Faculty Profiles - HATA Seiichi

Development of 3D stress measurement system for surgical simulator

YAMADA Daichi, HORI Simon, YAMAZAKI Takahiro, OKA Chiemi, SAKURAI Junpei, HATA Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2020 ( 0 ) page： J24111 2020

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In recent years, minimally invasive treatment has attracted attention, and catheter surgery is one of them. On the other hand, there is a problem that stress is applied to the blood vessel wall and it is damaged, so doctors are required the skill of catheter surgery. In order to improve the skill of catheter surgery, the authors have proposed a surgical simulator that realizes real-time visualization of stress by the photoelasticity. Photoelasticity is a property in which an isotropic elastic body such as glass or acrylic that receives an external force causes birefringence. It is often used as an experimental method to analyze the stress distribution of materials. In this study, it is proposed a measurement system for surgical simulator that can measure three-dimensional stress. The shape of the blood vessel model applicable to the proposed measurement system is determined and introduce a stress correction that guarantees constant accuracy. Finally, it is showed that the stress can be visualized in real time.

DOI： 10.1299/jsmemecj.2020.j24111

Preparation of blood vessel model with two-layer structure for a surgical simulator

YAMADA Daichi, HORI Simon, YAMAZAKI Takahiro, OKA Chiemi, SAKURAI Junpei, HATA Seiichi

The Proceedings of the Materials and processing conference Vol. 2020.28 ( 0 ) page： 156 2020

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

This study creates a blood vessel model for a catheter surgery simulator. In previous study was succeeded in producing a blood vessel model applicable to a surgical simulator using PVA hydrogel. On the other hand, the problem with the blood vessel model is that the reproducibility of the mechanical properties of blood vessels, which is important for the actual catheter operation sensation, is low. Therefore, in this study, creates a blood vessel model with a two-layer structure that reproduces the mechanical properties of the blood vessel wall and adipose tissue. In the proposed blood vessel model, it is shown that the mechanical properties can be reproduced by changing the compounding ratio of powdered PVA and the mass ratio of water and DMSO as a solvent. Furthermore, this study proposes a method for producing a two-layer structure and show that it is possible to produce a blood vessel model with a two-layer structure.

DOI： 10.1299/jsmemp.2020.28.156

Enhanced conversion efficiency in dye-sensitized solar cells using optical textured glass substrates

Nishiyasu Y., Yang N., Oka C., Hata S., Sakurai J.

MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science 2019.12

Publisher：MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science

In this paper, we fabricated optical textured glass substrates by a polydimethylsiloxane (PDMS) nanoimprint lithography (NIL) on the front glass to enhance conversion efficiency of dye-sensitized solar cells (DSSCs). Two types of nano-texture (N-Tx) and micro-nano-double texture (D-Tx) were prepared. Finally, we fabricated DSSCs with textured glass. The used dye was red N719. The cell size was 6 mm square. As the results, the conversion efficiency of DSSCs with textured glasses increased by 26% for N-Tx and 19% for D-Tx compared to DSSC with flat glass.

DOI： 10.1109/MHS48134.2019.9249295

Microvalves Utilizing Heat Generation of Magnetic Nanoparticles

Miwa D., Sakurai J., Hata S., Oka C.

MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science 2019.12

Publisher：MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science

Most microvalves need electrical wiring on each one, and the need prevents further integration and miniaturization of microfluidic systems. Hence, we propose novel microvalves remotely controlled without the wiring on each valve. The proposed microvalves are driven by heat from magnetic nanoparticles in an alternating magnetic field. The nano-scale magnetic particles, which possess superparamagnetic behavior, generate heat in the alternating magnetic field. There is a theoretical formula for the heat generation. However, few reports are available on comparing experimental values of the heat generation with theoretical values. In this study, the experimental heating power was compared with the theoretical values, and the possibility of the proposed microvalves was verified.

DOI： 10.1109/MHS48134.2019.9249321

Photoelastic stress measurement in real-time for surgery simulator using gel materials

Yamada D., Hori S., Oka C., Sakurai J., Hata S.

MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science 2019.12

Publisher：MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science

In recent years, minimally invasive treatment aimed at reducing the physical and mental burden of patients as well as treating diseases has attracted attention. Catheter surgery is one of the minimally invasive treatments. This surgical technique can reduce invasion compared to incision and replacement with artificial vessels. Furthermore, it is known to be superior in terms of safety. On the other hand, in catheter surgery, visual information is limited to only a two-dimensional image by an X-ray camera. Therefore, there is a problem that stress is applied to the blood vessel wall and it is damaged, so doctors are required the skill of catheter surgery. This study is proposed a catheter surgery simulator that visualizes the stress applied to the blood vessel wall in realtime using photoelasticity. The blood vessel model used for the surgery simulator focused on PVA hydrogel. Previous experiments by our group have shown that PVA hydrogel can be applied to a surgical simulator. This study has developed an image processing program to measure stress in real-time. It has verified that the application to a surgery simulator is possible by this image processing program.

DOI： 10.1109/MHS48134.2019.9249277

Novel dynamic force sensing system using magnetostrictive energy harvester

Yamazaki T., Furuya Y., Nakao W., Hata S.

MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science 2019.12

Publisher：MHS 2019 - 30th 2019 International Symposium on Micro-NanoMechatronics and Human Science

Dynamic force sensors play a key role in emerging smart technologies that can measure various types of human motions. Magnetostrictive force sensors are the most promising, lightweight, and reliable sensing technologies; however, an in-depth understanding of the sensing mechanism is still lacking. In this study, we focus on magnetic Barkhausen noise (MBN), which is generated by the inverse magnetostriction effect upon impact loading. Further, the stress-induced MBN characteristics of Fe-Co alloy/epoxy composites were investigated using a cyclic compression test. By measuring and analyzing MBN signals in magnetostrictive/epoxy resin composites, it was revealed that the root mean square value of MBN increased linearly with the increase in the stress rate. Additionally, we observed that the MBN outbreaks were affected by the magnetostriction constant. The proposed MBN force sensor system is expected to achieve high sensitivity, wide measurement range, and downsizing.

DOI： 10.1109/MHS48134.2019.9249081

Fabrication of textured substrates for dye-sensitized solar cells using polydimethylsiloxane nanoimprint lithography

Na Yang, Chiemi Oka, Seiichi Hata, Junpei Sakurai

Advanced Optical Technologies Vol. 8 ( 6 ) page： 491 - 497 2019.12

Language：English Publisher：FRONTIERS MEDIA SA

© 2019 THOSS Media & De Gruyter, Berlin/Boston. We proposed a fabrication of nanoimprinted textures on a front glass/transparent conductive oxide interface for dye-sensitized solar cells (DSSCs). These textures were fabricated through polydimethylsiloxane (PDMS) nanoimprint lithography on organosilsesquioxane solution. The texture structures were estimated via optical simulation. Master molds were anodic aluminum oxide templates with nano-texture (N-Tx) and micro-nano double texture (D-Tx). Meanwhile, replicate molds used a hard PDMS. Fluorine-doped tin oxide and titanium dioxide were deposited on textured glass substrates to generate electrodes for DSSCs. Unlike the DSSCs without texture, textured DSSCs realized 11.4% (N-Tx) and 10% (D-Tx) improvement in conversion efficiency.

DOI： 10.1515/aot-2019-0010

Web of Science

薄膜金属ガラスの大気中結晶化評価の基礎検討

鬼頭直希, 櫻井淳平, 岡智絵美, 林裕美, 山崎宏明, 秦誠一

精密工学会学術講演会講演論文集 Vol. 2019A ( 0 ) page： 5 - 6 2019.8

Language：Japanese Publisher：公益社団法人精密工学会

本研究では，サンプルとして，ガラス基板上に長さ4 mm，幅1 mm，厚さ500 nmの薄膜金属ガラスPd77Cu7Si16 at.%を10 mm間隔に成膜し，試作した温度傾斜加熱装置により，543 K以下，471 K以上の異なる温度で同時加熱試験を行った．この時の各温度での大気中における結晶化度の時間変化を，放射率変化としてサーモグラフィで捉えることに成功し，XRDにより結晶化度を測定した．

