Surface force measurement is important for elucidating the interaction between materials on the nano scales. In order to elucidate this, it is essential to quantify the dependency between the surface force and gap between the materials, and it is necessary to precisely control the nano-gap and measure the surface force with high sensitivity. Furthermore, it is possible to measure the local interaction distribution by using a micro probe. In this report, an attempt was made to develop a probe with an actuator that uses electrostatic force and elastic force in order to realize a surface force measurement method capable of controlling the gap.

In this study, polyimide films with high thermal conductivity are achieved by adding SiC particles with high thermal conductivity to a polyimide precursor (polyamic acids solution) with excellent insulation but very low thermal conductivity. Film formation by spin coating is achieved even after the maximum addition of 50 wt%. After the addition of SiC, the surface was rougher than that without the SiC particles, but an Al metal circuit by vapor deposition can be fabricated. The addition of SiC particles improved the thermal conductivity of the polyimide film, and the optimum amount was determined. The confirmation of the measurement accuracy of the 3ω method is for further study.

In this paper, we studied on a shape of origami-like heat radiation fin (called “origami-fin”) for flexible thermoelectric generator (TEG). The origami-fin possesses the folded configuration in order to obtain both flexibility to attach TEGs to curved heat sources and a high heat radiation performance for high output of the TEG. The shape of fin is crucial for its heat radiation performance and the simplest shape of the origami-fin is an accordion-fold. We evaluated the performance of the origami-fin with different number of accordion-folds and the same surface area. As a result, the smaller number of accordion-folds showed the higher heat radiation performance.

By combining different type of monomers or hydrogels with varying molecular weights, a double-network hydrogel with strength much higher than those of single-network hydrogels could be achieved. In our study, microstructured hydrogel was fabricated inside another hydrogel, which has different molecular weight, by spatially selective photo cross linking, enabling the fabrication of hydrogel that has non-uniform distribution of stiffness. To confirm the hydrogel network, two separate hydrogels were bridged by lines of hydrogel structure fabricated between the hydrogels. This method can be used for new optical and/or bio applications.

In this study, we made and evaluated an insulating layer on titanium for tough MEMS. The insulating layer was made of alumina, which has a thermal expansion coefficient close to that of titanium.We made insulating layers by using the metal organic deposition (MOD) method under atmospheric conditions. The insulating property was lost due to pinholes, but we improved it by making insulating layers multilayerd. By compareing insulating layers on 4 types of substrates, we found substrate surface confition suitable to make insulation layers. By the results of leakage current measurement, we found that the insulation resistance of arumina was more than 0.1MΩ, and it’s sufficient for MEMS device.

When falling below the microscale, various metallic materials have been proven to display unique physical properties and geometrical features compared to their bulk counterparts. In this study, Al whiskers with a diameter below 1 um were produced by utilizing the phenomenon of stress migration, according to which atoms migrate due to a stress gradient in the sample. A handling method through van-der-Waal forces was examined and the results are reported in this paper.

In this paper, we have introduced a new developed type of self-propelled robot which uses three standing wave type ultrasonic motors to realize holonomic movement on a surface. Recently, with the miniaturization of electronic devices, demand for mounting small chip components is increasing. Linear stages often used for chip mounting is fast and precise but with disadvantages of large vibration and poor energy efficiency. To overcome these problems, the minimization of size of the mounting device is important. The aim of this study is to develop a new type of miniature robot for precision works with low energy consumption, low vibration and better movement speed comparing to our previous works of miniature robots. This paper also introduces the experiment conducted with an image analysis system to test the robot’s repeatability under open-loop control and it’s result.

This paper reports caterpillar-inspired soft robot based on thermal expansion with stretchable bending and flexible temperature sensor. The movement of soft robot was based on thermal expansion with highly volatile liquid. On account of thermodynamic method, this soft robot must have a bending sensor for the movement and a temperature sensor to monitor the soft robot’s state at that moment. The primary objective of this research is to resolve the integration between soft sensor and actuator. The actuator bends due to thermal expansion. The system could control the thermal expansion change from the resistance of the calculated bending sensor.

