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Published: August 02, 2008
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Article type: Appendix
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Article type: Appendix
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Article type: Index
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A1-A5
Published: August 02, 2008
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Naruo SASAKI, Noriaki ITAMURA, Kouji MIURA
Article type: Article
Session ID: 301
Published: August 02, 2008
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We have performed molecular mechanics study of nanoscale peeling and adhesion processes of carbon nanotube (CNT) on the rigid graphite surface. First, as a model of CNT, single-walled carbon nanotube (SW-CNT) of the (3,3) armchair type with a length of l=99.3 Å comprised of 480 carbon atoms is used. In the simulation CNT physically adsorbed on the graphite substrate is peeled (retracted) from the surface and then adsorbed (approached) onto the surface. We have first obtained the vertical force-distance curve with the characteristic hysteresis loop derived from the bistable states between the line- and point-contacts during the peeling and adhesion processes. The analysis of the vertical and lateral force curves reveals that the CNT shows multiscale mechanics-both nanoscale mechanics on the order of CNT's length (≃ 100 Å) and atomic-scale mechanics on the order of CNT's diameter (≃ several Å). The deflection of CNT along z direction and the length l dependence of k_z, k_z αl^<-2.98>, can be well explained by theory of elasticity. Lastly the effect of the chirarity of the CNT on the peeling and adhesion processes is studied for the armchair, zigzag and chiral type CNTs for the length of about 50 Å. The hysteresis of the peeling curve shows the adhesive behavior derived from the difference of adhesive feature and the free edge structure among different chirality of CNTs.
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Hiroaki Amakawa, Kenji Fukuzawa, Hedong Zhang, Shintaro Itoh, Mitsuhir ...
Article type: Article
Session ID: 302
Published: August 02, 2008
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Conventional friction force microscope (FFM) had the disadvantage of low force sensitivity due to mechanical interference between torsion caused by friction force and caused deflection by normal force. We have developed dual-axis micro-mechanical probe. It measures the lateral force by detecting the deflection of the double cantilever and measures the vertical force by the torsion beam. However, the method of calibrating the probe lateral deflection has not been established. In this study, we present a new method precisely which calibrates the probe lateral displacement in order to detect the friction force.
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Akihisa MORIMATSU, Tsuneo AKUTO, Kohro TAKATSUKA, Masatsugu YOSHIZAWA
Article type: Article
Session ID: 303
Published: August 02, 2008
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Wiper is an important vehicle equipment to keep a clear view for a driver. The characteristics of the fluid flow around the blade lip of a wiper have been discussed in this study. The analytical model for the fluid flow and the governing equations for the model have been established. The governing equations have been numerically solved. It is concluded that there is a relationship between the water film thickness and the blade angle and the size of the gap. Moreover, meniscus force around the outlet of the gap will be considered.
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Toru MAEDA, Katsutoshi CHIKUMA, Kiyoshi NAGASAWA, Masatsugu YOSHIZAWA
Article type: Article
Session ID: 304
Published: August 02, 2008
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The development of a Micro Electro Mechanical System(MEMS) like a capsule endoscope such as located in a small-diameter tube is remarkable in recent years. It is also very interesting from the viewpoint of nonlinear dynamics associated with the fluid-solid interactions. For instance, gap flows between the MEMS and the surrounding wall change due to the vibration of the MEMS. In this research, we have observed the vortex-induced transverse vibration of a spring-supported circular cylinder in a narrow channel as fundamental investigations. In experiments using the dynamical similar model, we clarified particularly the effect of channel wall on the lock-in phenomena.
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Takahiko TSUJISAWA, Kazuhiro YAMAKAWA, Kazuyuki Abe
Article type: Article
Session ID: 305
Published: August 02, 2008
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In this paper, a new non-contacting torque sensor system using an iterative phase difference detection to eddy current sensor is proposed. The iterative phase difference detection means that the time between zero cross points of sensing coil voltage which indicates the phase difference is accumulated repetitively. Proposed method is characterized as a simple sensor which consists of very small size coils, oscillator circuits, and a microprocessor. Previously, the phase difference caused by inductance changes has been detected by a synchronous amplifier, especially a lock-in amplifier. The new method proposed in this paper will be equivalent to the synchronous detection technique, in which the lock-in amplifier is needless. The accumulation can be held by repetitive drive of the oscillator circuit which consists of sensing coil connected to a capacitor in series or parallel. In the experiment, a torque test unit is used, and torque which causes up to 0.2% torsional strain in test pieces is applied. For test pieces, AL2017 and SUS304 are selected. From experimental results, a linear relation between sensor output and applied torque is observed. And it is shown that the proposed method is effective.
