In recent years, the research on airless tire (Non-pneumatic tire, NPT) for passenger cars has received extensive attention. The background to this is the development of autonomous driving technology. Autonomous driving of Level 4 and above is unmanned driving, so it is more important to reduce the frequency of maintenance due to accidental failures, and punctureless airless tires are expected as tires for autonomous driving vehicles. Rolling resistance of tires is a highly important property for tire development. The reduction of rolling resistance of tires has become more significant in the tire industry, because it has close relation to the fuel consumption efficiency. As for conventional pneumatic tire, the rolling resistance is mainly generated by energy loss of tire components during tire deformation and it is well known that to reduce the rolling resistance, tanδ of rubber should be decreased. The purpose of this study is to clarify the contributing factors of airless tires to rolling resistance. As a result of measuring the tire force generated by a rolling experiment using a scale model airless tire, it was confirmed that the wheel load fluctuated impulsively. Therefore, we observed the tire deformation during rolling with a high-speed video camera and clarified the mechanism of tire force generation.

In this study, based on each inspection standard for automotive headlights, a headlight tester was used to investigate and analyze the correlation between high beam and low beam and irradiation characteristics of halogen headlights and LED headlights. The following contents were found from the experimental results. Compared to the proper irradiation characteristics of the halogen type headlight, when the headlight was replaced with the LED type, the irradiation direction did not fully satisfy the applicable range, but the irradiation luminous intensity increased two to three times. The irradiation intensity with respect to the irradiation time decreased by about 10% after 3 minutes and by about 30% after 40 minutes with the LED type. After that, there is little change until 120 min. With the halogen formula, the pressure gradually decreased by about 10 to 20% until 60 minutes later, and then remained little changed until 120 minutes. The irradiation direction with respect to the irradiation time is almost the same for both the LED type and the halogen type from immediately after lighting up to 120 minutes later.

In recent years, the demand of Personal Transporter(PT) is rising because of high demand for short-distance transportation and increasing the awareness of environmental protection. Among them, the inverted pendulum type personal transporter which runs independently on two wheels, is increasingly being used for airport security, transportation in tourist spots, and so on. In case of the PT is used for vehicle sharing, there is a problem that it requires personnel and labor to carry multiple PTs parked at the PT station. In such situations, required manpower and labor can be saved by driving the leading PT and the following PT run in an automatic platooning. The purpose of this study is to construct the platooning system for PT by using optimal control, tracking control, and self-localization by visual SLAM. This paper reports feasibility of the platooning system including turning control and asseses the stability and following performance of the platooning system.

This study introduces a control design strategy based on "Extended Model Based Development (EX-MBD)" as one solution to control the explosive man-hour increase in the "adaptation process" associated with the increasing complexity of electronic control and to customize the system to user preferences after sales. Extended model-based development is a concept of one control system design method that extends the models developed and used in model-based development to the controllers in the feed-forward part of the control system. The effectiveness of the proposed control strategy is confirmed by the results of a simulation study on a diesel engine common rail pressure control problem.

Airless tire (Non-pneumatic tire, NPT) is expected as new tire that are puncture less and can achieve performance that cannot be achieved with pneumatic tires. General NPT has the problem of increased rolling resistance due to a high proportion of the wheel load being supported by the spokes near the ground. To reduce rolling resistance, it is important to distribute the load over the entire tire. We performed FEA on a typical NPT structure and by using Static FEM Code “ABAQUS/Standard”, and discuss its characteristics. We propose New NPT with a Linked zig-zag structure that can maintain the wheel load on the entire circumference by equalizing the stress of the entire tire, which is important for reducing rolling resistance. This structure reduces the bending rigidity of the tire outer ring, making it possible to support the wheel load in the lower tanδ region of the material. And, it has been found that rolling resistance can be reduced.

In recent years, with the technological advance of electronic equipment, an increase in the calorific value of electronic equipment has become a problem. Efficiently cooling the heat generated inside electronic devices is essential. Therefore, the composite material which included a short carbon fiber (SCF) having a high thermal conductivity in aluminum (Al) attracts attention. In this study, Al powder containing SCF was repeatedly rolled and annealed to produce sintered compacts, and an attempt was made to align the axial direction of SCF within the material. The effects of rolling conditions on SCF orientation and thermal conductivity were investigated. As a result, it was confirmed that the SCF inside the specimen was preferentially oriented in the rolling direction. It was also confirmed that the composite had anisotropic thermal conductivity properties. It was shown that the orientation of SCF could be improved by changing the rolling conditions.

