the acoustic oscillations that occur in a fluid, the source of which can be not only an alternating, but also a constant electric field. The pulsating broadband acoustic oscillations arising under the action of a constant electric field can be spurious during the operation of electroacoustic transducers, which should be taken into account in their design. The results of field experiments on the model of an electroacoustic transducer confirm the theoretical results presented in the study. The stated theoretical and experimental results make it possible to solve the priority scientific–technical problem of designing and creating new types of acoustic emitters.

This review analyzes two approaches to describing the polarization of disperse systems when an alternating electric field is applied in the general case. Polarization models of Trukhan and Dukhin – Shilov are considered. As a result of this review, it follows that the most preferable model, which makes it possible to significantly increase the rate of electrophoresis of the dispersed phase, is the Dukhin – Shilov model, in the implementation of which a giant dispersion of the dielectric constant of a heterogeneous dispersed system may appear if the condition of a thin double layer around non-conducting dispersed particles in a conducting dispersive medium.

ДИЭЛЬКОМЕТРИЧЕСКИЕ ИЗМЕРЕНИЯ СТРУКТУРНЫХ ИЗМЕНЕНИЙ В РАЗБАВЛЕННЫХ ВОДНЫХ РАСТВОРАХ СОЕДИНЕНИЙ НАТРИЯМетодом низкочастотной диэлькометрии высокого разрешения зарегистрированы структурные изменения в водных растворах соединений натрия в диапазоне концентраций 10 -2 -10 -6 М. Все эксперименты проводились при комнатной температуре.Экспериментальные результаты в частотном диапазоне 50-1000 кГц представлены в виде зависимостей tg δ от логарифма частоты ω возбуждения колебательного контура, в катушку индуктивности которого помещена стеклянная пробирка с исследуемым раствором.Наблюдаемые зависимости носят выраженный спектральный характер, положения пиков в спектрах достоверно воспроизводятся и характеризуют катионный и