Terminal Electrodes Research Articles

Preparation of Fine Copper Powder With Chemical Reduction Method and Its Application in MLCC

In this paper, the preparation of fine copper powder with chemical reduction method was investigated. Polyhedron nonagglomerated monodispersed copper powders by the reaction of CuSO4ldr5H2O and ascorbic acid were synthesized at pH 6~7 and reaction temperature of 60degC~70degC. It was also found by X-ray diffraction (XRD) analysis that a mixture of copper and cuprous oxide could be obtained when [Cu(NH3)4]2+ was reduced by ascorbic acid. Reaction temperature and pH have great effects on efficiency and particle size of copper powders. Copper powders were applied as terminal electrode materials of base metal electrode-multilayer ceramic capacitor (BME-MLCC), and the microstructures, including cross section and interface, of copper thick film were discussed with scanning electron microscopy. The results indicated that copper thick film has a loose, porous cross section and a rough interface. The adhesion strength of copper electrode is high due to rough microstructure caused by interfacial reaction.

Construction of Functional Electrode Interface for Electroorganic Synthesis

Thin poly (acrylic acid) (PAA)-coated graphite felt (GF) is a promising electrode material for preparative organic electrosynthesis, because the electrode is not only stable and durable but also can be modified with various mediators and enzymes in the PAA layer. The TEMPO-modified GF electrode for electrocatalytic oxidation of several types of organic compounds were successfully constructed. The modified electrode had many advantageous properties compared with direct electrosynthesis or mediatory reaction synthesis which is still common as an electrochemical system. The use of a chiral nitroxyl radical-modified GF electrode afforded enantioselective oxidation of racemic alcohols or amines (remaining optically pure alcohols or amines) and asymmetric lactonization of methyl-substituted diols. A preparative electrocatalytic radical cyclization of bromo alkyl cyclohexenones was successfully achieved on a nickel (II) tetraazamacrocyclic complex-modified GF electrode. The PAA-coated GF electrode modified with viologen and palladium metal microparticles is effective for the electrocatalytic hydrogenation of olefins. An electrode immobilizing all components of mediator, enzyme, and coenzyme for electroenzymatic reactions was also prepared, and several electroenzymatic reactions were smoothly carried out. Substrate immobilization on GF for the solid-phase acetylene coupling reaction was achieved by electrochemical polymerization of the substrate precursor containing a pyrrole side chain, where the amount of substrate on the electrode surface was easily controlled by the number of repeated cyclic voltammetric scanning. Couplings between terminal acetylenes and the iodobenzene-modified GF electrode or aromatic iodides and the terminal acetylene-modified GF electrode in the presence of palladium catalyst proceeded smoothly with satisfactory yields.

Electric preconcentration and detection of latex beads with interdigitated electrodes

Latex beads are adhered to the surface of a chip containing polycrystalline silicon interdigitated electrodes by positive dielectrophoresis. The presence of the microparticles induces a change in the distribution of the electric fields and currents that can be detected by measuring either the conductance or the capacitance at the electrode terminals. This combination of actuation and detection with a single device is proposed as a suitable system applicable to biosensing.

Termination of BME–MLCC Using Copper–Nickel Bimetallic Powder as Electrode Material

Microstructure of termination of a base metal electrode multilayer ceramic capacitor (BME-MLCC) using copper-nickel bimetallic powder as electrode material was investigated. Thick film paste containing nonagglomerated monodispersed copper-nickel bimetallic powder was applied in preparing the termination electrode of a BME-MLCC. Influence of an inorganic binder on the microstructure of the termination of BME-MLCC was studied. The distribution of metallic copper on the surface of glass bubbles in termination was investigated by energy dispersive X-ray. A scanning electron microscope and a polarized light microscope were applied to discuss the microstructure of thick film. The results show that suitable binder and firing temperature result in the excellent connection between internal and termination electrode, as well as one between termination electrode and green chip. The BME-MLCCs with a dense surface of end termination, high adhesion, and qualified electrical behavior were obtained. The rough interface from interfacial reaction between glass and chip gives high adhesion