We developed a cell-based wireless odorant sensor using a chip LED and a chip photo diode (Fig.1). Cells are expressing olfactory receptors (ORs), and they emit fluorescence when odorants are added. The measured fluorescence is transmitted to PC by wireless communication. We optimized the device by changing types of LED and filter. We also changed brightness and exposure time to maximize the S/N ratio. Then we tried to detect change in fluorescence intensity after adding odorants. The device responded to addition of buffer with odorants, whereas it returned no response when buffer without odorants is added. This device would be useful for on-site odorant detection.

Cancer metastasis is a major obstacle to cancer treatment, however the underlying mechanism has not been well understood. In this study, we developed a microfluidic-based experimental setup to investigate the effect of blood-fluid shear stress on tumor cells. In order to mimic the fluid shear stress, this microfluidic device was designed to capture and hold cancer spheroids individually and apply fluid shear stress to part of the cancer spheroids. We succeeded in trapping cancer spheroids and applying fluid shear stress close to that in vivo, showing potential to mimic the situation of cancer metastasis in blood vessel.

This paper describes a DNA aptamer-linked structural color hydrogel sensor that can quantitatively and repeatably detect biochemical substances through visual information without any specific equipment. We co-polymerized a DNA aptamer that specifically binds to silver ions into acrylamide hydrogel and evaluated its quantitative shrinking response to silver acetate solution. In addition, we succeeded in initializing our DNA aptamer hydrogel sensor by heating, indicating that our chemical sensor could repeatably measure the target chemical substance for the long term. We believe that our structural color biochemical sensor could be applied to various routine monitoring such as healthcare diagnosis and water safety.

In order to make neuron-adhesive regions on the surface of a 1-μm-thick fragile SiN membrane, we developed a technique for patterning laminin, one of extracellular matrixes, without mechanical contact which causes membrane disruption. First, for feasibility test, a micropatterned Au surface on a glass plate was modified with non-cell-adhesive polyethylene glycol (PEG), and a glass surface was modified with laminin. Neurons cultured on the plate adhered to the laminin-modified regions and elongated their axons inside the regions. Next, this method was applied to a SiN membrane. As a result, some axons invaded the PEG-modified regions probably because laminin molecules remained on the PEG-modified regions due to insufficient washing of the membrane surface.

Retinal vein occlusion is a disease that causes vision disorder due to occlusion of the retinal vein which is one kind of micro-vascular spreading to the fundus. Most of the current treatments are aimed at suppressing symptoms caused by vascular occlusion, however, there is no method targeting the blood clots which is the root of the disease. In this study, we focused on the impact pressure of micro-jet generated by the collapse of the electrical-induced bubbles. This pressure can be worked as local and minimally invasive physical stimuli from the outside of the blood vessel to resolve the vascular occlusion itself. In this paper, we improved the design of our device and performed an examination for testing the blood clots removal ability by animal experiment.

We present a fabrication method of multi-connected collagen tubes to mimic branch vascular structure in vitro. The device is simply made by molding and can be flexibly deformed by manipulation or mechanical stimuli. Also, the device could be easily perfused because the collagen tubes are directly attached to silicone tubes. Moreover, perivascular cells could be co-cultured with endothelial cells by using collagen layer. We succeeded in fabricating multi-connected device in proper mechanical strength, and achieved to seed cells as a branch shape. We believe that this flexible culturing device could help the easy fabrication of matured branch blood vessels in vitro, and contribute to the development of vascular pathology.

Liquid-state electronics utilizing functional liquids confined in soft templates as the sensing and actuating component present the ideal platform for enabling conformal coverage of electronic systems on curved and soft surfaces. However, to date, optoelectronic devices based on functional liquid materials as represented by photodetectors and optical memories still have not been proposed; this advancement is crucial to scaling up current liquid-state devices to a system level. Here, this study proposes optoelectronic devices based on liquid metal and photo-switchable ionic liquid with liquid-liquid heterojunction technology. The sensing and memory schemes we present are generic for different liquid-state devices, enabling different functionality to be added to the liquid-state electronics. As a proof of concept, we demonstrate a light sensor composed of the ionic liquid, and an optical memory using a composite of the ionic liquid and polypropylene glycol. These devices are important advancements towards the realization of liquid-state electronic systems.