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Yoshitaka SHIMIZU, Hidenori SATOU, Hiroshige MATSUOKA, Shigehisa FUKUI
Article type: Article
Session ID: 306
Published: August 02, 2008
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Forced vibrations of a cantilever with a damping at the tip at the arbitrary position used in an atomic force microscope (AFM) have been analysed and vibration amplitude and phase shift of the cantilever end that will be measured by using the optical lever method have been predicted theoretically. It was found that the predicted amplitude and phase shift includes errors and correction of the amplitude and phase shift depending on the vibration freqency is necessary. The amplitude correction factor and phase correction value has been newly derived. These results are useful for ultrahigh accuracy measurements, especially dynamic measurements, using the AFM.
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Kentaro NISHIMURA, Hiroshi YABUNO, Takashi Someya, Masaharu KURODA
Article type: Article
Session ID: 307
Published: August 02, 2008
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Usage of self-excitation as an excitation method has been proposed for vibration machines as well as the cantilever-probe in an atomic force microscopy (AFM). The amplitude control is carried out by producing the dynamics of the van der Pol oscillator in the cantilever. The control has been performed by applying nonlinear feedback proportional to the squared angle and the angular velocity. In this study, we propose a new control method which has high performance even in the high-frequency range and realize van der Pol oscillator in the cantilever with laterally exited fixed end by not using differential of the measurement signal, but integral control with respect to the angle at the tip of the cantilever. This control method is demonstrated by our own making analog electrical circuit. Then, the steady state amplitude of self-excited oscillation with amplitude of 4nm is experimentally realized.
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Takashi SOMEYA, Kiwamu ASHIDA, Masaharu KURODA, Hiroshi YABUNO
Article type: Article
Session ID: 308
Published: August 02, 2008
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Self-excitation thechnique is known as an effective excitation method for a cantilever probe of the atomic force microscope to measure the surface of a biological sample in a liquid environment. In this research, we deal with a van der Pol type cantilever probe, which is previously proposed to realize the non-contact mode, and experimentally examine the relationships between the response frequency and amplitude and the gap of the cantilever probe and the surface of sample. We examine the natural frequency of the cantilever in liquid. From the result, it is confirmed that the cantilever oscillates with a low amplitude that can detect the surface of the sample without giving damage. While it is difficult to estimate natural frequency of the cantilever under external excitation in liquid, it is easy to estimate it under van der Pol type self-excited oscillation.
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Shogo TSUDA, Takaaki SUZUKI, Isaku KANNO, Hidetoshi KOTERA
Article type: Article
Session ID: 309
Published: August 02, 2008
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Piezoelectric MEMS deformable mirror resolution is studied for an adaptive optics device. In previous study, we have developed the piezoelectric MEMS deformable mirrors which have 19 actuator away. To improve the resolution of the deformable mirror, we designed hexagonal 61-element actuator array. In order to reduce the dead space for the lead lines between the actuators, they were prepared on the polyimide insulating layer. The displacement of each actuator was measured by using a lasor Doppler vibrometer and we confirmed a relatively large displacement of more than 1pm by applying a voltage of 10Vpp. Furthermore, we measured the relationship input voltage and displacement and fabricated DMs actuated linearly when applied -20〜20Vpp.
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Junya OGAWA, Takaaki SUZUKI, Isaku KANNO, Hidetoshi KOTERA
Article type: Article
Session ID: 310
Published: August 02, 2008
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In this paper, we propose and study innovative liquid pimping devices for microfluidic systems such as pTAS. In our study, microchaimels with vibrating wall were fabricated on silicon on insulator (SOI). The vibrating wall was composed of piezoelectric PZT thin films deposited on the microchannel wall. The microchannel can transport liquid by traveling wave induced on channel wall by applying sinusoidal voltages to each patterned top electrodes with different phase. The active microchannel of 200μm wide was fabricated by the deep reactive ion etching(DRIE) process. The displacement profiles of the vibrating wall and frequency response were measured by a laser Doppler vibrometer. We examined the difference of the characteristics that were the to the effect of the structure of channel wall.
