Slit Electrode Research Articles

Fabricating micro-core by EDM with multi-station narrow slit electrode

A method of fabricating micro-core on hard materials by electro-discharge machining (EDM) with multi-station narrow slit electrode was proposed. Instead of changing electrodes traditionally, the method of transforming the electrode station was applied, and the positioning error could be avoided. With the narrow slit structure of the electrode, the discharge debris could be excreted easily and the high depth-to-width ratio of micro-core could be fabricated. NAK80 was selected as the core material, while copper-tungsten alloy (70 % W) as the electrode material to carry out the fundamental experiments in which the relationship between the number of electrode stations and forming accuracy of micro-core was researched. The results demonstrate that using four electrode stations, the dimensional precision is within 3 μm, the root radius is within 10 μm, and the surface roughness is Ra 0.198 μm, and all this can be satisfied with the demand of molding for microfluidic chip. On the basis of the fundamental experiment results, a variable section micro-core was manufactured. The machining results show that the forming accuracy of the convex becomes worse with the decrease of the forming convex height. This phenomenon was analyzed in EDM principle and the error reflection mechanism.

Charging/Discharging Dynamics in Two-Dimensional Titanium Carbide (MXene) Slit Nanopore: Insights from molecular dynamic study

While most theoretical studies on slit nanopore electrodes are limited in their static properties, understanding the dynamic charge storage is crucial for promoting their electrochemical performance in the field of energy storage systems. In this article, the charging/discharging dynamics in MXene (Ti3C2(OH)2) electrode featuring intrinsic slit nanopore with room temperature ionic liquid are investigated by molecular dynamic simulation. The galvanostatic cycling is modeled to help to understand the dynamic charge storage mechanism. The simulation results show that the electrolyte ions spontaneously wet the Ti3C2(OH)2 slit nanopore in the absence of external potential, even at 0.7nm layer distance pore case. An intriguing electroneutrality breakdown and faster diffusion property is observed inside the nanopore. During charge/discharge process, the charge storage takes place by a fast counter-ion insertion and counter-ion/co-ion exchange. Besides, the spatial distribution of ions and the orientation of the cation dipoles inside the pore vary cyclically alone with the charge/discharge process, which helps to screen the external electric potential. Having elucidated the charge mechanism, we investigate the layer distance factor and show that the ions exhibit more significantly acceleration and more ordered dipole orientation inside the narrower pore. This will help Ti3C2(OH)2 electrode with narrower pore exhibit better power performance.

ECF micropump fabricated by electroforming with novel self-aligned micro-molding technology

This paper proposes and presents a novel ECF (electro-conjugate fluid) micropump with TPSEs (triangular prism and slit electrode pair) fabricated by electroforming process using newly developed self-aligned micro molds. ECF is a kind of functional and dielectric fluid. ECF micropump is based on the principle of ECF jet, which is a powerful and active jet flow generated between electrodes immerged in ECF, when high DC voltage is applied to the electrodes. Our previous research experimentally demontrated that the ECF micropump had high power density thanks to the 2D-integraton (serialized integration and paralleled integration) of our proposed MEMS fabrication method by using micro-molding and electroplating. Moreover, it was also proved that higher aspect ratio of TPSEs by the multilayer fabrication process resulted in higher flow rate of the ECF micropump. However, the multilayer fabrication has demerit to require precise alignment that is time-consuming and extremely difficult to be met. In order to improve alignment accuracy and alleviate fabrication difficulty, this paper proposes a novel self-aligned MEMS fabrication process for high aspect ratio TPSEs. The ECF micropump by this newly-proposed MEMS process was successfully fabricated and the feasibility was proved by experimentally investigating output performance of the ECF micropump.

Capacitance Optimization in Nanoscale Electrochemical Supercapacitors

We perform constant voltage Gibbs ensemble based grand canonical Monte Carlo simulations for nanosized supercapacitors comprising graphene slit electrodes in symmetric and asymmetric electrolytes. Our simulations demonstrate that external electrolyte at the electrode surface can be exploited to positively influence the structure and packing of that inside the slit, when the system is engineered to allow these to interact. Oscillatory dependence of capacitance on slit-pore size, seen in recent results from molecular dynamics simulation and density functional theory, is observed also in our Monte Carlo simulations. A detailed analysis suggests that maximum in capacitance occurs in subnanometre pores because of the interference between internal double layers (largely the Helmholtz parts) on the opposite sides of the slit, expelling the co-ions; and that the oscillatory character of capacitance with pore width is due to relative changes in counterion and co-ion populations with pore width, also dictated by th...