This report demonstrates an electrically controlled gel actuator by a three-dimensional(3D) helical microspring with liquid metal. Previously, 3D helical wiring with liquid metal was established based on core-shell hydrogel microspring fabricated using a double bevel-tip nozzle[1]. In this study, with combining this 3D liquid metal wiring and rod of a thermo responsive gel, an electrically controlled gel actuator was realized. In general, gel actuators require change of environmental parameter such as temperature in entire chamber and/or needs harsh environment such as strong acid solution. Therefore, it is difficult to control actuations of gel actuators electrically, and individually. In this study, we succeeded in shrinking and bending of the gel actuator by 36 % and 44 ° by electrical control. In addition, actuations of each gel actuator inside same chamber was controlled individually.

Monodisperse gold nanoparticles was prepared using glass microfluidic device with four inlets and semi-circular profile microchannel. In the synthesis, the flow rate of outer two-phase were changed to uniform the phase size in mixing section of the microchannel. The synthesized gold nanoparticles at inner flow rate of 0.05mL/min and outer flow rate of 0.03mL/min showed small full width at half maximum at the plasmon absorption peak. From these results, we confirmed that controlling of the flow rate difference of phases realized a fast synthesis of monodisperse gold nanoparticles comparing with that in two-phase microfluidic device.

This paper describes an edible biomedical electric device composed of biodegradable organic materials for monitoring in vivo biological information. Our device includes a planer coil and a capacitive sensor that are covered with an installing layer, enabling us to obtain the sensor information wirelessly. The insulator layer is made of fatty acid. We fabricated the planar coil made of magnesium by vapor deposition and examined its solubility and properties to confirm the feasibility of digestible coils in the body. We believe that this device would be applicable to a simple, inexpensive and edible wireless medical sensor that can be digested in our body without toxicity.

In this paper, we propose a triboelectric nanogenerator focus on contact interface. Various compositions and diameter of metal powders are mixed with PDMS to be flexible, easily charged negatively, and formed for micro/nano structure by oxygen ashing. As a result of SEM observation, the metal particles near the surface acted as an etching mask, and oxygen ashing formed a random micro/nano structure on the PDMS surface. In the power generation test, the power generation performance was 8.7 times that of the conventional PDMS devices due to the increased surface area by micro/nano structure. Power generation performance may be further improved by deep etching of PDMS.

Silicon-based infrared photodetector assisted by plasmonic structures have been attracting interest of research, whereas their responsivities remained low. We present in this paper an infrared photodetector with arrayed nanoholes. This device was designed to show better responsivity to backside illumination. In each nanohole on the n-type silicon substrate is a copper nano-plate which induces localized surface plasmon resonance (LSPR) and is electrically connected to outer circuit. We verified the contributions of backside illumination and LSPR towards better responsivity respectively. With its easy fabrication and LSPR being compatible with vertical incidence of light, the nanohole detector with backside illumination is a prospective approach for silicon-based infrared imaging elements.

Silicon-based infrared photodetector assisted by plasmonic structures have been attracting interest of research, whereas their responsivities remained low. We present in this paper an infrared photodetector with arrayed nanoholes. This device was designed to show better responsivity to backside illumination. In each nanohole on the n-type silicon substrate is a copper nano-plate which induces localized surface plasmon resonance (LSPR) and is electrically connected to outer circuit. We verified the contributions of backside illumination and LSPR towards better responsivity respectively. With its easy fabrication and LSPR being compatible with vertical incidence of light, the nanohole detector with backside illumination is a prospective approach for silicon-based infrared imaging elements.

This paper demonstrates the improvement in fabrication process of dry micro-needle electrodes by using sonication. In the medical field, wet electrodes are used to measure EEG which needs abrasion of stratum corneum and application of electrolyte paste as preparation. To avoid this pretreatment, we developed a candle-like microneedle electrode (CME). The electrodes avoid hair with the pillars and penetrate the stratum corneum with the micro-needles. In our previous research, we needed to take the air bubbles away from the point of the needles with our hands. However, since CME is usable only once in each experiment, we propose a new fabrication process for mass production. We use sonication for bubble removing and become it easier.

The function of roots is exceedingly important for crops and the observation of root growth is essential for understanding the plant physiology and improving crops productivity. The current study focused on the use of sound waves which can propagate in water and soil and are expected to interact with roots. In order to detect the growth of roots non-invasively, a prototype sound-based root growth detection system was developed, and its performance was evaluated on Komatsuna. The attenuation amount of transmitted sound intensity increased during the cultivation period, and a positive correlation between the attenuation amount and roots growth was observed. Based on this observation, a sound-based root growth detection system has the possibility to indirectly detect root growth by an extremely low-cost and simple method.

