Faculty Profiles - HATA Seiichi

Integrated MEMS library for high throughput evaluation for magnetostrictive material

KOBAYASHI Yoshinori, HONGAWA Yuki, MAETANI Takuya, HATA Seiichi

The Proceedings of Conference of Tokai Branch Vol. 2018.67 ( 0 ) page： 225 2018

Fundamental research of 3Dprinter using metallic glass

Akada Teppei, Mizoshiri Mizue, Sakurai Junpei, Hata Seiichi

The Proceedings of Conference of Tokai Branch Vol. 2018.67 ( 0 ) page： 219 2018

Basic research on micro processing characteristics of reversed lift-off process

NAKAGAWA Yuki, YAMADA Kyohei, MIZOSHIRI Mizue, SAKURAI Junpei, HATA Seiichi

The Proceedings of Conference of Tokai Branch Vol. 2018.67 ( 0 ) page： 216 2018

Fundamental research of internal stress control in the diaphragm structure of the thin film metallic glass

ISHIKI Ryuji, UEJIMA Shohei, MIZOSHIRI Mizue, SAKURAI Junpei, HATA Seiichi

The Proceedings of Conference of Tokai Branch Vol. 2018.67 ( 0 ) page： 221 2018

Fabrication of Miniaturized Capacitive Pressure Sensor Using Thin Film Metallic Glass

UEJIMA Shohei, OKA Chiemi, HATA Seiichi, SAKURAI Junpei

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2018 ( 0 ) page： J2220304 2018

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Further miniaturization of the diaphragm for capacitive pressure sensor requires thinner structures to deform micro diaphragm sufficiently by small differential pressure. Since stiffness of thinner structures decrease, the influence of internal stress introduced during processing cannot be ignored. In this paper, we proposed methods of controlling the internal stress for micro diaphragm using thin film metallic glasses (TFMGs). We fabricated micro diaphragms using Ru67Zr25Al8 [at.%] TFMGs. The TFMGs were fabricated by a r.f. sputtering system, and then as sputtered TFMGs had compressive internal stress. Subsequently, the as-sputtered TFMGs on Si substrate were annealed at 315-440°C for 5 minutes in vacuum. After annealing, micro diaphragms were fabricated by etching Si substrate using a reactive ion etching system. Although annealing temperatures were lower than glass transition temperature, initial internal stress was relaxed partially by the structural relaxation of the TFMGs during annealing process. While the tensile thermal stress was induced during cooling process at the interface between the substrate and TFMG. Although micro diaphragm was not induced thermal stress at interface between the substrate and TFMG, the tensile stress applied to diaphragm in the radial direction at the edge. When annealing temperatures were between 320°C and 340°C, the internal stress changed from compressive to tensile. A flat diaphragm was obtained when annealed at 330°C or higher. The pressure sensor modeled by diaphragm annealed at 340°C and the virtual electrode plate showed a linearity of 6.48 [%F.S.]. By proposed method, we succeeded the flat diaphragm and showed the method of tension control of the diaphragm.

DOI： 10.1299/jsmemecj.2018.j2220304

Fabrication of micro diaphragm using thin film metallic glass

ISHIKI Ryuji, Uejima Syohei, Oka Chiemi, SAKURAI Junpei, LIN Yu-Ching, Hata Seiichi

The Proceedings of Mechanical Engineering Congress, Japan Vol. 2018 ( 0 ) page： J2220303 2018

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

A diaphragm structure is a fundamental structure in a micro machine such as MEMS. Conventionally, Si has used as a diaphragm material. However, in recent years, in order to make the diaphragm structure more sophisticated and miniaturized, high sensitivity difficult to realize by using Si is required. Therefore, in this study, we aim to create a highly precise diaphragm structure by using the thin film metallic glass which is an amorphous alloy shown glass transition as a new material which meets these demands. Pd77Cu6Si17 (at. %) and Ru65Zr30Al5 (at. %) are used for thin film metallic glass. The thin film metallic glasses are deposited on the Si substrates by sputtering. Internal stress of each film is controlled by adjusting Ar pressure during sputtering and annealing after sputtering. The internal stress of the Pd77Cu6Si17 (at. %) thin film is always tensile stress and it is minimum at an Ar pressure of 0.5 Pa, and its value is 23.6 MPa. Under this condition, we can create a highly precise diaphragm. On the contrary, the internal stress of Ru65Zr30Al5 (at. %) thin film is always compressive stress in the range of sputtering Ar pressure. So, we try to relax the internal stress of Ru65Zr30Al5 (at. %) thin film by annealing. In the proper annealing conditions, a diaphragm having the same flatness level as Pd77Cu6Si17 (at. %) is realized.

