In this paper, we present a wrist-worn rotational electret energy harvester for wearable devices to capture energy from human walking. Based on power generation analysis with the arm swing model, an improved rotational electret energy harvester prototype with the natural frequency of around 1 Hz is developed. The output power of prototype was characterized with a 6-axis multi-link robot by mimicking arm swing motion. It is found that 6 times higher output power than a previous prototype has been obtained even at slow walking speeds.

We have been developing an on-site water monitoring system available for continuous monitoring of residual chlorine in environmental water. It is required that this system has high robustness to realize stable monitoring under severe environment for one year. Glass with diamond like carbon (DLC) coating is expected to reduce adhesion of mineral precipitation and biofilm. We propose fabrication protocol of glass micro-channel with DLC coating. DLC is coated on glass micro-channel with groove by Electron Cyclotron Resonance (ECR) sputtering, chromium (Cr) as adhesion layer is coated in advance. A cover glass is coated DLC in a similar way. Then these glasses are bonded, the micro-channel with DLC coating is completed.

This paper verifies whether the deformation characteristics of a vertically deformed planar spiral structure can be theoretically explained by pure vertical and inclined deformation. The vertical deformation has the following two features: one is that the amount of deformation is larger in the outer beam than the inner; and the other is that the amount of vertical deformation of the beam increases in an oscillatory manner, rather than monotonic increase. However, although it has been proposed that the two deformation characteristics is explained by pure vertical and inclined deformation, it has not been discussed theoretically. In this study, planar spiral structures with different beam widths and thicknesses are fabricated by laser processing of PET film, and the amount of vertical deformation is measured and compared with theory. We confirmed that the deformation characteristics of the planar spiral structure in practice could be reproduced by the theory.

This study aims to demonstrate label-free cell patterning in an arbitrary shape by magnetic scanning based on the magneto-Archimedes effect. By adding the paramagnetic compound to the cell suspension, cells were pushed away from the trajectory of a magnet. Based on the phenomena, we developed the system to pattern cells by scanning a permanent magnet beneath a cell culture dish. First, we confirmed that the system was able to pattern cells by removing cells above the trajectory of the magnet. Finally, the system scanned the magnet on the shape of our faculty’s symbol, that patterned cells in the symbol. The results show the diamagnetic cell patterning by magnetic scanning has a potential as a new technique to pattern cells.

This report deals a phenomenon of magnetic domain transition for the stepped magneto-impedance element. Our previous research shows that an element with 70 degree inclined easy axis has a typical characteristic of the domain transition, and the transition can be controlled by the normal magnetic field. In this presentation, we apply this controlling method to line arrangement adjacent many body elements, in which mutual magnetic interaction exists.

We have developed a small vibration energy harvester (VEH). Our developed VEH uses an electret which can keep constant its surface potential. However, when the surface potential is too high, the movable electrode is adhered to the electret on the fixed electrode by electrostatic attraction and power generation is inhibited. To solve this problem, an array of dots on a nanometer scale was applied to the electret surface. As a result, three advantages of reduction of electret adhesion force, improvement of surface potential, improvement of electric power generation were obtained. Our developed VEH generated the electric power of 26.7 μW for the vibration of acceleration of 0.2 g at 17.5 Hz, when the SiO2 electret with the nano-dots array (dot width and pitch are 0.75 μm and 2.0 μm, respectively) was employed.

Thermionic converter (TIC) using nanogap is expected to be an alternative of thermoelectric generator. Nanogap used in TIC requires few nm gap distance and smooth large area of opposing surfaces, but conventional methods to fabricate narrow nanogap do not meet these requirements. In this report, we fabricated nanogap with 57 nm distance and 21.5 μm² surface area by cleavage of single crystal silicon. Moreover, heat transfer between nanogap was measured while changing gap distance by electrostatic comb actuators. Temperature difference of more than 150K between nanogap was successfully formed, but the heat transfer observed was much smaller than calculation.

This paper proposes a technique to reform a lipid bilayer membrane by injecting an air bubble. Our group has been focusing on the method to form the artificial bilayer that can reconstitute membrane proteins. The bilayer can be formed at the interface of two water-in-oil droplets with a lipid bilayer. However, the bilayer often collapses and the droplets merges by either self-oscillation or sloshing. In the proposed technique, a bubble approximately 4 μL in volume is injected to split the droplet. When the bubble is retracted, the new bilayer is formed at the interface. The biggest advantage of this technique is that the re-formation of the artificial bilayer can be performed in situ and individually. The proposed technique was verified by measuring the current passing through the nanopore protein.

