This paper describes micro pattern tactile samples to characterize tactile feeling. We perceive many tactile sensations such as rough, bumpy, smooth by our skin. At present, what kind of parameters of texture relates to these sensations is not clear. We designed and manufactured micro pattern tactile samples to investigate the relationship between the surface characteristics and our tactile sensations. The tactile samples presented in this work are made of SU-8 and have micro striped patterns. The effects of the width and pitch of the stripes on the tactile feeling were investigated. In distinguishing the roughness, the experiments deduced that width was a more dominant factor over the pitch.

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We propose and demonstrate the autonomous tweezers driven by surface tension without any actuators. The tweezers are composed of only a pair of the polydimthylsiloxane (PDMS) cantilevers having different wettability. Since the front and back surfaces of the cantilevers have different wettability, they can bend due to the difference of surface tension and hydrostatic pressure exerted on each surface when they come in contact with the surface of liquid. Using this self-bending phenomenon, we succeed in not only grasping but also releasing a floating object under proper conditions. The autonomous tweezers will be useful for damage-less manipulation of biological samples without any actuators and external energy source.

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Microneedles are currently studied for various applications, such as biological signal measurement and transdermal drug delivery. Our group has already developed polymer-based microneedle electrodes in an attempt to continuously measure brain waves. The needles are flexible and short enough for painless measurement. However, It leads to low potential to penetrate the stratum corneum. One of crucial factors for successful insertion is the tension of the skin. Therefore, this paper proposes a sheath structure for a microneedle to stretch and apply tension to the skin. We microfabricated 5 types of sheath structures and conducted compression test to choose an effective one for exploiting buckling and stretching the skin. The proposed mechanism is readily applicable to improve insertion characteristics of microneedles.

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Semiconductor gas sensors are in widespread use for industrial applications. Some of them need heater based on the principle. Downsizing of both of the sensor and heater is required with MEMS technology to make the power consumption lower. At the same time, the sensor should be produced as low cost and high productivity as possible. Thus, we apply suspension coating approach to the sensor element fabrication on Si micro heater. The element has different size of nano-pores by mixing colloidal suspensions that contains different size of polystyrene micro-particles and SnO_2 nano-particles and then removing polystyrene particles after the self-assembly. We here present a demonstration of such nano-fractal porous gas sensor fabrication and its evaluation.

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QCM (Quartz crystal microbalance) is used as viscoelastic sensor not only as mass sensor. If it can measure the electric properties, it is expected to use for various applications. In this paper, a dual quartz sensor using a leakage electric field has been developed for analyzing the physicochemical properties of liquids. This sensor can measure the mechanical properties and the electrical properties simultaneously by integrating two types of ACR (Antiparallel coupled resonator) sensors on a same substrate. One is the sensor for measuring the viscoelasticity, another is the sensor for measuring the conductivity and dielectric constant. By changing the electrode portion on the sensing surface of ACR, ACR can evaluate the electrical properties of liquid using a leakage electric field. And this sensor can improve its stability in the air by adjusting the electrode area on the sensing surface.

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Thermal conductivity was measured by a contact temperature and thermal conductance combination method with the scanning thermal microscope (SThM). The multifunctional cantilever probe of SThM has thermal sensors which include Ni contact electrode, thermopile, thermocouple and two heaters. A Pt thin film of 440 nm thick on a cover glass as the measurement sample and a Cu bulk material as the reference sample were used for another electrode of contact thermocouple. The data measured with the force curve mode showed that heat flow from the probe to the sample and contact temperature were simultaneously measured as varying contact radius. As results, it was found that the method could detect different thermal conductivity between two samples. The order of measuring thermal conductivity of two samples was equivalent to that of each bulk value.

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Multilayered films with sub-100nm thick bilayers made of light metal and transition metal shows self-propagating explosive reaction, which is attractive as local heat source. By using the films, the authors have so far succeeded in flash solder bonding of Si wafers for hermetic package. However, multilayered films restrict applications because finely forming the films to free dimensions is difficult. To explore other applications, fabricating micro-sized particles having exothermic reaction function is required. In this paper, a new technique for fabricating exothermic reactive micro-scale particles is described. A dual-source magnetron sputtering apparatus was used for particle fabrication. The heat generation performance of the particles was compared to that of the films using differential scanning calorimeter (DSC) and high speed charge coupled device (CCD) camera.

