Masahiro Tawata

Virus-templated photoimprint on the surface of an azobenzene-containing polymer.

A photoimprint-based immobilization process is presented for cylindrical viruses on the surface of an azobenzene-bearing acrylate polymer by using atomic force microscopy (AFM). Tobacco mosaic virus (TMV), 18 nm in diameter and ca. 300 nm in length, was employed as a model virus. First, a droplet of an aqueous solution containing TMV was placed on the acrylate polymer surface. After drying the droplet, the polymer surface was irradiated with light at a wavelength of 470 nm from blue-light-emitting diodes. Finally, the surface was washed by aqueous solution with detergents. The polymer surface was observed at each step by AFM. TMV was shown to embed itself gradually on the polymer surface during photoirradiation in a time scale of tens of minutes because of the formation of the surface groove complementary to the shape of TMV. Analysis of immobilization efficiency of TMV on the polymer surface by the immunological enzyme luminescence indicated that efficiency increased proportional to the photoirradiation time. In these experimental conditions, the absorption band of the azobenzene moiety remained constant before and after the photoirradiation. These results show that TMV is physically held on the complementary groove formed on the polymer surface by the photoirradiation.

Area-selective photoimmobilization of a two-dimensional array of colloidal spheres on a photodeformed template formed in photoresponsive azopolymer film

We demonstrate that colloidal spheres can be arrayed on an azobenzene-containing polymer film, which has been patterned such that it forms a template, and that in a subsequent step, the spheres can be selectively photoimmobilized on the film. The steps were made possible by utilizing two photoresponsive properties of the polymer. The first is photoinduced surface deformation, which provides a patterned indented template. The spheres were organized on the surface in accordance with the template structure. The second is photoinduced immobilization, where small objects on the film are immobilized after irradiation. The area-selective immobilized patterns were obtained after washing.

Phase-hologram material by using four-center-type photopolymerization in the crystalline state

A new dry-process recording material using photopolymerization in the crystalline state is proposed as an ideal material for holographic interferometry, especially for real-time holographic interferometry. The performance of the complex recording material comprising m-PDA as a photopolymerizing reactant and picramide as a spectral sensitizer were evaluated. The development of this complex recording material is accomplished simply by heating it; fixation occurs at room temperature. We were able to make a holographic grating with resolution up to 1930 lines per millimeter using this material with a He-Cd laser oscillating at 442 nm. The maximum diffraction efficiency and the sensitivity corresponding to a 30% diffraction efficiency as a volume phase hologram were estimated as 36.3% and 5.6 mJ/cm2, respectively.

Dry formation of a fatty acid crystallized thin film and application as an electron beam resist

Abstract A crystalline fatty acid film was formed by vacuum evaporation and evaluated as an electron beam resist. For an actual process, a double-layer dry resist process using evaporated fatty acid and aluminium was proposed for fine pattern fabrication. A pattern of 4 μm lines and spaces was successfully fabricated.

Effect of laser irradiation on evaporated stearic acid

Abstract A thin stearic acid layer consisting of microcrystalline grains a few micrometres in diameter was formed by vacuum evaporation onto a metal-coated glass substrate at room temperature. The layer was maintained at a controlled temperature and then melted by laser beam irradiation at a wavelength of 633 nm; the melted grains recrystallized to give larger planar crystallites. The effects of laser annealing were influenced by impurities in the stearic acid, the type of substrate, the scanning conditions and the substrate temperature. When a metal-coated substrate with “grooves” was used, the size of the recrystallized stearic acid crystallites was larger than for a plane substrate.

Totally Dried Three‐Layer Resist Process Using Evaporated Fatty Acid

A totally dried three-layer resist process using evaporated fatty acid was proposed for fine pattern fabrication. Oriented thin film of stearic acid or ω-tricosenoic acid was formed on an aluminum-evaporated substrate by evaporation using a furnace with an orifice of a few millimeters in diameter. Electron-beam delineation was performed on the film and a 2-μm line and space negative pattern was developed successfully by heating the substrate and transferring it to aluminum by chlorine gas-etching through the resist window. The pattern on aluminum was transferred successfully to the third layer of polymer by oxygen plasma-etching

Measurement of SAW Propagation Properties Using a Laser Probe

Measurements of surface acoustic waves (SAW) propagation properties such as amplitude profiles and phase and group velocities on LiNbO3 have been done using a very stable and highly sensitive laser probe which is a type two-beam interferometer with minimum detectable SAW amplitude 8×10-3 A at 56 MHz on 127.86° rotating Y-cut LiNbO3. Amplitude profiles are measured for two types of interdigital transducers (IDT) with ten parallel finger pairs and ten circular-arc finger pairs. Results of phase velocity measurements are shown on a table and compared with the literature1) for certain orientations of LiNbO3 or LiTaO3.

Evaporated Fatty Acid Resist Process

Double layer resist process using fatty acid and Al was proposed for fine pattern fabrication. Oriented thin films of stearic acid and w-tricosenoic acid were formed on an Al evaporated substrate by evaporation using a furnace with an orifice of a few mm diameter. Electron beam exposure characteristics of the films were studied and 2um L/S pattern was successfully developed by heating the substrate and C12 etching of Al.

Effects of surface tension of substrate on annealing of evaporated stearic acid film

Stearic acid layers in the form of microcrystalline grains were formed by a vacuum evaporation method on several kinds of substrates. By annealing, the layer of microcrystalline grains was reformed into a plane crystalline film on the hydrophobic surface of plasma‐polymerized methane and evaporated gold with water contact angles larger than 30°. However, the crystalline film was not formed on the hydrophilic surface of oxygen plasma‐treated plasma‐polymerized methane, mica, and glass with water contact angles smaller than 18°.

Plane crystalline films of stearic acid and ω-heptadecenoic acid as electron-beam resist

Plane crystalline films of stearic acid and ω‐heptadecenoic acid were formed by annealing evaporated microcrystalline films and evaluated as an electron‐beam resist. The stearic acid film showed positive patterns at doses higher than 100 μC/cm2. For the ω‐heptadecenoic acid film exposed at a minimum dose of 7 μC/cm2, negative patterns were developed by heating in a vacuum. Positive patterns were also formed at doses higher than 100 μC/cm2.