Akihiro Miyauchi

Cell Culture on Nanopillar Sheet: Study of HeLa Cells on Nanopillar Sheet

This is the first report of the successful culturing of HeLa cells on nanopillar sheets–a new type of cell culture dish–in a different way from that on flat petri dishes. Nanopillar sheets were fabricated with a high-aspect ratio structure with a diameter of 80–1000 nm and a height of 1–3 µm using nanoprint technology. Nanopillar structure with 500 nm diameter and 1 µm height enabled easy subculture of the cells from the sheets without the conventional trypsinization method. Moreover, the HeLa cells divided and proliferated on the sheets in the same way as on the flat surfaces with different manner of adhesion.

Nanopillar sheets as a new type of cell culture dish: detailed study of HeLa cells cultured on nanopillar sheets.

Nanopillar sheets were fabricated with high-aspect ratio structures with a diameter of 160–1000 nm and a height of 1 μm by nanoimprinting. The suitability of nanopillar sheets as a new type of cell culture dish was examined by studying the behavior of HeLa cells cultured on the sheets using light microscopy, scanning electron microscopy, and fluorescence microscopy observing actin and vinculin molecules. The nanopillar structure enabled easy subculture of the cells from the sheets without conventional trypsinization. Moreover, the HeLa cells divided and proliferated on the sheets in a different way to that found on petri dish because of the manner in which the cells adhered to the materials.

The Role of Hydrogen Radicals in the Growth of a-Si and Related Alloys

A new method of the preparation of a-Si and its alloys is proposed. The role of atomic hydrogen in the growth of a-Si:H:(F) films by the glow-discharge of a mixture of SiF4 and H2 is clarified. Amorphous Si:H:(F) films have been prepared in a plasma-free environment by employing long-lifetime radicals, i.e., atomic hydrogen and SiFn radicals. Highly photoconductive a-Si:H:(F) films and related alloys, viz. a-SiGex:H:(F) and a-SiCx:H:(F), have been obtained at high deposition rates with the result that each radical is controlled independently.

Enhancement of fluorescence intensity from an immunoassay chip using high-aspect-ratio nanopillars fabricated by nanoimprinting

High-aspect-ratio structures (nanopillars) were used to enhance the fluorescence intensity of immunoassay chips. Nanoimprinting with elongation phenomenon was applied to fabricate polystyrene nanopillars. Human alpha fetoprotein was detected by a fluorescence immunoassay protocol. Fluorescence intensities were evaluated for areas with nanopillars of different surface areas. The area with nanopillars of 95nm diameter and 4.1μm height showed fluorescence intensity 34 times higher than that of flat areas.

Interface impurities of low-temperature (900 °C) deposited Si epitaxial films prepared by HF treatments

Impurities at the interfaces of HF‐treated Si (100) substrates and Si films prepared by low‐temperature (900 °C) chemical vapor deposition using SiH2 Cl2 were measured by secondary‐ion mass spectroscopy. Si substrates were prepared by 49% HF, 5% HF, and 0.05% HF acid solutions and loaded into the growth chamber without a water rinse. Carbon, fluorine, oxygen and chlorine were detected at the interfaces for 49% HF and 0.05% HF treated substrates, but they were not detected for 5% HF‐treated samples. Desorption of the contaminants appeared to be sensitively related to a difference in chemical states of the HF‐treated surfaces.

Does the aquatic invertebrate nipple array prevent bubble adhesion? An experiment using nanopillar sheets

The nipple array is a submicrometre-scale structure found on the cuticle surfaces of various invertebrate taxa. Corneal nipples are an antiglare surface in nocturnal insects, but the functional significance of the nipple array has not been experimentally investigated for aquatic organisms. Using nanopillar sheets as a mimetic model of the nipple array, we demonstrated that significantly fewer bubbles adhered to the nanopillar surface versus a flat surface when the sheets were hydrophilic. Many more bubbles adhered to the hydrophobic surface than the hydrophilic surfaces. Bubbles on the body surface may cause buoyancy problems, movement interference and water flow occlusion. Here, bubble repellence is proposed as a function of the hydrophilic nipple array in aquatic invertebrates and its properties are considered based on bubble adhesion energy.