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Recently, a multilayered thin film Nd_2Fe_<14>B/Ta permanent magnet (TFPM), which not only has a high remnant flux density and a high coercive force similar to those of conventional sintered bulk neodymium magnets, but also has high heat tolerance, was developed. In this study, micro magnetization assisted by laser heating under an external DC magnetic field was proposed and tested. The laser beam conditions were determined using unsteady heat conduction analysis. Using a magnetic field analysis simulator, neodymium PM arrays are designed to apply the DC magnetic field to the TFPM. Magnetized strips of 200 μrn in width were patterned in the TFPM of 4.5 μm in thickness. Agreement between measured and simulated magnetic flux densities over the TFPM was obtained.

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An increase of thermoelectric film thickness is important for thermoelectric film generators to convert thermal energy to electric energy with high efficiency. The aim of this study is to develop a patterning process of thermoelectric thick films. Thermoelectric thick films of Bi_2Te_3 materials were deposited by thermally-assisted sputtering method (TASM) and patterned using lift-off technique. The weight loss of polydimethylsiloxane (PDMS) was as small as 0.5% at 300℃ by thermogravimetry analysis. Therefore, PDMS was used as masks in the lift-off technique because the substrate temperature reached approximately 300℃ in TASM. The PDMS lift-off masks with 100 urn height were formed on the substrates using thick photoresist patterns as molds. After depositing the thick films, PDMS lift-off masks were removed from the substrates in acetone. Bi_2Te_3 thick film patterns with 300 μm width and 30 μm thickness were obtained. This patterning process can be applied to fabricate thermoelectric thick film generators.

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We fabricated multilayer ceramic actuator (MLCA) composed of piezoelectric layers with SrRuO_3 (SRO) internal electrodes by single sputtering deposition. We deposited approximately 500-nm-thick Pb(Zr,Ti)O_3 (PZT) layers on SiO_2/Si substrates through a movable shadow mask. The separated internal SRO electrodes are prepared by sliding the shadow mask and multilayered PZT thin films are deposited on a Si substrate with external electrodes on both sides of the PZT films. The PZT layers of MLCA have perovskite structure. The MLCA with five PZT layers have high-dielectric properties; a relative electric coefficient of approximately 1100 regardless of the number of PZT layers. The piezoelectric displacement of Si cantilever with MLCA increased with the number of PZT layers.

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It is well known that the Amontons' law holds well in various dry sliding solid object. Here we examine the sliding friction of the elastic block in which the Amontons' law holds locally by both of numerical and analytical methods. It is shown that the block as a whole does not obey the Amontons' law and the friction coefficient decreases with the applied load and depends on the apparent contact area. These behaviors are caused by local slips appearing below the maximum static friction force. The mechanism of these behaviors are discussed.

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To investigate feature of phonon energy dissipation in friction process, we compared frictions of isotopic diamonds atomic force microscope and atomic scale simulations. The friction of ^<13>C is lower than that of ^<12>C by approximately 3%. This result suggests that the lower friction of ^<13>C diamond results from the inhibition of the energy-dissipative phonon by a heavier atom mass.

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Course-grained Monte Carlo Brownian Dynamics simulations are used to simulate the nature of polyelectrolyte brushes. For the basic understanding, the effect of salt and surface charge density to the structure of polyelectrolyte brushes is studied. Polyions are grafted to the surface of up to several tens of nanometers pitch. For flexible polyion model of 128 segments, bond and bond angle degree of freedom is adopted. Linear charge density parameter of the polyion is set to 1.0 and 2.0 in order to discuss the Manning's counterion condensation. Thermal equilibrium structure in room temperature of a brush system without salt and a system of added 1:1 salt are compared. The effect of salt caused the decrease of film thickness as have been detected in small angle neutron scattering experiments. The difference of the thickness at the salt-free system is discussed with the polarization of counterion atmosphere.