In this study, we aimed to increase the hot extrusion rate of AZX611 castings, a flame-retardant magnesium alloy with added calcium. Typically, the hot extrusion rate decreases because the deformation resistance increases owing to strengthening of the solid solution during hot extrusion upon the addition of aluminum and owing to enhanced dispersion of second-phase particles upon the addition of calcium for flame retardance. We performed a high-temperature tensile test to investigate the high-temperature mechanical properties as a preliminary step toward increasing the hot extrusion speed of AZX611 alloy castings. The test conditions included a temperature range of 623–773 K (in air) and initial strain rates of 1 × 10^-3 to 1 × 10^-1 s^-1. The initial microstructure was a dendritic cell structure of approximately 30 μm, and secondphase particles were observed within coarse grains of several hundred micrometers. These second-phase particles were identified as Al–Mg, Al–Ca, and Al–Mn compounds via energy-dispersive X-ray spectroscopy. These particles had an average diameter and area fractions of approximately 3–4 μm and 6–7%, respectively. Furthermore, the dominant hightemperature deformation mechanism involved enhanced dispersion of the second-phase particles at 623 K and 673 K, and the dislocation creep by self-diffusion of pure Mg occurred at 723 K and 773 K. Hot ductility increased with increasing temperature up to 723 K and with decreasing initial strain rate.

A life prediction formula is proposed for random vibration fatigue design of electronic equipment solder joints which is essential for spacecrafts’ reliability. This formula is obtained by combining a solder joint evaluation index, and an experimental resonance magnification equation and an equivalent stress equation for random vibrations derived from the narrow band theory. The comparison between this formula calculation results and the experimental results of solder joint samples shows good correlations. This formula has simple closed form expressions and is expected to be useful for design optimization performed before trial productions at the conceptual stage.

We have investigated shooting a harpoon into a target as capturing system of Active Debris Removal (ADR) and evaluated the effect of various tip shape harpoons with friction on penetration through the numerical simulation. We employed four tip shapes of harpoons, such as “conical”, “spherical”, “flat” and “double-bladed”. Friction was taken into account in the numerical analyses while changing the value from 0 to 0.3 in 0.1 increments. The harpoon was shot into the target while changing the velocity in 0.5 m/s increments. We called a minimum velocity for the penetration “minimum penetration velocity”. When an oblique angle of the target is large, the minimum penetration velocity of the harpoon is rapidly increased but it is decreased with large friction. The spherical and flat harpoon tip shapes do not achieve suitable penetration velocity when the friction is small. Regarding the flat harpoon tip shape, the minimum penetration velocity in the oblique angle of 30 deg is smaller than that of the oblique angle of 0 deg when the friction was considered. We obtained an insight into the effect of friction on penetration behavior through these simulations.

In this study, fatigue and fretting fatigue tests were conducted in TiAl intermetallic with contact pads of nickel alloy at room temperature under axial loading with stress ratio of -1. The fatigue strength was reduced by 30% due to the effect of fretting, which was less compared to other structural materials such as titanium alloys and steels. The reduction in strength was significant in high stress - low cycle region compared to low stress - high cycle region, due to more surface damage caused by high stress amplitude in low cycle region. Moreover, by increasing the contact pressure from 50 MPa to 100 MPa, fretting fatigue life was slightly reduced due to more surface damage caused by high contact pressure. Fracture surfaces and microstructure were analyzed to discuss fatigue mechanism.

In considering the fatigue life of solder joints of onboard electronic components subjected to random excitation, which is an important issue in the reliability design of spacecraft, we conducted an experimental study on the resonance factor, which is the main factor controlling the life. An experimental system was constructed to measure the resonance factor of small components soldered to a circuit board under a wide range of excitation conditions from 20 to 2000 Hz. By organizing the results of measurements under various conditions, we were able to derive an equation that predicts the resonance factor as a function of the resonance frequency of the electronic component and the excitation intensity of the random excitation load.

Hypervelocity impact (HVI) of metallic projectile on Al or Ni multilayer composite structure or monolayer structure are simulated by molecular dynamics (MD) method with the relative velocity up to 14,000 m/s,. The translational kinetic energy of the projectile causes the formation of heat and the deformation of solid bodies. Damage, deformation and phase transformation of the solid bodies are analyzed from the mesoscopic viewpoint. The space distribution of physical quantities in the both structures in collision process are visualized by CG movie.

In this paper, the mechanical properties of two-dimensional zig-zag structure subjected to in-plane large compressive load was investigated. This structure has two counterphase layers consisted of inclined plate. The stiffness and the stored strain energy during the deformation were solved analytically based on the flexible bar theory proposed by Fly (1969). In particular, the effects of micro-architecture of the zig-zag model on these mecahnical properties were discussed. The obtained theoretical results agree fairly with FE results.

With combination of conductivity and biocompatibility, smart textile has shown great potential in wearable electronics for health monitoring, motion sensing and heat managing. Therefore, as a representative of smart textile, conductive non-woven fabric and its synthesis have attracted great attention. In this work, one-step fabrication technique of conductive non-woven fabric was developed by using ionic migration. By intentionally introduce the electric field concentration, the growth of Ag nanoparticles on the fabric was triggered. In contrast with the uniform electric field, the ionic migration was to some extent promoted. With the potential conductivity improvement of the obtained fabric, such technique are expected to contribute to create smart textile.

