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In this paper, we report on the demonstration of a portable immunoassay system consisting of a small centrifugal microfluidic device driver (bento box) and a centrifugal microfluidic device made of polypropylene and fabricated by injection molding. The bento box consists of a cheap DC motor and an Arduino microcontroller. It has a simple structure and is the size of a bento box, that is, 150 × 150 × 100 (W× D× H) mm3. The developed device can automatically execute an enzyme-linked immunosorbent assay (ELISA) process under a steady rotating condition because it was designed based on the principle of CLOCK, which we previously presented. Here, we first executed an ELISA using a system consisting of the bento box and a device made of polydimethylsiloxane (PDMS) and compared it with a servo-controlled device driver. It was confirmed that the results of the bento box were consistent with those of the servo-controlled device driver. The limit of detection (LOD) using the bento box was 0.759 ng ml−1. Therefore, the controllability of the bento box was demonstrated. Next, we evaluated the injection-molded device through multi-step fluid control. We confirmed, through real-time observation of the device, that accurate flow control in the designed ELISA procedure was executed. Lastly, ELISA was employed for the measurements of mouse IgG using the system consisting of the bento box and the polypropylene device. The system performed all fluidic controls within 12 min; we confirmed the specificity of the system, and the LOD was 0.320 ng ml−1.

A micromixer based on a surface acoustic wave (SAW) has attracted a great deal of attention because of their ability to mix liquids and multiphase flows with very high mixing efficiency. However, since microfluidic channels cloud only be formed directly on the piezoelectric substrate in conventional SAW devices, contamination problems have arisen. In this study, by placing a solution that propagates sound waves between the microfluidic channel and the SAW excitation substrate, vibrations caused by SAWs are propagated into the micro-well to form a micro-mixing system. This system can provide a micromixer that is removable, replaceable, and contamination-free.

The formation of biofilm on graphene materials was investigated in this study. Two kinds of laboratory biofilm reactors were used to produce biofilms artificially on glass specimens (on the laboratory scale). One of them was a loop-type and the biofilms were measured by Raman spectroscopy. The other one was the static immersion test in a culture containing bacteria. The biofilm formation was evaluated by using crystal violet. We expected that the graphene would have a strong resistance against biofilm formation. However, on the contrary, graphene tended to become more sensitive to biofilm formation when the portion of graphene increased. When we come to think about the future application for graphene, it should not be used for biomaterials, but as sensor for infectious diseases.

A transparent, optically observable microfluidic device for microwave-induced chemical reactions using 24.125 GHz ISM band incorporating was developed. The microfluidic channels can pass through gaps in the post-wall waveguide. The post-wall waveguide allows microwave irradiation to be applied to designed area of the microfluidic channel. In this study, Polydimethylsiloxane (PDMS), commonly used in microfluidic devices, was used as the microwave waveguide material. A glass plate sputtered with indium tin oxide was used to shield microwave leakage to the top and bottom. 4 W of microwave input power was used to heat ethylene glycol, which is used as a solvent in chemical synthesis, in the channels of the fabricated device, and a temperature rise to 100 °C was observed in 70 s. We believe that the use of PDMS as a waveguide material will facilitate observation during microwave irradiation using optics and combination with other microreactors.

This study reports the first demonstration of an enzyme-linked immunosorbent assay (ELISA) using a microfluidic device that was fabricated in a three-dimensional (3D) printer. The centrifugal microfluidic device is driven by a mini-centrifuge realized fluidic control for the ELISA, including the injection of a reagent, incubation and reaction, and washing and draining of the reagent, by simply applying the reagent and spinning the device. The analysis of the reaction was accomplished by smartphone-based colorimetric measurements using a free application, and the results suggest that the microfluidic device followed by the use of the smartphone application showed a detection limit (0.89 ng ml−1) that was comparable with conventional absorbance measurements (0.96 ng ml−1) using a plate reader. Therefore, our results suggest that widely available equipment, such as mini-centrifuges, smartphones, and, in the near future, 3D printers, can potentially contribute to the commercialization of the microfluidic immunoassay system.