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Makoto IWASAKI, Tetsuyou WATANAVE, Hidekazu MATSUMURA, Zhongwei JIANG
Article type: Article
Session ID: 311
Published: August 02, 2008
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Our previous paper showed the adhesion state can be checked by analyzing the data obtained by laser displacement meter. However, the following problems happen. 1) The endeffector must be located at the specific point where laser displacement meter can measure oscillation. 2) The adhesion state can not be checked if something blocks the light/laser or the target leaves measuring point. 3) The total system becomes very large. Then, this paper firstly presents a method for checking the adhesion state by piezo-transducer. Next, to achieve more precision manipulation, we propose a method to move the endeffector with a more precision step. Adding DC input to the input for oscillating the endeffector for relaxing adhesion forces, we control the endeffector movement relaxing adhesion forces. Based on this method, we propose a method for checking the adhesion state more accurately and automatically. The first mode resonance frequency shifts with the increase of the amount of pushing the object by the endeffector. Using the amount of shift, we develop a method for checking the adhesion state.
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Akihiro NAKATA, Shinzi TANAKA, Koji SUGANO, Toshiyuki TSUCHIYA, Osamu ...
Article type: Article
Session ID: 312
Published: August 02, 2008
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A novel electrical equivalent circuit model of the microfluidic system containing a valveless micropump and a viscoelastic PDMS microchannel was developed by considering inner-wall deformation of viscoelastic PDMS microchannel. The viscoelastic deformation of the PDMS inner wall was represented by a generalized viscoelastic model. Elastic and viscous moduli in the generalized visoelastic model were optimized based on the measured viscoelastic property. The validity of the developed model was evaluated by comparing the dynamic flow behavior calculated by the equivalent circuit model with μ-PIV measurement result. The good agreements concluded that a dynamic flow characteristic of the whole microfluidic system is able to be analyzed precisely by the developed equivalent circuit model.
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Yasuhiro MITA, Hironori ISHIBASHI, Kazuyuki MINAMI, Katsuya SATO
Article type: Article
Session ID: 313
Published: August 02, 2008
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The actuators using electrostatic energy have been reported. However, these actuators generally can generate low power. We proposed the novel drive principle of the microactuator, that makes electrostatic energy/force collaborate with the elastic energy/force. It is necessary to design the spring with the non-linearity to make the microactuator highly effective. In this paper, the non-linear spring was designed by using the FEM analysis. Mechanical performance of the micro actuator is also evaluated. Initial generated force of non-linear spring type is 2770 times higher than that of linear spring type.
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Naoko Koda, Hideta Ooiso, Maho Hosogi, Gen Hashiguchi
Article type: Article
Session ID: 314
Published: August 02, 2008
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We have demonstrated contact sensing using a self-excitation vibration of comb-drive actuator. Through an immittance analysis of comb-drive actuator using Lagrange's equation, three terminal comb-drive actuator shows maximum propagation admittance at its resonance frequency. Furthermore, the phase between input voltage and output current become zero at the resonance; these satisfy self-oscillation condition with a proper amplifier. Our sensing probe is oscillated by the self-oscillation circuit and we detect its frequency change when the probe touched an opposing object. In this paper, we report an experience of surface imaging using a developed self-oscillation probe.
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Hiroki Ogawa, Ming Yang, Yukiko Matsumoto
Article type: Article
Session ID: 315
Published: August 02, 2008
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In this study, microelectron beam welding was applied to the joining of two thin metal foils. An electron beam is adaptable to microwelding due to its deep penetration and thin width. The foil materials used were SUS and Ti with a thickness of 20 μm. The relationship between the input energy of electron beam irradiation and the size of the welding spot was investigated. Furthermore, spot welding and overlap welding were carried out for foils of either the same or different materials. The surface and cross section of the welded zone were observed by a scanning electron microscope (SEM) or confocal laser scanning microscope (CLSM). In the case of the same material, it was possible to weld two overlapped Ti foils (marked as Ti/Ti) with thickness of 20 μm. In the case of different materials, it was possible to weld SUS304 was top and Ti was bottom (marked as SUS304/Ti) with thickness of 20 μm. The results show that microwelding can be considered a new technology for microelectrical mechanical systems (MEMS) in addition to microfabrication.
