Faculty Profiles - HATA Seiichi

Thin-film thermoelectric generator with ball lens for using near-infrared solar energy Reviewed

Yoshitaka Ito, Mizue Mizoshiri, Masashi Mikami, Tasuku Kondou, Junpei Sakurai, Seiichi Hata

2015 International Symposium on Micro-NanoMechatronics and Human Science, MHS 2015 2016.3

Language：English Publishing type：Research paper (international conference proceedings) Publisher：Institute of Electrical and Electronics Engineers Inc.

A thin-film thermoelectric generator (TEG) with ball lenses which enable the visible light to pass through was designed and fabricated. When diameters of the ball lens and the pinhole were 6 mm and 200 μm, respectively, 76% of the visible light and 36% of the infrared light were transmissive to the TEG under the condition that the ball lens position from the device substrate was 0 μm. Thin-film TEGs were fabricated using lithography and thermoelectric thin film deposition processes. The thin film thermoelectric elements were formed on the glass substrate without removal by inserting the Cr buffer layers between the thermoelectric thin films and the substrate. The width of the elements were up to 10 μm greater than that of the designed one. The difference between the fabricated and the designed one was less than 10%, which is negligible value for the internal resistance of the TEGs.

DOI： 10.1109/MHS.2015.7438318

Direct writing of Cu -based micro -temperature detectors using femtosecond laser reduction of CuO nanoparticles Reviewed

Mizoshiri Mizue, Arakane Shun, Sakurai Junpei, Hata Seiichi

APPLIED PHYSICS EXPRESS Vol. 9 ( 3 ) page： 36701 - 36701 2016.3

Language：English Publisher：Institute of Physics

Cu-based micro-temperature detectors were fabricated using femtosecond laser reduction of CuO nanoparticles. Cu-based microstructures were directly created by laser scanning on a CuO nanoparticle solution film. Cu-rich and Cu<inf>2</inf>O-rich microstructures were selectively formed to electrically connect two Cu thin-film electrodes for use in temperature detectors. Cu-rich and Cu<inf>2</inf>O-rich micro-temperature detectors were fabricated at scanning speeds of 500 and 1000 µm/s, respectively, at a pulse energy of 1.2 nJ. The temperature coefficient of resistance values of the Cu-rich and Cu<inf>2</inf>O-rich microstructures were positive and negative, respectively; these temperature behaviors are typical of metal and semiconductor materials, respectively.

DOI： 10.7567/APEX.9.036701

Fabrication of Combinatorial Evaluation Substrates for Chlorine Evolution Electrode Catalyst Reviewed

6. 機械材料・材料加工(<小特集>技術ロードマップから見る2030年の社会) Invited Reviewed

秦誠一, 大塚年久, 古川英光, 中尾航

日本機械学会誌 Vol. 119 ( 1170 ) page： 300 - 302 2016

S. Takagi, M. Miyamoto, M. Mizoshiri, S. Hata, J. Sakurai

2016 INTERNATIONAL SYMPOSIUM ON MICRO-NANOMECHATRONICS AND HUMAN SCIENCE (MHS) 2016

Language：English Publishing type：Research paper (international conference proceedings) Publisher：IEEE

In this study, we proposed and demonstrated combinatorial evaluation substrates, which were fabricated by micro electro mechanical systems (MEMS) process, for brine electrolysis. Proposed evaluation substrate has 9 electrode catalyst samples on the glass substrate. Ir-Ru/Ti and Ir-Ru-Ti/Ti electrode catalyst samples were prepared by a combinatorial co-sputtering system. We evaluated the maximum current density of polarization curves and the durability during brine electrolysis. In the case of binary Ir-Ru/Ti evaluation substrate (composition of Ru ranged from 35.1 to 58.8 at.%.), the maximum current density increased with increasing Ru-content. From these results, we confirmed the usability of proposed combinatorial evaluation substrate for the brine electrolysis. Finally, we evaluated the electrochemical characteristics of 9 Ir-Ru-Ti/Ti samples. Their electrochemical characteristics depend on alloy composition.