In this paper, in order to propose an interface that reproduces a thermal sensation, the skin temperature change when a human touches an object was measured, and temperature reproduction was performed using a Peltier device. The response and followability of the Peltier device were evaluated in experiments using objects with different thermal properties. The results showed that the heat transfer was generally terminated when the object is touched for about 10 seconds, and after that the temperature change was small. Furthermore, using the manufactured thermal sensation presentation device, we attempted to generate the wet sensation of a plurality of dry fabrics. The subjects evaluated the wet sensation of the initial temperature controlled the fabrics (dry or having a moisture content of 20-30%). As a result we concluded that the wet sensation can be generated when the initial temperature of the dry fabrics is lower than the skin temperature.

Elastic constants are indispensable for mechanical design and stress analysis as material constants that govern the deformation and natural frequency of materials. And they are closely related to various physical properties and important physical properties. In addition to the development of lightweight and high-strength materials such as CFRP (Carbon Fiber Reinforced Plastics) in recent years, analysis of elastic anisotropy and high-accuracy measurement of materials have become important issues. In this study, we established a precise measurement method of resonance frequency under free vibration using a small test piece, and completed a natural vibration analysis (inverse analysis method) combining the finite element method and the Rayleigh-Ritz method. The objective is to determine the elastic modulus matrix of a material with high accuracy. The purpose of this study is to realize elastic anisotropy analysis of magnesium alloy that are assumed to have elastic anisotropy formed by extrusion and rolling. We discuss the results of calculating the elastic modulus matrix obtained by inverse analysis.

The optical trapping, or optical tweezer has a long history, also celebrated with the Nobel prize in 2018. A large population of researchers mainly with an expertise of optics or lasers has long been trying to manipulate single smaller particles. Generally speaking, it is more difficult to trap smaller particles by optical trapping approach because of the smaller force field with the same laser power. Therefore, they have been intensively trying to enhance the force to trap. The most conceptually simple approach is the development of a laser source with a higher power density. What is expected as more feasible or promising is the use of plasmonic approach. This is the combination of an existing laser source with substrates with specified structures. The pursuit of optical trapping technique for smaller particles and molecules has been focused on the stronger trapping. However, the meaning of strong trapping leaves some ambiguity in the physical quantity. Some researchers aim at stronger force, and some at larger difference of potential energy. These are different physical characteristics, but somehow never been clearly addressed. Here, we clarify this point to reveal that the significant role of force field shape.

We combined two types of the Polydimethylsiloxane (PDMS); namely those of high thermal conductivity without stretchablity (hPDMS) and low thermal conductivity with stretchablity (PDMS) to fabricate a thermally conductive PDMS sheet with the high stretchablility of 60%. The hPDMS shows the thermal conductivity of 3.3 W/m K, which value is one order magnitude higher than that of the pristine PDMS. The hPDMS sheet, therefore, lowers the thermal resistance of the Thermoelectric Generator (TEG) to enhance the output power by 20%.

Measurement of the mass transfer coefficient in microchannel is essential to estimate the chemical reaction rate in a micro reactor. In this study, the local mass transfer coefficient on the wall of the microchannel was estimated by the luminol chemiluminescence. By conducting the luminol and H₂O₂ mixture into microchannel with copper wall, the luminol chemiluminescence appears in Cu(II) boundary layer which was served as a catalyst of the luminol reaction. Numerical calculation shows clearly the total reaction rate in the boundary layer corresponds to the local mass transfer coefficient. Thus, the local mass transfer coefficient in microchannel can be evaluated by the chemical reaction rate obtained from the chemiluminescence intensity.

In this study, we developed a MEMS heat flux sensor to measure surface local heat flux in flow boiling in a minichannel. The MEMS heat flux sensor has stacked structure of two thin film resistance temperature detectors, and the local heat flux can be calculated by 1-D transient heat conduction simulation using the measured two temperatures as boundary conditions. The measured heat flux clearly shows thin film evaporation, dry-out of the thin liquid film and rewetting of the dried surface. The developed sensor was confirmed to be a powerful tool to explore the boiling heat transfer mechanisms.