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Ryuichi KOBAYASHI, Ming YANG
Article type: Article
Session ID: 316
Published: August 02, 2008
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A nanostructured surface was designed and created by synthesizing Carbon Nanotubes (CNTs) on a plane substrate. Multi-walled carbon nanotubes (MWNTs) were synthesized on a Si/SiO_2 substrate by alcohol catalytic chemical vapor deposition (ACCVD). The MWNTs were vertically aligned on the surface, and the structure and characteristics of the surface, such as wettability, were evaluated. The surface with the MWNTs was also treated by coating with Au and subsequent plasma irradiation, in order to change the wettability from hydrophobic to hydrophilic. The results of wettability tests show that the surface with the MWNT film behaved as a super-hydrophobic surface before plasma treatment, but behaved as a super-hydrophilic surface after the plasma treatment. Furthermore, experiments using water droplets on the MWNTs and subsequent drying was carried out, and the resulting changes in the structure and characteristics of the MWNTs were evaluated using scanning electron microscopy (SEM). The MWNTs subjected to plasma treatment were found to clump together forming bundles after dropping water and drying; we found that the CNTs moved after the water was dropped on them.
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Syotaro Kageyama, Yuichi Nakazato, Sugiya satou
Article type: Article
Session ID: 317
Published: August 02, 2008
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Recently, the mechanism composed of them is not seen though a minute composition material of each pm has come out. Then, a minute material is physically grasp, and the manipulator that can assemble a minute material mutually is made. It aims at the development of the micro manipulation system that a three-dimensional handling a small material is possible also under the vacuum or the plasma-environment not only air it like in the electron microscope and the plasma-process etc. The system for the micro manipulation that can be operated under the plasma environment/vacuum is constructed. And, handling a small material was examined with the operation. Moreover, a bonding and a fixed method of a minute material that uses the plasma irradiation and the ion beam, etc. are researched.
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Kensuke KANDA, Yuichiro Noda, Takaaki SUZUKI, Isaku KANNO, Hidetoshi K ...
Article type: Article
Session ID: 318
Published: August 02, 2008
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A novel concept of a liquid transport technique utilizing frequency modulation and local resonance oscillation is proposed and it is applied to a micromixer. Meta-structure distributing local masses for generating local resonant oscillation is developed. Vibration of the meta-structure with sweeping frequency produces changes in the positions with large oscillation amplitude. This complex structural oscillation makes eddy-like disturbance of flow in a microchamber, and it produces high mixing efficiency. Using this technique produced a mixing index of 0.92 with the volumetric flowrate of 1 μL/min, while it was 0.49 for a conventional technique employing a vibration at a fixed frequency.
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Hiroyuki SENZAI, Daisuke HIRAMARU, Takashi MIURA, Takaaki SUZUKI, Isak ...
Article type: Article
Session ID: 319
Published: August 02, 2008
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Recently, studies of positional relationships of cells are seemed to be very important for cell biology. We proposed a novel concept that self-organized vasculatum integrates artificial orifices on a device by VEGF (Vascular Endothelial Growth Factor), and a method of uniformly plating HUVEC (Human Umbilical Vein Endothelial Cells) for efficient vasculature integration. Sucking and clamping of Alginate Calcium gel beads containing VEGF, it is able to induce angiogenesis to orifices on embedded channels. Endothelial cells characteristically organize vasculature by themselves in collagen gel and grow along the VEGF concentration gradient. HUVEC were cultured on device for about 7 days in the collagen gel and artificial vasculature mere immobilized on orifices by self-organized. And viscosity control of the suspension mixed with HUVEC, collagen gel and medium at low temperature made HUVEC uniformly-plated.
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Yukihiro SONOBE, Yuichi NAKAZATO
Article type: Article
Session ID: 320
Published: August 02, 2008
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The patient's load is requested from reduction minimally invasion on a clinical site. This study has aimed at the development of the In-pipe Micro Robot thought that the examination in the blood vessel and the removal of the tumor, etc... As the drive system for the robot, the expansion of the balloon by the force feed of the physiologic saline and the peristalsis movement mechanism using shrinkage were designed and produced. In this study, we developed two type in-pipe micro robots, and examine the effectiveness of these robots experimentally. From several experiments, availability of these robots is confirmed.
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Ken YAMAMOTO, Satoshi OGATA
Article type: Article
Session ID: 321
Published: August 02, 2008
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In nature, many surfaces having micro scale roughness are superhydrophobic and self-cleaning. Some of them like lotus leaf have double (micro- and nano-) scale roughness, but the effectiveness of double roughness is not clear. In addition, although many previous studies reported the methods to make such surfaces with high contact angle, none of them could be a guide to achieve superhydrophobicity and those of thermodynamic mechanisms are not well understood. In this study, three types of 3-D model pillar textured surfaces, cavity surfaces and double roughened surfaces- are chosen and thermodynamically analysed focusing on the surface free energy. By calculations, equilibrium CA, Free Energy Wall (FEW) and CA hysteresis are obtained. Based on these calculations, the factor of the determination of sliding angle is indicated. Additionally, based on these results, one of the optimal geometries for superhydrophobic surfaces are suggested.
