[Show abstract][Hide abstract] ABSTRACT: A study was performed to investigate the effects of the application of an atmospheric-pressure plasma jet during polycrystalline diamond (PCD) micro- end-milling. A comparison was made between SiC surfaces after milling, with and without the application of the plasma jet. The plasma jet was found to allow the formation of a high-quality surface with an average roughness (Ra) of 0.73 nm. The proposed plasma jet is highly effective in improving both the chip formation process, by imparting hydrophilicity to the tool and workpiece surfaces, and removing surface contamination at the tool edge during machining.
[Show abstract][Hide abstract] ABSTRACT: To fabricate novel micro-textured surfaces with valleys, dimples and plateaus as well as patterned composition as a strategy to improve surface characteristics, we combine fine particle peening (FPP) and precision surface grinding. Combined with a shallow angled FPP to form self-patterned ridge texture on aluminium surface, precision surface grinding with the specific conductive-bonded wheel removes the ridge peaks and simultaneously deposits Cu on the valleys by reducing Cu ions which are condensed in the grinding fluid. The series of those methods are the promising way to create well-processed surfaces which can be applied to tribological and biological devices.
[Show abstract][Hide abstract] ABSTRACT: We show the principles of the communication protocol, on-line calibration, off-line data format as well as basic visualisation and data analysis software implemented for the EUSO-TA on-ground experiment, being the first step towards implementation in a future space based mission. EUSO-TA is an on-ground detector for measuring UV (290–430 nm) light from extensive air showers induced by cosmic rays. It is a prototype experiment for the JEM-EUSO space-borne mission, built according to the same constraints of low mass, low power consumption and thus low computing power. Nevertheless, it needs to process a huge amount of data in short time, taking exposures for 2304 channels.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2015; 773. DOI:10.1016/j.nima.2014.08.045 · 1.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Single point inclined axis grinding techniques, including the wheel setting, wheel-workpiece interference, error source determination and compensation approaches, were studied to fabricate small aspheric moulds of high profile accuracy. The interference of a cylindrical grinding wheel with the workpiece was analysed and the criteria for selection of wheel geometry for avoiding the interference was proposed. The grinding process was performed with compensation focused on two major error sources, wheel setting error and wheel wear. The grinding results showed that the compensation approach was efficient and the developed grinding process was capable to generate small aspheric concave surfaces on tungsten carbide material with a profile error of smaller than 200 nm in PV value after two to three compensation cycles.
[Show abstract][Hide abstract] ABSTRACT: This paper discusses the grinding of sapphire for mirror surfaces by coarse grain size diamond wheels. Sapphire is a hard-to-machine material because it has excellent mechanical properties and indentation hardness. Since it is effective for hard materials to use metal-bonded diamond wheels, the authors had two experiments to investigate mirror surface grinding by coarse grain size diamond wheels. The 1st experiment was investigating appropriate grinding conditions, and the 2nd experiment was investigating protrusion height of abrasive grains. Although the conventional methods could not acquire mirror surface, the results of the experiments show that mirror surface (Ra: 5 nm <) were obtained by the #270 and #325 mesh size wheels. These results indicate the possibility of decreasing grinding processes by coarse grain size diamond wheels.
International Journal of Nanomanufacturing 01/2014; 10(3):309 - 318. DOI:10.1504/IJNM.2014.060801
[Show abstract][Hide abstract] ABSTRACT: A sensor chip for use in an ion channel biosensor based on an incubation-type planar patch clamp was formed using both side hot embossing and focused ion beam (FIB) processing. A biosensor was constructed using the PMMA chip, and the performance of this chip was investigated by measuring the laser-stimulated ion channel current of a channel rhodopsin wide receiver (ChRWR) expressed on HEK293 cells. The observed current profile and membrane potential dependences agreed well with the data measured using a pipette patch clam p. The noise level of the channel current recorded using a 1 kHz low pass filter was 7 pA (rms). The sensor chip fabrication processes are readily modified to permit multi-point measurements; therefore, the excellent performance of the PMMA chip indicates that the chip is suitable for use in high-throughput ion channel biosensor screening applications.
International Journal of Nanomanufacturing 01/2014; 10(3):281-294. DOI:10.1504/IJNM.2014.060798
[Show abstract][Hide abstract] ABSTRACT: Micro biofabrication technologies have been developing aiming to fabricate 3D artificial organs, 3D scaffolds, and complex tissue structures. We are now developing a new inkjet bio-printing method via electrostatic phenomenon. The merits of the new method are of high resolution, and of ability to eject highly viscous liquid and media. In this paper, we attempted to apply the proposed method for precision printing cells and biomaterials. Living cells and scaffolds have successfully been printed and the biochemical characteristics have been investigated. A 3D cell structure which had a cavity to create blood vessels has also successfully fabricated by this method.
[Show abstract][Hide abstract] ABSTRACT: The demand for micromachining methods for single-crystal silicon has been steadily increasing. Micro tools made of polycrystalline diamond (PCD) have considerable promise in this regard. However, the contamination of the PCD tool surface increases the frictional resistance during machining, leading to degradation of the surface integrity of the workpiece. In this study, the feasibility of surface conditioning using a specific electrochemical technique was investigated. The technique was found to be effective in removing the surface contamination without damage to the tool edges. The conditioning method proposed in this paper is expected to bring about excellent machining performance of micro PCD tools, such as longer tool life, lower machining load, and higher machined surface integrity.