Molybdenum disulfide (MoS₂), a layered material, has long been used as a self-lubricating solid material due to its low surface energy. In a previous study, about 20 layers of MoS₂ were successfully formed by mist CVD at 400°C under atmospheric pressure, but α-MoO₃ formation was also observed at the same time, and suppression of oxidation was identified as an issue. The study also indicated the need for fine control of the number of layers for the introduction of MoS₂ into nano-scale mechanical systems. In this study by mist CVD, we succeeded in eliminating α-MoO₃-derived peaks and improving the crystallinity of MoS₂ by introducing a cooling process in which cooling is performed in an N₂ gas atmosphere. In addition, by precisely controlling the flow rate of the carrier gas of the mist, we succeeded in controlling the number of layers from the bulk to two or three layers. Furthermore, by introducing NaCl as a supporting agent, the formation of MoS₂ became possible with a very small amount of material supply, and the deposition efficiency was successfully improved.

Ring-on-disk type friction tests under lubrication using lubricants prepared with different amounts of the friction modifier glycerol monooleate (GMO) and fullerene showed that the degree of friction reduction associated with the addition of fullerene increased as the amount of GMO decreased. The synthetic roughness was calculated using the Stribeck curve as a reference and rearranged according to the reciprocal of the value of lubrication condition. The results showed that the effect of low friction due to the addition of fullerenes increased with better lubrication conditions，and the effect increased more at the boundary lubrication.

Nanofibers are fibrous nanostructures with diameters less than 1 μm and aspect ratios (length/diameter) higher than 100. They are characterized by high surface area-to-volume ratio effect, nanosize effect, and high aspect ratio. Our group has developed a unique technique for the rapid fabrication of silver nanofibers using a catalytic reduction method. This method reduces silver nitrate to silver using hydrogen gas that generated from the thermal decomposition of polymer materials under the effect of catalytic nanoparticles. The advantage of this method is that it does not require an external supply of hydrogen gas during the reduction, making it independent and simple. This advantage has high potential for applying the catalytic reduction method to fabricate other metallic nanofibers. In this paper, we report the results of our investigation of various nickel salts for the fabrication of nickel nanofibers using the catalytic reduction method. Although we were not succeeded in producing nickel nanofibers, nickel oxide nanofibers were achieved. This finding is useful for improving the conventional fabrication of nickel oxide nanostructures, which is complicated and time-consuming due to the heat treatment at high temperatures.

Microneedle patches, which are attracting attention as a new administration route for drugs, are required to have reliable insertion properties in order to control the dosage. Therefore, research on dedicated applicator that uses a spring force to hit the application body site with a microneedle patch is also active. One of the major problems is that there is no test method to evaluate insertion property of microneedle patches simulating clinical conditions. In this study, we developed a test prototype applicator and dedicated measurement system in order to measure the compressive load transition generated when it hits an artificial material or a living body. In addition, we measured the mechanical properties of the skin and examined the relationship with the compressive load transition. As a result, it was found that the compressive load transition differs greatly depending on the applied body part. The tendency did not match the mechanical properties of the skin surface, suggesting that the structure of the subcutaneous tissue is also an important factor. In addition, by using a highly flexible material, it was possible to reproduce the compressive load transition similar to the case of hitting the living body. The results of this study will lead to the development of a test method to evaluate the insertion property of microneedle patches.

Advancing medical applications, artificial auditory epithelia which emulate cochlear sound reception have been developed by microelectromechanical systems technologies. Successfully fabricating an arched trapezoidal piezoelectric thin-film device designed for cochlea's 3D spiral structure, we confirmed resonance characteristics using laser Doppler vibrometer. However, lead-free organic piezoelectric thin films for future animal tests have the length in the longitudinal direction of 3 mm, hindering precise voltage output measurement. Consequently, verifying frequency selectivity remains incomplete. To address this bottleneck, we optimized performance through reevaluated annealing conditions by analyzing the crystal structure of the piezoelectric film using X-ray diffraction. Assessing frequency selectivity through voltage output in silicone oil, replicating endolymph fluid properties, we found distinct resonance frequencies of 100 kHz and 130 kHz at different positions, showing cochlear implant potential for natural-like frequency selectivity.