High throughput evaluation of thermal properties for high formability shape memory alloys

MURAKAMI Motoki, MIZOSHIRI Mizue, HATA Seiichi, SAKURAI Junpei

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240101 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In this paper, we investigated the temperature dependence of electrical resistance of amorphous Ti-Ni-Zr high formable shape memory alloys (HFSMAs) for combinatorial measurement of glass transition temperature (Tg) and crystallization temperature (Tx). The electrical resistances of the Ti-Ni-Zr amorphous samples (ie. thin film metallic glasses: TFMGs) were measured using a four-terminals method. The samples were heated by a SiC heater in the vacuum chamber with heating rate of 10 K/min. The Tg and Tx were also measured by a differential scanning calorimetry (DSC) with heating rate of 10 K/min. We confirmed that the electrical resistance of Ti32Ni51Zr17 (at.%) TFMG decreased slightly at the Tg of 697 K. Moreover, the electrical resistance was decreased drastically over the Tx of 741 K. On the other hand, the Tg and Tx measured by the DSC measurement were 712 K, 763 K, respectively. The difference of thermal properties between two measurements was caused by the accuracy temperature measurement of heating equipment for measuring electric resistance.

DOI： 10.1299/jsmemecj.2016.j2240101

Micro forming of Ti-Ni-Zr high formable shape memory alloys

WATANABE Hiroto, MIZOSHIRI Mizue, HATA Seiichi, SAKURAI Junpei

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240105 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Micro forming method of Ti-Ni-Zr high formable shape memory alloys (HFSMAs) using viscous flow in supercooled liquid region (SCLR) was investigated. Planer Ti38Ni50Zr12 (at.%) samples were prepared by r.f. magnetron sputtering and were thin film metallic glasses (TFMGs). Glass transition temperature (Tg) and crystallization start temperature (Tx) were 704 and 764 K, respectively. SCLR (=Tx -Tg) was 60 K. Planer specimens were deformed and fixed using micro jigs. When they were heated to around the SCLR, the stress relaxation occurred by their viscous flow. We investigated heating conditions to stress-relax completely. Finally, we successfully obtained waved Ti38Ni50Zr12 TFMGs in room temperature. The waved Ti38Ni50Zr12 TFMG samples were annealed at 873, 973, 1073 K for 1 hour in order to crystallize and become waved SMAs. Martensitic transformation start temperature and the reverse martensitic transformation start temperature also increased with increasing the annealing temperature. These SMA samples exhibited a shape memory effect and/or superelasticity.

DOI： 10.1299/jsmemecj.2016.j2240105

Thin-film thermoelectric generators with ball lenses which transmittance the visible light

ITO Yoshitaka, MIZOSHIRI Mizue, MIKAMI Masashi, SAKURAI Junpei, HATA Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240204 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

We designed and fabricated thin-film thermoelectric generators (TEGs) with ball lenses on a glass substrate that transmit the visible solar light and convert the near-infrared (NIR) solar light to electric energy. In the calculation, the ball lenses separated the visible light and the NIR light using the chromatic aberration to defocus the NIR light and to focus the visible light onto the glass substrates. The NIR light was irradiated onto the hot sides of pn junctions on the glass substrate. The visible light was transmitted the glass substrate to use as daylight through the pin hole in the center of the TEGs. The torus-shaped TEGs which composed of serially connected pn junctions were designed using ray tracing method. The outer and inner diameters of the TEG were 1000 μm and 52 μm, respectively. The TE thin-film elements (p-type: Bi0.5Sb1.5Te3, n-type: Bi2Te2.7Se0.3) were formed using lithography and radio-frequency magnetron sputtering. The generation properties and the open-circuit voltage and the maximum generation power were 0.076 mV/pair and 0.018 nW/pair, respectively when the solar light was irradiated at 298K.

DOI： 10.1299/jsmemecj.2016.j2240204

Internal stress control of micro-structures using a thin film metallic glass

ABE Shuhei, MAETANI Takuya, MIZOSHIRI Mizue, SAKURAI Junpei, HATA Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240102 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In order to apply the magnetostrictive materials to the sensor, the magnetostrictive materials are required to have a large magnetostriction and high relative permeability. We have studied the high throughput evaluation method using the MEMS device to search for materials having such characteristics. The MEMS device has a structure of the cantilever to measure the magnetostriction and relative permeability. However, it is difficult to measure magnetostrictive properties accurately because of a deflection of the cantilever. The purpose of this study is reduction of the deflection of the cantilever using internal stress relaxation of the thin film metallic glasses. We carried out heat treatment of Pd-Cu-Si deposited on a Si substrate. From the results, the conditions for internal stress relaxation of Pd-Cu-Si were searched. Using these conditions, heat treatment of the micro-structures consisted of Pd-Cu-Si and Fe-Ni-Cr was carried out. As a result, we succeeded in reducing the deflection of the micro-structures.