In this study, we fabricated the piezoelectric microelectromechanical systems (MEMS) speakers with Pb(Zr,Ti)O₃ (PZT) thin films. In order to improve the performance of piezoelectric speakers, we fabricated the 2 mm square MEMS speaker with a diaphragm structure of PZT/Si and photosensitive polyimide. The optimal structure was investigated by finite element method (FEM) simulation. The 2 μm thick PZT thin films were deposited on SOI wafers by radio frequency (RF) magnetron sputtering, and microfabricated into unimorph diaphragm. We measured the vibration amplitude of the piezoelectric MEMS speakers as a function of frequency. We confirmed that the resonance frequency was 25.6 kHz that is out of audible range. In addition, the speaker could generate large sound pressure level (SPL) of 82 dB at 6 V_pp.

BiFeO₃ thin film on DyScO₃ substrate was fabricated by RF sputtering and annealing. The BFO thin film is expected to be used for ferroelectric memories, piezoelectric devices, sensors and solar cells. DyScO₃ substrate is the small-lattice-mismatched substrates for BFO thin film. The lattice constant of DyScO₃ (a=0.394nm) is similar to the lattice constant of BiFeO₃. We developed the BiFeO₃ film on the DyScO₃ substrate. The materials of BiFeO₃ thin film on DyScO₃ substrate have the effectiveness in the future.

This paper reports on an equipment for inclined/rotated lithography with liquid type UV curable material. Recently, in MEMS field, Poly-ethylene-glycol diacrylate (PEGDA) hydrogel, which is UV curable material, has been widely used in photolithography because of tunable mechanical properties and bio-compatibility. It is desired to apply 3D photolithography to PEGDA in order to obtain complex spatial structure. However, the conventional exposure system that rotates a target wafer and UV curable material is not suitable for PEGDA because of liquid state before curing. In this paper, we proposed a method for inclined/rotated UV photolithography with liquid curable material. The proposed equipment consists of a shading plate masking vertical UV light and angle-variable mirrors rotating around the wafer.

In this research, we designed, fabricated and evaluated a PZT thin-film piezoelectric MEMS transformer. First, the disk-shaped device with the ring-dot structure was designed using Finite Element Method (FEM) analysis. At this time, since the piezoelectric transformer is driven in resonance, we confirmed resonance frequency and vibration mode of the transformer. Next, a PZT thin film was deposited on a silicon on insulator (SOI) substrate using RF magnetron sputtering method, and then microfabricated into a piezoelectric transformer. Finally, we measured the impedance and transformation properties of the piezoelectric MEMS transformer. The resonance frequency was observed at 4.57 MHz, and the transformation ratio was found to be about 0.3.

We proposed a system that can identify small amphibians at low cost and read biological information even in a wet environment. With the conventional individual identification technology, it has been difficult to have a steady identification for a long period of time. For this study, we focused on the magnetism which is strong against the water and decided to utilize the heat generation by the relaxation phenomenon of iron nanoparticles by high frequency magnetic field. Since the thermal distribution appears as a pattern depending on the presence or absence of the magnetic materials, individual identification can be achieved by observing by thermography. This time, we aimed at the heat generation of the iron plate and iron nano powder, and thus we optimized the experimental setup for Neel relaxation. This study contributes to the environmental technology and sensing / tracing technology.

Human lymphocyte cells which had their membranes stained with fluorescent dye DiI were immobilized on microholes of 5.5 μm in diameter, and stimulated with sodium butyrate (NaB), which induced DiI-stained micrometer-size extracellular vesicles (EVs) to be produced and separated from the cells through the microholes. We trapped EVs on the surface of a glass plate placed directly under the microholes, and measured the size and number of EVs from fluorescence images of the glass plate surface. As a result, it was found that an average of 547 EVs were produced in each well having 64 microholes. This means that an average of 8 to 9 EVs were produced from a single cell. Also, EV size distribution peaked at 1 to 2 μm and the maximum EV size was about 10 μm.

In this study, wearable device that can monitor the multi vital signs of Jaundice, SpO₂, and heart rate from newborn foreheads was developed. In order to observe details of body conditions of newborns, it is crucial to detect the multi vital signs such as Jaundice, heart rate and oxygen saturation of peripheral artery (SpO₂). In addition, considering the handling of the devices, it is should be convenient to detect them from one device on the forehead, which does not need to take off their clothes or move newborns. In this study, we implemented the functionalities of Jaundice, heart rate and SpO₂ measurements into the device. The device irradiated newborn's forehead with BLUE, GREEN, RED, and IR (infrared) LED lights, and measure the 3 vital signs by reflected lights. Using the device, clinical experiments were conducted on neonates 1-5 days after birth. The device succeeded in the detection of bilirubin concentration, heart rate, and SpO₂.