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Hiroshige KUMAMARU, Kazuhiro ITOH
Article type: Article
Session ID: 322
Published: August 02, 2008
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Molecular dynamics analyses have been performed on the liquid flows driven by an external force in parallel plates. Calculated velocities have been compared with those obtained from the Navier-Stokes (NS) equation. In the case of Ar flow, calculated velocities (both profiles and absolute values) by MD analyses agree with those by the NS equation for flow channel widths greater than -5 nm. On the other hand, in the case of water flow, calculated velocities by the MD analyses are greater than those by the NS equation at least for channel widths lower than -50 nm, while calculated velocity profiles by the MD analyses are parabolic for channel widths greater than -5 nm.
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Takahiro TANAKA, Tomoyasu AIHARA
Article type: Article
Session ID: 323
Published: August 02, 2008
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Molecular dynamics simulation of pure argon fluid was performed under NVT ensemble for gas and liquid phases including critical point. Atom level density of the fluid fluctuates in space and time. They are analyzed by statistical calculation. Structure factor S(q) indicates spatial fluctuation. Temporal fluctuation is evaluated by dynamic structure factor S(q,ω). Long range spatial fluctuation is shown at low q correlation of S(q,ω). Frequncy dependent diffusion coefficient D(ω) and thermal conductivity λ are calculated from coordinate and velocity of atom.
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Tomoaki HAGA, Kentaro DOI, Satoyuki KAWANO
Article type: Article
Session ID: 324
Published: August 02, 2008
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A rapid and low-cost sequencing method for DNA base arrangements has been studied in recent years. Resolution of single base pair of DNA is required in order to realize the practical technique. From the theoretical viewpoint, all atom simulations of DNA consume too much resource and more efficient methods should be proposed. This work presents a mesoscale coarse-grained model of DNA in which typical properties of DNA are maintained. Several types of interaction potentials have been suggested to keep the double strand structure. Coulomb interaction, which is one of the most important components, is added to consider the influence of external electric fields on the DNA structure. Potential for dihedral angle is efficient to realize the double strand structure. Dynamics of our model has been discussed using Langevin dynamics simulations. Not only the double strand structure but also the ladder one has been recognized. Transformation between these two states has occurred across the transition state.
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Takamasa UEMURA, Kentaro DOI, Satoyuki KAWANO
Article type: Article
Session ID: 325
Published: August 02, 2008
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It is required that flow characteristics of DNAs can be precisely controlled for development of bio-nano technologies. Recently, many experimental methods for DNA base-pair analysis have been proposed. Denaturing Gradient Gel Electrophoresis (DGGE) method is widely used to determine the base sequences of DNAs. In this study, we theoretically analyze the flow dynamics of DNA fragments using molecular dynamics (MD) simulations. Two types of 10 base-pairs DNA (5'-TTTTTTTTGG-3'), a rigidly bonding type and a partly dissociated one, are prepared for the simulations. As a result, the relationship between the hydrated structures and the fluidity of DNA has been clarified. Water molecules which concentrate around O and N atoms in base molecules are concerned with the hydrated structures and reduce the fluidity of the DNA fragments.
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Tomoaki AKITOMI, Masamichi OISHI, Marie OSHIMA
Article type: Article
Session ID: 326
Published: August 02, 2008
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Droplet-based microfluidic systems have shown to be capable of performing a variety of digital fluidic operations. To make more use of them, it is important to obtain a better understanding of mechanism on formation of micro-droplet. This paper aims to investigate numerically the formation of micro-droplet by CIP method, which is in recent years widely used method for multiphase flow researches. In this paper, we describe a computational scheme based on CIP CSLR, and the analysis result of droplet formation in a microchannel. We compared the analysis result with the experimental result, and discussed the reason of the difference.
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Ryo OKITA, Seichi TANAKA, Hiroshi TSUKAMOTO, Koji MIYAZAKI
Article type: Article
Session ID: 327
Published: August 02, 2008
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Pump characteristics of a Y-shaped valveless micropump were measured to investigate the effect of channel geometry for various branching angle of Y-shaped channel. The test micropumps consisted of Y-shaped channel and a variable volume chamber with a diaphragm which produced oscillating flow. Pump characteristics of four types micropumps were measured for various drive frequencies and volume fluctuations. The experimental results showed that branching angle of Y-shaped channel was effective for the pump performance.
