IOP PublishingActa Medica Okayama0021-49226332024Evaluation of transducer for cryogenic actuators by equivalent circuit model03SP03ENKazukiKuboGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityKairiYagiGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityTakefumiKandaGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityKoaYasudaGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityDaisukeYamaguchiGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityShuichiWakimotoGraduate School of Environment, Life, Natural, Science and Technology, Okayama UniversityCryogenic environments are increasingly used in scientific and industrial fields. Recently, cryogenic environments are also used for storage and supply of liquid hydrogen, which is considered essential for the realization of a decarbonized society. Actuators to drive a valve that controls such a low-temperature fluid are required. In this study, a piezoelectric transducer that can be driven in the cryogenic environment has been fabricated and evaluated. Although the performance of piezoelectric elements degrades at cryogenic temperatures in general, the application of a preload can suppress the degradation of performance. Equivalent circuits were used for evaluation, and force factors and figures of merit were compared. As a result, the force factor was as high as that at RT even at cryogenic temperatures, and a high figure of merit was obtained. The result indicates that the transducer can be used for the driving of micro actuator at cryogenic temperature.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama0021-492262122023Photoelectron holographic evidence for the incorporation site of Se and suppressed atomic displacement of the conducting layer of La(O,F)BiSSe125001ENYaJunLiEngineering Research Center of Integrated Circuit Packaging and Testing, Ministry of Education, Tianshui Normal UniversityZeXuSunNara Institute of Science and Technology (NAIST)NoriyukiKataokaGraduate School of Natural Science and Technology, Okayama UniversityTaroSetoguchiGraduate School of Natural Science and Technology, Okayama UniversityYusukeHashimotoNara Institute of Science and Technology (NAIST)SoichiroTakeuchiNara Institute of Science and Technology (NAIST)ShunjoKogaNara Institute of Science and Technology (NAIST)KazuhisaHoshiDepartment of Physics, Tokyo Metropolitan UniversityYoshikazuMizuguchiDepartment of Physics, Tokyo Metropolitan UniversityTomohiroMatsushitaNara Institute of Science and Technology (NAIST)TakanoriWakitaGraduate School of Natural Science and Technology, Okayama UniversityYujiMuraokaGraduate School of Natural Science and Technology, Okayama UniversityTakayoshiYokoyaGraduate School of Natural Science and Technology, Okayama UniversityLa(O,F)BiS2-xSex is a layered material that is considered to be a candidate exotic superconductor as well as a promising thermoelectrical material. We performed soft X-ray photoelectron holography to study the Se incorporation site and the local atomic arrangement of the conducting layer. A comparison of the experimental holograms with the simulated holograms indicates that Se atoms preferentially occupy the S sites in the conducting Bi–S plane of La(O,F)BiS2. A comparison between the state-of-the-art holographic reconstructions of La(O,F)BiSSe and La(O,F)BiS2 suggests that Se substitution suppresses the displacement of S atoms in La(O,F)BiS2. These results provide photoelectron holographic evidence for the Se incorporation site and the Se-induced suppression of in-plane disorder.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama0953-20483552022Experiment and numerical simulation of the combined effect of winding, cool-down, and screening current induced stresses in REBCO coils054001ENHiroshiUedaGraduate School of Natural Science and Technology, Okayama UniversityHideakiMaedaJapan Science and Technology AgencyYuSuetomiRIKEN Center for Biosystems Dynamics ResearchYoshinoriYanagisawaRIKEN Center for Biosystems Dynamics ResearchThis paper overviews the combined effects of winding, cool-down, and screening current-induced stresses in REBCO coils. First, a simulation method to model the circumferential stress modification effect due to the screening-current is overviewed. The simulation includes coil winding, cooling down, and coil charge up to the operating current. Second, we will compare the numerical simulation results with the experimental results. The numerical simulations for a dry coil and an epoxy impregnated coil agree well with the experimental results. Third, the enhanced circumferential stress did not degrade the performance of a dry winding REBCO coil, but the improved increased compressive stress buckled the coil structure. Finally, it is demonstrated that epoxy impregnation has beneficial effects in reducing the stress modification effect. However, the circumferential stress is enormously enhanced at the coil ends, sometimes resulting in degradation of the coil performance.