Electrodeless Method Research Articles

Electrodeless method for ultra-low mobility with carrier-resolution of nanochannel

As the channel lengths of electronic devices are scaled down to the nanometer range, the conventional methods to evaluate charge-carrier mobility approach a technical limit that is imposed by interfering effects of the electrode and forcing field. In this study, we demonstrate that electron spectroscopy provides additional (yet hidden) information on unipolar charge transport, which is free from conventional problems. We demonstrate that the estimated effective diffusion current through the target sample allows the measurement that is precise enough (10−4 cm2/V s) to obtain the mobility of electrons μelectron and holes μhole in nanolength organic channels. Using this method, we show how μelectron and μhole are correlated with the local structural order of poly(3-hexylthiophene) at the nanoscale. This method enables in situ charge-resolved observations of μelectron and μhole by eliminating the need for electrode and forcing field and will help to expand our understanding of charge conduction in nanoscale materials.

Increasing the Accuracy of Measuring the Resistance of the Grounding System with an Electrodeless Method

Recently, electrodeless methods of measuring the resistance of grounding devices have appeared, with the help of special clamps. But a large methodological error limits the possibility of their use, especially when rationing low resistances. The article shows the possibility to improve the accuracy of electrodeless measurement methods using commercially available measuring instruments.In electrical installations of telecommunication networks of buildings, structures and industrial enterprises, the form of the AC voltage signal of the industrial supply network (~220V, 50/60Hz) can be differ greatly from the sinusoidal for short periods of time. The causes of distortions are usually associated with a sudden change in the network load [1], for example, when you turn on a powerful electric motor, furnace, welding machine, etc.The occurrence of impulse overvoltages and interference caused by electromagnetic effects (lightning, switching, radio frequency and others) on low-voltage networks, not only leads to failure of electrical installations, cables, switchboards, but also to damage the terminal equipment and malfunction. This is due, primarily, to the saturation of modern buildings and structures with information, telecommunications and other digital equipment, which has a very low level of protection against impulse overvoltages and interference. All this makes it necessary to carry out appropriate protective measures. To reduce interference, it is necessary to perform a separate (working) ground loop, the resistance of which must be measured and periodically monitored.There are devices that allow an electrodeless method to monitor and evaluate the resistance of the ground loop. But these devices have a greater measurement error than devices that measure the resistance of the earth electrode method.The article deals with existing instruments (CA6410, MZC-303E) which can evaluate the resistance of the earth electrode and the possibility of increasing the accuracy of the measurement with the help of special current clamps is shown. Using a predetermined value of neutral impedance, the measurement error of the calculated resistance of the earthing switch can be determined with great accuracy.

Electrodeless conductivity tensor imaging (CTI) using MRI: basic theory and animal experiments.

The electrical conductivity is a passive material property primarily determined by concentrations of charge carriers and their mobility. The macroscopic conductivity of a biological tissue at low frequency may exhibit anisotropy related with its structural directionality. When expressed as a tensor and properly quantified, the conductivity tensor can provide diagnostic information of numerous diseases. Imaging conductivity distributions inside the human body requires probing it by externally injecting conduction currents or inducing eddy currents. At low frequency, the Faraday induction is negligible and it has been necessary in most practical cases to inject currents through surface electrodes. Here we report a novel method to reconstruct conductivity tensor images using an MRI scanner without current injection. This electrodeless method of conductivity tensor imaging (CTI) utilizes B1 mapping to recover a high-frequency isotropic conductivity image which is influenced by contents in both extracellular and intracellular spaces. Multi-b diffusion weighted imaging is then utilized to extract the effects of the extracellular space and incorporate its directional structural property. Implementing the novel CTI method in a clinical MRI scanner, we reconstructed in vivo conductivity tensor images of canine brains. Depending on the details of the implementation, it may produce conductivity contrast images for conductivity weighted imaging (CWI). Clinical applications of CTI and CWI may include imaging of tumor, ischemia, inflammation, cirrhosis, and other diseases. CTI can provide patient-specific models for source imaging, transcranial dc stimulation, deep brain stimulation, and electroporation.