Current–voltage characteristics of GaAs nanowhiskers

Abstract The current–voltage characteristics of GaAs whiskers with an average diameter of 100 nm and a population of 100–1000 were measured using a device structure with two terminal electrodes. An ohmic contact to the tip of whiskers which were buried in spin-on glass between a metal electrode and n-type GaAs(1 1 1)As substrate was realized by heat treatment at 430 °C. The measured results show that the current–voltage curve for the whiskers is better approximated by the polynomial of the voltage to the power of 1.5 than by the exponential of the voltage. The dependence of the current on the voltage suggests that a space-charge layer was formed in the nanowhiskers. Step-like current fluctuations were also observed at 77 K, and this behavior was reproducible and unchanging even under a magnetic field. This suggests that the charge on the surface of the whiskers had a significant effect on carrier transport along the whiskers.

Nanomechanical switch fabrication by focused-ion-beam chemical vapor deposition

Focused-ion-beam chemical vapor deposition (FIB-CVD) is an excellent technology to form three-dimensional nanostructures. Various three-dimensional nanostructures such as an inductance, a capacitor, a resistance, and a filter-circuit have been demonstrated by applying FIB-CVD with phenanthrene (C14H10) source gas using a computer-controlled pattern generator (CPG). The electrical resistivity measurement of the free-space-nanowiring was carried out by two terminal electrode method. The resistivity was 1×102Ωcm in the case of using C14H10. To reduce the electrical resistivity, tungsten hexacarbonyl [W(CO)6] is added to C14H10 as a source gas. Increasing content of W(CO)6, the electrical resistivity becomes lower from 1×102to2×10−2Ωcm at room temperature. By using free-space-nanowiring fabrication technology, the world smallest nanomechanical switch composed of a coil and a nanowiring has been fabricated and confirmed the switching operation by applying a voltage.

Polypyrrole-Supported Graphite Felt for Acetylene Coupling Reaction in Solid Phase

Substrate immobilization on graphite felt for solid-phase acetylene coupling reaction was achieved by electrochemical polymerization of the substrate precursor containing a pyrrole side chain, where the amount of substrate on the electrode surface was easily controlled by the number of repeated cyclic voltammetric scannings. Couplings between terminal acetylenes and the iodobenzene-modified graphite felt electrode or aromatic iodides and the terminal acetylene-modified graphite felt electrode in the presence of palladium catalyst proceeded smoothly in satisfactory yields.

Influence of terminal electrodes onLC resonance frequencies in glass-coated Co83.2B3.3Si15.9Mn7.6 microwires

A new super-giant magnetoresonance effect was found in LC resonators consisting of a glass-coated microwire with capacitive terminal electrodes. The changes of resonance frequencies were examined as a function of the electrode dimensions in amorphous Co83.2B3.3Si5.9Mn7.6 microwires. The widths of two capacitive electrodes at the end of the microwire were varied from 3 to 6 mm, and the gap lengths between the electrodes were also varied from 6 to 9 mm. The shape of the impedance curves as a function of a dc magnetic field changed dramatically near the LC resonance frequency. The phase angle was also strongly dependent on this field. The sudden change of impedance by as much as 6400% with a change of phase angle as large as 180° is a new phenomenon, which is evidence for the occurrence of the magnetoresonance at a given intensity of the external dc field. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrochemical, AFM and QCM studies on ferritin immobilized onto a self-assembled monolayer-modified gold electrode

A ferritin-immobilized electrode based on self-assembled monolayer (SAM)-modified gold electrodes was developed. Various alkane thiols containing functional groups as the terminal group were used for the SAMs. The ferritin-immobilized SAM-modified electrodes were characterized by electrochemical, atomic force microscopy (AFM) and quartz crystal microbalance (QCM) techniques. The results indicated that ferritin was selectively immobilized onto amino terminal alkane thiol-modified electrodes by the electrostatic interaction between ferritin and the terminal functional groups of the SAMs. The ferritin-immobilized modified electrode showed a direct electron transfer reaction between ferritin and the electrode. The electrochemically regulated uptake and release of iron ions for ferritin immobilized on the SAMs was demonstrated. The AFM and QCM results showed that ferritin molecules covered the whole electrode surface at almost a full monolayer level. The results obtained in this work indicate that ferritin has potential for a biomaterial in nanomaterial synthesis for potential magnetic, catalytic and biomedical sensing applications.