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In order to reveal a chemical mechanical polishing (CMP) mechanism of a sapphire substrate by a colloidal silica abrasive grain, we investigated a polishing process of an α-Al_2O_3(0001) surface by a SiO_2 cluster under water environment by a first-principles calculation. The results show that the mechanical pressing by the SiO_2 cluster and the chemical reaction with a H_2O molecule introduce the break of the Al-O bond of the α-Al_2O_3(0001) surface. In addition, after the chemical reaction with H_2O, an Al(OH)_3 molecule is generated and desorbs from the α-Al_2O_3 surface in the CMP process.

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It is known that diamond-like carbon (DLC, a-C:H) coatings show low friction and high wear resistance under inert gas environment. However, hydrogen-free DLC (a-C) coatings show relatively high friction under such environment. And, both a-C coatings and a-C:H coatings can not achieve relatively low friction coefficient. So, super-low friction of a-C coatings and a-C:H coatings under humid N_2 gas environment is achieved in this study by introducing running-in period and controlling relative humidity. We conduct friction tests of a-C coatings, a-C:H coatings under various humid environment. When contacts between each coatings are maintained respectively and we increase relative humidity (4.2-40 %RH, 0.7-40 %RH), value of friction coefficients are 0.021 and 0.027 respectively and independent of relative humidity. It is considered that humid is a key of super-low friction of carbon based hard coatings.

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We performed friction simulations of hydrogen terminated carbon nitride (H-CNX) using our first-principles molecular dynamics (FPMD) and tight-binding quantum chemical molecular dynamics (TB-QCMD) simulators. In FPMD simulation, H-CN_X showed low friction coefficient of 0.15 and 0.10 at 5 and 10 GPa, respectively. This is because terminated hydrogen atoms prevented the bond generation at the films interface. In TB-QCMD simulation, under 1 GPa, H-CN_X and H-DLC also showed low friction coefficients of 0.05 because terminated hydrogen atoms prevented the bond generation at the films interface. On the other hand, under 5 GPa, while H-CN_X showed a low friction coefficient of 0.07, a friction coefficient of H-DLC takes a high value of 0.42. Although C-C bonds were generated at the interface of H-DLC films under high pressure, nitrogen atoms of H-CN_X prevented C-C bond generation at the interface. We found that H-CN_X is more stable and shows lower friction than H-DLC under high pressure.

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Si doped DLC films as solid lubricant exhibit excellent tribological properties of low friction and high wear resistance. One of the low friction reasons is the structure change from sp^3 carbon to sp^2 carbon on the surface of DLC films by Si doping. In this study, to reveal the mechanism of the structure change of the DLC surface by Si doping, we investigate the surface structure of the Si doped diamond using the first-principles calculation. The results show the structure change from six-membered ring to five-membered ring on the surface of Si doped diamond since a Si atom has larger atomic radius than a C atom. Furthermore, the structure change from sp^3 carbon to sp^2 carbon results in the generation of graphene, which would affect the low friction of Si doped DLC films.

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There has been increasing interest in developing a single-molecule technique for biosensing applications such as viral screening and DNA sequencing. Solid-state nanopore, a nanometer-sized hole sculpted in a thin membrane on a silicon wafer, is one of the promising platforms that enables electrical detections of single-molecules by measuring resistive ionic current pulses during their translocation through a pore. In this presentation, I will briefly introduce recent progress in nanopore technologies. Then, I will present an ongoing effort devoted for realizing sequencing by transverse tunneling current through a single-molecule DNA by using a pair of nanoelectrodes embedded in a pore and discuss the potential of the method for the goal of nanopore sequencers.

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We have developed a micro-fabricated chip to separate DNA molecules by their molecular sizes based on the principle of the size exclusion chromatography (SEC). However, there was a problem of resolution lowering due to the spreading of DNA molecules in the direction of electrophoresis when they entered into the area where the micro-structures for molecular sieving were formed. In this study, we fabricated DNA separation tip that has nano-slit structure for online concentration of DNA samples and experimentally verified the effectiveness of the preconcentration. Experimental results showed that the preconcentration was effective for the improvement of detection sensitivity and resolution of size separation.