Our research group has developed a fully implantable artificial cochlea using biomimetics to aid patients with sensorineural hearing loss. An artificial cochlear sensory epithelium that mimics the organ of Corti was fabricated using MEMS technology and realized frequency selectivity ranging from 157 to 277 kHz by the position of maximum amplitude. Unfortunately, multiple peaks of amplitude were observed in the high frequency. This causes the position of peak to overlap at different frequencies. To enhance its frequency selectivity, we turned our attention to the intriguing phenomenon of traveling waves known to occur in the organ of Corti. To investigate this aspect, we employed a full-field optical coherence microscope for precise measurements of oscillation. The use of a heterodyne interferometer in this measurement system allowed us to capture oscillation at low frame rates, utilizing the interference of two lights with slightly different frequencies for improved resolution and shortened measurement times. The results showed that the resonance frequency in the 1st mode was 120 kHz, and in the 2nd mode, it was 200 kHz. One peak was observed in the 1st mode, while two were seen in the 2nd mode. Moreover, the velocity of the traveling wave in the 1st mode measured 102.6 m/s. In contrast, in the 2nd mode, the peak's velocity at the resonance position reached 118.7 m/s, while the other peak exhibited a velocity of 62.1 m/s. We discussed the result by using two-dimensional wave equation in cylindrical coordinate system. This indicated the difference in velocity depend on the wavelength. Present observation demonstrated that the velocity increases at the resonance position, promising possibilities for further enhancement of the frequency selectivity in our cochlear implant.

Analysis using multiple reagents, such as enzyme-linked immunosorbent assay (ELISA) in microfluidic paper-based analytical devices (μPADs), requires fluid control in paper channel. In this study, a valve mechanism using thermo-responsive polymer was developed as a fluid control technology applicable to μPADs. To demonstrate fluid control of multiple solutions with μPADs using thermo-responsive valve, fluid control test was conducted with two different coloring liquid. However, fluid control couldn’t be achieved because the valve didn’t operate properly during the test. To investigate the condition under which the valve can properly perform its open and close function, we evaluated the relationship between the heating time, temperature, and valve performance. As a result, we confirmed that the valve could retain its closing function afterwards if heated at 45℃ or less for 15 minutes or less.

With the aging of the population worldwide, musculoskeletal diseases in the elderly are becoming more important, and osteoarthritis caused by cartilage wear and tear is a problem because it leads to a reduced quality of life. Since cartilage does not have blood vessels and has poor self-repair capabilities, research on artificial joints, artificial cartilage, and regenerated cartilage as alternatives has been vigorously conducted. One approach is to elucidate the lubrication mechanism of articular cartilage. Hydration of biopolymers on the cartilage surface contributes to low friction. One of these biopolymers is proteoglycan (hereafter referred to as PG). In this study, we evaluated the lubricating effect of PG on cartilage tissue scale. An agarose-chondrocyte model was prepared by seeding chondrocytes in agarose gel, cultured under compressive loading, and the frictional behavior was evaluated using a rheometer. The amount of PG synthesized by the chondrocytes and accumulated in the model and the dynamic viscoelasticity of the model was then measured by colorimetric analysis and dynamic viscoelasticity test. As a result, we were able to quantitatively evaluate the lubricating effect of PG on the various parameters that constitute frictional behavior and changes in dynamic viscoelasticity.

In recent years, it has been recognized that the loss of muscle mass as a result of ageing is the cause of various diseases such as bedriddenness. Normally, the muscle proteins that constitute muscles are continuously being built and broken down to maintain a constant amount of muscle strength, but due to ageing and lack of exercise, the amount of muscle protein breakdown exceeds the amount of synthesis. This reduces muscle mass and the body's motor function, resulting in bedriddenness. This condition is called "sarcopenia" and the number of patients is increasing. There is currently no specific treatment for this symptom, and research is underway to find an effective treatment. Traditionally, studies have used drug-treated or genetically engineered mice to model muscle disease. However, due to the many extraneous factors in animal experiments and the inferior quantification due to individual differences, there is a need for cell assay tools that can be evaluated more quantitatively and rapidly. In this study, we aim to establish a more reproducible muscle disease model by producing artificial muscle using a C2C12 cell line and performing culture experiments in a microgravity environment using a clinostat.

In recent years, bioactuators using biomaterials such as cells and tissues as actuators have attracted attention. Among them, skeletal muscle cell-based bioactuators without automaticity can be relatively easily controlled by external stimuli. However, the skeletal muscle actuators can contract but cannot extend by themselves, which makes it difficult to control their length. In this study, we fabricated the fin oscillation mechanism in which two tissue-engineered muscles derived from the mouse myoblast cell line C2C12 were antagonistically arranged. The mechanism used the linear motion caused by contractions of the tissue-engineered skeletal muscles to oscillate the fins via polyimide film. The length of the tissue-engineered skeletal muscles was adjusted to 8.5 mm to drive the fin at the maximum force. The tissue-engineered skeletal muscles were stimulated alternately with bipolar pulses of ±0.5 V/mm amplitude and 4 ms width for 500 ms via the Pt electrodes. This caused the fin to oscillate at 1 Hz with an oscillation angle of 6°.