DOI： 10.1299/jsmemecj.2016.j2240102

Preparation of microparts for fabricating three-dimensional periodic structures by self-assembly

Iijima Yuki, Mizoshiri Mizue, Sakurai Junpei, Hata Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240201 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

We prepared 10 μm-sized poly(dimethylsiloxane) (PDMS)-based cubic microparts to form 3D microperiodic structures by self-assembly of the microparts. Self-assembly is a promising candidate for fabricating the 3D periodic structures such as optical microdevices. The PDMS-based microparts, which have high transparency in ultraviolet (UV) to near infrared (NIR) light, were fabricated by a combined process of photolithographic techniques and UV-ozone treatment. First, cubic molds of thick photoresist were formed by the lithography. Then, PDMS filled into the molds, following that it was cured by heating at 80°C. After that, the microparts were separated using UV-ozone treatment and ultrasonic microwaves. The microparts were dispersed into the water an ethanol mixed solution with surfactant F-127 to prepare the suspension. The surfactant was useful to prevent aggregation of microparts. Finally, we demonstrated the self-assembling of the PDMS microparts by putting a droplet of the suspension on a glass substrate, and drying at room temperature with turning substrate upside down. The microparts were partly aligned with the cubic closed packing by self-assembly. This result indicates that PDMS-based cubic microparts have possibility of forming three-dimensional periodic structures.

DOI： 10.1299/jsmemecj.2016.j2240201

Fabrication of nano-porous electrode film filters by chemical dealloying and its application for a sensor

YOSHII Yusuke, MIZOSHIRI Mizue, SAKURAI Junpei, HATA Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240203 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Cr nano-porous electrode film filter could be prepared by co-sputtering Cu and Cr, followed by annealing for 1 h at 573 K and dealloying for 15 h in 32.5% HNO3. Its pore-sizes depend on initial Cu-Cr compositions. To control pore sizes of the nano-porous Cr thin film, initial Cu-Cr compositions for the fabrication conditions was researched by using combinatorial technique. We investigated a wide compositional range between 32 and 22 at.% Cr. Between 28 and 22 at.% Cr, dealloying produces low residual Cu composition ratio less than 10 at.%. The pore sizes obtained were <20 nm for 32 at.% Cr, 20-40 nm for 28 at.% Cr, 40-60 nm for 25 at.% Cr and >60 nm for 22 at.% Cr. The initial composition ratio of 28 at.% Cr was tested for fabricating a Cr nano-porous electrode film filter for a moisture sensor which takes sandwich structure of the nano-porous Cr thin film/polyimide film/Ag electrode. The final residual Cu composition ratio was 17 at.%, not less than 10 at.%, because of using a thin film with uniform composition. The changes in electrostatic capacity of the moisture sensor to changes in relative humidity (50%RH-90%RH) was studied, and the sensor exhibited the followability to changes in relative humidity in the air.

DOI： 10.1299/jsmemecj.2016.j2240203

Fabrication of combinatorial evaluation substrates for chlorine evolution catalyst electrodes

TAKAGI Shingo, MIYAMOTO Masashi, MIZOSHIRI Mizue, HATA Seiichi, SAKURAI Junpei

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2240103 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

In this study, we proposed and demonstrated combinatorial evaluation substrates, which were fabricated by micro electro mechanical systems (MEMS) process, for brine electrolysis. Proposed evaluation substrate has 9 catalyst electrode samples on the glass substrate. Ir-Ru/Ti and Ir-Ru-Ti/Ti alloy catalyst electrode samples were prepared by a combinatorial co-sputtering system. We evaluated the maximum current density of polarization curves and the durability during brine electrolysis. Their polarization curves were measured by a linear sweep voltammetry in NaCl solution of 30 g/L. Measurement system consisted of beaker cell, potentiostat/galvanostat, function generator, and data logger. In this measurement, working electrodes were fabricated catalyst electrodes, reference electrode was Ag|AgCl electrode, counter electrode was Zr plate. Durability was evaluated by the observation of catalyst surface and X-ray diffractometry before and after brine electrolysis. In the case of binary Ir-Ru/Ti evaluation substrate (composition of Ru ranged from 35.1 to 58.8 at.%.), the maximum current density increased with increasing Ru-content. From these results, we confirmed the usability of proposed combinatorial evaluation substrate for brine electrolysis. Finally, we evaluated electrochemical characteristics of 9 Ir-Ru-Ti/Ti samples. Their electrochemical characteristics depend on alloy composition.