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In this study, we propose an efficient on-chip cell electroporation that utilizes preconcentration of plasmids by isotachophoresis. The microfluidic device is a simple straight microchannel with a constriction that strengthens the electric field for the electroporation. We leverage the isotachophoresis to preconcentrate the plasmids in the constriction for efficient delivery of the molecules into living cells. We here demonstrate the feedback position control of the preconcentrated layer based on pressure driven flow and electrical current. The designed feedback system successfully shows the stabilization of the position of the preconcentrated layer in the constriction.

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A patterining technique of single cells is required for studying cell-cell communication. The objective of this research is to develop a versatile cell manipulation system capable of patterning of single cells in high precision and super parallel format. We develop cell manipulation technique by an electroosmotic (EO) flow with a microprobe-array and micropipette. Application of DC voltage (5 V) generated an EO flow through the hollow channels of the probe-array and pipette. Cells moved toward tips of the micro-probe array or the pipette by EO flow. The cells were tracked and analyzed. Cell damage was characterized under optical observation. A cell swelling and loss of the fluorescence was observed 180 s after the cell capture.

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It is well known that hair cells in cochlea can detect nanometer-order range vibration. Mecano-electrical transduction mechanism of hair cells is worthy to apply MEMS device and technology. This will be breakthrough in today's MEMS device development. In this study, hair cells model is investigated numerically by using finite-element analysis commercial software, COMSOL Multiphysics Ver.4.3b. Computational result shows that eignfrequencies of the present hair cell model was ranged from 10^5 to 10^6Hz, and there were various types of vibration modes. Furthermore, it was found that the rootlet of the present hair cell model supported signal stabilities of transduction electric current flow.

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Dynamic Optical Coherence Straingraphy (D-OCSA) can visualize tomographically and non-invasively strain rate tensor distribution in biological tissue at the micro scale, using tomographic images consecutively captured by Optical Coherence Tomography (OCT) with tissue deformation. D-OCSA can time-continuously provide the accurate deformation vector distribution, by recursively applying the speckle cross-correlation method as well as the high accurate subpixel analysis of upwind gradient method and image deformation method. In this study, D-OCSA was ex vivo applied to articular cartilage proteoglycan-degenerated by enzyme treatment with compression test, so as to evaluate space and time dependent bio-mechanical behaviors. Consequently, D-OCSA can discover compressive strain rate concentrated locally on the surface zone. These observations are thought to be generated by not only depth-dependent elastic properties determined mainly by collagen fiber orientation, but also viscous properties related with water permeability. It was concluded that D-OCSA is biomedically effective as a directly diagnosing technique of micro-biomechanics, such as clinically diagnosis of osteoarthritis.

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The medical microrobot is one of the most attractive applications in the field of minimally invasive robotic therapy. The wireless control of microrobot(s) inside the human body is a challenging problem, and we have been proposing a simplified control method of the external magnetic field to drive a microrobot in a blood vessel. In this paper, we propose two methods for the branch selection. We have experimentally investigated the required magnetic force and direction for the branch selection while varying the flow speed.

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We have studied deformation process of a bridged carbon nanotube (CNT) during Joule heating by in-situ transmission electron microscopy. Although thinning process at central portion of the bridged CNTs has been reported, shrinking deformation along an axial direction was observed in the present study. This result suggested that these deformation process strongly depended on how release the tensile stress applied to the CNTs caused by sublimation of carbon atoms during the Joule heating, so that the stress were measured by using an cantilevered probe with rather low spring constant as the electrode of the Joule heating. Experimental result indicated that the shrinking deformation of CNTs occurred with loading tensile stress under 0.31N/m^2. It is also suggested that carbon atoms selectively evaporate from a specific region, where many topological defects such as 5- or 7- membered rings are gathered, in the shrinking deformation.