In recent years, microplastic pollution in the environment has been considered a problem. Neuston nets are widely used to collect microplastics, but the mesh size is approximately 300 μm, making it difficult to collect microplastics smaller than the mesh size. We have investigated the applicability of acoustic focusing for microplastic collection and demonstrated the collection of 10 μm particles. However, the flow rates in our previous studies were 1 mL/min, which was not sufficient for environmental distribution studies. Circular tubes are known to provide two-dimensional focusing and can increase particle collection efficiency. We experimentally investigated the performance of acoustic focusing in a circular tube with an inner diameter of 0.8 mm. The suspensions of 2, 6, 15, 200, and 300 μm particles were prepared and sent to the circular tube. We evaluated the focusing performance of the circular tube by measuring the focusing width. The experimental results showed that the acoustic separation in the circular tube could collect microplastics at a flow rate of 10 mL/min.

In this study, PIV experiments were conducted during neutralized chemical reaction in partially miscible solvents using Hele-Shaw cell. The acetic acid in iso-butanol (AC) were set on the sodium hydroxide aqueous solution (NaOH) in the cell. Ratio of initial molar concentrations was unity which was defined by R = C₀, _AC/C₀, _NaOH. For C₀ = 0.2 mol/L, the vorticity was initially generated at the liquid-liquid interface due to Marangoni convection while the vorticity was also generated at the iso-butanol layer due to Rayleigh-Taylor instability. The vorticity decreased monotonously with time. On the other hand, for C₀ = 2.0 mol/L, the vorticity was found to increase and decrease for a while and then eventually decay. It was suggested that the increment and decrement of the vorticity could be caused by both the interfacial flow due to Marangoni convection and interface fracture at the liquid-liquid interface.

To understand an ion transport phenomenon in micro- and nanoscale, a novel evaluation method is required. In this study, we propose a method to quantitatively evaluate the viscosity of water by focusing on ion transport in micro- and nanochannels. A micro- and nanofluidic channel with a test section of 20 × 1.0 × 0.5 μm (L × W × D) is filled with 10 μM KCl, NaCl, and LiCl solutions, and the viscosity of water is analyzed from the electrical conductivity obtained from the current-voltage characteristics. The temperature dependence of the conductivity in the range from 303 to 343 K reveals the existence of a scaling factor between the water and the electrolyte solutions, and it is also clarified that the quantitative evaluation of liquid viscosity is possible by using the scaling factor associated with the Andrade’s equation.

A dynamical model for nonlinear wave propagation in phononic crystals is constructed. A lattice model is introduced as a discrete model of phononic crystals that consists of scatter and background material. Nonlinearity of material is considered as nonlinear mass density. In the proposed lattice model, massed of the mass points is described as a function of the local strain of the system. Nonlinear dynamics of the proposed lattice system is confirmed by numerical simulation. Moreover, frequency shift of phonon mode that is required for the switching dynamics is confirmed.

To improve the throughput of nanopore sequencers based on the well-known Coulter’s principle, novel methods using optical manipulation techniques for efficient transportation of nanoparticles into the sensing section have been proposed. Notably, we achieved successful electrical detection of both Au nanoparticles and polystyrene particles. However, the current response of Au nanoparticles exhibited conductive pulses rather than resistive pulses. The influence of light absorption of Au nanoparticles on ionic current responses requires further investigation. Au nanoparticles with a diameter of 200 nm are optically manipulated and brought into a nano-orifice using a Gaussian beam irradiated in a 0.05 × PBS electrolyte solution. When a Au particle just escapes from the nano-orifice, a conductive pulse appears in the ionic current. The conductive pulse of a Au particle in a 0.05 × PBS solution is surprisingly larger than that previously observed in a 0.5 × PBS solution. These findings underscore the relationship between the optical force and electrolyte concentration in ionic current modulations, providing a valuable insight into the single particle sensing.

Flash method and Periodic heating method, that are representative thermal diffusivity measurement methods, require blackening on surface of a sample to improve measurement accuracy. But to add blackening layer on surface of a sample changes measured thermal diffusivity that is apparent value. To obtain accurate thermal diffusivity from measurement result of blackening sample, change of apparent thermal diffusivity attributed blackening layer should be estimated. To estimate apparent thermal diffusivity measured by Flash method, half time method using temperature raise curve obtained by simulation model is used. Validity of simulation model is ensured by fitting theoretical temperature rise curve against it. To estimate apparent thermal diffusivity measured by Periodic heating method, phase delay of temperature response obtained by simulation model is calculated. As a result, the larger thickness of blackening layer is, the lower apparent thermal diffusivity of blackening sample is in both of Flash method and Periodic heating method. The result of Flash method has influence of blackening layer more than Periodic heating method.

The miniature specimens made from Sn-3.0Ag-0.5Cu (SAC) solder tend to show larger variation in the tensile strength than the ordinary size specimen. We assumed that the distribution morphology of the primary tin crystal in the specimen affected the strength of the specimen and investigated the relationship between the morphology and the strength. Then, we found that primary tin crystals whose longitudinal direction made 0-10° and 80-90° to the loading direction were frequently observed in the high-strength specimen, while those whose direction was 30-40° were frequent in the low-strength specimen. In this study, we conducted nanoindentation tests to investigate the deformation characteristics of the primary tin crystal and the eutectic structure in a miniature SAC solder specimen which could be useful information for discussing the direction dependency mentioned above. The result shows that the tin crystal has larger elastoplastic compliance than the eutectic structure, while the eutectic structure has larger creep compliance than the tin crystal.