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama0021-492262SJ2023Acoustic metasurfaces and topological phononics for acoustic/elastic device designSJ0803ENKenjiTsurutaDepartment of Electrical and Electronic Engineering, Okayama UniversityThis paper reviews recent progress in acoustic metasurfaces and the novel concept of "topological acoustic/phononics" for designing compact yet efficient acoustic devices. After a brief review of this research area and its impact on ultrasonic technologies, some of the efforts to develop highly efficient sound absorption devices using acoustic metasurfaces are introduced. A resonance-based mechanism to achieve efficient absorption in metasurface structures thinner than the wavelength of the incident sound is briefly discussed, and its extensions to a broad spectrum are highlighted. Next, a valley topological phononic system is introduced, and its applications to the design of phononic waveguides are exemplified. The band structure design for extracting topologically protected edge modes is shown together with a numerical and experimental demonstration of the robustness of phononic waveguides constructed in both acoustic and elastic regimes.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama1741-25601842021Modelling the visual response to an OUReP retinal prosthesis with photoelectric dye coupled to polyethylene film045006ENKoichiroYamashitaGraduate School of Natural Science and Technology, Okayama UniversityPrathimaSundaramDepartment of Electrical and Computer Engineering, University of TorontoTetsuyaUchidaGraduate School of Natural Science and Technology, Okayama UniversityToshihikoMatsuoGraduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama UniversityWillyWongDepartment of Electrical and Computer Engineering, University of TorontoObjective. Retinal prostheses have been developed to restore vision in blind patients suffering from diseases like retinitis pigmentosa. Approach. A new type of retinal prosthesis called the Okayama University-type retinal prosthesis (OUReP) was developed by chemically coupling photoelectric dyes to a polyethylene film surface. The prosthesis works by passively generating an electric potential when stimulated by light. However, the neurophysiological mechanism of how OUReP stimulates the degenerated retina is unknown. Main results. Here, we explore how the OUReP affects retinal tissues using a finite element model to solve for the potential inside the tissue and an active Hodgkin-Huxley model based on rat vision to predict the corresponding retinal bipolar response. Significance. We show that the OUReP is likely capable of eliciting responses in retinal bipolar cells necessary to generate vision under most ambient conditions.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama1748-60411642021Development of highly durable retinal prosthesis using photoelectric dyes coupled to polyethylene film and quantitative in vitro evaluation of its durability045001ENKoichiroYamashitaGraduate School of Natural Science and Technology, Okayama UniversityTenuTanakaGraduate School of Natural Science and Technology, Okayama UniversityToshihikoMatsuoGraduate School of Interdisciplinary Science and Engineering in Health SystemsTetsuyaUchidaGraduate School of Natural Science and Technology, Okayama UniversityRetinal prostheses have been developed to restore vision in blind patients suffering from such diseases as retinitis pigmentosa. In our previous studies, we developed a retinal prosthesis called dye-coupled film by chemical coupling of photoelectric dyes, which absorb light and then generate electrical potential, with a polyethylene film surface. The dye-coupled film is nontoxic, and we recovered the vision of a monkey with macular degeneration. The amount of dye on the dye-coupled film, however, decreased to one-third after five months in the monkey’s eye. The photoelectric dye consists of a cation with photoresponsivity and a bromide ion (Br−). Therefore, an anion-exchange reaction could be applied to the dye-coupled film to improve its durability. In this study, the anion-exchange reaction was conducted using bis(trifluoromethanesulfonyl)imide ion (TFSI−), which has lower nucleophilicity than Br−. First, the long-term durability was examined without using animal subjects and in a short period. Subsequently, an elemental analysis was performed to confirm the exchange between Br− and TFSI−, and chemical properties, such as photoresponsivity and durability, before and after the anion exchange, were evaluated. It was quantitatively confirmed that the long-term durability of dye-coupled films can be evaluated in an in vitro environment and in a short period of one-thirtieth by utilizing a saline solution at 60°C, compared with an in vivo environment. In addition, the durability of the dye-coupled film with TFSI− was improved to 270%–320% compared with that of the dye-coupled film with Br−.