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We have developed the in-situ scanning electron microscopy (SEM) nanomaterial manipulation system including newly designed Electrostatically Actuated NAnotensile Testing devices (EANATs), in order to investigate mechanical characteristics of multi-walled carbon nanotubes (MWCNTs) synthesized by an atmosphere pressure-chemical vapor deposition (APCVD). The new EANATs can measure uniaxial tensile displacement of nanomaterials with the capacitive displacement sensor incorporated to the cantilever motion amplification system. The nanomaterial manipulation system functions to pick up an individual MWCNT from a substrate and to fix it on EANATs. Stress-strain relations of MWCNTs were successfully obtained from the nanotensile tests, and Young's moduli were estimated to be 243 to 623 GPa. The shear strength at stick-slip event during interlayer sliding of MWCNTs under tensile loading was directly derived from the shear interaction force in tensile force-displacement curves and SEM observations.

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Diamond-Like Carbon (DLC) film is carbon-based hard thin film in amorphous state having an intermediate structure of graphite and diamond. DLC has excellent characteristics as a coating material such as high hardness, low friction, abrasion resistance, and chemical stability. Further, in recent years, with the development of nanotechnology, DLC film has been expected as a protective coating for a fine three-dimensional structure. So optimization of DLC film deposition technique to a fine three-dimensional structure are necessary. In the present study, DLC films were prepared using a bipolar-type plasma based ion implantation and deposition (bipolar PBII&D) system on the micro-scale trench patterns and uniformity of film thickness deposited on each trench surface was evaluated.

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Bipolar-type plasma based ion implantation and deposition (bipolar PBII&D) is a promising surface coating technique for complex-shaped target surfaces. In this study, diamond-like carbon (DLC) films were deposited on steel rods with various radii of curvatures using bipolar PBII&D and the plasma behavior in surrounding of the steel rods (i.e., flux and energy of incident ions and electrons) was calculated using Particle-In-Cell Monte Carlo Collision (PIC-MCC) Method. The positive and negative pulse voltages varied from +1.0 to +1.5 and from -1.0 to -5.0, respectively. The structure of DLC films was evaluated by Raman spectroscopy and the hardness of DLC films was measured using nanoindentation. It was found from Raman and nanoindentation measurements that the structures of DLC films coated on the rod-shaped surfaces are different from those of DLC films coated on the flat-shaped surfaces, which are affected by the flux and energy of incident ions and electrons.

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Effects of silver catalyst structure on synthesis of carbon onion film were investigated. Silver thin films were sputter-deposited on silicon wafers at several different temperatures, and then carbon ions were implanted into the film using a plasma based ion implantation (PBII) technique. The films were heated to evaporate silver component so that carbon material would remain on the wafers. The sample surfaces at each step were observed using scanning electron microscopy. We found crystal grains of the films become larger when the sputtering temperature is higher. Defects were found on grain boundary, which were considered sites of nucleation and growth of carbon nano particles (CNP). The CNP film synthesized in the silver film deposited at 350℃ consisted of CNPs whose diameter was around 10nm, while that was around 20nm when the deposition temperature was 150℃. The silver film deposited at 350℃ showed island structure, resulting in island-shape hull structure of CNP film.

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In this research, carbon nano-particle (CNP) films were developed by bi-polar Plasma Based Ion Implantation method with silver catalyst films and the structure and tribological properties of CNP films were investigated. The fabricated film consisted of two layers. The bottom layer was composed of CNP cluster with the thickness of 100nm. Besides, the amorphous membrane structure with the thickness of 30nm covered the CNPs. The coefficient of friction of a CNP film tested by ball-on-disc friction meter at first lowered from 0.2 to 0.1 but gradually increased. The size of wear scar by the CNP film was reduced in half in comparison to that by bare silicon. Deformation and fluidity of CNPs during friction may result in the dispersion of the area where the contact pressure reached a region of plastic flow judging from the scattered wear track of the CNP film after the sliding.

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Microscopic objects in fluid are subject to thermal fluctuation. The thermal fluctuation of the surrounding fluid molecule leads to Brownian motion, and diffusion coefficient indicates the overall speed of diffusive motion in the long time limit. In our previous work, we have shown that the diffusion anisotropy of a prolate particle can be extracted from the time-series trajectory data even if there is no explicit information of particle orientation at each time step, as far as the precision, resolution, and total amount of the data is sufficient (Phys. Rev. E, vol.85, 051134 (2012)). The analysis was based on the large deviation principle. In this study, we apply our methodology to the thermal motion of a polymer molecule in aqueous solution. In particular, we analyze the time series data of end-to-end distance. We show that the numerically-obtained approximate values of large deviation quantities indicate the clear difference of intra-molecular interactions while the time-averaged value is close.