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Yoshitaka NAKA, Masaki FUCHIWAKI, Kazuhiro TANAKA
Article type: Article
Session ID: 328
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The development of micro pumps are actively conducted in recent years. A micro pump used for □-TAS transports at a micro flow rate with a high precision. Moreover, it is also needed to transport high-viscosity fluid since there are various types of drugs to be transported. In this study, the authors propose a micro pump with soft actuators by conducting polymers as a driving source. It is possible to build a micro pump that transports fluid in one direction by a micro pump with two soft actuators with opening and Contracting movement and that it can transport fluid even with the viscosity that is 140 times as large as that of water in addition.
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Yuhei FUJIWARA, Ichiro KANO, Ichiro TAKAHASHI
Article type: Article
Session ID: 329
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A micro-electrohydrodynamics (EHD) pump to generate an oscillating flow is newly developed and experimentally tested. The EHD pump is the overall dimensions of 30 ×30×7.8 mm and has a pumping channel of 24×24×0.9 mm which is bend in parallel. In order to generate symmetric oscillating flow, alternate voltage was applied. Experimental results indicate that the newly developed pump is the twice as good as previous pump at static pressure and flow rate. A new model pump generated up to 550 Pa at an applied voltage of 1kV. New model pump generate higher static pressure and higher flow rate by the use DBS in place of DBE at working fluid. The amplitude of oscillating flow become smaller with decreasing the frequency.
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Hiromichi OBARA, Shinichi TASHIRO
Article type: Article
Session ID: 330
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Micropump device is one of the most important devices in the microfluidic system for bio- and nano- analysis systems and medical instruments. In this study, we developed a novel micropump driven by gas-liquid interfaces utilizing a surface tension for next generation of the drug delivery system. And the basic characteristics of this micropump were demonstrated with an experimental approach using the test channel made of a PDMS (Polydimethylsiloxane). This micropump has three pairs of the side channels to generate the interfaces and this micropump is operated with controlled interfaces of liquid and gas at the intersection of the main channel in a micro channel. These controlled interfaces can choke the flow in the main channel and can push out the flow to downstream. As a result, the basic properties of the micropump were investigated and three dimensional shape of the interfaces is significant to estimate the performance of this micropump.
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Keigo SHIMIZU, Satoshi OGATA
Article type: Article
Session ID: 331
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We studied the mechanism of drag reduction due to the slip in Newtonian laminar flow through a rectangular micro channel. Fine fabrication was given to the test wall surface, and the surface was coated with PTFE for hydrophobic processing. Visualization experiment was carried out using a 5 x 0.5 mm micro channel. Shear rate is changed with the result of pressure loss measurement and the form of the air-liquid interface was visualized. A series of experiments showed that the air layer thickness decreased as the shear rate increased. Trethway et al (2004) showed that slip length rises dramatically as the air layer thickness increases. So the air layer thickness affects the drag reduction on textured surface.
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Thien Xuan DINH, Yoshifumi OGAMI
Article type: Article
Session ID: 332
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Mixing performance of an active mixer which mixes two fluids without diffusion by three-dimensional flow surrounding a rotating shuttlecock rotor in continuous mixer is numerically investigated. The mixer consists of a step contraction-expansion microchannel and a shuttlecock micro-rotor placed in the step. The obtained results show that the effects of mean velocity and rotation speed are resulted in the effect of Strouhal number. Streaklines demonstrate that two fluids from the inlet can penetrate into the space between the paddles of the rotor, and then are mixed here before flowing to the exit channel. Two fluids are twisted 90 degrees after passing the rotor region. It implies that mixing in downstream flow behind the rotor takes place in the height instead of the width of the exit channel, which makes the mixer applicable for channels with high aspect ratio of the cross section. It is observed that mixing is dominantly enhanced in the rotor region and increasing Strouhal number results in faster mixing in the mixer.
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Shuta NORO, Masaya SHIGETA, Seiichiro IZAWA, Yu FUKUNISHI
Article type: Article
Session ID: 333
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The purpose of this study is to find a method to accomplish rapid mixing in a small-scale channel. The relation between interface characteristics and mixing enhancement in a small-scale is investigated by an experiment and a numerical simulation. By comparing the results of the experiment to those of two-dimensional and three-dimensional numerical simulations, it is shown that it is essential to threat the flow field as three-dimensional. It is also shown that the interface length does not always predict the mixing enhancement, and it is important to stretch the interface where the concentration gradient is high.