Free-space-wiring fabrication in nano-space by focused-ion-beam chemical vapor deposition

Focused-ion-beam chemical vapor deposition (FIB-CVD) is an excellent technology for forming three-dimensional nanostructures. Various diamond-like-carbon (DLC) free-space-wirings have been demonstrated by FIB-CVD using a computer-controlled pattern generator, which is a commercially available pattern generator for electron-beam (EB) lithography. The material composition and crystal structure of DLC free-space-wiring were studied by transmission-electron microscopy and energy-dispersive x-ray spectroscopy. As a result, it became clear that DLC free-space-wiring is amorphous carbon containing a Ga core in the wire. Furthermore, the electrical resistivity measurement of DLC free-space-wiring was carried out by two terminal electrodes. Au electrodes were fabricated by EB lithography and a lift-off process. The electrical resistivity was about 100 Ω cm at room temperature.

High‐density 3D packaging sidewall interconnection technology for CCD micro‐camera visual inspection system

AbstractThe authors have developed 3D packaging sidewall interconnection technology, which enables a higher packaging density in the 3D stack direction, in order to realize a CCD micro‐camera visual inspection system integrated on the front of an experimental wireless micromachine for a visual inspection robot moving by itself in pipes of diameter 10 mm ϕ in an electric power generation plant. This technology was achieved by exposing the high‐aspect‐ratio circuit wiring layers at the edge of a stack‐unit substrate as sidewall footprint. The sidewall footprint has a high aspect ratio, which is a superior shape for the electrode terminals, by designing the Cu‐filled stacked vias to be laid out directly on the core substrate in a build‐up multilayer wiring substrate. With regard to the alignment between the stack‐unit substrates that determines the relative precision of the sidewall footprint, the process of dividing into the individual 3D packaging modules after multiple‐unit layout stack‐unit substrate lamination was used to improve the precision of sidewall footprint. By using this packaging technology, a prototype 3D packaging module consisting of a CCD video signal transmission circuit and a CCD control signal circuit in a CCD micro‐camera visual inspection system obtained an excellent CCD output signal and confirmed the effectiveness of the technology for high‐density packaging in a microspace. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(8): 67–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10063

Copper Powder for Termination Electrode in MLCC

Conventional copper powder used to form terminations of MLCC generally contains large flakes with high aspect ratios and large agglomerate spherical particles. The use of agglomerate powder and large flakes results in low dry film density, and thus a thicker film. In our research, we focused on highly dispersed, uniform, and fine flakes and powder that did not contain coarse particles, and examined the paste characteristics and their effect on firing conditions. We found that a smaller particle size would increase the thixotropic value and result in an earlier start to firing. We also discovered that the agglomerate condition of powder had a significant influence on the rheology of the paste. A higher degree of agglomeration would result in higher viscosity and a higher thixotropic value, but would not have a major effect on the firing condition.

Electrical conduction in canine pulmonary veins: electrophysiological and anatomic correlation.