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We have performed an atomistic analysis of the transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level using classical molecular dynamics simulations. The new empirical valence bond (EVB) model is developed based on the previous study of EVB model reported by Walbran et al. in order to improve the description of proton mobility in both aqueous and Nafion environments. A large contribution of Grotthuss mechanism for the diffusion of hydronium ions has been found at high water contents and this implies the important impact of Grotthuss mechanism in the membrane as well as in the bulk aqueous solutions.

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The electro-osmotic flow through a channel between two undulated surfaces is considered. An analytic model equation that describes the flow rate is derived for the case in which the channel width varies very slowly. It is shown that the variation of the channel width reduces the flow rate, compared with the case of the electro-osmotic flow through a straight channel. In addition, the direct numerical analysis using the lattice Boltzmann method is performed, and the fast variation of the channel width is shown to further reduce the flow rate.

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In this study, a numerical simulation method for microscopic liquid-liquid two-phase flow was proposed that adopted a lattice-Boltzmann method (LBM) as solution scheme for fluid-dynamic equations and also a phase-field model (PFM) for fluid interface formation and interfacial-tension forcing. Instead of Cahn-Hilliard-type advection equation in conventional PFM-based methods for two-phase flows, a conservation-improved Allen-Cahn-type equation was used for lower-cost calculation of diffuse-interface advection. The method was applied to mono-dispersed slug droplets flow problem in T-junction microchannel with square cross section. The volumetric flow rate ratio was set within low Reynolds, capillary and Weber numbers for a silicone oil-water system with hydraulic diameter of 100 nm, interfacial tension of 41.6 mN/m and kinematic viscosity of 1.0 cSt. The major findings were as follows: (1) The continuous and dispersed-phase droplets became shorter at nearly-constant length difference between them as their flow rates were increased; (2) The slug lengths agreed with experimental data.

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We report a development of a micro viscosity sensor, named η-MEMS, which is manufactured by processing technology of micro electro mechanical systems. The small package of the sensor-holder made from stainless steel has a size of a USE memory. The viscosity can be easily measured by dipping the sensor holder into the sample liquid directly. The basic shape of the viscosity sensor is double spiral. In the present study, we evaluated the performance of the USB memory sized holder and new signal processing method. In the new system, the viscosity of the liquid is obtained by detecting the amplitude of the vibration of the sensing spiral. The performance of the holder and the system were evaluated. In experiment with DC bridge amplifier, electromagnetic noise disturbed the appropriate signal processing. On the other hand, AC bridge amplifier decreased the noise and detected the reasonable signal. Finally, The theoretical relationship between the amplitude and viscosity is verified.

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An infrared hyper-spectral imager based on a piezoelectrically driven tunable Fabry-Perot filter and a two dimensional scanning detector for spectrum analysis has been developed. The Fabry-Perot filter consisting of two parallel ZnSe mirrors and a miniaturized movable stage actuated by a stacked piezoelectric actuator was fabricated. The measured transmittance of Fabry-Perot filter using a laser with wavelength of 1550 nm showed a good agreement with the theoretical value. In addition, interferogram of broadband source (hot water in quartz beaker) through Fabry-Perot filter was also obtained, which meets with the theoretical waveform. Furthermore, according to the comparison of conditions with or without a polyethylene film placed in the optical path, we find an absorption point whose corresponding gap distance is times to the half of released absorption band of polyethylene.

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Nanometer-thick liquid lubricant films are used for the lubrication of micro mechanical systems, such as MEMS devices and hard disk drives. For the lubrication design, it is essential to clarify the mechanical properties of such thin films under the shearing motion. In this study, we succeeded in measuring shear rate dependence of viscous friction at high shear rates of 10^5 to 10^8 s^<-1>, which can be comparable conditions in the actual mechanical systems. To measure viscous friction, we used the highly sensitive shear force measuring method, which we called the fiber wobbling method. We observed that viscosity decreased exponentially along with the increase of shear rates, which is called the shear thinning behavior.