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Naoki ONO, Minoru SAKATA
Article type: Article
Session ID: 334
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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As heat generation increases in CPUs and other small electronic devices, more miniaturized and efficient cooling technology has been required. In this study the authors investigated combination of impinging flow and boiling heat transfer in mini channels. By employing aluminum miniature multi-channels in practical use, the authors performed experiments and compared the heat transfer between normal parallel flow mode and impinging flow mode. Impinging flow was realized by making T-junction structure with the aluminum channel. It was found from the experimental results that the impinging flow of T-junction gave higher cooling ability and lower thermal resistance.
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Hiroshi UTASHIRO, Eigo TAGASHIRA, Yousuke HASEGAWA, Nobuhide KASAGI, Y ...
Article type: Article
Session ID: 335
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Heat transfer characteristics of two-phase slug flow without phase change in a 600 μm tube are examined Since the contribution of the gas phase on heat transfer is negligibly small, we focus on the effects of the Reynolds number, and slug length on the Nusselt number inside liquid slug. It is found that the Nusselt number in liquid slug is independent of the Reynolds number, and increases with decreasing the slug length. These trends agree fairly well with previous numerical results. The present results suggest that the two-phase flow has a potential to achieve around 4 times larger heat transfer rate than single-phase flow, while heat transfer per unit pumping power is kept almost unchanged.
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Hideo IDE, Ryuji KIMURA, Masahiro KAWAJI
Article type: Article
Session ID: 336
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An optical measurement system was used to investigate gas-liquid two-phase flow characteristics in wetting and poorly wetting circular microchannels of 100 μm diameter. By examining the optical sensor signals from which void fraction and the lengths and velocities of gas slugs and liquid slugs were measured, the effects of wetting on the adiabatic two-phase flow characteristics of nitrogen gas and water were investigated. Besides the flat nose and tail of gas slugs at low gas and liquid flow rates, poorly wetting microchannel showed higher void fraction and shorter length and lower velocities of liquid slugs rather than that in well-wetting microchannel.
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Makoto NOBAYASHI, Yousuke KITAJIMA, Shouhei WATANABE, Yoshinori SAWAE, ...
Article type: Article
Session ID: 337
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Engineered cartilages are expected to be used for the treatment of cartilage defects. Cartilage tissue is avascular; hence transport phenomena are controlled by diffusion and also advection by so called "pumping mechanism" of tissue. The objective of present paper is to evaluate the contribution of both diffusion and advection in engineered tissue for the control of transport phenomena.
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Kunito OKUYAMA, Akihito KAWAMOTO, Yuya HAMAGUCHI, Shoji MORI
Article type: Article
Session ID: 338
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Ink-jet technology is expected as a new technique for making artificial organs since minute droplets ejected from a small nozzle, whose size is several tens microns and in the order of cells, can be put precisely at high frequencies and a three-dimensional structure for cell proliferation may be built quickly through the two-dimensional patterning. The present study demonstrates the formation of a multi-layered gel structure as the scaffold using the ink-jet method. Small droplets of sodium alginate (Alg-Na) solution are ejected from a ink jet nozzle into calcium chloride (CaCl_2) solution to make microcapsules. Necessary conditions such as substrate preparation as well as solution concentrations and the distance between droplets for the gel structure formation are investigated experimentally.
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Yuriko MAEGAMI, Takashi SASAKI, Fumitada IGUCHI, Hiroo YUGAMI
Article type: Article
Session ID: 339
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Hydrogen energy system is expected as a key technology for the sustainable developing society. The surface grating technologies enable to control the thermal radiation spectrum. We are applying this technique to promote the chemical reaction to produce hydrogen. In this study, we research to make hydrogen production promoted in the process of methane steam reforming by spectrally resonant thermal radiation. The thermal radiation spectrum is adjusted to vibrational absorption bands of methane and water molecules by making a two-dimensional surface grating with microcavities on the radiative surface. By matching the peak of thermal radiation to the absorption bands of gases, it is clearly observed that the chemical reaction is promoted by the optical excitation of vibrational energy levels of molecules.
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Osamu NAKABEPPU
Article type: Article
Session ID: 340
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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New distinguished thermal analysis and calorimetry have been developed with the MEMS technology. Performance in temperature and heat measurement have been dramatically improved, and a very fast thermal analysis or a high-sensitive calorimetry has demonstrated a nano-gram thermal analysis, observation of a rate dependent phase transition, very small exothermic reactions. This paper shows nano-thermal analysis with cantilever type nanocalorimeters as well as a metabolism observation of cells with an integrated thermopile sensor.