DOI： 10.1299/jsmemecj.2016.j2240103

Characteristics for administrating liquid medicine in passive drug delivery system

KUMENO Yuki, TAKAKUWA Akira, ITO Keitaro, MIZOSHIRI Mizue, SAKURAI Junpei, ARAI Fumihito, HATA Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2016 ( 0 ) page： J2230101 2016

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

We proposed new passive drag delivery system (DDS), which consists of flexible pad as medicine tank, medicine reservoir with medicine sending membrane, microvalves using photoprocessible thermoresponsible gel, and so on. The DDS makes use of external force by normal activities of daily life to administrate liquid medicine and controls administration timing by microvalves using MEMS technology. Therefore, the DDS has advantage of lower power consumption than micropump DDS and higher controllability than percutaneous absorption DDS. We fabricated the medicine sending part of new passive DDS and evaluated characteristics for administrating liquid medicine. At that time, the DDS was filled with DI water and tested under external force. As a result, it was confirmed that the DDS was possible to repeatedly administrate DI water every 2 minutes. Moreover, it was revealed that the DDS could administrate more than 70% of DI water in medicine tank.

DOI： 10.1299/jsmemecj.2016.j2230101

Characteristics of Ti-Ni-Zr Thin Film Metallic Glasses / Thin Film Shape Memory Alloys for Micro Actuators with Three-Dimensional Structures

Sakurai Junpei, Hata Seiichi

International Journal of Automation Technology Vol. 9 ( 6 ) page： 662 - 667 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Fuji Technology Press Ltd.

In this paper, we investigate the characteristics of Ti-Ni-Zr thin film metallic glasses (TFMGs)/ shape memory alloys (SMAs) for microelectromechanical systems (MEMS) applications with three-dimensional structures. The amorphous Ti-Ni-Zr thin films having a Ni content of more than 50 at.% and Zr content of more than 11 at.% undergo glass transitions and are TFMGs. The Ti39Ni50Zr11 TFMG has the lowest glass transition temperature Tg of 703 K and a wide supercooled liquid region ΔT of 57 K. Moreover, it has high thermal stability at Tg. However, the apparent viscosity of the Ti39Ni50Zr11 is higher than those of other Ti-Ni-Zr TFMGs. Moreover, the Ti-Ni-Zr TFMG exhibits higher viscosity than conventional TFMGs because the alloy composition of Ti-Ni-Zr TFMGs/SMAs is far from the eutectic point.

DOI： 10.20965/ijat.2015.p0662

Reverse Lift-Off Process and Application for Cu-Zr-Ti Metallic Glass Thick Film Structures

Watanabe Shigetaka, Sakurai Junpei, Mizoshiri Mizue, Hata Seiichi

International Journal of Automation Technology Vol. 9 ( 6 ) page： 646 - 654 2015.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Fuji Technology Press Ltd.

In technologies involving micro electromechanical systems, lift-off processes combined with sputter deposition are general patterning methods for the formation of amorphous alloy thick film structures. However, the thicknesses of structures fabricated in this manner are not uniform because sputtered particles are blocked by the sidewalls of the lift-off layer. In this paper, a reverse lift-off process is proposed as a new patterning method for fabricating amorphous alloy thick film structures of uniform thickness. In the reverse lift-off process, a template of the desired structure is formed on top of the chosen substrate. The thick film structure is then formed by sputter deposition on the top surface of the template. In contrast to a conventional lift-off process, here the thickness of the structure is uniform because there is nothing to hinder the sputtered particles. To demonstrate this process, we successfully fabricated a Cu-Zr-Ti metallic glass thick film structure with a uniform film thickness and a rectangular cross section across different target structure widths and thicknesses. This demonstrates that the reverse lift-off process is more suitable than conventional lift-off processes for the fabrication of metallic glass thick film structures.