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama0021-492260SD2021Low-frequency sound absorbing metasurface using multilayer split resonatorsSDDA01ENShotaTakasugiDepartment of Electrical and Electronic Engineering, Okayama UniversityKeitaWatanabeDepartment of Electrical and Electronic Engineering, Okayama UniversityMasaakiMisawaDepartment of Electrical and Electronic Engineering, Okayama UniversityKenjiTsurutaDepartment of Electrical and Electronic Engineering, Okayama UniversityAmong the acoustic metasurfaces that can control the propagation of sound waves with the structure far thinner than the wavelength at the operating frequency, the split tube structure has shown its effectiveness in the lower frequency band. Here we focus on multiply layered split tubes to broaden the absorption spectrum. By numerical analysis, we show up-to six-layer structure possessing wideband (1–1000 Hz) sound absorption. The absorbing peaks in the frequency band below 1000 Hz are shown to be multiplexed not only by simple superposition of vibrational modes of each layer, but also by hybridization of the modes indicating collective motion of tubes.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama1367-2630212019Superconductivity in a new layered triangular-lattice system Li2IrSi2093056ENKHoriganeResearch Institute for Interdisciplinary Science, Okayama University,KTakeuchiGraduate School of natural science and technology, Okayama UniversityDHyakumuraDepartment of Physics and Mathematics, Aoyama Gakuin UniversityRHorieResearch Institute for Interdisciplinary Science, Okayama UniversityTSatoInstitute for Materials Research, Tohoku UniversityTMuranakaDepartment of Engineering Science, University of Electro-CommunicationsKKawashimaDepartment of Physics and Mathematics, Aoyama Gakuin UniversityHIshiiNational Synchrotron Radiation Research CenterYKubozonoResearch Institute for Interdisciplinary Science, Okayama UniversitySOrimoInstitute for Materials Research, Tohoku UniversityMIsobeNational Institute for Materials Science (NIMS)JAkimitsuResearch Institute for Interdisciplinary Science, Okayama UniversityWe report on the crystal structure and superconducting properties of a novel iridium-silicide, namely Li2IrSi2. It has a Ag2NiO2-type structure (space group R-3m) with the lattice parameters a = 4.028 30(6) Å and c = 13.161 80(15) Å. The crystal structure comprises IrSi2 and double Li layers stacked alternately along the c-axis. The IrSi2 layer includes a two-dimensional Ir equilateral-triangular lattice. Electrical resistivity and static magnetic measurements revealed that Li2IrSi2 is a type-II superconductor with critical temperature (Tc) of 3.3 K. We estimated the following superconducting parameters: lower critical field Hc1(0) ~ 42 Oe, upper critical field Hc2(0) ~ 1.7 kOe, penetration depth λ0 ~ 265 nm, coherence length ξ0 ~ 44 nm, and Ginzburg–Landau parameter κGL ~ 6.02. The specific-heat data suggested that superconductivity in Li2IrSi2 could be attributed to weak-coupling Cooper pairs.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama0953-89843332020Soft x-ray irradiation induced metallization of layered TiNCl035501ENNoriyukiKataokaGraduate School of Natural Science and Technology, Okayama UniversityMasashiTanakaGraduate School of Engineering, Kyushu Institute of TechnologyWataruHosodaGraduate School of Natural Science and Technology, Okayama UniversityTakumiTaniguchiGraduate School of Natural Science and Technology, Okayama UniversityShin-ichiFujimoriMaterials Sciences Research Center, Japan Atomic Energy AgencyTakanoriWakitaGraduate School of Natural Science and Technology, Okayama UniversityYujiMuraokaGraduate School of Natural Science and Technology, Okayama UniversityTakayoshiYokoyaGraduate School of Natural Science and Technology, Okayama UniversityWe have performed soft x-ray spectroscopy in order to study the photoirradiation time dependence of the valence band structure and chemical states of layered transition metal nitride chloride TiNCl. Under the soft x-ray irradiation, the intensities of the states near the Fermi level (EF) and the Ti3+ component increased, while the Cl 2p intensity decreased. Ti 2p–3d resonance photoemission spectroscopy confirmed a distinctive Fermi edge with Ti 3d character. These results indicate the photo-induced metallization originates from deintercalation due to Cl desorption, and thus provide a new carrier doping method that controls the conducting properties of TiNCl.