Electrode and electrodeless impedance measurement for determination of orange juices parameters

AbstractElectrical impedance spectroscopy (EIS) is a non-destructive, rapid and real-time measurement method which does not require special high-tech measurement devices and can be applied to food quality assessment. This method is rapid, effective and affords low-cost investigation of the product. The conventional EIS method requires a set of metal electrodes in direct contact with the medium to be measured. The complicated electrochemical processes on the electrodes-electrolyte interface could substantially affect the value of the impedance measured. The present study sought to explore the possibilities of using the impedance method for quality control in orange juices, to introduce the electrodeless method of electrolyte impedance measurement and to compare this with the conventional impedance methods. The electrical properties of the orange juices were described with the help of an equivalent circuit. An equivalent circuit was designed with constant phase element approximation. The values of the equivalent circuit components were fitted using a non-standard algorithm inspired by the behaviour of actual ant colonies. Implementing the electrodeless method obviated the electrodes phenomena effects and the behaviour of the electrolyte is similar to inductance. The proposed electrodeless method is generally applicable to measuring the electrochemical properties of electrolytes.

Electrode-less Electrolyte Impedance Measurement

Classical methods of impedance of electrolytes measurement require a set of metal electrodes which are in direct contact with measured medium. The complicated electrochemical processes on the interface electrodes–electrolyte could substantially influence the value of measured impedance. The aim of this article is introduction of transformer-based electrode-less method of electrolyte impedance measurement. The problems due to complicated transfer function of transformers are avoided by calibration and deconvolution. For experimental verification of method, the properties of juice assessment using impedance spectroscopy are used.

Interpretation of the Early Hydration Procedure of Standard Cement Materials by Electrodeless Resistivity Method

In this paper, the early hydration procedure of standard cement materials is tested and analysized with electrodeless resistivity method. The experimental results show that for standard cement material, the early hydration procedure can be divided into 4 stages: dissolution period, setting period, acceleration period and deceleration period, respectively. Moreover, the characteristic point according the experimental data can be defined to determined stage in the hydration procedure, and be related with the key parameters for cement materials in hydration procedure, such as water/cement ratio. The electrodeless resistivity method can be used to predict the hydration behavior, especially early hydration behavior of cement as a new measurement technology.

Interpretation of the Early Hydration Procedure of Standard Cement Materials by Electrodeless Resistivity Method

In this paper, the early hydration procedure of standard cement materials is tested and analysized with electrodeless resistivity method. The experimental results show that for standard cement material, the early hydration procedure can be divided into 4 stages: dissolution period, setting period, acceleration period and deceleration period, respectively. Moreover, the characteristic point according the experimental data can be defined to determined stage in the hydration procedure, and be related with the key parameters for cement materials in hydration procedure, such as water/cement ratio. The electrodeless resistivity method can be used to predict the hydration behavior, especially early hydration behavior of cement as a new measurement technology.

Degradation of trichloroethylene using iron, bimetals and trimetals

A cold, electrodeless method was used to prepare bimetals (Fe/Cu, Fe/Ni) and trimetals (Fe/Cu/Ni) for the treatment of trichloroethylene (TCE). With Fe/Cu, the degradation of TCE was observed to increase with increasing copper content up to 9.26 % (w/w) with a first-order degradation rate constant approximately 10 times faster than that of zero-valent iron (ZVI) alone. For copper content greater than 9.26 %, the TCE degradation rate decreased. Dechlorinated compounds were initially observed but they were transitory and accounted for no more than 9 % of initial TCE mass on a carbon molar basis. Ethylene was the primary end product of TCE reduction. Similarly for Fe/Ni, increasing rates of degradation were observed with increasing amounts of nickel with a maximum degradation rate constant of about 30 times higher than that of ZVI alone. However, the amount of nickel needed to reach the maximum rate was only 0.25 %. When copper and nickel were plated onto iron, the maximum reaction rate constant was approximately 50 times higher than that of ZVI. The maximum degradation of TCE was observed for a copper and nickel content of 4.17 % and 0.40 %, respectively. The experimental results indicated that TCE degradation was enhanced by more than one order of magnitude when copper and/or nickel was plated onto the zero-valent iron. However, copper or nickel plated onto iron by the elctrodeless process was found to leach out during the reaction which may, in turn, impact the contaminated water.

