Goro Matsumoto

Dielectric properties of europium oxide films

Abstract We have investigated the dielectric properties of europium oxide films for use in thin film capacitors. Annealing is found to improve the dielectric properties of these films owing the recovery of stoichiometry in the films.

Electrical properties of glassy-carbon electrodes

Some electrical properties of the glassy-carbon electrode are presented. The electrode impedance is inversely proportional to the measurement frequency. The glassy-carbon electrode has pH sensitivity. The polarisation characteristic is given. To analyse these results, it is better that the adsorption of ions on the surface of the electrode is taken into consideration. This is inferred from XPS spectra.

Dependence of Electrical Conductivity on Fixed Charge Density in Articular Cartilage

A new system for measuring the resistivity of articular cartilage is based on the four-point probe technique. The system measures resistivity as a function of depth from the articular surface. The measurements obtained showed that the conductivity, kappa, of articular cartilage equilibrated in Ringers solution (pH, 7.4) is constant in all zones, with a value of 6-10 X 10(-3) mho/cm. Conversely, kappa of articular cartilage equilibrated in distilled water varies distinctly, being low in the superficial zone (about 0.7 X 10(-3) mho/cm) and high in the middle to deep zone (about 3 X 10(-3) mho/cm). This is almost the same variation shown by the fixed charge density, FCD, which was measured by the tracer cation method; a linear correlation between kappa and the FCD was found (correlation coefficient, 0.88). These observations were well understood based on the Donnan equilibrium; the mobility of Na+ in cartilage was thought to be independent of FCD.

Negative resistance in ion−implanted Al−Al2O3−Au junctions

Conduction has been investigated in Al−Al2O3−Au sandwiches whose oxide is implanted with O or Al ions. The results reveal that ion implantation gives a junction type which can be electroformed, and which exhibits negative resistance in air at atmospheric pressure.

Visualization of electric fields around a biological body

A system was developed that can visualize the spatial distribution of the ELF (extremely low frequency) electric field around an object with a complex shape such as a biological body. A mechanical X-Y scanner controlled by a microcomputer moves an optical sensor, automatically scanning the space around the object. The measured data are processed and the field distribution is represented in a color distribution pattern. Using an object with a simple shape such as a cylinder, the accuracy of the measurement was confirmed by comparison to a numerical calculation. The field distributions around experimental animals (a rat and a cat) were measured and it was shown that a conductor model can be used instead of a living body in the ELF range. The field distribution around a human model was measured in various postures, showing reasonable agreement with measurements for a real human body standing under transmission lines.<<ETX>>

Fundamental study on measurement of ELF electric field at biological body surfaces

In a study of biological effects of extremely-low-frequency (ELF) electric fields, a few techniques were developed which make it possible to measure the electric field at a biological body surface with practical accuracy and spatial resolution. The following techniques were developed: pressing down a field sensor against the body surface using a thin flexible sensor: and covering the body surface with a conductive layer while leaving the point of measurement uncovered. The characteristics of these techniques were also examined with a view toward practical applications, such as the measurement of the electric field at a human surface located under high-voltage transmission lines. >

Electrical properties of the carbon fibre electrode and its application

IN recent years, several new materials for industrial application have been developed. Carbon fibre as a structural material is a new one in this field. Carbon fibre has high stiffness, a high tensile strength and is suitable for use as a composite material and as carbon fibre reinforced plastic. Carbon fibre is used as a harness of artificial arms because of its strength (RING et al., 1971). In addition to these properties, carbon fibre has good conductivity. The electrical potential response of a single carbon fibre (7t~m in diameter) to pH changes in an aqueous electrolyte solution was examined by V. J. Jennings (JEr,rNINGS et al., 1975), who found a linear relationship between the potential and pH, with a slope of abodt 50 mV/pH at about 20~ They concluded that the, single carbon fibre electrode is very useful for titrations of small volume of liquids. In view of their results, studies of the biomedical applications of carbon fibre were made. In this note, the experimental results are concerned with the investigation of the impedance and the polarisation characteristics of the carbon fibre. An application associated with a recording electrode for the e.e.g, signal is presented.

A study of gold migration in Au-Y2O3-Y junctions by secondary ion mass spectrometry

Abstract Secondary ion mass spectrometry has been used to detect the migration of gold from the electrode into the oxide layer of Au-Y 2 O 3 -Y junctions during the electroforming process. The depth profiles obtained showed an increase of gold migration after the development of conductivity and again after the appearance of a voltage-controlled negative resistance when a forming voltage was applied. The results are discussed in terms of localized conduction at defects which are observed on the junction surface.