Toshihiko Sakuhara

In-situ monitoring of microrheology on electrochemical deposition using an advanced quartz crystal analyzer and its application to polypyrrole deposition

Abstract This paper introduces a technique for studying the microrheology of a thin film on a quartz crystal by considering the contrast of the resonant frequency change and resonant resistance change of the quartz crystal. An advanced measuring system was developed for the in-situ measurement of the resonant resistance on the electrochemical reaction. The system was used to monitor polypyrrole deposition by cyclic voltammetry and the constant current method. In the electrochemical deposition, not only the resonant frequency change but also the resonant resistance increase was observed, i.e. the deposited film was a viscoelastic film. The resonant resistance was changed in the range of 100–600 Ω for the resonant frequency change of 10 000 Hz; it showed a small change in the early stage of film deposition which increased after a resonant frequency change of 5000 Hz. The swelling of the film was observed corresponding to the unusual resonant resistance increase for the constant current deposition of 6 mA cm −2 .

Control of structure in Langmuir-Blodgett films of terphenyl liquid crystal compound

Abstract The structure in monolayer assemblies of 4-cyano-4″-pentyl- p -terphenyl (C 5 TPCN) as a terphenyl liquid crystal compound has been investigated in relation to some electrical properties. We have found that the deposition types can be controlled by the surface conditions of the solid plates and mixing ratios with the cadmium arachidate (C 20 Cd). In the case of a 2:1 mixture of C 5 TPCN and C 20 Cd well-defined Y- and Z-type multilayers can be built up depending on the hydrophilicity of the solid surface. The molecular orientation in the multilayers was investigated by polarized UV spectra and the IR spectra. The results indicate that the terphenyl group is oriented nearly perpendicular to the film plane. From capacitance measurements, the dielectric constant for a multilayer of C 5 TPCN was found to be 5.77. Furthermore, the pyroelectric effect was observed with the Z-type multilayers of the 2:1 mixture and the pyroelectric coefficient was approximately 1 × 10 −10 C cm −2 K −1 at room temperature.

Development of a new type piezoelectric micromotor

We designed and fabricated a piezoelectric micromotor which has a new structure suited for miniaturization. The prototype piezoelectric micromotor we fabricated has 2 mm in diameter and 2 mm in height. It consists of a disk-shaped rotor, a cantilever stator and several oscillators with elements made by PZT ceramics. These elements are integrated into the prototype piezoelectric micromotor in a flat configuration. The rotor rotates at 50 to 450 rpm and a drive voltage ranging from 2 to 10 V/sub pp/.

Orientation control of liquid crystals by Langmuir-Blodgett films

Abstract Orientations of liquid crystals on modified surfaces with different chemical groups were investigated using Langmuir-Blodgett (LB) films, in order to clarify the alignment mechanism in liquid crystal cells. The surfaces, covered with carboxyl, hydroxyl, amine, cyano and alkyl groups, were prepared by combination of a conventional LB method and a horizontal lifting method. It has been found that the molecular alignment in liquid crystal cells depend on the dipole interaction term in the surface energy of the substrate film. LB films with polar groups, such as carboxyl and hydroxyl, at the outermost surface, used for the substrate, produced good liquid crystal cell properties, involving small pre-tilt angles, clear in-plane anisotropy of transmittance and sharp voltage response, as compared with polyimide films.

Fabrication of micro parts using only electrochemical process

We have investigated two kinds of electrochemical processes that scan a processing electrode to fabricate metal micro parts. They are, electroforming on the mold made by electrochemical processing, and shape forming by electrochemical processing after electroplating. An electroformed Ni gear with diameter of 600 /spl square/m and thickness of 100 /spl square/m was fabricated by the former method, and a Ni gear with diameter of 1700 /spl square/m and thickness of 30 /spl square/m was fabricated by the latter method.

Electrochemical and optical processing of microstructures by scanning probe microscopy (SPM)

Two micro processing techniques based on scanning probe microscopy (SPM) are described. One is electrochemical etching and deposition using a scanning tunneling microscope (STM). STM is very useful tool of nm-scaled observation, and it can be also used as precise positioner in micro processing. In micro electrochemical processing system, a potentiostat for processing is externally attached to STM system, a STM probe was set very closely to a metal substrate in electrolyte solution, and voltage was applied between the substrate and the probe. Then electrochemical reaction occurs in restricted area of the substrate. Therefore, micrometer-size structures are produced by faradic current. A line pattern, which is 200-300 nm in width and 100 nm in depth, was electrochemically etched. When polarity of applied voltage was inverted, a bump pattern, 300 nm in diameter, 200 nm in height, was electrochemically deposited. Another processing method is using a scanning near-field optic/atomic force microscope (SNOAM). The SNOAM provides simultaneous topographic and optical images with high resolution beyond the diffraction limit, better than 100 nm. The optical processing is demonstrated in the photoresist film by the SNOAM. We obtained pit and line patterns down to 100 nm in diameter and width, respectively.

Fabrication of optical micro-cantilever consisting of channel waveguide for scanning near-field optical microscopy controlled by atomic force

We developed a novel optical micro-cantilever for scanning near-field optical microscopy (SNOM), evaluated its mechanical properties, and applied it for SNOM. A cantilever-shaped channel waveguide with an aperture is bent and it is operated in atomic force mode. By combining the conventional lithography techniques and the waveguide bending process, we can fabricate a probe with the shape and the mechanical properties most desirable for given samples and conditions. Our optical micro-cantilever has resonance frequency similar to the conventional optical fiber probe, and it has a spring constant much smaller. We used this optical micro-cantilever for SNOM in contact mode, and confirmed that it gives optical images with a resolution beyond the diffraction limit.