Papers by Keyword: AC Electric Field

Abstract: In order to clarify the relation between ReKω and the electrical property of each intracellular part, we loaded temperature stress on the cells. In this experiment, the electrical property of the intracellular part means the cytoplasm electrical conductivity (σ₃) and the cell membrane capacitance (C_m). ReKω of the cells was measured using dielectrophoresis (DEP) levitation, and the electrical property of each intracellular part was analyzed from the measurement result in applying a single shell model. In this experiment, mouse hybridoma 3-2H3 cells were used as the sample cells. Temperature stress was loaded on the sample cell at 5% CO₂ in a CO₂ incubator. The result of the frequency characteristic of ReKω using DEP levitation showed that both ReKω and the crossover frequency of the single cell in the high frequency region decreased with increasing temperature. Furthermore, both the cytoplasm electrical conductivity and the cell membrane capacitance decreased with increasing temperature stress.

Abstract: In this study, we analyzed differences in cell species using dielectrophoresis (DEP) and propose a particle packed bed type chromatography device using DEP. Mouse-hybridoma 3-2H3 cells were used as the sample cells. The 3-2H3 cell suspension was fed pulse-wise to a carrier flow and the sample was measured by an absorption spectrometer. The analytical characteristic of chromatography using DEP was evaluated by the retention time difference. We examined the effects of the diameter of packed particles on the retention time difference. The retention time difference in the case of the packed particles of 100 μm diameter was larger than that of 500 μm, which suggests that packed particles of smaller diameter are suitable for analysis using DEP chromatography.

Abstract: In this paper, many experiments on effect of the sliding speed on friction and wear behaviors of pure carbon strip/copper contact line under the AC electric field are conducted on a ring-on block high-speed sliding tester. The result indicates that coefficient of friction increases with increasing sliding speed. And the friction coefficient without electric current is much larger than that with electric current. While the wear rate of pure carbon strips without electric current is much smaller than that with electric current. And wear rate slightly increases with the increase of the sliding speed. Comparison of worn surface profiles in different electric current, it can be found that the profile of worn surface increases with increasing electric current.

Abstract: Deposition of ceramic nanoparticles (dispersed in non-aqueous suspension) on in-plane electrodes and under the influence of AC electric fields in the frequency range of 0.01 Hz - 10 kHz is investigated. Analysis of the particle response to the applied field is a difficult task due to the mutual effect of electric and hydrodynamic forces which are present in the system. In this work, however, we show the possibility of dividing the frequency range into four domains with four distinct governing mechanisms. Possible mechanisms are suggested and dominant forces are determined for each domain. In situ optical microscopy observations are used for visualization of nanoparticles´ movement dispersed in liquid medium. These observations show that applying AC electrophoresis at frequencies below 10 kHz is an effective way for manipulating ceramic nanoparticles and device fabrication.

Abstract: This article simulated the collision and agglomeration between bipolarly charged particles in an electrostatic agglomerator. The EHD turbulent flow was solved and the flow parameters were extracted a priori. The particle initial charge was obtained by tracking particles with a certain diameter in the charging zone. When simulating collision and agglomeration in the agglomerating zone, the initial charge on a particle was sampled from the charge distribution by statistical analysis. The classical stochastic model for calculating collision between neutral particles was extended to calculate collision between charged particles, and the effect of particle charge on collision and agglomeration was embodied in the agglomeration criteria. The effect of an external DC and AC electric field on the collision and agglomeration was investigated.

Abstract: This paper reports the separation of cells using a dielectrophoretic (DEP) chromatography device. The device consists of a micro channel and an array of interdigitated microelectrodes on a glass substrate. The sample cells were fed pulse-wise into the carrier flow using a micro-injector. The cells in the sample received a non-uniform electric field made with an electrode array. The direction of DEP motion is towards the higher field when the cell is more polarizable than the medium (positive DEP), while the direction is towards the lower field when the cell is less polarizable than the medium (negative DEP). Therefore, the cell separation depends on the size and dielectric characteristic. The effects of carrier flow rate, frequency, applied voltage, and sweep frequency on the retention time of the sample in the device were examined. In this study, mouse-hybridoma 3-2H3 cells and yeast cells were used as the sample cell. The analytical characteristic of the DEP chromatography device was evaluated according to the difference of retention time by the electric field. As a result, the separation in the cells in the negative DEP using the DEP chromatography was found to be effective. In addition, the effect of the sweep frequency on the difference in the retention time of the mouse hybridoma 3-2H3 cells and the yeast cells was very large. Consequently, the effectiveness of the DEP chromatography device was proven.

Abstract: In this paper, electrophoretic deposition of multiwall carbon nanotubes (MWNTs) using low frequency (0.01-1000 Hz) AC electric fields, is reported. The effect of depositing parameters such as frequency and waveform on deposit yield is investigated. Results show that the deposit yield decreases with frequency. The rectangular waveform yields more deposit yield than sinusoidal and triangular waveforms. The deposition pattern is also different in AC and DC electric fields. This technique may be used for deposition of MWNTs thick films.