We aim to develop a microdevice that measures material permeation via epithelial tight junction (TJ) to evaluate its barrier function. This device is equipped with microchambers filled with collagen gel, so that a flat epithelial sheet is formed on the device. By covering the inner space of the microchamber with a cell sheet, the influx and efflux of the substrates are restricted. If the permeability of TJ is increased by drugs, the target substrate concentration in the microchamber changes due to the diffusion. In this study, the mass transfer of fluorescent dextran, a model substrate, was measured in correlation to the morphology of MDCK cells. Finally, the alteration of the paracellular permeation in response to the drug was demonstrated.

In this paper, we develop the novel micro-machined cochlea for in vivo evaluation. The device is made of polyvinylidene difluoride membrane to stimulate the auditory nerves in animal tests. Microelectromechanical systems allow the device to have the dimensions of micrometer order to be implanted in the guinea pig cochlea. In this paper, we measure vibration characteristics of the device based on the optical methods. An oscillation is induced by applying a sound stimulation from a speaker. A displacement of the device is measured by using a laser Doppler vibrometer. An amplitude of the displacement is nanometer order and increases linearly as the amplitude of the sound pressure. This micro-machined cochlea can shed light on a guide for future experiments on animals.

Cortical bone has a hierarchical structure and is a composite material at the nanostructure with hydroxyapatite (HAp) crystals and collagen fibrils. Many studies have reported the deformation behavior of HAp crystals under external loads; however, the anisotropy of HAp crystal strain and its correspondence to the mechanical properties have not been elucidated. In this study, each five strip specimens aligned in 0°, 30°, 60°, and 90°to the bone axis were taken from the femoral cortical bone of a bovine. The HAp crystal strain ε^H in the specimen axis under the tensile tissue strain ε was measured by X-ray diffraction. The ε^H/ε had a statistical correlation with the cosine of orientation angle. The distribution of elastic modulus was also obtained as a two-dimensional orthotropic material model. The similar trends suggest that its hierarchically structural anisotropy may affect both the HAp crystal deformation and tissue mechanical properties.

To execute efficient and precise handling tasks in micro world, a bilateral system which connects the micro and macro worlds in both directions has been developed. In order to improve the work efficiency, 3-dimensional observation of objects in the micro world is necessary. Two images with parallax are necessary for the 3-D observation, but it is difficult to obtain these images under a microscope. In this research, we proposed a method of obtaining parallax images by inserting a glass plate under the microscope, tilting the plate and thus changing the optical path by a small distance. In order to electrically control the tilt of the glass plate, we developed a swinging actuator driven by voice coils. In addition, mechanical characteristics of the swinging glass stage and characteristics of the feedback control system were confirmed.

In this paper, we propose a shape design of 2D metamaterial structure for elastic layer of piezoelectric vibration energy harvester (PVEH). Since the 2D metamaterial structure is the flexibility microstructure, the performance of the PVEH is improved by using it for elastic layer. In order to further improve the power generation performance of the PVEH, we evaluated the mechanical properties of various metamaterial structures. As a result of structural-piezoelectric coupled analysis, strain amount and strain rate of the piezoelectric layer were improved by metamaterial structure consisted of zigzag and liner structures. Therefore, power generation of the designed PVEH was improved compared with the conventional flat plate type elastic layer.

Size control of gold nanoparticles with microfluidics by changing a flow rate was reported. We proposed the synthesis of copper nanoparticles (CuNPs) to apply this simple flow rate control method to a metallic material with low cost. CuNPs in ethylene glycol was prepared by the microfluidic device using ascorbic acid as both antioxidant and reducing agent. The experimental results found for the first time that the effect of the flow rate and temperature of reagents on particle size of the synthesized CuNPs in the device.