Paroxysmal atrial fibrillation in patients is often initiated by foci in the pulmonary veins. The mechanism of these initiating arrhythmias is unknown. The aim of this study was to determine electrophysiological characteristics of canine pulmonary veins that may predispose to initiating arrhythmias. Extracellular recordings were obtained from the luminal side of 9 pulmonary veins in 6 Langendorff-perfused dog hearts after the veins were incised from the severed end to the ostium. Pulmonary veins were paced at the distal end, the ostium, and an intermediate site. During basic and premature stimulation, extracellular electrical activity was recorded with a grid electrode that harbored 247 electrode terminals. In 4 hearts, intracellular electrograms were recorded with microelectrodes. Myocyte arrangement immediately beneath the venous walls was determined by histological analysis in 3 hearts. Extracellular mapping revealed slow and complex conduction in all pulmonary veins. Activation delay after premature stimulation could be as long as 96 ms over a distance of 3 mm. Action potential duration was shorter at the distal end of the veins than at the orifice. No evidence for automaticity or triggered activity was found. Histological investigation revealed complex arrangements of myocardial fibers that often showed abrupt changes in fiber direction and short fibers arranged in mixed direction. Zones of activation delay were observed in canine pulmonary veins and correlated with abrupt changes in fascicle orientation. This architecture of muscular sleeves in the pulmonary veins may facilitate reentry and arrhythmias associated with ectopic activity.

A novel Y-type reactor for selective excitation of atmospheric pressure glow discharge plasma

A novel Y-type atmospheric pressure ac glow discharge plasma reactor has been designed and tested in CO reduction with hydrogen and the reverse water–gas shift reaction. The reactor consists of a Y-type quartz tube with an angle of 120°–180° between the two long arms, two metal rod electrodes serving as high voltage terminals and two pieces of aluminum foil which were wrapped outside of the quartz tubes as a ground electrode. Different combinations of input power applied on this three- electrode system can lead to selective plasmas on one side, two sides, or can also generate a stable arc between the two high voltage terminal electrodes. The ability to selectively activate different species with this type of apparatus can help to minimize side reactions in plasmas to obtain desirable products. The Y-type reactor may provide a novel means to study fundamental problems regarding radical reactions.

Inhomogeneous Transmural Conduction During Early Ischaemia in Patients with Coronary Artery Disease

P. Taggart, P. M. I. Sutton, T. Opthof, R. Coronel, R. Trimlett, W. Pugsley and P. Kallis. Inhomogeneous Transmural Conduction During Early Ischaemia in Patients with Coronary Artery Disease. Journal of Molecular and Cellular Cardiology (2000) 32, 621–630. Electrical inhomogeneity and conduction slowing are critical factors in the initiation and maintenance of ventricular arrhythmias during early ischaemia. Studies in animal models have shown delay in epicardial activation compared to endocardial activation. Epicardial activation delay has been attributed to either enhanced sensitivity of epicardium to ischaemia or to mid-myocardial conduction delay. No information is available in humans and in particular in patients with chronic ischaemia due to coronary artery disease who may have altered electrophysiological properties. Twenty-three patients undergoing routine coronary surgery were studied. All had severe two or three vessel coronary artery disease and a documented history of angina for a mean of 2.4 years. On cardiopulmonary bypass a 3 min period of ischaemia was created by cross clamping the aorta between the input from the pump oxygenator and the coronary arteries. During atrial pacing (normal endocardial to epicardial activation) intramyocardial activation time within the left ventricular free wall between subendocardial and subepicardial plunge electrode terminals, increased from 12.7±1.5 ms (control) to 28.2±3.2 ms after 3 min ischaemia at the base. At the apex, the activation time increase (over the same distance) was less (19.5±2 ms at 3 min ischaemia). This difference in increase in activation time at the base and apex was significant (P<0.05). At the apex the ischaemia induced activation delay occurred primarily over the endocardial half of the wall, whereas the opposite was observed at the base of the heart. Using an epicardial electrode array stimulation along the long axis of the epicardial fibres showed minimal conduction delay during ischaemia whereas stimulation transverse to the epicardial fibres resulted in substantial conduction time prolongation, as was the case with intramural conduction. Intramural conduction during ischaemia was similar in non-infarcted regions of infarcted hearts compared to hearts with no previous MI. To conclude, in patients with coronary artery disease epicardial activation delay early during ischaemia is caused primarily by intramural delay and not by delay along the epicardium. Moreover, the ischaemia-induced transmural activation delay is inhomogeneous.