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Recording media with grooves such as discrete track media (DTM) and bit-patterned media (BPM) are considered to be some of the most promising media for achieving ultrahigh track densities. It is becoming increasingly important to analyze the static and dynamic characteristics of flying head sliders over DTM/BPM media using the molecular gas-film lubrication (MGL) equation. In this paper, we established an analysis method of van der Waals forces acting between slider and a disk with two-dimensional distribution of material properties by using Fourier series expansion. The characteristics of the van der Waals forces are quantitatively clarified.

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To achieve magnetic recording densities of more than 10 Tb/in^2, the head-disk interface (HDI) spacing should be less than 2-3 nm. Thus far, thermally assisted magnetic recording (TAMR) technology has been studied and developed to achieve such ultra-high magnetic recording densities. However, the use of ultra-thin liquid lubricant films as well as DLC thin films on the disk surface in TAMR leads to critical issues with regard to the HDI. In addition, HDD technology with head-disk assembly mechanism in which He gas is enclosed has been developed. In this study, the effect of lubricant bonding mechanisms on lubricant depletion has been studied. Furthermore, the mechanisms of lubricant depletion due to laser heating have bean investigated and discussed.

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Data recovery technology of the hard disk drives (HDDs) is important, because the HDDs may be sometimes troubled by unfortunate causes. However, it has been almost impossible to recover data from crushed HDDs. In this study, the data recovery method was studied by the tape cleaning of wear particles on the magnetic disk surface by the head-disk crush. The "process condition of tape cleaning for disk surfaces with the scratch by the head-disk crush was determined and the head flyability was compared on the disks with and without the tape cleaning. Finally, the data recovery was performed and confirmed the efficiency of the tape cleaning process for the crushed disks.

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In this letter, characteristics of the electric power generation in the multi-ferroic composites, composed of the ferromagnetic Fe_<70>Pd_<30> alloy (thickness of 90 μrn) with large magnetostriction and ferroelectric PZT (260 μm), were investigated at the point of view of the possibility for applying to micro-passive devices. The three-layered Fe_<70>Pd_<30>/PZT (C-3)/Fe_<70>Pd_<30> composite exhibits high magneto-electric-voltage (V_p) of about 0.7 V/Oe by the driving external AC magnetic field (H_<AC>) of 1 Oe at a resonant frequency (f_r) of 62 kHz. The improvement in the magneto-electric-voltage might be originated from a simultaneous effect of higher piezoelectric voltage constants (g_<33>) and lower relative dielectric constant (ε_<33>^T/ε_0). Moreover, output on the five-layered composite, i.e. (Fe_<70>Pd_<30> x 2)/PZT (C-62)/(Fe_<70>Pd_<30> x 2) composite reaches about 160 μW/Oe by the H_<AC> of 1 Oe at f_r, which is equivalent to 1.39 mW/cm^3 in the harvesting power density. The power remarkably increases with the number of Fe-Pd layer.

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Magnetoelectric(ME) coupling in multi-ferroic composite designed by (PZT) and ferromagnetic amorphous alloy FeSiB was investigated to apply to small magnetic sensor. Magnetostrictive FeSiB (25-75μm) ribbons rapid solidified were glued on both surfaces of PZT. The magnetostriction of the FeSiB ribbon was about 30 ppm at low magnetic field of 100 Oe, and the value of annealed FeSiB increased. When a driving ac magnetic field H^ of frequency f = 0.07 Hz〜70 kHz and low dc bias magnetic field of 30 Oe were applied along the length by coil about the laminate composites, the ME charge generated across the samples was measured by charge amplifier. The output ME voltage for the FeSiB - PZT laminate composites exhibited large peak at a resonant frequency of 61 kHz〜72 kHz and a maximum V_<ME> was 1.8 V/Oe.

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A novel piezoresistive three-axis accelerometer featuring a ring-shaped beam for stress-relaxation against shrinkage force of resin-mold packaging was improved to achieve remarkably high shock durability of 20000 G By a simulated shock test, fracture mechanism was estimated that the ring was broken due to a momentary increase in tensile stress just after a mass crashed into a cap. Therefore, the ring shape was improved in strength against tensile load without reduction in stress-relaxation effect, and gaps between the mass and the caps were reduced to 2 μm for softenning the crash. Shock durability over 20000 G was finally confirmed with improved test samples.