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama1755-13074652020Animal Biotechnology Roles in Livestock Production012001ENHiroakiFunahashiDepartment of Animal Science, Graduate School of Environmental and Life Science, Okayama UniversityCurrently, meat and milk productions are significantly increasing especially in Asia. The supply of these products is vital to people's health and well-being, whereas the efficiency of beef production appears to be still lower than other meat productions. Improvements in the quality and functionality of their livestock products, as well as their production efficiency, are required for further production. Animal biotechnologies have contributed to genetic improvement, genetic diversity maintenance of domestic animals, etc. Basic animal biotechnologies, such as artificial insemination and embryo transfer, have been well established and applied as powerful tools for genetic improvement of livestock. In the applications of artificial insemination techniques, the use of sexed semen has been now widely spread, and also efforts are also made in the development of the technology using a small amount of sperm. For embryo transfer, several types of vitrification technologies have been applied to improve pregnancy rates and contributed to the international/domestic supply of livestock embryos. Conventional animal biotechnologies, such as in vitro fertilization and intracellular sperm injection, have been applied to not only livestock production and also human-assisted reproductive medicine. For in-vitro production of embryos in domestic animals, currently, oocytes have been collected from medium or large follicles (3-6 mm or larger in diameter) of ovaries. Although the oocytes derived from small follicles (less than 3 mm in diameter) exist more on the surface of ovaries, the developmental competence of the oocytes has been known to be significantly lower than those from medium follicles. If we could improve the competence of oocytes derived from small follicles significantly, we may be able to increase the number of female gamete resources for in vitro embryo production. Also, the development of techniques for producing transgenic and cloned animals has greatly contributed to the creation of pharmaceuticals and organs for xenotransplantation. Recently, furthermore, genome editing technologies, such as combined use of CRISPR/Cas9 and PiggyBac, have been developed and have made it possible to correct specific parts of the genome and introduce mutations by homologous recombination. In this review, I would like to discuss the application and progress of the above biotechnologies, including our recent research results.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama2632-3338132020On the Occurrence of Clathrate Hydrates in Extreme Conditions: Dissociation Pressures and Occupancies at Cryogenic Temperatures with Application to Planetary Systems80ENHidekiTanakaResearch Institute for Interdisciplinary Science, Okayama UniversityTakumaYagasakiResearch Institute for Interdisciplinary Science, Okayama UniversityMasakazuMatsumotoResearch Institute for Interdisciplinary Science, Okayama UniversityWe investigate the thermodynamic stability of clathrate hydrates at cryogenic temperatures from the 0 K limit to 200 K in a wide range of pressures, covering the thermodynamic conditions of interstellar space and the surface of the hydrosphere in satellites. Our evaluation of the phase behaviors is performed by setting up quantum partition functions with variable pressures on the basis of a rigorous statistical mechanics theory that requires only the intermolecular interactions as input. Noble gases, hydrocarbons, nitrogen, and oxygen are chosen as the guest species, which are key components of the volatiles in such satellites. We explore the hydrate/water two-phase boundary of those clathrate hydrates in water-rich conditions and the hydrate/guest two-phase boundary in guest-rich conditions, either of which occurs on the surface or subsurface of icy satellites. The obtained phase diagrams indicate that clathrate hydrates can be in equilibrium with either water or the guest species over a wide range far distant from the three-phase coexistence condition and that the stable pressure zone of each clathrate hydrate expands significantly on intense cooling. The implication of our findings for the stable form of water in Titan is that water on the surface exists only as clathrate hydrate with the atmosphere down to a shallow region of the crust, but clathrate hydrate in the remaining part of the crust can coexist with water ice. This is in sharp contrast to the surfaces of Europa and Ganymede, where the thin oxygen air coexists exclusively with pure ice.