Effects of a pulsing electric signal on the cross membrane potential and the cell division potentiality of a single cell of tobacco

A pulsing electric signal (pulse width 10 s) was applied to a single cell of cultured tobacco, line BY-2, by inserting a multifunctional microelectrode (MME) into the cell. The electric voltage ( V ET) was loaded between the electrode terminals of the MME and the reference electrode situated in the extracellular medium. Since the electrical impedance of the MME was as large as that of the cell membrane, the effective potential acting across the cell membrane ( V CMP) should be only some portion of V ET. The MME enabled simultaneous measurement of V ET and V CMP. When V ET was varied from 0 to −1 V, V CMP changed linearly in proportion to V ET. When V ET variation range was enlarged (from 0 to −2 V), V CMP changing pattern became a declined curve. When V ET variation range was further enlarged (from 0 to −5 V), the V CMP changing pattern showed a saturation curve. Under this condition, the cell division potentiality decreased accordingly. Based on these results, the feasibility of V CMP as an indicator of the effective intensity of an electric stress signal is discussed. In the present case of a BY-2 cell, a proper intensity of V CMP that could cause an appreciable stress and not a lethal signal was estimated as −250 mV.

Altered migrating myoelectrical complex in an animal model of cholesterol gallstone disease: the effect of erythromycin

Background—The ground squirrel on a high cholesterol diet exhibits prolonged intestinal transit, a pathogenetic factor in cholesterol gallstone formation.Aims—To examine the effect of a high cholesterol diet on the characteristics...

Electrochemical promotion of electronically isolated and dispersed Pt catalysts

In this paper we discuss the first attempts to induce the effect of Electrochemical Promotion or Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA) on highly dispersed catalyst-electrodes systems which can compete in terms of dispersion and surface area with industrial catalysts. Three systems are discussed: 1. Electrochemical promotion of C2H4 oxidation on electronically isolated Pt catalysts on Y2O3-stabilized-Zirconia (YSZ) where NEMCA is induced via potential application between two terminal Au electrodes also supported on the solid electrolyte (bipolar design). 2. Electrochemical promotion of C2H4 oxidation on a finely dispersed Pt catalyst deposited on a Au electrode which is supported on YSZ. 3. Induction of NEMCA during CH3OH oxidation on Pt without external voltage application by utilizing the potential difference developed between the catalyst and a catalytically inert counter electrode.

Effects of electrochemical hydrogen charging on lead-based relaxor ferroelectric multilayer ceramic capacitors

Lead-based relaxor ferroelectric multilayer ceramic capacitors (MLC's) were placed in 0.05 M NaOH solution to evolve hydrogen on their silver termination electrode by electrolysis of water. After this treatment, the MLC's failed as their insulation resistance was greatly decreased, their dielectric loss was considerably increased, and their capacitance was obviously decreased. By annealing in air at 650 °C for 30 min, the properties of the MLC's were restored. It is proposed that electrochemically generated hydrogen atoms can diffuse into the ceramic body of MLC's and undergo reduction to it, which may be one of the reasons for the negative influence of electroplating on lead-based relaxor ferroelectric MLC's.

5518836 Flexible carbon fiber, carbon fiber electrode and secondary energy storage devices

A novel flexible carbon fiber is disclosed which has a generally non-circular or tubular cross-sectional shape, a Young's modulus of from greater than 1 MM psi (6.9 GPa) to 55 MM psi (380 GPa), and a bending strain value of from greater than 0.01 to less than 50%. The invention also resides in an electrode for a secondary energy storage device utilizing the carbon fibers of the invention and containing a non-aqueous electrolyte. The invention further resides in a secondary energy storage device comprising a water impermeable housing having at least two cells containing at least one shared bipolar electrode made of the flexible carbon fibers of the invention. Also disclosed is a pseudo bipolar electrode and terminal electrode for use in a lithium ion battery in which the fibers or a portion of the carbon fibers are coated with an ion active lithium salt of a metal oxide. Also disclosed is a novel battery stack and a method of manufacture of the secondary energy storage device.