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Motohiko Nohmi, Juan G. Santiago
Article type: Article
Session ID: 341
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Electroosmotic flow is applied to form a denaturing gradient on a microchip. Quick measurement of electroosmotic flow velocity on site is required for precise process control. Proposed method is applied to the microchannel with a Y-shaped junction. High voltage signals are applied to the two wells upstream of the junction and the downstream well is grounded. A neutral dye is added to one of the upstream wells. Under the condition of constant sum of two high voltage signals, two voltage signals are fluctuated in a square waveform with known frequency. From the image analysis of the flow with propagating cyclic disturbance of a dye, the flow velocity can be calculated easily.
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Satoshi OGATA, Kensuke KANDA, Kazuyoshi JINGU, Ming YANG
Article type: Article
Session ID: 342
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The Particle motion at near-surface is greatly important for efficiency in micro chip. In this paper, concentration distribution of polyethylene latex particle (diameter 100 nm) at near-surface in micro-channel is evaluated by total internal reflection fluorescence microscopy. And particle-wall interaction forces (van der Waals, electrostatic, and lift force) are investigated. The results show the concentration is the largest at specific location from the wall surface. The location is consistent with balance position of theoretical particle-wall interaction force in static fluid. In flow field, the largest value location is far away from wall as increasing velocity. This impact is lower with high-ionic strength.
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Masahiro MOTOSUKE, Kouki YUSA, Hidetomo NAGAYO, Shoji KAMIUNTEN, Shinj ...
Article type: Article
Session ID: 343
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Hydrogen energy is highly expected as renewable energy for its environmental compatibility. To achieve the hydrogen energy-oriented society, precise management or measurement of hydrogen flow rate is required in every phase of manufacture, transportation, and utilization. MEMS sensor has outstanding characteristics such as compact, sensitive, low energy consumption, and also has applicability for various fluid monitoring including hydrogen. In this study, evaluation of output characteristics in MEMS-based mass flow sensor using air and helium. alternative to hydrogen. is performed. Three types of sensors with different element geometry are tested, and output characteristics are obtained. We can confirmed that the sensor output is sensitive to area or distance of heater elements in both gases.
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Dai AKUTSU, Masahiro MOTOSUKE, Shinji HONAMI
Article type: Article
Session ID: 344
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Temperature of microfluids is greatly sensitive because of fast heat conduction and small heat capacity. The purpose of this study is development of a measurement system for the temperature field in a microfluidic device with high spatial and temporal resolution. Measurement method is laser induced fluorescence using Fluorescein with the temperature dependence of fluorescent intensity. In order to measure the step response temperature field, an image-intensified high-speed camera is utilized. Although this has low signal-to-noise ratio, it can be reduced by time- or phase- averaging scheme. Applying the synchronization mechanism, phase-averaged temperature data with time resolution of 500 μs can be obtained in this study.
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Yusuke OZAWA, Keisuke MATSUDA, Shingo OISHI, Shin-ichiro AOSHIMA, Tosh ...
Article type: Article
Session ID: 345
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An optical fiber probe method is one of the efficient and reliable measurement methods for gas-liquid two-phase flows. For measurement of small and medium size bubbles/droplets, we developed a Four-Tip Optical fiber Probe (F-TOP) and a Single-Tip Optical fiber Probe (S-TOP). In this study, we newly developed an optical fiber probe (OFP) processed by femtosecond pulse laser in order to measure tens micrometer bubbles/droplets. We demonstrated a measurement of millimeters size droplets and discussed its capability for measurement of velocities and diameters of droplets. As a result, the difference of measurement results of droplets diameter and velocity between the new OFP and visualization is within 5%.
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Ryo HORITA, Yasuhiko SUGII
Article type: Article
Session ID: 346
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to develop an efficient micro heat exchanger and micro fuel cell, a number of studies of two phase flow such as liquid-gas in micro scale have been reported. In the micro scale, since surface tension became dominant, micro droplet or liquid film on a wall affects the dynamics of fluid. In the paper, in order to improve measurement accuracy of the three-dimensional shape measurement method for droplet based on a micro laser induced fluorescence technique, experimental conditions such as micro fabrication method, concentration of fluorescence dye, and intensity of excitation light were optimized. The technique was applied to a micro droplet on a wall resulting in achievement of high spatial and temporal resolution. The measurement accuracy of the present method was 0.57μm in comparison to a laser microscope. The result indicated that the present method is suitable for investigation of two phase flow in micro scale.
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