Rapid and sensitive chemical sensing using a microfluidic device equipped with a sterically bulky three-dimensional gold nanostructure (Au3D) was demonstrated. Au3D was expected as a surface-enhanced Raman scattering (SERS) active structure. Au3D was fabricated by convective self-assembly, known as a “coffee-ring”, of the mixed solution of gold colloidal nanoparticles and polystyrene latex particles. SERS measurements of a trace amount of 4,4$'$-bipyridine (4bpy) in aqueous solution were performed using Au3D in batch and flow format, and typical spectra of 4bpy with enhanced peaks were immediately observed after dropping (batch) or injecting (flow). While the detection limit was about the 10 nM 4bpy in batch measurement, the detection of a further enhanced spectrum of 1 nM 4bpy was accomplished in flow measurement. We confirmed that Au3D was available for convenient SERS optofluidic measurement.

Microfluid filters were fabricated, which possessed 2,100 cylindrical through-bores (φ40 μm) in 200 μm-thickness polymethylmethacrylate (PMMA) sheets (φ3 mm), by deep X-ray lithography using synchrotron radiation. To evaluate the microfluid filters as a device for an immunoassay, we bound the goat anti-mouse immunogloblin G (IgG) antibody to the surface of the filters, and set the filters between reaction vessels stacked vertically in a microreactor. An enzyme-linked immunosorbent assay (ELISA) of mouse IgG using the goat anti-mouse IgG/horseradish-peroxidase (HRP) conjugate indicated that mouse IgG could be quantitatively detected in the range of 0–100 ng/ml, demonstrating the applicability of vertical microfluidic operation to the immunoassay.

In the present paper, a study was undertaken of molecular transport in ploy(dimethylsiloxane) microchannels that were fabricated by ultraviolet (UV)-photolithography and synchrotron radiation (SR)-lithography characterized and compared for microchip capillary electrophoresis by evaluating in-channel molecular dispersion. A fluorescent tag, sulforhodamine B was used as the probing molecule. It was found that microchannels made by SR-lithography fabrication were superior to those made by UV-photolithography fabrication in terms of molecular transport performance. A deep insight into surface conditions characterized by scanning electron microscopy suggested it was related to the difference in surface roughness. Chromatographic retention in electropherograms further supported such a conclusion, which depended on the phase ratio of the channel surface. The results revealed for PDMS microchannels in this work were in good agreement with the phenomenon found for glass microchannels in the literature.

In the present paper, a study was undertaken of molecular transport in ploydimethylsiloxane microchannels that were fabricated by ultraviolet UV-photolithography and synchrotron radiation SR-lithography characterized and compared for microchip capillary electrophoresis by evaluating in-channel molecular dispersion. A fluorescent tag, sulforhodamine B was used as the probing molecule. It was found that microchannels made by SR-lithography fabrication were superior to those made by UV-photolithography fabrication in terms of molecular transport performance. A deep insight into surface conditions characterized by scanning electron microscopy suggested it was related to the difference in surface roughness. Chromatographic retention in electropherograms further supported such a conclusion, which depended on the phase ratio of the channel surface. The results revealed for PDMS microchannels in this work were in good agreement with the phenomenon found for glass microchannels in the literature.

Multilayer structures of tungsten and beryllium were synthesized onto flat silicon single-crystal substrates by the neutral atom beam sputtering technique. Structures of constituent tungsten and beryllium thin films were evaluated. The standard deviation of the interface roughness of the multilayer was estimated to be ~2.5 Å. Reflectivities of multilayer mirrors were measured at a grazing incidence of 5.0°. The observed reflectivity of 30% at 1055 eV was in good agreement with the calculated value considering the interface roughness and oxygen contamination for a tungsten–beryllium structure having a period of 77.0 Å.

Multilayer structures of tungsten and beryllium were synthesized onto flat silicon single-crystal substrates by the neutral atom beam sputtering technique. Structures of constituent tungsten and beryllium thin films were evaluated. The standard deviation of the interface roughness of the multilayer was estimated to be ~2.5 Å. Reflectivities of multilayer mirrors were measured at a grazing incidence of 5.0°. The observed reflectivity of 30% at 1055 eV was in good agreement with the calculated value considering the interface roughness and oxygen contamination for a tungsten-beryllium structure having a period of 77.0 Å.

The suppression and removal of contaminants on X‐ray masks are required for the application of X‐ray lithography to practical semiconductor production, because contamination is easily transferred to the replicated resist patterns and degrades the LSI patterns. In order to study contamination of a Ta/SiN X‐ray mask, its growth process was investigated using an atmospheric reaction chamber and in situobservation apparatus for gases at atmospheric pressure. It was found that the contamination particles were ammonium sulfate and oxalate. The sources of the salt particle were also identified.