This paper reports the repair of self-healing wiring using electric field traps in thick electrode and the change in resistance after repair. After self-repairing the copper wiring with artificial gap of 20 μm using gold nanoparticle dispersion, the resistance of the repaired portion was investigated. We successfully repair the electrode with thickness of 50 μm. Furthermore, there was no change in the wiring resistance due to the change in thickness. The possibility of applying self-healing wiring technology using electric field traps to the electrical cord was found to be able to repair thick wiring.

In this report, we discuss a method of measurement of subsurface scattering related to visual textures. Visual texture how a surface of object looks, such as glossy or matte, is related to the characteristics of light scattered or reflected with respect to incoming light. In previous study, a method presents an intermediate visual texture between glossy and matte has been proposed by juxtaposing the main surfaces of diffuse reflection and specular reflection. However, this method is not enough to reproduce actual visual texture because subsurface scattering is also important factor to visual texture. In this study, in order to grasp the relation between visual texture and subsurface scattered light and use findings for reproduction of visual texture, we considered the method to measure subsurface scattered light. The experiment showed subsurface scattered light was observed on translucent object, and almost not on transparent and opaque object.

We examined the structure of the suction cup to adhere to deformable surfaces. For flexible devices attachable to human bodies, suction cups have superior properties to other conventional attachment mechanisms, because they enable to use repeatedly and show relatively high adhesion forces. However, the attachable devices with suction cups are still difficult for the use in the attachment to deformable surfaces. In this study, we fabricated several suction cups which had different Young's modulus and measured those adhesion forces to a rubbery membrane as a model of the deformable surface. We found that the lower the Young's modulus was, the smaller the preload required for the suction cup to initiate attachment was. In addition, we found that when the suction cups had the same shape, the maximum adhesion forces decrease when Young's modulus of suction cups increase.

We employed gel dispersion of metal nanoparticles to provide self-healing function to metal interconnects. Upon the application of voltage on a damaged metal interconnect covered with the gel, dielectrophoretic force produced by the electric field move the metal nanoparticles towards the crack to form a bridge structure in-between, which enables the metal interconnect to regain its conductive property. In previous studies, however, water was used as the dispersion medium of metal nanoparticles; the device required a reservoir to maintain the solvent. In order to eliminate the reservoir, we proposed the usage of self-standing gel for self-healing. In this study, we fabricated a hydrogel with dispersed metal nanoparticles and evaluated its self-healing property. The result confirms that agarose gels with dispersed gold nanoparticles possess the capability of restoring conductivity of a damaged metal interconnect. Here, the diameter of gold nanoparticles was 5 nm, and the gel concentration was 0.1% g/ml.

In our previous work, it is demonstrated that multi-axial force and can be detected by tactile sensor using Si microcantilevers with thin-film strain gauge embedded in the elastomer. In this work, Si microcantilever with PZT thin film was fabricated and characterized. The cantilever was embedded in the elastomer to detect vibrations. As a result, it is confirmed that the output voltage from PZT on the fabricated microcantilever depends on frequency of applied vibration. Furthermore, the cantilever was thinned by dry etching process for improve the sensitivity. It was suggested that sensitivity can be controlled by thinning the cantilever. Moreover, a strain gauge and a piezoelectric detector were deposited on a single cantilever, and a sensor for measuring static load and vibration was fabricated.

This paper is a study on miniaturization of Surface Plasmon Resonance (SPR) chemical sensor. An Au grating is formed on the n-Si wafer to make the sensor detect SPR electrically. We demonstrated a back side illumination method to excite SPR from the n-Si side. The excitation light is diffracted by the grating. SPR can be coupled to an interface of Au/sample and the excitation light is absorbed. The absorbed energy excites free electrons on the Au surface so that the SPR can be detected electrically by a Schottky barrier diode formed on the Au/n-Si interface. We compared the current responses by the backside illumination method with changing the refractive index of sample using air and pure water. Depending on the change of the sample, peaks appeared at different angles in the currents response curve. We verified that the proposing device can behave as a sensor for the sample species on the Au.

Multi-scale direct writing method of metal microstructures using a 405 nm blue laser was proposed and demonstrated. We succeeded in fabricating the conductive metal structures in gelatin matrix containing silver nitrate by photoreduction using a blue laser. The concentration of silver nitrate in the sample solutions was optimized by measuring the conductivity of the fabricated silver structures. It was possible to control the fabrication line width by changing scanning speed of laser. A fabricated silver structure at 80 mW had a network structure in the sample, and it also had high conductivity. Finally, we demonstrated multi-scale modeling from micro to millimeter scale using objective lenses with different NA.

