Toshiyuki Uenoya

Mechanical Properties of Electrodeposited Ni-SiO2 Nanocomposite

Nanocomposite materials consisting of a nanocrystalline Ni matrix with grain size ranging from 23 to 40 nm, and nano-size SiO2 particles with average particle size of 7 nm, have been produced by pulse electrodeposition. Grain size was controlled by peak current density. It was observed that SiO2 particles precipitated within grain interior by the transmission electron microscopy (TEM). Hardness and tensile strength of nanocomposites with a grain size larger than 35 nm was higher than that of nanocrystalline pure Ni possibly as a consequence of Orowan precipitation hardening. However, hardness of Ni-SiO2 nanocomposites with a grain size smaller than 30 nm was the same as that of nanocrystalline pure Ni. It was considered that the SiO2 particles do not contribute to hardening because deformation occurs by a grain-boundary-mediated mechanism such as grain-boundary sliding.

Development of blood vessel searching system for HMS

In this study, we develop a new 3D miniature blood vessel searching system by using near-infrared LED light, a CMOS camera module with an image processing unit for a health monitoring system (HMS), a drug delivery system (DDS) which requires very high performance for automatic micro blood volume extraction and automatic blood examination. Our objective is to fabricate a highly reliable micro detection system by utilizing image capturing, image processing, and micro blood extraction devices. For the searching system to determine 3D blood vessel location, we employ the stereo method. The stereo method is a common photogrammetric method. It employs the optical path principle to detect 3D location of the disparity between two cameras. The principle for blood vessel visualization is derived from the ratio of hemoglobins absorption of the near-infrared LED light. To get a high quality blood vessel image, we adopted an LED, with peak a wavelength of 940nm. The LED is set on the dorsal side of the finger and it irradiates the human finger. A blood vessel image is captured by a CMOS camera module, which is set below the palmer side of the finger. 2D blood vessel location can be detected by the luminance distribution of a one pixel line. To examine the accuracy of our detecting system, we carried out experiments using finger phantoms with blood vessel diameters of 0.5, 0.75, 1.0mm, at the depths of 0.5 ~ 2.0 mm from the phantoms surface. The experimental results of the estimated depth obtained by our detecting system shows good agreements with the given depths, and the viability of this system is confirmed.

Development of a blood extraction device for a miniature SMBG system

In this study, a vacuum driven blood extraction device for the self-monitoring of blood glucose (SMBG) was newly developed. The health monitoring system (HMS) for SMBG consists of a blood extracting system and a drug delivery system (DDS). Our HMS extracts the blood through a micro-needle and measures the blood sugar level accurately. The main purpose of this work in HMS development are, 1) minimally invasive blood extraction, 2) a handy type automatic blood extraction, and 3) a continuous measurement of the blood sugar level. We adopted a vacuum driven type blood extraction mechanism. The vacuum driven blood extraction unit consists of a) a puncture part to open the vacuum part, b) an extraction part, and c) a measurement part. The puncture and extraction parts consist of a minimally invasive micro-needle, whose inner diameter is less than 100μm and made of titanium alloy, and a vacuum chamber, which is covered by a very thin membrane. A SMA spring and two bias springs are employed to penetrate the blood vessel through the skin with the micro-needle, and to execute the punctuation to slash the membrane in order to open the vacuum chamber. The blood is extracted into the vacuum chamber, seeps into the unwoven cloth according to the capillary principle, and is finally deposited on the blood sugar level sensor. Results show, our vacuum driven blood extraction device succeeded in extracting 12.7μl of human blood within 2 seconds. The blood sugar level was measured successfully by using a glucose enzyme sensor. Finally, the availability of our HMS device was confirmed.

Development of MgSiO 3 biocompatible piezoelectric film for bio-MEMS actuator

In this study, a sputtering technique for a Bio-MEMS thin film piezoelectric actuator is developed, by employing a newly designed biocompatible piezoelectric material MgSiO3 that has a tetragonal perovskite lattice crystal structure. This crystal structure was designed by using numerical analyses, such as the HSAB rule, the geometrical compatibility assessment and the first principle based DFT calculation. In general, MgSiO3 has an orthorhombic perovskite structure in the nature. Therefore, we try to generate a tetragonal structure by employing 1) the helicon wave plasma sputtering (HWPS) method, which can produce large energy atoms under a low working pressure and easy to control the lattice constant for growing the tetragonal structure of MgSiO3 and 2) a bio-compatible substrate Ir/Ti/Si, to produce a thin film of MgSiO3 tetragonal perovskite. Ir/Ti/Si substrate has better compatibility with MgSiO3 (111) plane, because of its close lattice constant. An optimal condition of HWPS to generate MgSiO3 tetragonal perovskite structure was sought by using the experimental design method and the response surface method. We found that 1) the substrate temperature and 2) the target composition ratio are significant influent factors for MgSiO3 film generation. In this searching process, we evaluated the properties of MgSiO3 films by 1) the surface roughness measured by AFM, and 2) the chemical compositions measured by XPS, and 3) the crystal structure by XRD. Finally, MgSiO3 thin film was successfully fabricated and the piezoelectric and ferroelectrics properties were measured.