DOI： 10.11522/pscjspe.2019a.0_5

表面活性化接合用新規高速原子ビームガン

森崎諒, 岡智絵美, 櫻井淳平, 平井隆巳, 高橋知典, 辻裕之, 秦誠一

精密工学会学術講演会講演論文集 Vol. 2019A ( 0 ) page： 687 - 688 2019.8

Language：Japanese Publisher：公益社団法人精密工学会

表面活性化接合は半導体分野における三次元積層技術として利用されている．しかし，表面活性化接合に用いられる高速原子ビームガンは，短時間の使用で内部が磨耗してしまう．そこで，高速原子ビームの高効率な照射により，接合回数に対する相対的な長寿命化を目指す新規高速原子ビームガンの開発を行った．また，新規高速原子ビームガンを用いて，その照射特性を評価し，更なる高性能化を目指した設計指針の確立を目指した．

DOI： 10.11522/pscjspe.2019a.0_687

Preparation of Nonspherical Monodisperse Polydimethylsiloxane Microparticles for Self-assembly Fabrication of Periodic Structures

Mizoshiri Mizue, Iijima Yuuki, Hata Seiichi

IEEJ Transactions on Sensors and Micromachines Vol. 139 ( 6 ) page： 132 - 136 2019.6

Language：English Publishing type：Research paper (scientific journal) Publisher：The Institute of Electrical Engineers of Japan

Nonspherical monodisperse polydimethylsiloxane (PDMS) microparticles were fabricated by lithography and ultraviolet ozone (UVO) treatment for self-assembly of periodic structures. PDMS solution was poured into photoresist molds on glass substrates, whereupon it was cured at 80°C. After irradiating ultraviolet to the surface of the PDMS, remaining thin PDMS films on the molds were eliminated using ultrasonic waves. Attenuated-total-reflection Fourier-transform infrared spectra indicated that the surface of the UVO treated PDMS was changed to glass SiO2-like materials, resulting that the remaining thin PDMS films could be ultrasonically removed by fracture. The PDMS microparticles were separated from the substrates using ultrasonic waves, and microparticles of a desired shaped were formed. A suspension was prepared by mixing the PDMS microparticles in deionized water, and a droplet of the suspension was placed on a hydrophobic template substrate. The PDMS microparticles self-assembled on the substrate along the template walls, leading to PDMS microparticles being closely packed. Such PDMS microfabrication would be useful for microdevices.

DOI： 10.1541/ieejsmas.139.132

Fabrication of a novel nanoporous film via chemical dealloying of a Cu-Cr alloy for sensing moisture in oil Reviewed International journal

Yusuke Yoshii, Junpei Sakurai, Mizue Mizoshiri, Seiichi Hata

Journal of Microelectromechanical Systems Vol. 28 ( 2 ) page： 279 - 289 2019.4

Language：English Publishing type：Research paper (scientific journal)

© 1992-2012 IEEE. Based on our prior combinatorial analysis aimed at materials discovery, Cu82Cr18 and Cu80Cr20 were selected in chemical dealloying experiments as candidates for incorporation in sensors for the first time. The Cu82Cr18 film was Cu-dealloyed, altering its composition to Cu25Cr75 after 7 min of dealloying. The dealloyed Cu82Cr18 film exhibited a Cr-based nanoporous structure with 20-40-nm-diameter pores, indicating that Cu was sufficiently dealloyed. In contrast, the Cu80Cr20 film could not be sufficiently Cu-dealloyed, which was consistent with the results of the combinatorial analysis; the original composition was changed to Cu46Cr54 after 7 min, and the pores were not visible. Sensors A and B were fabricated via chemical dealloying of Cu82Cr18 and Cu80Cr20, respectively, and they were evaluated with respect to a reference sensor in both air and oil. The measured hysteresis in the air was 7.4% full scale (FS) for sensor A, which was below the acceptable limit of 10.0% FS, whereas that for sensor B was 13.3% FS. Moreover, the 90% response time in oil was 8 min for sensor A and 10 min for sensor B, as compared to 12 min for the reference sensor; thus, the response time of sensor A was below the acceptable limit of 10 min. [2018-0242]

DOI： 10.1109/JMEMS.2019.2895164

Web of Science

Fabrication and Evaluation of Tactile Pins for Passive Type Tactile Displays using High Formability Shape Memory Alloys

Draft Genome Sequence of Ralstonia sp. Strain SET104, Isolated from Root Nodules of Aeschynomene indica.