A beamline especially designed for atmospheric photochemical reactions has been constructed at the NTT synchrotron radiation facility. By inserting a buffer helium chamber with Be and Si3N4partition windows between the beamline and the reaction chamber, studies can be performed without the differential pumping systems normally used in existing photochemistry beamlines. The reaction chamber is equipped with a gas supply system and analysis systems to investigate gas‐phase and surface reactions. Purging using dry purified gases in combination with water‐bubbling gives effective control of water concentration in the reaction chamber.

The formation of biofilm on graphene materials was investigated in this study. Two kinds of laboratory biofilm reactors were used to produce biofilms artificially on glass specimens (on the laboratory scale). One of them was a loop-type and the biofilms were measured by Raman spectroscopy. The other one was the static immersion test in a culture containing bacteria. The biofilm formation was evaluated by using crystal violet. We expected that the graphene would have a strong resistance against biofilm formation. However, on the contrary, graphene tended to become more sensitive to biofilm formation when the portion of graphene increased. When we come to think about the future application for graphene, it should not be used for biomaterials, but as sensor for infectious diseases.

The potential to fabricate metallic nanoparticles directly on silicon substrates from liquid solutions is ideal for three-dimensional lithography systems, drug delivery materials, and sensing applications. Here, we report the successful synthesis of Au, Cu, and Fe nanoparticles from the corresponding liquid solutions [gold(I) trisodium disulphite, copper(II) sulfate, and potassium ferricyanide] by synchrotron (SR) X-ray irradiation. The deposition of gold nanoparticles in the gold(I) trisodium disulphite solution was performed by monochromatic X-ray exposure from synchrotron radiation. The use of ethanol as an additive enabled the nucleation and growth of Cu particles, while no Cu particles were produced in the copper sulfate solution without ethanol with polychromatic SR X-ray irradiation. Fe particles were generated by direct polychromatic SR X-ray irradiation. These results demonstrate the behavior of three-dimensional printers, enabling us to build composite material structures with metallic and plastic materials.

This paper presents strategies that attempt to solve two key problems facing the commercialization of microfluidics: cost reduction in microfluidic chip manufacturing and microfluidic device driver development. To reduce the cost of microfluidic chip manufacturing, we propose to use of three-dimensional (3D) printers for direct digital manufacturing (DDM). An evaluation of 3D micro-scale structure printing using several 3D printers is reported, and some of the technical issues to be addressed in the future are suggested. To evaluate micro-scale printing, three types of 3D printers, with the ability to print structures on the scale of several hundred meters, were selected by first screening six 3D printers. Line and space patterns with line widths of 100-500 um and an aspect ratio of one were printed and evaluated. The estimated critical dimension was around 200 um. The manufacturing of a monolithic microfluidic chip with embedded channels was also demonstrated. Monolithic microfluidic chips with embedded microchannels having 500 x 500 and 250 x 250 um2 cross sections and 2-20 mm lengths were printed, and the fidelity of the channel shape, residual supporting material, and flow of liquid water were evaluated. The liquid flow evaluation showed that liquid water could flow through all of the microchannels with the 500 x 500 um2 cross section, whereas this was not possible through some of the channels with the 250 x 250 um2 cross section because of the residual resin or supporting material. To reduce the device-driver cost, we propose to use of the centrifugal microfluidic concept. An autonomous microfluidic device that could implement sequential flow control under a steadily rotating condition was printed. Four-step flow injection under a steadily rotating condition at 1500 rpm was successfully demonstrated without any external triggering such as changing the rotational speed.

Amino acid precursors are synthesized from an N2, CO2and H2O vapor mixture by synchrotron radiation induced photochemical reactions at atmospheric pressure and at room temperature. It was found that the alanine and aspartic acid in the precursors are enriched in the L-isomer by about 15% over the antipodal D-isomer.

Si films were grown on Ge substrates by Synchrotron Radiation (SR)-excited crystal growth around the low substrate temperature limit for epitaxial growth. From the observation of Reflective High Energy Electron Diffraction and Raman scattering spectra, it was found that the crystallinity of the Si film was clearly improved by SR irradiation. From the temperature dependence of the growth rate, it was confirmed that SR irradiation greatly enhances the growth rate in the lower temperature region below 500°C.