Facilitated Recrystalization of the Hard-to-Recrystalize Structure in 16% Cr Steel Sheets by one-Pass ECAP Prior to Cold Rolling

The extended band structures of cold-rolled high Cr steel sheets are recrystallization resistant, and tend to become the so-called grain colony as a recovered state. It is shown that a novel approach involving strain-path change by introducing one-pass ECAP prior to cold rolling facilitated recrystallization. Indeed, recrystallization temperature was reduced by 100 °C, compared with cold rolling alone imposing the same equivalent strain. Dense deformation bands introduced during ECAP perturbed the banded structures and enhanced the recrystallization at final annealing.

Formation of Deformation Twins and Related Shear Bands in Copper Single Crystals Pressed by ECAP

The pure copper single crystals with specific crystallographic orientated were subjected to ECAP for one pass at room temperature. Two types of shear bands were observed. Type 1 shear bands were constructed with clusters of distorting micro shear bands and matrix. Micro shear band and matrix were delineated by large-angle grain boundaries, and these two orientations are in a twinning relationship. Parallel sets of deformation twins were observed in the matrix. Type 2 shear bands had no crystallographic feature, and shear band and matrix were considered as low-angle grain boundaries. Deformation twin was not observed both in matrix and the shear bands.

Development of a blood vessel searching device for HMS

In this study, an automatic blood vessel searching system (BVSS) is newly developed, which is built in the health monitoring system (HMS) and the drug delivery system (DDS) to extract the blood, evaluates the blood sugar level and injects the insulin for the diabetic patients. Main subjects of our BVSS development are 1) a transmittance photo imaging of the finger by using the LED light as a near-infrared light source with peak wave length of 870 nm, and 2) an image processing to detect the location of the center of the blood vessel cross section. The sharp edge focus method was applied in our BVSS to detect the depth of blood vessel. We carried out experiments by using blood vessel phantoms, which consist of an artificial cylindrical blood vessel and skin tissue, which are made of the teflon tube and the silicone rubber. The teflon tube has the size of 0.6 mm in diameter and is filled with the human blood. The experimental results demonstrated that the estimated depth, which is obtained by image analysis corresponding to given depths, shows a good agreement with the real values, and consequently the availability of our BVSS is confirmed.

Effect of matrix toughness on fatigue life of plain woven carbon fabric composites

The effect of matrix toughness on the fatigue life of polymer matrix composites using plain woven carbon fabrics (pw-CFC) was studied. In order to vary the matrix toughness without changing the inherent cohesion properties such as adhesive strength between matrix and fibers, two different curing agents (acid anhydride and amine types) were used. Static tensile and tension/tension fatigue cyclic loads were applied to pw-CFC specimens. It was observed that the fatigue life was significantly affected by matrix toughness. During the fatigue tests, damage progression was observed intermittently by using a thermo-elastic stress analyzer (TSA). The stress re-distribution occurs due to fatigue damage progression. TSA can identify such stress re- distribution by means of detecting surface temperature amplitude. Highly fatigue-damaged area of pw-CFC was localized if the matrix toughness was high, although moderately damaged area grew all over the specimen. The experimental results indicate that the fatigue life and damage of pw-CFC are strongly governed by matrix toughness.

Polymer Matrix Composites. Acoustic Emission Characterization of Damage Accumulation during Early Creep State in E-glass Fiber Fabric/Epoxy Laminates.

In this paper, the residual life and the creep damage for glass fiber reinforced plastics are studied experimentally. For this purpose, emphasis is placed upon introducing a new damage parameter defined by acoustic emission (AE) intensity in order to evaluate the micro-damage accumulation generated before macro-crack initiation in a composite. Short-term creep experiments were carried out on three types of specimens, consisting of glass fiber fabric reinforced epoxy laminated composites with different weaves, counts, densities and thickness. The single-edge notched specimens were subjected to a series of stepwise loadings with increasing peak loads, in edgewise four-point bending so that tensile stress arose at the front end of the notch. AE activity was monitored with measuring mechanical displacement during a test using various AE intensities, which were analyzed in detail. The new damage parameter showed a good correlation with a conventional damage parameter defined by non-elastic deformation caused during cyclic load holdings. The correlation depended on test conditions and materials but was presumed to stand up under tensile deformation.