DOI： 10.20965/ijat.2015.p0646

Direct patterning of Cu microstructures using femtosecond laser-induced CuO nanoparticle reduction Reviewed

Shun Arakane, Mizue Mizoshiri, Seiichi Hata

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 54 ( 6 ) 2015.6

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP PUBLISHING LTD

Cu-based microstructures were directly patterned using femtosecond laser-induced CuO nanoparticle reduction. CuO nanoparticle-based solution, consisting CuO nanoparticles, ethylene glycol, and polyvinylpyrrolidone, was spin-coated on glass substrates. Microstructures were formed by irradiating focused femtosecond laser pulses. Cu and Cu2O peak intensities were observed in the X-ray diffraction (XRD) spectra of the microstructures. Compared to single scan, the Cu peak intensities increased by double scan. This result suggests that double scan is effective for increasing the amount of Cu from CuO nanoparticle solution. Cu- and Cu2O-rich microstructures were formed selectively by controlling laser irradiation conditions. The resistivity of the Cu-rich microstructures was estimated by 528 mu Omega m which was 10(4) times and 10 times larger than the values of Cu and Cu2O, respectively. This large resistivity could be applied for microheaters. (C) 2015 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.54.06FP07

Fabrication of Cu-Zr-Ti thick film metallic glass structure by double metal mask lift-off process Reviewed

REDUCTION PROPERTIES OF NICKEL MICROSTRUCTURES FABRICATED BY DIRECT FEMTOSECOND LASER REDUCTION PATTERNING Reviewed

Mizue Mizoshiri, Kenki Tamura, Junpei Sakurai, Seiichi Hata

Proceedings of 2015 ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment page： MoB-2-2 2015.6

Watanabe Shigetaka, Sakurai Junpei, Hata Seiichi

MICROELECTRONIC ENGINEERING Vol. 135 page： 45 - 51 2015.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE BV

In micro-electro-mechanical systems (MEMS) technology, one of the conventional patterning methods used for metallic thin films is the lift-off process using a photoresist material. However, there is concern regarding the photoresist material generating gas due to the long-term annealing or the high power used in sputter deposition. Thin-film amorphous alloys, such as thin-film metallic glass (TFMG), when used in the device, become crystallized by such heating and outgassing during sputtering. Unlike photoresist material, a metal mask does not generate gas during sputtering. However, a metal mask is subject to deformation by the stress in the sputtered film on the mask. The pattern shape of the TFMG structure can thus collapse due to this mask deformation. Its cross-sectional shape then deviates significantly from a rectangle. We propose a novel lift-off process using a double metal mask for reducing changes in the cross-sectional shape, and maintaining the amorphous nature of the TFMG structure. The characteristic of the double metal mask lift-off process is duplication of the metal mask for restraint of the lower metal mask deformation. Since nearly all of the sputtered material is deposited on the upper metal mask, the material is only minimally deposited onto the lower metal mask. In this work, the double metal mask lift-off process was compared with the conventional lift-off process, and important points for using the double metal mask lift-off process were elucidated. Using the double metal mask lift-off process, a very thick amorphous TFMG structure could be obtained, as compared to the conventional lift-off process. To maintain the rectangular cross-sectional shape of the structure, it was found to be necessary to decrease the height of the double metal mask, as compared to the conventional lift-off process, in anticipation of upper metal mask deformation. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.mee.2015.02.041

Influence of target-target distance for composition distribution in new facing targets sputtering

Maetani T., Nakamitsu Y., Sakurai J., Hata S.

2014 International Symposium on Micro-NanoMechatronics and Human Science, MHS 2014 2015.1

Publisher：2014 International Symposium on Micro-NanoMechatronics and Human Science, MHS 2014

Combinatorial New-Facing Targets Sputtering (combi-NFTS) is one of the co-sputtering method applied to the combinatorial method. Combi-NFTS could easily control the composition range by changing the distance from substrate to targets. Furthermore composition gradient is relatively linear comparing to other thin film deposition method. In this paper, the influence of the distance between target and target gives for the composition distribution is investigated. As a result, it was elucidated that composition distribution and gradient increase as the TT distance increase. This is caused by the peak position of amount of deposited sputtering atom on the substrate change by the TT distance.

DOI： 10.1109/MHS.2014.7006100