This paper describes investigation of the brain activity in an adapting process to inversion vision through electroencephalogram (EEG). In particular, we used Candle-like microneedle electrodes, which does not require any preparation for measuring high-quality EEG. Note that conventional wet electrodes require abrasion of stratum corneum and application of electrolyte paste as preparation for measurement of EEG and they give discomfort to subjects and take time for experimenters. In our previous study, EEG fluctuations of High β，Low γ，and Mid γ waves were detected during the adapting process to inverted vision. In this study, we measured EEG 3 days during the pointing task under an inverted vision state. We detected the long-term adapting process to inverted process using EEG fluctuations and discovered that the detection position had strong correlation with the dominant eye.

This paper reports the relationship between electroencephalogram (EEG) and working memory . In the conventional measurement of EEG, we have used the wet electrode. Therefore, it is needed to grind of stratum corneum and apply electrolyte paste. This process gives the subjects discomfort and takes a lot of time for experiments. In oreder to solve these problems, we developed dry microneedle electrodes which can measure EEG without pretreatment. In this study, we measured EEG with dry microneedle electrodes during doing the memory test we made. The memory test consists of learning process and remembering process. We discovered the power spectrum density of θwave becomes higher in the process of remembering process than learning process. However, we cannot see the correlation between the result of the memory test and power spectrum density.

This paper describes evaluation of tensile crack propagation behavior of at alloy thin film in-situ scanning electron microscope (SEM) observation. Al alloy thin films deposited by sputtering were subjected to uniqxial tensile test using specially developed compact tensile test equipment. A tensile crack initiated at a notch tip in a specimen, and then propagated along slip lines. The EBSD measurement around the tip notch revealed that the crystal orientation changed before cracking. This mdicate that it is possible to predict where a crack will occur under stressing.

In this study, we fabricate a microfluidic device for the electrical detection of single nanoparticles. A microchannel of 1.88 μm × 3.50 μm cross-section is made from polydimethylsiloxane, and Pt thin-film microelectrodes with a gap of 6 μm are formed in the channel. When polystyrene particles of a diameter of 830 nm, transported by a pressure-driven flow, pass by the electrodes, electrical signals on the order of 100 pA are detected. Simultaneously observing the transport phenomenon of a particle, ionic current responses related to the particle behavior are measured. We succeeded to detect micro- and nanoparticles from both ionic current spikes and image data. This method suggests to give more detailed information about the dynamical behavior and characteristics of particles sensed between the microelectrodes.

In this research, we observed the change in thermal and electrical properties of HPT (High Pressure Torsion) processed silicon wafer and powder. HPT is one of the Severe Plastic Deformation (SPD) processes. HPT processed sample has structure distribution because of the introduced strain which depends on the distance from center of the sample. In our findings, we observed a decrease in the thermal conductivity of HPT silicon by approximately one order after the process. This reduction is caused by the formation of nanograin boundaries and metastable phases Si-III and Si-XII which show effects of phonon scattering. However, the large change in Seebeck coefficient by HPT was not observed and we have not detected whether this change results from the structure distribution or not.

In order to improve thermoelectric performance of printed halide perovskite, CsSnI3 thin films were fabricated under different conditions. The cross-plane thermal conductivities of thin films were measured by 3ω method. The surface morphology was observed using Scanning Electron Microscopy. Thin films annealed at 100oC and 130oC had uneven and smaller crystal grains than the one at 70oC. Thin films which have finer crystal grains on the surface tend to have lower thermal conductivity. Influence of phonon grain boundary scattering is considered as one of the factors for lower thermal conductivity. For further development, we will observe cross-sectional crystal grains since the thermal conductivity was measured along the film thickness direction.

Electrical and mechanical characterizations of stretchable wires printed on elastomer-based substrates using polyurethane-based conductive pastes containing silver fillers were conducted. Electrical resistivity of the wires sensitively increased during uniaxial cyclic tensile test. The magnitude of increasing in electrical resistivity was decreased with increasing hardness of the substrates. This implies mechanical behavior of the wires influenced by that of elastomer substrates. In fact, a nano-indentation test show elastic modulus of the wires was varied depending on hardness of the substrates. As increasing hardness of the substrates, deformation of electrical contacts between fillers is believed to be suppressed to stabilize electrical conductivity of the wires. Design of wire structures is needed to be establish stretchable printed wires for advanced microsystems.