Viscosity and electrical resistivity of Al-Li melts

The kinematic viscosity and electrical resistivity of Al-Li alloys in the liquid state are studied by a combined electrodeless method. Some theoretical calculations performed to determine the viscosity and electrical resistance by comparing the calculated and experimental data are estimated.

Ambipolar-transporting coaxial nanotubes with a tailored molecular graphene–fullerene heterojunction

Despite a large steric bulk of C(60), a molecular graphene with a covalently linked C(60) pendant [hexabenzocoronene (HBC)-C(60); 1] self-assembles into a coaxial nanotube whose wall consists of a graphite-like pi-stacked HBC array, whereas the nanotube surface is fully covered by a molecular layer of clustering C(60). Because of this explicit coaxial configuration, the nanotube exhibits an ambipolar character in the field-effect transistor output [hole mobility (micro(h)) = 9.7 x 10(-7) cm(2) V(-1) s(-1); electron mobility (micro(e)) = 1.1 x 10(-5) cm(2) V(-1) s(-1)] and displays a photovoltaic response upon light illumination. Successful coassembly of 1 and an HBC derivative without C(60) (2) allows for tailoring the p/n heterojunction in the nanotube, so that its ambipolar carrier transport property can be optimized for enhancing the open-circuit voltage in the photovoltaic output. As evaluated by an electrodeless method called flash-photolysis time-resolved microwave conductivity technique, the intratubular hole mobility (2.0 cm(2) V(-1) s(-1)) of a coassembled nanotube containing 10 mol % of HBC-C(60) (1) is as large as the intersheet mobility in graphite. The homotropic nanotube of 2 blended with a soluble C(60) derivative [(6,6)-phenyl C(61) butyric acid methyl ester] displayed a photovoltaic response with a much different composition dependency, where the largest open-circuit voltage attained was obviously lower than that realized by the coassembly of 1 and 2.

Non-resonant, electrode-less method for measuring the microwave complex permittivity of ferroelectric thin films

A procedure is described for measuring the complex permittivity of dielectric thin films with relatively large dielectric constants (ε: about 102–104) and considerable losses (tan δ: about 10−3–1). The ferroelectric films studied here are deposited on a relatively low-ε dielectric substrate and placed in the centre of a rectangular waveguide parallel to the direction of wave propagation. The dielectric constants and losses of thin films are determined not by the shift of the resonant peak, but by numerical analysis of measured scattering parameters using a vector network analyser. The proposed method does not require electrode deposition on the film surface, and provides the natural properties of the film without complications due to conductive electrodes and their interfaces.

What is new on the levitation front?

The principles for simultaneous measurements of the electrical conductivity and the permeability of materials ranging from ionic to semiconductors to insulators, using a non-invasive, electrodeless method, are presented succinctly. Recent results obtained for a variety of materials at room temperature and at the melting point illustrate the validity of the method. Special emphasis will be given to the fact that transport properties are now accessible over a regime of temperature never achieved before. Of particular interest is the fact it is now possible to monitor the inductance as a function of cooling, allowing a determination of changes accompanying the electrical properties and the magnetisation in the liquid and supercooled states.