Fast Response and Wide Viewing Angle Vertical Alignment Mode with X-Shape Electrode

We proposed the fast response and high transmittance vertical alignment mode by generating the axial symmetry of the liquid crystal (LC) director. To control the LC director, we adopt the x-shaped slit electrode on the only pixel electrode. Using a polymerization of the reactive mesogens (RMs) mixed into the alignment layers, we can memorize the falling direction of LCs and thus the fast switching characteristics can be achieved. Owing to infinite LC domains with the axial symmetry, wide viewing angle characteristics was achieved and high transmittance also was obtained by introducing a quarter wave plate.

The importance of gold‐electrode‐adjacent stationary high‐field Böer domains for the photoconductivity of CdS

When the electron density decreases stronger than linearly with the electric field in photoconductive CdS due to field quenching, high‐field domains must occur that remain attached to either the cathode or anode in slit electrode geometry with blocking cathodes. These Böer domains1 are easily seen by their shift in optical absorption due to the Franz‐Keldysh effect and offer unique opportunities to analyze field dependent parameters within the range of constant electron density and electric field, such as the carrier density or mobility as a function of the field, and give information of the light dependent work function. They also provide insight why a 200 Å thick cover layer of CdS on top of a CdTe solar cell increases its efficiency from 8 to 16% . The behavior of these Böer domains escapes conventional current voltage analyses except for their visual observation, while other high‐field domains with their current fluctuations or oscillations are easily observed and are the subjects of thousands of publications and many books. In this review we will exclude detailed discussion of dynamic domains, but include some new specifics that help to understand the mechanisms of the Böer domains and their applications. Only properties at low optical excitation intensities are discussed that exclude Joules heating. Within the p‐type regime of the anode‐adjacent domain extremely steep electronic quenching signal becomes visible that could signalize an intrinsic donor level slightly above the middle of the band gap that may be responsible for not allowing CdS to ever become p‐type by doping. image

Electrically switchable cholesteric gratings based on slit electrodes

An electrically switchable diffraction grating (ESDG) based on cholesteric liquid crystal (CLC) filled into the cell with slit electrodes is demonstrated in this study. On one hand, with low voltage, the ESDG has high second order diffraction efficiency because of the alternating planar and fingerprint textures. With high voltage, on the other hand, the ESDG has high first order diffraction efficiency because of the alternating planar and homeotropic textures. The first and second order diffraction efficiencies of ESDG are electrically swapped. The maximum diffraction efficiency of the ESDG is approximately 32% at each grating mode.

Thermodynamics in Porous Electrodes for One- and Two-Component Electrolytes

Thermodynamics in porous electrodes is discussed for simple model electrolytes in slit porous electrodes. Adsorption of surface charge and ions, pressure, and the selectivity of ions for the case of multi-component electrolytes were analyzed by using the methods of analyses that have been used in the study of porous adsorbents in the last decades. We compare the results for adsorbents and those for porous electrodes and clarify the similarities and differences.

Thinning of a Two-Inch Silicon Carbide Wafer by Plasma Chemical Vaporization Machining Using a Slit Electrode

In recent years, silicon (Si) has been mainly used in power devices, but the limit of its performance is being reached. Therefore, silicon carbide (SiC) power devices have been attracting attention because they enable the fabrication of devices with low power consumption. To reduce the on-resistance in vertical power transistors, backside thinning is required after device processing. However, it is difficult to thin a SiC wafer with a high removal rate by conventional mechanical processing because its high hardness and brittleness cause cracking and chipping during thinning. Therefore, we have attempted to thin a SiC wafer using plasma chemical vaporization machining (PCVM), which is plasma etching using atmospheric-pressure plasma. In this study, we describe a machining property using a newly developed slit electrode that is composed of two parts and has a slit that allows for a new gas to pass.