DOI： 10.1299/jsmemecj.2018.j2220303

Fabrication of optical substrate for dye-sensitized solar cells

YANG Na, MIZOSHIRI Mizue, HATA Seiichi, SAKURAI Junpei

The Proceedings of Conference of Tokai Branch Vol. 2018.67 ( 0 ) page： 702 2018

Fabrication of thin-film thermoelectric generators with ball lenses for conversion of near-infrared solar light Reviewed

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

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 56 ( 6 ) 2017.6

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

We designed and fabricated thin-film thermoelectric generators (TEGs) with ball lenses, which separated visible light and near-infrared (NIR) solar light using a chromatic aberration. The transmitted visible light was used as daylight and the NIR light was used for thermoelectric generation. Solar light was estimated to be separated into the visible light and NIR light by a ray tracing method. 92.7% of the visible light was used as daylight and 9.9% of the NIR light was used for thermoelectric generation. Then, the temperature difference of the pn junctions of the TEG surface was 0.71 K, determined by heat conduction analysis using a finite element method. The thin-film TEGs were fabricated using lithography and deposition processes. When the solar light (A.M. 1.5) was irradiated to the TEGs, the open-circuit voltage and maximum power were 4.5 V/m(2) and 51 mu W/m(2), respectively. These TEGs are expected to be used as an energy supply for Internet of Things sensors. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.56.06GN06

Ni-based composite microstructures fabricated by femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles Reviewed

Kenki Tamura, Mizue Mizoshiri, Junpei Sakurai, Seiichi Hata

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 56 ( 6 ) 2017.6

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

Ni-based composite micropatterns were fabricated by the femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles. A NiO/Cr mixed nanoparticle solution including ethylene glycol and polyvinylpyrrolidone was irradiated with focused femtosecond laser pulses. The X-ray diffraction spectra of the fabricated micropatterns indicated that NiO nanoparticles were well reduced under atmospheric conditions in the laser scanning speed range of 5-15mm/s. In contrast, micropatterns including NiO were formed at a laser scanning speed of 1mm/s, indicating that the reduced Ni was reoxidized by overheating. These results were supported by those of energy-dispersive X-ray spectrometry analysis and the electrical resistivity of the micropatterns. The compositions such as Ni, NiO, Cr2O3, and Ni-Cr in the fabricated micropatterns depended on laser scanning speed. The selective fabrication of a ferromagnetic free microgear from the substrate and an axis fixed on the substrate was demonstrated by controlling the laser scanning speed. The fabrication process for Ni-based composite microstructures is useful for the fabrication of ferromagnetic microdevices. (C) 2017 The Japan Society of Applied Physics

DOI： 10.7567/JJAP.56.06GN08

Direct writing of three-dimensional Cu-based thermal flow sensors using femtosecond laser-induced reduction of CuO nanoparticles Reviewed

S. Arakane, M. Mizoshiri, J. Sakurai, S. Hata

JOURNAL OF MICROMECHANICS AND MICROENGINEERING Vol. 27 ( 5 ) 2017.5

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

We have demonstrated the fabrication of two types of thermal flow sensors with Cu-rich and Cu2O-rich microheaters using femtosecond laser-induced reduction of CuO nanoparticles. The microheaters in the shape of microbridge structures were formed to thermally isolate from the substrates by four layer-by-layer laminations of two-dimensional micropatterns. First, we evaluated the patterning properties such as dispensing coating conditions and degree of reduction for the selective fabrication of three-dimensional Cu-rich and Cu2O-rich microstructures. Then, a hot-film flow sensor with a Cu-rich microheater and a calorimetric flow sensor with a Cu2O-rich microheater were fabricated using their respective appropriate laser irradiation conditions. The hot-film sensor with the Cu-rich microbridge single heater enabled us to measure the flow rate in a wide range of 0-450 cc min(-1). Although a large temperature dependence of the Cu2O-rich microbridge heaters caused a large error for the hot-film flow sensors with single heaters, they showed higher heat-resistance and generated heat with a lower drive power. The temperature coefficient of resistance of the Cu2O-rich microstructures had a semiconductor-like large absolute value and was less than -4.6 x 10(-8) degrees C-1. The higher temperature sensitivity of the Cu2O-rich microstructures was useful for thermal detection. Based on these advantages, a calorimetric flow sensor composed of the Cu2O-rich microbridge single heater and two Cu2O-rich thermal detectors was proposed and fabricated. The calorimetric flow sensor was driven by a circuit for measuring the temperature difference. The Cu2O-rich flow sensor could detect bi-directional flow with a small output error.