In this study, Sn nanodots were formed on the surface of Bi2Te3 nanoplates by electroless plating. The nanodot density in nanoplates was controlled by varying the SnCl2 concentration in the plating solution. SEM and EDS analyses showed that Sn nanodots were formed on the nanoplates and that the nanodot density varied with the plating concentration. The electrical conductivity increased and the Seebeck coefficient decreased as the Sn nanodot density increased. The thermal conductivity decreased with increasing Sn nanodot density, possibly in part due to phonon scattering by the Sn nanodots.

In this presentation, a new method for active control of the strength of SiO₂ film using Si nanodots (Si-NDs) is proposed. An electron beam (EB) irradiation creates Si-NDs in an SiO₂ film. The number, size, and distribution of the Si-NDs in the film can be controlled by EB irradiation energy. Since Si has higher fracture toughness than SiO₂, a crack, initiated in SiO₂, propagates into the film while preventing Si-NDs during fracture. Consequently, the fracture of SiO₂ film can be controlled by Si-NDs, leading to active control of strength for SiO₂-coated Si microelectromechanical systems (MEMS).

In recent years, the sintering and bonding technology of silver (Ag) nanoparticles has been attracting attention in the bonding of SiC power devices. This is because Ag nanoparticles enable us to do sintering and bonding at relatively low temperatures. However, the vacancies encapsulated in the sintered Ag layer become a source of stress concentration of the cyclic thermal stress, which generates cracks leading to failure. In this paper, a new paste, hybrid paste (HYP) containing Ag and copper oxide (CuO) nanoparticles, is introduced firstly. Then, to suppress cracking, a double layered Ag/HYP sintering technique is proposed. The effectiveness of the technique towards long-term reliability of the die attach assemblies under thermal shock test (TST) is discussed based on cross sectional scanning electron microscope (SEM) images, finite element analysis (FEA), and material testing results.

Recently, more efficient heating technology, such as local heating, low power consumption and low carbon dioxide emissions, is required in the field of electrode bonding and JISSO (electronics packaging). An Al/Ni multilayer material with a self-propagating exothermic reaction has attracted attention because they are environmentally friendly with no outgassing and are suitable for local heating. In this study, exothermic characteristics of Al/Ni multilayer powder materials with self-propagating exothermic reaction fabricated by aluminum foil and porous nickel plating technique were investigated experimentally. The exothermic reaction properties of Al/Ni multilayer powders prepared by laminated roll bonding milling were compared with two different nickel layer fabrication techniques using nickel foil and porous nickel plating. As a result of the maximum temperature and reaction time measurements during exothermic reaction, the porous nickel plating technique with only 20 passes exhibited superior or better characteristics rather than using the nickel foil technique with 40 passes. It is expected to be a novel and efficient heating source.

Recently, with the development of Internet of Things (IoT) technologies, the amount of information processed in the cloud is getting larger. This situation can cause a delay in data transfer and an increase in power consumption. Therefore it may cause negative effects on any information processing, like machine learning. Physical reservoir computing (PRC) is a solution, where we can use physical dynamics as a computational resource to reduce the amount of power consumption. In this report, we propose to utilize a surface acoustic wave (SAW) device for PRC, and for this purpose, we designed and fabricated SAW phase modulators that have a waveguide to modulate a SAW efficiently. We prepared devices with waveguide lengths of 5 mm, 10 mm, and 15 mm and widths of 10 μm and 18 μm and evaluated signal attenuation and modulation effects. As a result, we clarified the effect of these parameters to the properties of SAW modulators.

In this study, the cantilever planar shape was improved to increase the sensitivity of a cantilever-type MEMS tactile sensor to normal force and shear loading. Analysis showed that a trapezoidal shape, which extends from the fixed end to the free end, can improve the sensitivity to normal force. However, it was found that if the shape of the Cr layer patterning for stress is the same as before, it becomes curved when the free end direction is widened, resulting in a decrease in sensitivity. We fabricated a new cantilever with Cr longitudinal stripes and radial patterning. As a result, we were able to improve the sensitivity to vertical load by a factor of about 5 and to shear load by a factor of about 7.

This paper reports on the development of molybdenum microfabrication technology for MEMS sensor applications. In this research, molybdenum microfabrication was performed under various conditions using an electrolytic etching process. The duty ratio, agitation, and processing time were changed in the processing conditions, and the etch rate and etch factor were evaluated, respectively. The optimized conditions were a duty ratio of 75% under constant agitation. This is thought to be caused by a thinner diffusion layer formed on the surface of the electrode by the electrolytic process. On the other hand, the diffusion layer on the processing side wall improves the etch factor by reducing the processing speed of the side wall. The etching profiles obtained by the electrolytic etching showed a higher etch factor than those obtained by a wet chemical etching method. Finally, an etch factor of about 1.5 and an etch rate of 1.0 μm/min was obtained under the optimum conditions.