2204 三角柱-テーパースリット電極対を用いたECFマイクロポンプ(センサ・アクチュエータ(2))

2204 三角柱-テーパースリット電極対を用いたECFマイクロポンプ(センサ・アクチュエータ(2))

2208 三角柱-スリット形電極対の三次元集積化によるECFマイクロポンプ(マイクロデバイス,一般講演)

This paper proposes and presents an electro-conjugate fluid (ECF) micropump whose pumping sources are integrated inside flow channels three-dimensionally. ECF is a kind of functional and dielectric fluid. A strong and active jet flow of ECF is generated between electrodes surrounded by ECF, when high DC voltage is applied to the electrodes. To combine easy fabrication and high performance, we developed a novel ECF pumping source that consists of a triangular prism electrode and a slit electrode fabricated by MEMS technology. Thanks to the advantages of MEMS technology it is easy to integrate plenty of triangular prism and slit electrode pairs in a plane. The plane integration of these electrode pair results in the realization of ECF micropumps for high output power density. In order to obtain higher output power density, we make an attempt to integrate the triangular prism and slit electrode pair three-dimensionally in addition to the plane integration. To figure out the effectiveness of three-dimensional integration of ECF pumping sources, we develop the prototype and investigate the characteristics experimentally by using the prototype. The experimental results show that the ECF micropump by 3D integration can be a good candidate as a higher output power hydraulic power source.

Tube-type micropump by using electro-conjugated fluid (ECF)

This paper proposes and presents an electro-conjugate fluid (ECF) micropump whose pumping sources are mounted on the inside of flow channels and are serially located through the flow channels. ECF is a kind of functional and dielectric fluid. A strong and active jet flow of ECF is generated between electrodes surrounded by ECF when high DC voltage is applied to the electrodes. To combine easy fabrication and high performance, we propose a novel ECF-jet generator that consists of a triangular prism electrode and a slit electrode for the tube-type ECF micropump. The maximum output pressure obtained is 64 kPa and the maximum flow rate is 1.12 cm 3/s at the applied voltage of 6 kV. The result shows that the proposed ECF-jet generator and whose tube-type ECF micropump can be a good candidate as a driving source for forced liquid cooling systems, new microactuators and so on.

2A2-K15 三角柱-スリット型電極の直列・並列化によるECFマイクロポンプの性能評価(アクチュエータの機構と制御)

Electro-Conjugate Fluid (ECF) is a kind of functional and dielectric fluid. When a high DC voltage is applied to a pair of electrodes immersed in the ECF, a strong and active jet flow of ECF (ECF-jet) is generated between these two electrodes. A high power tube-type ECF micropump that consists of triangular prism and slit electrode pairs was proposed and fabricated by MEMS technology including photolithography with thick photoresist and nickel electroplating in the previous report. In this paper, we present advanced ECF micropumps in which the electrode pairs were serialized and parallelized for high performance in demand. The experiment results of the ECF micropumps show that parallelizing the electrode pairs does not affect output pressure significantly and also prove that the flow rate is proportionally dependent on the number of parallelized electrodes.

제3전극에 의한 전계변화가 수중 전기물리화학적 특성에 미치는 영향

In this paper, after the third electrode type oxidant generator which could format non-uniform electric field in water had been manufactured and installed, by direct electrolysis, the effects of the hydrogen potential and oxidation reduction potential characteristics attendant upon electric field change on a higher concentration oxidant generation characteristics were investigated. Consequently, as the third electrode was installed in the middle of two slit electrodes and the polarity of applied power was changed, it was observed that the third electrode system with the positive electrode can generate a higher concentration oxidant, hydrogen potential and oxidation reduction potential as compared with that of the negative electrode. It is because the positive electrode was bombarded mostly energetic electrons and the negative electrode was bombarded mainly by less energetic positive ions.