The electrical conductivity of levitated liquids

The electrical conductivities of aerodynamically levitated liquid spheres have been determined by an electrodeless method. It is shown that this technique is reliable over a wide range of temperatures; results are presented for a variety of systems including metals, semiconductors at room temperature and at their melting points, and solid and liquid Al2O3.

Dielectric spectroscopy of biological cells

In this paper, we describe some applications of dielectric spectroscopy to studies of the internal structure of biological cells, monitoring of cell growth in fermentation and imaging of biological cells. The composite cell models proposed for biological cells, including intracellular organelles, successfully simulate the dielectric behavior of lymphocytes and plant protoplasts. A new electrode-less method based on electromagnetic induction has been demonstrated to be a powerful method for the dielectric monitoring of cell growth in whisky and beer fermentation. The scanning dielectric microscope is a promising tool for dielectric imaging of biological cells.

Electrodeless measurement of RF dielectric constant and loss

A new electrodeless method is developed for RF dielectric constant and loss measurements. In the new method a sample coil is used instead of a conventional parallel plate capacitor sample cell. The changes in coil impedance due to the sample placed inside the coil are measured by a Q-meter. This method is not as accurate as previous methods but is convenient and mostly applicable to studies of polar liquids and solutions. Test measurements are made with various measuring conditions. An example application to glycerol-water mixtures verifies its applicability.

Electrodeless measurement of ionic conductivity of RbAg4I5: Temperature dependence

An electrodeless method has been applied to the measurement of an ionic conductivity of a single crystalline RbAg4I5 as a function of temperature. The activation energy obtained by this method is in good agreement with those of earlier works.

Electrodeless Method for Measuring Photoconductivity Spectrum of Heat Treated Silicon

An electrodeless method for measuring photoconductivity spectra using microwave (10 GHz) absorption has been applied to high-resistivity silicon heat-treated at high temperatures. Experimental results show that this method is useful for measuring the photoionization energies for several kinds of defects, especially in high-resistivity materials.

Electrodeless method for the measurement of ionic conductivity of RbAg4I5

An electrodeless method has been developed for measuring an ionic conductivity of a superionic conductor. This technique allows us to obtain an intrinsic ionic conductivity, free from the ambiguous electrode–specimen interface problem. In principle, the application of alternating magnetic field to the pelletized RbAg4I5 specimen induces ionic current. The ionic conductivity of the specimen can be evaluated from the magnetic field generated by the ionic current. A AgI specimen is used to calibrate the measuring system. The ionic conductivity of RbAg4I5 measured by this method is in good agreement with those of earlier works.

A Passive Electrodeless Method for Determining the Interior Field of Biological Materials

A passive remote-sensing method is proposed for the measurement of the electric-field distribution within a biological sample. The instrument analyzes the intermodulation spectrum reradiated by a diode imbedded within the sample exposed to a dual-frequency illumination. Experimental results in a waveguide system indicate that the relative intensities of the intermodulation products are a unique function of the field intensity at the diode. These results are also used to determine the basic scattering properties of the diode. A low-power free-space apparatus is described which exposes the principal problem associated with this method: the inadvertent generation of intermodulation frequencies. Isolation techniques are described which eliminate this problem. Finally, an analysis of a complete system shows that at 910 MHz fields can be measured in 4.0 cm of soft tissue, tan delta = 0.5, without exceeding an incident power density of 10 mW/cm/sup 2/.

Difference-field method for determining electrical conductivity.

An electrodeless method for determining electrical conductivity at various frequencies is presented. Two sinusoidal magnetic fields of equal amplitude and a constant phase displacement of 180 degrees are balanced, and the resultant eddy current field perturbation produced by the insertion of a sample in a specified region of the system is measured. A mathematical expression relating the conductivity of the sample to the circuit parameters is derived and tested on a system of equivalent 'sample loops' whose conductivities are known for annuli of samples placed in the position of the same loop. Also presented are preliminary results obtained for determination of conductivities of aqueous solutions of hydrochloric acid by the 'difference-field method'.