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama1755-130724032019Numerical study of air-entraining and submerged vortices in a pump sump032001ENShinichiroYanaseDepartment of Mechanical and Systems Engineering, Okayama UniversityRyoYamasakiTechnical Division, Tsurumi Manufacturing Co.ToshinoriKouchiDepartment of Mechanical and Systems Engineering, Okayama UniversityShunsukeHosodaDepartment of Mechanical and Systems Engineering, Okayama UniversityYasunoriNagataDepartment of Mechanical and Systems Engineering, Okayama UniversityHiguchiShunjiTechnical Division, Tsurumi Manufacturing Co.ToshihikoKawabeTechnical Division, Tsurumi Manufacturing Co.ToshihiroTakamiDepartment of Mechanical and Systems Engineering, Okayama University of ScienceNumerical detection of harmful vortices in pump sumps, such as an air-entraining vortex (AEV) and a submerged vortex (SMV), is crucially important to develop the drain pump machinery. We performed numerical simulations of the benchmark experiments of the pump sump conducted by Matsui et al. (2006 and 2016) using the OpenFOAM and compared the simulation results with the experimental data considering the effects of turbulence model, grid density and detection method of the vortices. We studied the threshold of the gas-liquid volume fraction of the VOF method and the second invariant of velocity gradient tensor to identify AEV and SMV. The methods proposed in the present paper were found to be very effective for the detection of the vortices, and the simulation results by RANS with the SST k-omega model successfully reproduced the experimental data. LES with the Smagorinsky model, however, was sensitive to the grid system and difficult to reproduce the experimental data even for the finest grid system having 3.7 million cells in the present study.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama2515-7639232019Solid-state nuclear magnetic resonance study of setting mechanism of beta-tricalcium phosphate-inositol phosphate composite cementsENToshiisaKonishiGraduate School of Natural Science and Technology, Okayama UniversityKoheiYamashitaGraduate School of Natural Science and Technology, Okayama UniversityKoheiNagataOrganization for the Strategic Coordination of Research and Intellectual Property, Meiji UniversityPoon NianLimDepartment of Mechanical Engineering, National University of SingaporeEng SanThianDepartment of Mechanical Engineering, National University of SingaporeMamoruAizawaDepartment of Applied Chemistry, School of Science and Technology, Meiji UniversitySolid-state nuclear magnetic resonance (NMR) spectroscopy is a technique, which can be used to provide insight into the chemical structure of non-crystalline and crystalline materials. Hence, the present study aimed to elucidate the setting mechanism of CPC, which was fabricated using beta -tricalcium phosphate (beta -TCP)-inositol phosphate (IP6) composite powder using NMR In addition, the effect of IP6 on the local chemical structure of the beta -TCP-IP6 composite powder and its hardened cement would also be investigated. The H-1 -> P-31 heteronuclear correlation NMR spectrum revealed that an amorphous hydrated layer, along with small amount of hydroxyapatite (HA) was formed on the surface of beta -TCP during the ball-milling process. Results demonstrated that the IP6 in the hydrated layer on the surface of beta -TCP inhibited the formation of HA. Moreover, the setting reaction of the cement was mainly triggered by the dissolution of the amorphous hydrated layer on beta -TCP surface, and subsequent precipitation, followed by the inter-entanglement between the HA crystals on the beta -TCP.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama2053-1591752020Synthesis of solvent-free conductive and flexible cellulose-carbon nanohorn sheets and their application as a water vapor sensor056402ENKarthikPaneer SelvamGraduate School of Natural Science and Technology, Okayama UniversityTomohiroNakagawaGraduate School of Natural Science and Technology, Okayama UniversityTatsukiMaruiGraduate School of Natural Science and Technology, Okayama UniversityHirotakaInoueGraduate School of Natural Science and Technology, Okayama UniversityTakeshiNishikawaGraduate School of Natural Science and Technology, Okayama UniversityYasuhikoHayashiGraduate School of Natural Science and Technology, Okayama UniversityCarbon nanohorns (CNHs) are mixed with cellulose to make freestanding thin-film conductive sheets. CNHs, at different