International Journal of Nanomanufacturing 01/2014; 10(1/2):201 - 214. DOI:10.1504/IJNM.2014.059009
[Show abstract][Hide abstract] ABSTRACT: We are developing surface modification techniques for dental implants with the aim of reducing the time required to realize good adhesion between bone and implant surfaces. A nanosecond Nd:YVO4 laser was used to modify the surfaces of commercially pure titanium (CP Ti) disks and their bioactivities were then evaluated. The surfaces of the CP Ti disks were covered by lines after laser treatment. This treatment created complex microasperities of titania with rutile and anatase crystal structures. This results in the formation of hydroxyapatite on surfaces immersed in 1.5-times concentrated simulated body fluid for 7 days, whereas no hydroxyapatite was observed on conventionally polished surfaces that were immersed under the same conditions. This indicates that laser treatment improves the bioactivity of CP Ti, which is a critical property for osseointegrated implants.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this paper is to prove the reliability of artificial hip joints’ surface generated by the electrolytically treated grinding process; the evaluation was carried out in a hip simulator and animal tests. The evaluation indicated that the fabricated hyper-hemispherical shaped artificial hip joints presented a high quality smoother surface than 10 nm in Ra. The fabricated surface also showed its ability to prevent crystalline phase transition during the hip simulation test, suggesting that the stably modified layer was generated via grinding process. The results of animal test showed that the fabricated surface could have a highly-improved biocompatibility.
[Show abstract][Hide abstract] ABSTRACT: This paper deals with surface roughness and surface profile in high precision methods of materials finishing. One of them is ELID process and the second method is grinding. There is surface profile and roughness compared of the three materials samples – carbide steel and two aluminium alloys. In the paper are shown results of surface measurement between ELID and ground surface. Both methods are very precision in the focus on surface roughness – measured units in nano scale. Paper shows possibilities in finishing methods for production, automotive, aerospace, medicine and cosmic industry.
[Show abstract][Hide abstract] ABSTRACT: We will present two kinds of terahertz (THz) 3D imaging performed with a continuous-wave (CW) source and phase-shifting
interferometry. The first one is THz computed tomography (CT) by using phase information instead of intensity
information. This minimized the effect of change in the signal strength due to diffraction and artifacts especially emerged
around the edge of boundary between different materials. The second one is for the depth imaging of the surface of
reflecting materials. By using a simple Michelson’s interferometer, we achieved the depth resolution of 1.1 μm,
corresponding to 1/440 of the used wavelength (480 μm).
[Show abstract][Hide abstract] ABSTRACT: We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme
Universe Space Observatory, on-board the Japanese Experiment Module of the
International Space Station. Designed as a mission to explore the extreme
energy Universe from space, JEM-EUSO will monitor the Earth's nighttime
atmosphere to record the ultraviolet light from tracks generated by extensive
air showers initiated by ultra-high energy cosmic rays. In the present work, we
discuss the particularities of space-based observation and we compute the
annual exposure in nadir observation. The results are based on studies of the
expected trigger aperture and observational duty cycle, as well as, on the
investigations of the effects of clouds and different types of background
light. We show that the annual exposure is about one order of magnitude higher
than those of the presently operating ground-based observatories.
[Show abstract][Hide abstract] ABSTRACT: Solar cell is one of the key technologies in this century because this
has possibility to clear energy problems. We tried to pattern good
titania layer of dye-sensitized solar cell (DSC) utilizing electrostatic
inkjet. The electrostatic inkjet has good merit; that is ability to
eject highly viscous liquid. We applied the merit for patterning titania
paste on fluorine-doped tin oxide (FTO) glass. In this paper, we
investigated fundamental characteristics to pattern titania layer on FTO
glass because efficiency depends on thickness of titania layer.
Japanese Journal of Applied Physics 05/2013; 52(5). DOI:10.7567/JJAP.52.05DC23 · 1.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The goal of this study is to fabricate precision three-dimensional (3D)
biodevices those are micro fluidics and artificial organs utilizing
digital fabrication. Digital fabrication is fabrication method utilizing
inkjet technologies. Electrostatic inkjet is one of the inkjet
technologies. The electrostatic inkjet method has following two merits;
those are high resolution to print and ability to eject highly viscous
liquid. These characteristics are suitable to print biomaterials
precisely. We are now applying for bioprint. In this paper, the
electrostatic inkjet method is applied for fabrication of 3D biodevices
that has cave like blood vessel. When aqueous solution of sodium
alginate is printed to aqueous solution of calcium chloride, calcium
alginate is produced. 3D biodevices are fabricated in case that calcium
alginate is piled.
Japanese Journal of Applied Physics 05/2013; 52(5). DOI:10.7567/JJAP.52.05DB20 · 1.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To improve the detection limits of a portable total reflection X-ray fluorescence (TXRF) spectrometer using white X-rays (i.e., both characteristic X-rays and continuum X-rays) from a 5 W X-ray tube, the measurement was performed in vacuum. The TXRF spectrum measured in vacuum was compared with that measured in air. The spectral background was significantly reduced when the scattering of the incident X-rays from air was reduced using a vacuum pump, leading to improvement in the detection limit. A detection limit of 8 pg was achieved for Cr when measuring in vacuum.
The Review of scientific instruments 04/2013; 84(4):046108. DOI:10.1063/1.4803166 · 1.61 Impact Factor