DOI： 10.1088/1361-6439/aa6820

Three-dimensional Cu microfabrication using femtosecond laser-induced CuO nanoparticle reduction Reviewed

Shun Arakane, Mizue Mizoshiri, Junpei Sakurai, Seiichi Hata

Applied Physics Express Vol. 10 page： 017201 2017.4

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

Three-dimensional Cu microstructures were formed using a combined process of dispensing coating and femtosecond laser-induced reduction of CuO nanoparticles. Layer-by-layer lamination of two-dimensional Cu micropatterns was performed by alternately coating with a CuO nanoparticle solution and using direct laser writing, followed by the removal of nonirradiated CuO nanoparticles. The resistance of the 3D microstructures decreased as the number of layers increased, indicating that each layer was electrically connected to the others. We also demonstrated the fabrication of a microbridge heater composed of electrode pads and a microbridge, and found that its heating characteristics are suitable for use in microsensors, such as thermal-type flow sensors.

DOI： 1882-0786/10/1/017201

Fabrication of combinatorial evaluation substrates for chlorine evolution electrode catalyst

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

2016 International Symposium on Micro-NanoMechatronics and Human Science, MHS 2016 2017.1

Publisher：2016 International Symposium on Micro-NanoMechatronics and Human Science, MHS 2016

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.

DOI： 10.1109/MHS.2016.7824159

Three-dimensional Cu microfabrication using femtosecond laser-induced reduction of CuO nanoparticles Reviewed

Shun Arakane, Mizue Mizoshiri, Junpei Sakurai, Seiichi Hata

Applied Physics Express Vol. 10 ( 1 ) 2017.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Society of Applied Physics

DOI： 10.7567/APEX.10.017201

Fabrication of a Cr Nanoporous Thin Film via Sputter Deposition and Investigation of Its Applicability as a Water-oil Separation Electrode in a MEMS Moisture Sensor

Yoshii Yusuke, Fukagawa Yuuki, Mizoshiri Mizue, Sakurai Junpei, Hata Seiichi

IEEJ Transactions on Sensors and Micromachines Vol. 137 ( 1 ) page： 15 - 22 2017

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

A moisture-in-oil sensor, with a sandwich structure of Cr nanoporous thin film/polyimide film/Au electrode, was fabricated using a lithographic process, sputter deposition, and chemical dealloying. One of the Cr nanoporous thin films used as a molecular filter was made using oblique incidence film formation and sputter deposition at 2.5 Pa of argon and a 60 degree attaching angle. The fabricated Cr nanoporous thin film consisted of 30-50 nm pore sizes as a result of a “shadowing effect”. A moisture-in-oil sensor made with this Cr nanoporous thin film showed favorable responsiveness in oil, with a response time of about 7 minutes, well within the desired maximum value of 10 minutes. To further improve the responsiveness of the sensor, another Cr nanoporous thin film was prepared using a chemical dealloying process, which facilitates control of the pore sizes. This process consists of co-sputtering Cu and Cr, annealing for 1 h at 573 K and dealloying for 15 h in 32.5% HNO3. The thin film pore sizes depend on the initial Cu-Cr compositions, which were researched using a combinatorial technique at various fabrication conditions. We investigated a wide compositional range between 32 and 22 at.% Cr. It was found that between 28 and 22 at.% Cr, chemical dealloying results in low residual Cu, 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 used to fabricate a Cr nanoporous electrode film filter for a moisture sensor. Unfortunately, the final residual Cu composition ratio was 17 at.%, which is more than the desired maximum of 10 at.%, because the thin film had a uniform composition. The changes in the electrostatic capacity of the moisture sensor as a function of relative humidity (50%RH-90%RH) in air were studied, and the sensor output followed changes in the relative humidity.