In this study, we have developed a fabrication process to produce 3D porous microparts made of hydroxyapatite (HAp), which are synthesized using a simulated body fluid, by microstereolithography using an optical fiber. In experiments, we evaluated the fabrication resolution of HAp slurry by using an optical fiber of core diameter 25 μm. A simple 3D porous structure was fabricated successfully. We also evaluated crystallites of powder of degreased body of HAp slurry, powder heated under the degreasing condition and HAp powder. In the near future, we will optimize the fabrication conditions of HAp 3D porous structures and conduct cell culture experiments. The HAp 3D porous structure will be useful for hematopoietic stem cells culture scaffolds.

This paper describes a system that amplifies a change in structural color by embedding a microscale mesh object with mechanical properties of mechanical metamaterial in a structural color gel. We fabricated the structural color gel by encapsulating colloidal crystals in a temperature-responsive N-isopropylacrylamide (NIPAM) hydrogel, and confirmed the change in structural color depending on the temperature. We also constructed the microscale mesh object by two-photon stereolithography and then embedded this object in the poly N-isopropylacrylamide (PNIPAM) hydrogel. We analyzed the motion of this microscale mesh object in the PNIPAM hydrogel. We believe that this system would be an effective approach for practical use of structural color gel sensors with high measurement sensitivity.

Cilia are hairlike organs that are found on the surface of small organisms in water such as paramecia. The movement pattern of cilia is known as a metachronal wave, which realizes efficient fluid transport. Our study aims to mimic the metaclonal wave of cilia and apply it to micro pumps. Artificial cilia fabricated using elastic material dispersed with magnetic particle could generate a metachronal wave by applying a rotating magnetic field. We fabricated five types of artificial cilia and conducted comparative experiments. The experimental results showed that the different flow was made depending on the design parameters of the cilia, and the cilia with metachronal wave improved the flow rate compared with cilia with synchronous motion.

Mechanotransduction is a well-known mechanism by which cells may sense the surrounding mechanical environment and convert the mechanical stimuli into biochemical signals. However, the underlying mechanism has not been fully understood. Primary cilia existing on the surface of the cell membrane have been considered to help cells to sense surrounding mechanical stimuli such as fluid shear stress and thus believed to be mechanosensors. It is important to measure mechanical properties of primary cilia for better understanding of the role of cellular primary cilia. In this study, the Young’s moduli of primary cilia were measured by using a customized micro-tensile tester and found to be from ca. 50 kPa to ca. 200 kPa at different physiological strain rates.

Most of chronic kidney disease patients need to go to hospital three times per week and must receive more than 4 hours of dialysis treatment each time. Therefore, we aim to develop a multi-layered micro dialysis device which is composed of micro titanium channels and nano-porous PES membranes. However, it takes time to process titanium. Therefore, in this study, I made channels with acrylic, which is easier to process than titanium. In addition, we fabricated a device using an acrylic channel and observed the cohesion of protein to the channel surface by flowing human whole blood. From this result, it was confirmed that the acrylic channel is useful for a short period of about one week. It is necessary to process the surface and coat with antithrombotic material for long-term use.

In this study, we developed discrimination methodology of normal skin fibroblast (SF-TY) and malignant melanocytes (G-361) by using dielectrophoretic force and fluid-induced shear force. According to a difference of dielectric properties, cell types could be discriminated. We developed a dielectrophoretic chamber assembled by transparent conductive slide-glasses and silicon rubber spacer. Using this chamber the nonuniform electric field was generated between surface electrode and comb-like electrode to move living cells by positive or negative Dielectrophoresis (DEP). It was found that normal skin fibroblasts (SF-TY cells) and malignant melanoma cells (G-361 cells) showed negative-DEP movement at 1, 5 kHz respectively, whereas showed positive-DEP movement at 100 kHz. A fluid-induced shear force was applied on the SF-TY and G-361 cells in a direction perpendicular to the slit-like electrode by a syringe pomp under negative-DEP at 500 Hz, 1, 5 kHz. The G-361 cells remained between the comb-like electrode whereas the SF-TY cells were removed by the fluid-induced shear force. In summary, the difference in negative-DEP force between normal skin and melanoma cells could be distinguished using our dielectrophoretic chamber combined with fluid-induced shear force.