1209 MEMS技術を用いた高出力管路形ECFマイクロポンプ(アクチュエータのためのマイクロナノプロセス,一般講演)

This paper proposes and presents an electro-conjugate fluid (ECF) micropump whose pumping sources are mounted on the inside of flow channels and are serially located through the flow channels. ECF is a kind of functional and dielectric fluid. A strong and active jet flow of ECF is generated between electrodes surrounded by ECF, when high DC voltage is applied to the electrodes. To combine easy fabrication and high performance, we propose a novel ECF-jet generator that consists of a triangular prism electrode and a slit electrode for the tube-type ECF micropump. In order to determine the main parameters of MEMS-based ECF micropump, this research performs the experimental optimization of the prototype fabricated by mechanical machining, by changing the following parameters: slit width; electrode gap ; and tip angle. Experimental results by the prototype show that the optimal values are 200μm in slit width, 200μm in electrode gap, and 19° in tip angle. Based on these values, MEMS-based tube-type ECF micropump is successfully fabricated. The maximum output pressure obtained is 19 kPa at 2 kV of the applied voltage. The result shows that the tube-type ECF micropump can be a good candidate as a driving source for forced liquid cooling systems, new microactuators and so on.

Simulation of a High Current Vacuum Arc in a Transverse Magnetic Field

This paper presents the results of simulations using a model that describes constricted high current (>15 kA) vacuum arcs driven by a transverse magnetic field in a 2-D configuration (parallel rail electrodes). The simulations investigate a number of cases of practical interest for the use of vacuum interrupters. The influence of the electrode gap distance on the arc motion is discussed. It is found that faster arc velocities are obtained for larger gaps. For large gaps (ges5 mm), the Lorentz forces and pressure gradients acting on the plasma jets originating from the hot electrodes strongly affect the arc structure. The arc tends to expand on a longer distance and can efficiently preheat the next area of current attachment. The model also describes the jump of the arc over an electrically nonconductive part of an electrode (slit). This is possible due to the ability of the arc column to expand in the direction of motion and to prepare current attachment at a point beyond the slit. The characteristics of the jump depend on a function of the slit width, electrode gap, and current. Finally, the thermal effect on the electrode surface and the electrode bulk for an arc returning several times to the same position is investigated for a fixed DC current. The results show that the minimum surface temperature increases the first few times the arc returns, before stabilizing at a temperature given by the balance between the arc heat flow and the cooling by metal evaporation and conduction into the electrode.

Electro-optical characteristics of omnidirectional liquid crystal domain mode using doughnut-shaped slit electrodes

This paper proposes a liquid crystal (LC) display (LCD) mode, characterized by an azimuthally continuous nematic domain, driven by patterned electrodes with circular- and doughnut-shaped slits producing conelike fields, as a vertically aligned (VA) nematic LC mode. This proposed mode is focused on achieving a high transmittance display with omnidirectionally uniform optical characteristics by utilizing the proposed electrode structure. Consequently, the experimental results of the proposed LCD mode show high brightness and wide viewing angles that correlate well to numerical calculations. Other electro-optics characteristics of this mode correspond to the patterned VA LC mode.

ディスプレイ―ＩＤＷ’０７を中心に―Ｎｅｍａｔｉｃ Ｏｐｔｉｃａｌｌｙ Ｃｏｍｐｅｎｓａｔｅｄ Ｂｉｒｅｆｒｉｎｇｅｎｃｅ（ＮＣＢ）Ｍｏｄｅ ＬＣＤの作製と評価

We investigated the design conditions of the nematic optically compensated birefringence (NCB) mode and found that a small pretilt angle and a short slit electrode distance is required to make a stable dual-domain structure in an ECB cell. The fabricated NCB mode LCD had a fast response time of less than 4 ms and a high contrast ratio of over 800:1.

Fringe-Field Switching Mode with Three Electrodes for Low Operating Voltage

In this paper, we proposed fringe-field switching (FFS) mode with new electrode structure whose additional slit electrode in addition to conventional slit electrode is located on gate insulator for low operating voltage. Using in-plane field between first and second slit electrode as well as fringe field between first slit electrode and box electrode, the overall operating voltage is decreased from over 5 to around 4 V. However, the maximum transmittance is decreased due to strong tilt-up and over twisting effect.

Tunable-Focus Cylindrical Liquid Crystal Lens

A cylindrical lens is demonstrated using two planar substrates and a homogeneous liquid crystal (LC) layer. The top substrate has slit electrodes on its outer surface and the bottom has a transparent electrode on its inner surface. An applied voltage across the cell induces a cylindrical-like gradient refractive index within the LC layer which causes light to focus. The focal length is tunable by the applied voltage. Such a cylindrical lens can be easily fabricated with wide aperture size.