DOI： 10.1541/ieejsmas.137.15

Polymer-based blood vessel models with micro-temperature sensors in Eve Reviewed

Mizue Mizoshiri, Yasuaki Ito, Takeshi Hayakawa, Hisataka Maruyama, Junpei Sakurai, Seiichi Ikeda, Fumihito Arai, Seiichi Hata

Proceedings of SPIE - The International Society for Optical Engineering Vol. 10167 2017

Language：English Publisher：SPIE

Cu-based micro-temperature sensors were directly fabricated on poly(dimethylsiloxane) (PDMS) blood vessel models in EVE using a combined process of spray coating and femtosecond laser reduction of CuO nanoparticles. CuO nanoparticle solution coated on a PDMS blood vessel model are thermally reduced and sintered by focused femtosecond laser pulses in atmosphere to write the sensors. After removing the non-irradiated CuO nanoparticles, Cu-based microtemperature sensors are formed. The sensors are thermistor-type ones whose temperature dependences of the resistance are used for measuring temperature inside the blood vessel model. This fabrication technique is useful for direct-writing of Cu-based microsensors and actuators on arbitrary nonplanar substrates.

DOI： 10.1117/12.2265050

Direct-writing of copper-based micropatterns on polymer substrates using femtosecond laser reduction of copper (II) oxide nanoparticles Reviewed

Mizue Mizoshiri, Yasuaki Ito, Junpei Sakurai, Seiichi Hata

Proceedings of SPIE - The International Society for Optical Engineering Vol. 10167 2017

Language：English Publisher：SPIE

Copper (Cu)-based micropatterns were fabricated on polymer substrates using femtosecond laser reduction of copper (II) oxide (CuO) nanoparticles. CuO nanoparticle solution, which consisted of CuO nanoparticles, ethylene glycol as a reductant agent, and polyvinylpyrrolidone as a dispersant, was spin-coated on poly(dimethylsiloxane) (PDMS) substrates and was irradiated by focused femtosecond laser pulses to fabricate Cu-based micropatterns. When the laser pulses were raster-scanned onto the solution, CuO nanoparticles were reduced and sintered. Cu-rich and copper (I)-oxide (Cu2O)-rich micropatterns were formed at laser scanning speeds of 15 mm/s and 0.5 mm/s, respectively, and at a pulse energy of 0.54 nJ. Cu-rich electrically conductive micropatterns were obtained without significant damages on the substrates. On the other hand, Cu2O-rich micropatterns exhibited no electrical conductivity, indicating that microcracks were generated on the micropatterns by thermal expansion and shrinking of the substrates. We demonstrated a direct-writing of Cu-rich micro-temperature sensors on PDMS substrates using the foregoing laser irradiation condition. The resistance of the fabricated sensors increased with increasing temperature, which is consistent with that of Cu. This direct-writing technique is useful for fabricating Cu-polymer composite microstructures.

DOI： 10.1117/12.2261398

Selective fabrication of pn thermocouples using femtosecond laser reduction of CuO/NiO mixed nanoparticles

MICRO FOLDING STRUCTURE USING TI-NI-ZR HIGH FORMABLE SHAPE MEMORY ALLOYS

Watanabe H., Mizoshiri M., Hata S., Sakurai J.

2017 INTERNATIONAL SYMPOSIUM ON MICRO-NANOMECHATRONICS AND HUMAN SCIENCE (MHS) 2017

Mizoshiri Mizue, Sakurai Junpei, Hata Seiichi

The Proceedings of the Symposium on Micro-Nano Science and Technology Vol. 2017.8 ( 0 ) page： PN-17 2017

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

Thermoelectric couples which consisted of p-type and n-type thermoelectric elements were directly written on glass substrates using femtosecond laser reduction of CuO/NiO mixed nanoparticles. CuO/NiO nanoparticle solution including CuO and NiO nanoparticles, ethylene glycol, and polyvinylpyrrolidone, was spin-coated on glass substrates. Then, p-type and n-type thermoelectric elements were formed by raster scanning of focused femtosecond laser pulses. After rinsing the samples into ethylene glycol and ethanol, the thermoelectric couples were fabricated on the substrates. Cu–Ni- and Cu2O/NiO-rich micropatterns were selectively formed by controlling the laser scanning speed. The Cu–Ni-based and Cu2O/NiO-based micropatterns exhibited n-type and p-type thermoelectric properties, respectively. An open-circuit voltage of the fabricated thermoelectric couple was 0.25 mV/K which was almost consistent with the estimated values using each Seebeck coefficient of the p-type and n-type thermoelectric elements. This selective direct-writing process of p-type and n-type thermoelectric materials is useful to fabricate various thermoelectric-type sensors.

DOI： 10.1299/jsmemnm.2017.8.pn-17