Seimei Sha

Thin film characteristics of fluorine-substituted monolayers prepared by chemical adsorption from solution

Abstract Monolayers containing a fluorine-substituted carbon chain were prepared by the chemical adsorption (CA) technique. Characteristics of the monolayers were evaluated by spectroscopy, copper decoration technique, current-voltage characteristics (current density and resistivity), measurement of the contact angle, and friction tests. By the copper decoration technique, the CA monolayer was more pinhole free and uniform than a Langmuir-Blodgett film. The characteristics (such as the leakage current density, resistivity, critical surface tension and coefficient of kinetic friction) of the fluorine-substituted monolayers depended markedly on the number of substituted fluorine atoms.

Formation of electrically conducting polypyrrole fine lines in arachidic acid Langmuir-Blodgett films

A new method is proposed for preparing electrically conducting fine lines in Langmuir-Blodgett films: during transference of arachidic acid L film containing pyrrole monomers to an indium-tin-oxide (ITO)-coated glass substrate, a voltage was applied between the ITO and the platinum counterelectrode dipped in the water subphase. From microscopic observations and conductivity measurements, it was confirmed that conducting filaments of polypyrrole were formed by this new method along the contact line between the substrate and the water surface by electrochemical polymerization of pyrrole monomers in an arachidic L film.

Stable Potential Oscillation of Lipid Membrane Supported by a Micropore

A rhythmic, sustained, stable potential oscillation was reproducibly observed for a lipid membrane supported by a micropore of a thin membrane tip micropipette. Amplitude and period of the oscillation voltage was controlled by changing the pore diameter. The relationship between oscillation period and pore diameter when the pore diameter was below 8 µm was different from that when the diameter was larger than 8 µm.

Electrical evaluation of ultrathin organic films on solid substrates

Abstract We established two evaluation methods for monolayer-order organic films on solid substrates and evaluated various kinds of films, i.e. Langmuir-Blodgett films of monoalkyl lipids, dialkyl lipids, dialkylsilane, and fluorocarbon, and chemically adsorbed films of three kinds of trichlorosilane compounds. One method is the measurement of the electroplating current during copper decoration, and the other the measurement of I–V characteristics using a micromanipulating mercury probe. Electrical characterization of the films with monolayer-order thickness is possible by using both types of liquid top electrodes, and a clear dependence of the electrical properties on monolayer number has been found quite reproducibly.

Dynamic Behavior of Lipid across a Micropore during Self-Excited Potential Oscillation

This letter reports observation with an optical microscope on dynamic behavior of a lipid across the oil/water interface, which are formed at a micropore of 2 µm in diameter during self-excited potential oscillation. Periodical movement of dome-shaped body on the interface is observed, and its expansion and shrinkage are quite synchronous with the potential oscillation.

Self-excited potential oscillation of lipid across a micropore controlled by hydrostatic pressure

Effects of the hydrostatic pressure difference across the oil to water interface on a self-excited potential oscillation at a micropore have been investigated by potential measurement and microscopic observation. The amplitude and frequency of the oscillation are precisely controlled by means of changing the hydrostatic pressure. This effect of hydrostatic pressure is due to the change in the diameter of a dome that is built at the micropore. These results are qualitatively consistent with our previous ones [Jpn. J. Appl. Phys. 30 (1991) L1435]; i.e., the self-excited potential oscillation can be controlled through changes in the shape or the size of the interface.

Membrane oscillator as chemical sensor - Part 2: Stable potential oscillation of lipid membrane across a micropore

A rhythmic, sustained, stable potential oscillation was reproducibly observed for a lipid membrane supported by a micropore of a thin membrane tip micropipet. Amplitude and period of the oscillation voltage were controlled by changing the pore diameter. The smaller the hole diameter, the smaller the amplitude and the period became. We call this relationship “size effect.”We observed with an optical microscope dynamic behavior of lipids across the oil/water interface, which are formed at a micropore of 2 μm in diameter during self-excited potential oscillation. Periodical movement of a dome-shaped body on the interface is observed, and its expansion and shrinkage are quite synchronous with the potential oscillation.We also applied this self-excited potential oscillation device as a chemical sensor, and reported the effect of chemical substance added into the water phase as a model for the biological chemoreceptive membrane. The experimental results of microscopic observation show that the sensing system using the micropore can distinguish different chemical substances as well as their concentrations, suggesting its application as a chemical sensor.

Membrane oscillator as a chemical sensor - Part 1: Fabrication of TM pipet

A rhythmic, sustained, stable oscillation was reproducibly observed for a lipid membrane supported by a micropore of a thin membrane tip micropipet (TM pipet). The construction of the TM pipet was accomplished by implementing a microfabrication method that allowed the transference of a Si3N4 film with a hole from the Si substrate to the glass tube tip. The main part of the fabrication method is the sealing process: a mix between thermal and amodic bonding. The TM pipet fabrication is described in detail with emphasis on the thermal-anodic bonding process. In addition, a general account of the new devices main features, including various applications, is given.

Self-excited oscillation device of lipid across a micropore and its dynamic behavior

A rhythmic, sustained, stable potential oscillation was re producible observed for a lipid membrane supported by a micropore of a thin membrane tip micropipette. Amplitude and period of the oscillation voltage was controlled by changing the pore diameter. In order to clarify the mechanism, the dynamic behavior of a lipid across a micropore during the self-excited potential oscillation phenomenon was observed by an optical microscope. The potential change during self-excited oscillation was quite synchronous with the expansion and shrinkage of the domelike lipid aggregate formed in the water phase.