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In this research, a micro sensor which can detect cavitation in a microchannel has been fabricated by using piezoelectric polymer thin film. P(VDF/TrFE) was used as the sensor material. We have applied integration by using the photolithography process to miniaturize sensors. We have succeeded in fabricating the micro-sensor whose thickness is 158μm. We have also succeeded in receiving waveform in the high frequency range. Thus the sensor would detect cavitation by using frequency analysis of bubbles collapse sound.

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We achieved three-dimensional (3D) fabrication of heterogeneous microstructures using an in situ photo-polymerization method, vertical continuous flow lithography (VCFL). Utilizing a projection system including a Digital Mirror Device, 3D microstructures were fabricated in a layer-by-layer fashion with the thickness of each layer controlled by UV absorber and exposure time. In addition, VCFL fabricated heterogeneous microstructures by exposing light patterns to multiple laminar flows. We demonstrated three-layered structures and long fibers whose cross-sectional geometries were changed. We also fabricated two-layered Janus structures. We believe that VCFL will be applicable to making anisotropic microparticles for material science and bottom up tissue engineering.

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We developed micropatterned polymeric ultra-thin films (nanosheets) consisting of biodegradable poly(lactic-co-glycolic acid) (PLGA) and magnetic nanoparticles (MNPs), on which monolayer of retinal pigment epithelial (RPE) cells were formed. The viability of RPE cells on the micropatterned nanosheets were evaluated along the syringe manipulation equipped with a clinical needle. Finally, subretinal injectability of the macropatterned nanosheets was demonstrated by using ex vivo swine eyes in terms of handleability and physical stability. The micropatterned nanosheets injectable by clinical syringe hold a great promise to transplant functional RPE cells minimum invasively.

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Recently, many neural probes with various materials and shapes have been developed for treatments of cerebropathy and analyses of the brain function. Among these probes, silicon neural probe attracts much attentions because various kinds of functional structures such as microfluidic channel and optical waveguides can be fabricated by semiconductor micro- and nano-fabrication technologies. On the other hand, it was reported that the recording quality of the neuronal signals deteriorated when nervous tissues were damaged due to insertion and placement of the silicon neural probes. In this research, lower invasive Si neural probes with small shank cross-sections and sharpened tips were successfully fabricated using silicon anisotropic etching techniques. Also, insertion characteristics of the probes were carefully evaluated, indicating that the probe will cause less damages to nervous tissues in the brain.

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A lead-free piezoelectric AlN based bent cantilever was fabricated with a heavy proof mass at free end to convert ambient vibration energy to electric energy. High fracture toughness stainless steel substrate was employed to enhance output power and reduce resonate frequency of vibration energy harvester. This device was comprised of stainless steel film as a bottom electrode, Al thin film as a top electrode and c-axis oriented AlN film as functional layer in the middle. Furthermore, the devices were utilized to scavenge both vertical direction and longitudinal direction vibration of cantilever surface. And it presents the high output power of 28.11 μW for vertically induced vibration and 51.73 μW for longitudinally induced vibration when vibration acceleration was 1.0 g.

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In order to achieve stable and efficient use of the output power of electret generators for battery-less sensor network nodes, a prototype of the power management circuit is developed. The performance of the circuit integrated with an electret generator and a RF circuit is characterized in a series of experiments.

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Power sources based on micro solid oxide fuel cells (SOFC) for mobile electronic devices were thermally designed to achieve thermal consistency and compatibility with other electronic circuits. Considering the loss of heat flux from the surface and heat transportation by exhaust gases, Thermal balance was evaluated at the operating temperature of 300℃ to 500℃. The result suggested that thermal insulation structure using vacuum zone, and heat exchangers, which recycled heat of exhaust gases, were effective especially at high temperature. As a result, both requirements were achieved by micro-SOFC system with the thermal insulation structure of vacuum zone and heat exchangers. Detailed thermal insulation structure was designed in accordance with the results of design.

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