One of the problems with using PMIs for inhalation treatment is that there are cases in which patients fail to spray a dose at proper timing. In order to solve this problem, for this research, we developed an automatic spraying device (automatic inhaler) that automatically sprays according to the monitored timing and studied the changes in inhalation status under the continuous use of the device.As a result, because the subjects were not required to spray a dose at proper timing with the use of the automatic device, we could approximate the inhalation speed and volume to the desired values. Also, as some of the subjects learned the proper timing through the continuous use of the device, they became able to spray a dose at the proper timing even without using the device. However, because the device requires a medicine bottle to be pushed a force of over 50N to spray, even though the subjects started to push their bottles with perfect timing, some ended up missing the optimal timing to spray.

Stimulation of the sensory nervous system has been investigated as a rehabilitation method to activate the entire swallowing reflex circuit. We have investigated the effects of frequency and location of electrical stimulation on swallowing movements. Biphasic bursts of stimulation pulses were applied to either the back or neck of adult rats at a randomly generated frequency with a Gaussian distribution with a median value of 30 Hz or 300 Hz. The activity of normal swallowing before and after electrical stimulation was compared by measuring electromyography (EMG) of the swallowing muscles. The results showed that the maximum EMG potentials were larger when both the back and neck were stimulated in all cases. In addition, the 30 Hz pulse frequency produced greater EMG potentials than the 300 Hz pulse frequency. In conclusion, the results suggest the usefulness of electrical stimulation at a central probability frequency of 30 Hz, and further suggest that stimulation to the back activates more swallowing muscles with more beginning stimulation than stimulation to the neck.

Jumping phenomenon is known as one of the problems of endovascular treatment. This is that after the tip of the device stops, it suddenly bounces and damages the vessel wall.The purpose of this study is to investigate the factors of jumping. Using a crank-shaped blood vessel phantom with a circular cross-section made by a 3D printer, a device combining a catheter and a guide wire was inserted into this blood vessel phantom. We observed the behavior of the inserted device with a camera from one direction. The captured video was divided into a series of images. The tip of the device was manually identified to calculate the stationary time and jumping distance per frame. Furthermore, the strain energy was calculated from the device tracked by the MRF method.In the case of the blood vessel phantom with the largest angle, the time that the tip stopped at the curve part was 0.6-0.8 s. When jumping occurred, the distance was 10-20 pixels. The shorter the distance between the catheter and the guidewire, the shorter the total stop time and the jumping distance. In order to prevent irregular device behavior in blood vessels, it is desirable to operate the catheter and the guide wire close to each other.

Based on the consideration of that the diaphragm movement during breathing is different in the diaphragmatic ventilation between healthy people and patients with respiratory diseases, this study was aimed to reveal the relationship between diaphragm morphology and respiratory function for the purpose of computer aided diagnosis and treatment. First, a geometric model was generated from CT images of the exhalation and the inhalation states. The ratios of the diaphragm area at the end of expiratory to the diaphragm area at the end of inspiratory were obtained and compared with percentage vital capacities. It is found that there is a positive correlation between the ratio and percentage vital capacity. Furthermore, breathing simulation of the diaphragm was performed by introducing muscle material model representing the direction of muscle fiber. The contraction of diaphragm was reproduced by applying the activity to the muscle material model until the resulted deformation to be consistent with the shape of diaphragm at the end of inspiration. To investigate the effect of deformation in different location of diaphragm, the diaphragm was divided into 11 parts. The contraction ratios, defined as the area at the end of inspiration to the area at the end of expiration, of COPD and ACO patients were compared with those of healthy person. The results show the correlation between the contraction ratio and diseases.

It is often reported that endovascular treatment may damage blood vessels due to the difficulty of manipulating the device. As for the rotation operation of the device, it is found that the distribution of the contact force between the device and the blood vessel wall is one of the factors that make the rotation operation difficult. In order to investigate the contact force distribution of a device inserted into a blood vessel, in this study, we proposed the method to estimate the overall shape and contact force distribution of a device from a single image. the 3D shape was calculated under the condition that the strain energy of the device inserted in the blood vessel was minimized. When the device node moves to the outside of the vessel wall, the movement is obstructed by the vessel wall. Then, the node and the vessel wall are judged to be in contact. The contact force can be calculated as the constraint force that satisfied the constraint described above. The estimated 3D shape of the device obtained the same accuracy as the previous research. The Hausdorff distance was 0.24 mm. Regarding the contact force distribution, the contact force error was 4.24 N. In order to increase the estimation accuracy of the contact force distribution, it was found that the method needs to be improved. Estimating the contact force distribution accurately will contribute to expect the degree of the potential difficulty in rotating operation of a device. This proposed technique will leads to reduce the probability of accidents in intravascular operation.