ratios (5, 10, 25, 50 wt%), form composites with cellulose (hydroxyethylcellulose). Freestanding cellulose-carbon nanohorn (CCN) sheets were fabricated using a 100 mu m-thick metal bar coater. Surfactants or any other chemical treatments to tailor the surface properties of CNHs were avoided to obtain composite sheets from pristine CNHs and cellulose. Utilizing the hygroscopic property of hydroxyethylcellulose and the electrical conductivity of CNHs paved a path to perform this experiment. The synthesis technique is simple, and the fabrication and drying of the sheets were effortless. As the loading concentration of CNH increased, the resistance, flexibility, and strength of the CCN composite sheets decreased. The maximum loading concentration possible to obtain a freestanding CCN sheet is 50 wt%. The resistance of the maximum loading concentration of CNH was 53 k omega. The response of the CCN sheets to water vapor was 4 s and recover time was 13 s, and it is feasible to obtain a response for different concentrations of water vapor. High-resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, resistance measurement, tensile strength measurement, and thermogravimetric analysis were used to investigate the mechanical, morphological, electrical, and chemical properties of the CCN sheets.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama2053-1591732020Inhomogeneous superconductivity in thin crystals of FeSe1-xTex (x=1.0, 0.95, and 0.9)036001ENRitsukoEguchiResearch Institute for Interdisciplinary Science, Okayama UniversityMegumiSendaGraduate School of Natural Science and Technology, Okayama UniversityEriUesugiGraduate School of Natural Science and Technology, Okayama UniversityHidenoriGotoResearch Institute for Interdisciplinary Science, Okayama UniversityAkihikoFujiwaraDepartment of Nanotechnology for Sustainable Energy, Kwansei Gakuin UniversityYasuhikoImaiJapan Synchrotron Radiation Research Institute (JASRI)ShigeruKimuraJapan Synchrotron Radiation Research Institute (JASRI)TakashiNojiDepartment of Applied Physics, Tohoku UniversityYojiKoikeDepartment of Applied Physics, Tohoku UniversityYoshihiroKubozonoResearch Institute for Interdisciplinary Science, Okayama UniversityWe investigated the temperature dependence of resistivity in thin crystals of FeSe1-xTex (x = 1.0, 0.95, and 0.9), though bulk crystals with 1.0 x 0.9 are known to be non-superconducting. With decreasing thickness of the crystals, the resistivity of x = 0.95 and 0.9 decreases and reaches zero at a low temperature, which indicates a clear superconducting transition. The anomaly of resistivity related to the structural and magnetic transitions completely disappears in 55- to 155-nm-thick crystals of x = 0.9, resulting in metallic behavior in the normal state. Microbeam x-ray diffraction measurements were performed on bulk single crystals and thin crystals of FeSe1-xTex. A significant difference of the lattice constant, c, was observed in FeSe1-xTex, which varied with differing Te content (x), and even in crystals with the same x, which was mainly caused by inhomogeneity of the Se/Te distribution. It has been found that the characteristic temperatures causing the structural and magnetic transition (T-t), the superconducting transition (T-c), and the zero resistivity (T-c(zero)) are closely related to the value of c in thin crystals of FeSe1-xTex.No potential conflict of interest relevant to this article was reported.IOP PublishingActa Medica Okayama0964-172620102011Design of a variable-stiffness robotic hand using pneumatic soft rubber actuatorsENJun-yaNagaseShuichiWakimotoToshiyukiSatohNorihikoSagaKoichiSuzumoriIn recent years, Japanese society has been ageing, engendering a labor shortage of young workers. Robots are therefore expected to be useful in performing tasks such as day-to-day support for elderly people. In particular, robots that are intended for use in the field of medical care and welfare are expected to be safe when operating in a human environment because they often come into contact with people. Furthermore, robots must perform various tasks such as regrasping, grasping of soft objects, and tasks using frictional force. Given these demands and circumstances, a tendon-driven robot hand with a stiffness changing finger has been developed. The finger surface stiffness can be altered by adjusting the input pressure depending on the task. Additionally, the coefficient of static friction can be altered by changing the surface stiffness merely by adjusting the input air pressure. This report describes the basic structure, driving mechanism, and basic properties of the proposed robot hand.No potential conflict of interest relevant to this article was reported.