Tanaka A, Suzuki T, Uesaka K, Hata S

Microbiology resource announcements Vol. 8 ( 2 ) 2019.1

Keita Nambara, Keiichirou Iki, Chiemi Oka, Seiichi Hata, Junpei Sakurai

2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems and Eurosensors XXXIII, TRANSDUCERS 2019 and EUROSENSORS XXXIII page： 1854 - 1857 2019

Language：English Publisher：IEEE

© 2019 IEEE. We report on the fabrication and evaluation of tactile pins for passive-type tactile displays using high formable Ti-Ni-Cu shape memory alloy. These pins were fabricated by utilizing a viscous flow of Ti-Ni-Cu metallic glass. After crystallization, the material transformed to a shape memory alloy and was driven by the superelastic effect. In this manner, we successfully acquired the desired three-dimensional structure and measured a reaction force of 20 mN or larger, necessary to deform the skin. Additionally, we successfully varied the reaction force by controlling the temperature and demonstrated the potential application of these tactile pins.

DOI： 10.1109/transducers.2019.8808618

Web of Science

Combinatorial Evaluation for corrosion resistance of High Formable Shape Memory Alloys

CHIZUWA Kaname, OKA Chiemi, HATA Seiichi, SAKURAI Junpei

The Proceedings of the Materials and processing conference Vol. 2019.27 ( 0 ) page： 207 2019

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In this study, we propose a combinatorial evaluation method for evaluating the corrosion resistance of the Ti-Ni-based high formable shape memory alloys (HFSMAs) based on anodic polarization tests. The proposed evaluation substrates compose nine samples which have different compositions. These samples are deposited on a glass substrate by carousel sputtering system and microelectromechanical processes. Further, we performed anodic polarization tests on the Ti–Ni–Zr and Ti–Ni–Cu HFSMAs samples. The polarization curves are obtained by sweeping the potential and the current density at the passive state (ips) of each composition tested is compared. In case of the Ti–Ni–Zr alloy, ips varied depending on the Zr content. When the Zr content ranged from 10 to 15 at.%, their ips were comparable with that of Ti48Ni52 used in medical devices. On the other hand, in case of the Ti-Ni-Cu alloy, their ips were similar to that of Ti48Ni52 regardless of Cu content. We obtained Ti–Ni–Zr and Ti–Ni–Cu HFSMAs having a corrosion resistance equivalent to that of Ti48Ni52. Furthermore, we conducted XPS analysis to investigate the passive film of HFSMAs. The thin surface film of Ti-Ni-Zr alloys were composed of TiO2 and ZrO2, while that of Ti-Ni-Cu alloys were composed of only TiO2. We have concluded that the formation of TiO2 enriched protective thin surface film might have been responsible for the high corrosion resistance.

DOI： 10.1299/jsmemp.2019.27.207

Improvement of conversion efficiency of dye-sensitized solar cell by textured substrates

NISHIYASU Yuji, YANG Na, OKA Chiemi, HATA Seiichi, SAKURAI Junpei

The Proceedings of the Materials and processing conference Vol. 2019.27 ( 0 ) page： P04 2019

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In this paper, we fabricated two types of optical textured glass substrates by a polydimethylsiloxane (PDMS) nanoimprint lithography (NIL) on the front glass to enhance conversion efficiency of dye-sensitized solar cells (DSSCs). Two types of master molds for nano-texture (N-Tx) and micro-nano-double texture (D-Tx) were prepared by an aluminum anodic oxidation. Both N-Tx and D-Tx showed higher total transmittance and lower reflectance than bare glass. Finally, we fabricated DSSCs with textured glass. The used dye was red N719. The cell size was 6 mm square. As the results, the conversion efficiency of DSSCs with textured glasses increased by 26% for N-Tx (η of 3.67%) and 19% for D-Tx (η of 3.47%) compared to DSSC with flat glass (η of 2.91%).