This study aims to develop an automated single-cell collection technology based on photocuring of gelatin methacrylate (Gel-MA) by multipoint light irradiation. Target single cells were observed through an inverted microscope, and irradiation pattern was automatically generated through image processing. A processed image was used to cure Gel-MA around the target cells. The viability of cells at various light irradiation time was measured. In future, residual Gel-MA will be removed by the biodegradable property of Gel-MA.

Biofeedback, which is a technique for controlling human physiological indices by detecting outputs such as heartbeats and brain waves and re-outputting them through a feedback device, has attracted attention. This technique has been applied to the treatment of diseases and maintenance of health. We developed an application that transfers heartbeats detected using a wearable device to a smartphone and re-outputs them to the subject by presenting vibrations. In order to verify the effect of tactile biofeedback using this system, we analyzed the heart rate variability when subjects were given stress-related tasks. The results showed that the heart rate improved when stress was applied compared to the control task.

A liquid micro-flow calibration rig is developed, which is consisted of a syringe pump and a gravimetric weighing tank system. Calibration flow rate range is from 0.001 mL/min～10 mL/min. The weighing tank system has been improved to reduce influence of evaporation. The syringe pump was calibrated using the weighing tank to check an influence of evaporation error. The calibrated syringe pulse factors all agreed within ±0.1%.

We propose an electronic device capable of being deformable into a target shape and memorable of the shape, by using a shape memory polymer (SMP). Flexible electronic devices attachable to curved surface have been developed by using flexible materials or a rigid material of which the degree of freedom is reduced by structuring. However, most of previous flexible electronic devices return to initial shape by releasing loads, namely not possible to retain its deformed structure by itself. In this study, we fabricated a deformable but shape-memorable electronic device by sealing a flexible wiring in a SMP and evaluated deformation, shape fixity and shape recovery of the device. We found that the electronic device including flexible wiring sealed in SMP was able to fix its shape to same extent with SMP itself. In addition, we confirmed that the electronic device including flexible wiring recovered to its original shape by reheating it.

The goal of our project is to build a growth navigation system capable of controlling the plant growth even under changeable growth environment such as weather, soil components, etc. To achieve it, we have developed integrated IoT sensors for determination of photo-synthesis parameters, a plant growth analyzer with using image processing, a nutrient analyzer from soil or stem directly, those of which can be deployed near plants due to their compactness. In addition, a novel plant growth estimation technology based on a micro-fluidic circuit model of plant vascular system was developed. Using this system, the daily nutrient uptake and the growth factor can be estimated and utilized to predict future plant growth state. According to the prediction, additional fertilizing protocol, such as amount, timing etc., is computed by referring a paddy rice growth database. Finally, a drone type fertilizing machine is employed along the scenario given by the computed protocol.

This paper reports on Signal Noise ratio (S/N) improvement of an Au/Si nano-antenna photodetector by converging light onto a small device area. The infrared light energy was efficiently absorbed by Au nano-antenna, and was transduced to photocurrent by the Schottky barrier formed on Cr/n-Si interface. When the device area was reduced to 1/25, the amount of dark current noise decreased by about 95%. By converging the incident laser diameter to 1/10 of the initial spot size, S/N improved about 5 times at 1500 nm. Because this method is S/N improvement by a small device area and converging light, it will serve as a fundamental way to efficient infrared measurement with a Schottky photodetector.

We propose a novel method to control the Q-factor. Heat flow path in the MEMS resonator is mechanically trimmed to modify the effect of thermoelastic dissipation. Both Q-factors in X and Y axis could be independently controlled by the method.

When a DNA molecule passes through a nanochannel which depth is smaller than its size, the molecule is trapped in front of the nanochannel based on an entropy trap. Trapping time τ is a parameter to characterize the entropy trap and measuring trapping time τ accurately is required to design DNA separation and concentration methods based on the entropy trap. In this study, we proposed an experimental measurement method of trapping time τ using DNA concentration method. We fabricated a chip device with a nanogap of 25-nm depth in a microchannel using microfabrication technique and succeeded in determining the voltage V dependence of trapping time τ of 48.5-kbp DNA by experiments with 0.8 - 1.2 V.

Humans t actile sensation is composed of tactile elements such as roughness, hardness, wetness and friction sensation. How humans feel the tactile sensation is strongly dependent on the human cognitive characteristics. In this study, we considered that there is a tendency specific to each person in how they receive each tactile element and its combination. As an experiment, sensory evaluation was conducted on each tactile sensation using tactile samples with different micro grooves. By using machine learning to the results, we made it possible to identify tactile samples with convex widths and pitches corresponding to each sensory evaluation based on a tendency specific to each participant.