In this study, a stretchable array of resistive pressure sensors which could ignore the effect of stretch deformation was demonstrated. In terms of stretchable pressure sensors composed of elastic materials, pressure sensors itself are deformed during strain of the devices, which becomes large error of the pressure measurement. Our resistive sensors in a array are based on patterned porous conductive silicone (Ecoflex). The substrate consists of hetero-silicone rubbers of two different elastic silicones. In addition, resistances of column and row electrodes in the matrix of mapping are much lower than the pressure sensors. This substrate and control of electrode resistances can prevent stretch deformation of the device from affecting the sensing of pressure. The error of the pressure sensor in our device during 150 % strain was one sixth less than the one by conventional elastic pressure sensor composed of organic materials. This result suggests possibility to apply stretchable pressure sensor on largely deformed area of body, and soft robots.

In this study, we propose a novel fabrication method of quartz glass resonators using temporal Au supporting structures, which were used as (1) the mechanical support during the fabrication process and (2) the heat spreader to keep the device temperature low during the plasma process. The temporary structures and mechanical anchors were made by Au-Au thermocompression bonding. The maximum process temperature was less than 400°C, which makes the method likely to fabricate quartz glass microstructures on a wide variety of substrates, possibly including the complimentary metal-oxide semiconductor (CMOS) chips.

We propose a triaxial piezoresistive force sensor composed of four monoaxial sensors using kirigami structure. Kirigami structure deforms out of plane when in-plane force is applied, and the out-of-plane deformation can be detected by surface doping only. By using kirigami structure, not only out-of-plane force but also in-plane force can be detected, so it is possible to fabricate the surface doped triaxial sensor. In this study, we first designed triaxial force sensors using kirigami structure and fabricated two types of sensors which has kirigami structure. Then, we measured electrical resistance change of fabricated sensors by applying out-of-plane force and in-plane shear force. Finally, we confirmed that applying force caused electrical resistance change and out-of-plane deformation in kirigami structure.

A novel plant growth estimation technology based on a micro-fluidic circuit model of plant vascular system was newly developed. Using this system, the daily nutrient uptake and the growth factor can be estimated and utilized to predict future plant growth state. Accordingly, those are used to navigate fertilizing condition.

We report a method to construct a three-dimensional integrated structure of microcomponents (MC) using water/oil (W/O) interface as a template. By forming a W/O interface at a specific part of a template to define the size and shape of the area to which MCs adsorb, it became possible to form an integrated structure of MCs, such as photofabricated parts and microbeads, with a high degree of freedom. We also demonstrated immobilization of MCs using a photo-crosslinking gel in an aqueous solution to remove the assembled structure out of the template.

This paper describes EEG-Hat, which is the hat-type electroencephalograph with dry microneedle electrode. Current wearable EEG devices has the problems, no EEG device which can measure EEG at hairy part easily. Therefore, we developed candle-like dry microneedle electrode (CME). CME can measure EEG at hairy part by its structure. We also developed the EEG-Hat as the device which fixes CME to the head. EEG-Hat is designed to make EEG measurement simple. EEG-Hat has the shutter mechanism to separate hair and the spring to press CME to the head. We measured P300, one of the event-related potential (ERP), with EEG-Hat at 5 channels. We applied the oddball task consisted of two kinds of pure sounds. As a result, we could observe the waveform that seems to be P300.

Machine miniaturization is remarkable due to recent development of mechanical technology. The influence of capillary force by wet environment is dominant in small machines. For this reason, the influence of the wet phenomenon can not be ignored in designing of small machines. Therefore, it is important to evaluate the capillary force under humid environment. The capillary force is closely related to the meniscus shape. In this research, in order to record the force under wet environment and the meniscus shape, firstly we developed a device which can precisely observe the wet area and measure the surface force simultaneously. Subsequently, we report on the relationship between the surface force and the meniscus shape.

Weakly nonlinear propagation of plane progressive pressure waves in water flows containing many spherical gas bubbles is theoretically investigated especially focusing on a drag force and translation of bubbles. The incident frequency of waves is lower than the eigenfrequency of bubble oscillations and wavelength is larger than the bubble radius. The volumetric oscillations and translation of bubbles are considered as a bubble dynamics. From the method of multiple scales, we derive the Korteweg–de Vries–Burgers (KdVB) equation from the basic equations for bubbly flows in a two-fluid model (Egashira et al,. Fluid Dyn. Res., 2004). The KdVB equation derived here has a partially different form as that derived in previous study neglecting the drag force (Kanagawa et al., J. Fluid Sci. Technol., 2010). As a result, we clarified that the drag force contributes a wave attenuation.