Ge fraction dependent improved thermal stability of in situ doped boron in polycrystalline Si1-xGex (0≤x≤0.5) films on SiON

Postannealing characteristics of in situ doped B atoms in poly-Si1−xGex (x⩽0.5) films on SiON have been investigated. Supersaturated electrically active B (2×1020cm−3) is obtained for as-chemical vapor deposition samples, and their thermal stability is significantly improved by increasing Ge fraction, e.g., the stability for poly-Si0.6Ge0.4 is ten times as high as that for poly-Si at 700–800°C. Such a Ge induced improvement will be a powerful tool to achieve poly-SiGe gate electrode for the next generation ultralarge scale integrated circuits. In addition, the deactivation process of electrically active B has been analyzed. Results indicated that deactivation processes consist of fast and slow processes. The former is due to movement of B atoms from substitutional to interstitial sites, which is enhanced by a local strain induced by the difference in atomic radii between Si and B atoms. The slow process was due to trapping of B at grain boundaries during grain growth. The two-state model based on the loca...

Hole Transport in a-Si:H(F) Prepared by Hydrogen-Radical-Assisted Chemical Vapor Deposition

The modes of hole transport in both non-doped and BF3-doped a-Si:H(F) films prepared by hydrogen-radical-assisted chemical vapor deposition (HRCVD) were investigated by the time-of-flight method. Non-dispersive transport was observed at temperatures above approximately 300 K, and dispersive transport below this temperature. The drift mobility conforms with a multiple-trapping model which assumes that the valence-band tail is distributed exponentially in terms of energy. The characteristic temperatures provided by this model, 310 K for non-doped a-Si:H(F) and 286 K for a-Si:H(F) doped using 30 ppm of BF3, are lower than the corresponding value for a-Si:H films prepared by an R.F. glow discharge of SiH4. This result shows that the distribution of valence-band tail states is narrower in the case of HRCVD. Sub-bandgap profiles based on the wavelength dependence of photoconductivity also reveal a decrease in the density of mid-gap states.

High-aspect-ratio nanopillar structures fabricated by nanoimprinting with elongation phenomenon

The authors found that fine pillar structures (nanopillars) with a high aspect ratio were formed by nanoimprinting with elongation phenomenon. Polymer nanopillars with higher aspect ratios than that of corresponding holes on the mold were obtained without any etching processes after nanoimprinting. The finest nanopillars were 95 nm in diameter and 4.1 μm high made of polystyrene. Elongated nanopillars of poly(methylmethacrylate) and polystyrene were confirmed. Elongation of nanopillars depended on process conditions such as the diameter of holes on the mold, the unmolding temperature, and the molecular weight of the polymer resin.

Fabrication of 200-nm Dot Pattern on 15-m-Long Polymer Sheet Using Sheet Nanoimprint Method

Nanoimprint technology is one of the more promising methods for nano-fabrication. The thermal nanoimprint method can fabricate various kinds of thermoplastic materials and its process consists of heating, pressing, cooling, and separation and a lot of research was reported. We proposed and developed a sheet nanoimprint system that enables for continuous treatment of these four basic steps by introducing a belt-shaped nano-mold. We tried to fabricate dot patterns on polymer films by using a sheet nanoimprint method in this work. A 200 nm in diameter and 240 nm tall dots (aspect ratio 1.4) were formed directly onto a 15-m-long polystyrene film. It is important in the field of industrial applications to fabricate nano-scale patterns over a large area with a high throughput. We demonstrated that the sheet nanoimprint is an attractive method for the direct patterning of nano-scale patterns on thermo-plastic films.