Cancer is the leading cause of death in Japan, and improvements in cancer treatment technology are needed. The current main treatments, chemotherapy, surgery, and radiotherapy are highly invasive to the body. Hyperthermia is a minimally invasive treatment that takes advantage of the heat-sensitive properties of cancer cells by heating the tumors to kill it. Magnetic nanoparticle （MNPs） mediated magnetic hyperthermia is one of the cancer treatments, particularly for its ability to affect cell death of deep-seated tumors. However, the heat generation characteristics of MNPs and the method of measuring the temperature inside the body have not yet been clarified, so their practical use has not yet been realized. The aim of this research is to control the temperature of magnetic nanoparticles and measure the temperature in the body. To this end, the laser-induced fluorescence （LIF） method was used to assess how the heat generated by MNPs is transferred to the agar phantoms that simulate a living body during the heating experiment.

Respiratory muscles have the function of generating ventilation, and muscle weakness of respiratory muscles is known to be one of the causes of respiratory failure. Previous reports have not directly measured the muscle strength of the respiratory muscles, and have used indices to evaluate the strength of the respiratory muscles as a whole, so the effects and mechanisms of the degree and location of muscle weakness on respiratory function are unknown. In this study, using a finite element model of the thorax, we conducted a breathing simulation that reproduced muscle weakness of the respiratory muscles by adjusting the excitability of the external intercostal muscles and diaphragm individually. As a result, it was clarified how the ventilation rate changes depending on the excitability of the respiratory muscles. The respiratory muscles were divided into five groups, and each group was analyzed by applying normal excitability and reduced excitability. The results showed that the upper right side of the external intercostal muscles decreased the volume of ventilation the most. Furthermore, it was found that diaphragm muscle weakness reduced the amount of air inflow, but did not reduce ventilation because it increased the amount of air outflow.

A McKibben artificial muscle and a Warszawa artificial muscle, which are typical pneumatic soft actuators, are configured with a rubber tube and fibers. The braider machines for making strings can make such pneumatic soft actuators because they can weave the fibers with various arrangements around the rubber tube. In this report, several pneumatic soft actuators developed by using braider machines and functional fibers are introduced. It is found that braider technology is useful for development of the pneumatic soft actuators.

Design has been a core of human history and development. However, its critical role has been unclear not only for the manufacturing industry but also for society, because it had been spontaneous until the modern era. As the contents of artifacts become more complicated, the meaning of design is expanding. Multi-disciplinary design optimization, design thinking, model-based design, and virtual engineering are representative of its recent subordinate developments. When carefully observing the circumstances of Japanese firms under the global trends, it must be a question of whether the whole shape of those recent developments in the design and their backgrounds is adequately understood. This talk will provide some viewpoints on those issues and pose an image of the frontier of design engineering by reviewing the history of artifacts and associated manufacturing activities under a comprehensive view of the design.

During the endochondral ossification, the bone is formed from the cartilage. In this study, we fabricated scaffold-free spheroids using mouse pre-chondrocyte ATDC5 cells. Real-time PCR results represented that the spheroid culture for ATDC5 cells after 14 days up-regulated chondrocyte marker as well as hypertrophic chondrocyte marker compared beyond the 2-day cultured spheroids. In addition to the biochemical analysis, we also conducted 3D image analysis in conjunction with optical clearing techniques and confirmed the enlargement of the cells in the spheroid after the long-term culture. Our present study suggested that the spheroid culture for ATDC5 cells provoked the initial stage of endochondral ossification process involving the hypertrophy chondrocyte differentiation.

Recent years have seen an increased interest in three-dimensional (3D) cell culture models as they better represent in vivo conditions than two-dimensional (2D) cultures. Utilizing human mesenchymal stem cells, we have fabricated spheroids and demonstrated an increase in osteocyte markers in the early phase compared to the 2D culture as well as mineralization in the late phase. Assessing their mechanical properties and behavior is crucial to verify their bone formation potential in vitro. In this study, we conducted uniaxial compression tests to measure Young's modulus of the spheroids and evaluated their behaviors over time after compression in order to evaluate their elasticity and viscoelasticity. Our results revealed that Young's modulus of spheroids cultured for 35 days was 2.5 times higher than those cultured for 2 days, which is thought to be caused by the progression of ossification from the spheroid's center. Moreover, the shape of the spheroid fully recovered after compression for 1 minute, whereas the spheroid showed plastic deformation after compressing for more than 5 minutes. In order to evaluate the bone-likeness of the spheroids in detail, measurement of the local mechanical properties directly targeting the calcified areas inside the spheroid will be necessary in the future beyond the evaluation of the global mechanical properties conducted in this study.