DOI： 10.1299/jsmemp.2019.27.p04

Development of real-time photoelastic 3D stress measurement system for surgical simulator

YAMADA Daichi, HORI Simon, OKA Chiemi, SAKURAI Junpei, HATA Seiichi

The Proceedings of the Materials and processing conference Vol. 2019.27 ( 0 ) page： P01 2019

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In recent years, minimally invasive treatment has attracted attention, and catheter surgery is one of them. On the other hand, in catheter surgery, visual information is limited to only a two-dimensional image by an X-ray camera. Therefore, there is a problem that stress is applied to the blood vessel wall and it is damaged, so doctors are required the skill of catheter surgery. In order to improve the surgeon's surgical technique, the authors have proposed a surgical simulator that realizes real-time visualization of stress by the photoelastic method. In this study, we propose a measurement system using a photoelastic method that can visualize stress in three dimensions and examine the blood vessel model shape applicable to the proposed measurement system.

DOI： 10.1299/jsmemp.2019.27.p01

Fabrication of MEMS mirror using reverse lift-off process

YAMADA Kyohei, NAKAGAWA Yuki, OKA Chiemi, SAKURAI Junpei, YOSHIDA Saori, KIYOMOTO Tomofumi, HATA Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2019 ( 0 ) page： J22208P 2019

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

MEMS mirror device is a device that reflects and scans a laser by the torsion of the beam structure. By miniaturization of the device, the reduction of the deflection angle of the mirror becomes to be an issue. In this research, we fabricated a MEMS mirror structure using film metallic glass formed by sputtering as a new material for the beam structure. In order to avoid the deterioration of the cross-sectional shape of the structure caused by the film thickening, a reverse lift-off method was used in the fabrication process. It is the method that forms film on a desired pattern and remove the others to obtain the flat and uniform thickness structure. Several conditions of the anneal was tested and the structure annealed at 200 ℃ shows less deflection than others. The fabricated structure was driven by external excitation, and it was confirmed that the resonance frequency was almost as designed.

DOI： 10.1299/jsmemecj.2019.j22208p

Effect of heat accumulation on femtosecond laser reductive sintering of mixed CuO/NiO nanoparticles Reviewed

Mizue Mizoshiri, Kenta Nishitani, Seiichi Hata

Micromachines Vol. 9 ( 6 ) 2018.6

Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI AG

Direct laser-writing techniques have attracted attention for their use in two- and three-dimensional printing technologies. In this article, we report on a micropatterning process that uses femtosecond laser reductive sintering of mixed CuO/NiO nanoparticles. The writing speed, laser fluence, and incident total energy were varied to investigate the influence of heat accumulation on the micropatterns formed by these materials. Heat accumulation and the thermal history of the laser irradiation process significantly affected the material composition and the thermoelectric properties of the fabricated micropatterns. Short laser irradiation durations and high laser fluences decrease the amount of metal oxide in the micropatterns. Selective fabrication of p-type and n-type thermoelectric micropatterns was demonstrated to be possible with control of the reduction and reoxidization reactions through the control of writing speed and total irradiation energy.

DOI： 10.3390/mi9060264

Fabrication of a novel nanoporous film by chemical dealloying of CU-CR and its application for a sensor

Yoshii Y., Sakurai J., Mizoshiri M., Hata S.

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) Vol. 2018-January page： 1104 - 1107 2018.4

Publisher：Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)

In this study, novel transparent nanoporous films exhibiting insulating properties were fabricated by a new chemical dealloying method of Cu-Cr with no requirement of high-temperature annealing. Furthermore, for the first time to the best of our knowledge, the fabricated nanoporous film was successfully applied as a nanoporous electrode film filter of a moisture-in-oil sensor: The fabricated moisture-in-oil sensor exhibited outstanding sensitivity and a low hysteresis of 7.4% FS in air, which was less than the desired value of 10.0% FS. Furthermore, the sensor exhibited a favorable 90% response time in oil, which was 8 min and well less than the desired value of 10 min.

DOI： 10.1109/MEMSYS.2018.8346753