研究者詳細 - 秦　誠一

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

Tamura, K; Mizoshiri, M; Sakurai, J; Hata, S

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 6 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

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.

DOI： 10.7567/JJAP.56.06GN08

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

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

JOURNAL OF MICROMECHANICS AND MICROENGINEERING 27 巻 ( 5 ) 2017年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Micromechanics and Microengineering

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 × 10-8 °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

Fabrication of combinatorial evaluation substrates for chlorine evolution electrode catalyst

Three-dimensional Cu microfabrication using femtosecond laser-induced CuO nanoparticle reduction 査読有り

Shun Arakane, Mizue Mizoshiri, Junpei Sakurai, Seiichi Hata

Applied Physics Express 10 巻頁： 017201 2017年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

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

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

2016 International Symposium on Micro-NanoMechatronics and Human Science, MHS 2016 2017年1月

出版者・発行元：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 査読有り

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

APPLIED PHYSICS EXPRESS 10 巻 ( 1 ) 2017年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

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

電気学会論文誌Ｅ（センサ・マイクロマシン部門誌） 137 巻 ( 1 ) 頁： 15 - 22 2017年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電気学会

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

CiNii Research

Polymer-based blood vessel models with micro-temperature sensors in EVE 査読有り

Mizoshiri, M; Ito, Y; Hayakawa, T; Maruyama, H; Sakurai, J; Ikeda, S; Arai, F; Hata, S

NANOSENSORS, BIOSENSORS, INFO-TECH SENSORS AND 3D SYSTEMS 2017 10167 巻 2017年

記述言語：英語出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering

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 査読有り

Mizoshiri, M; Ito, Y; Sakurai, J; Hata, S

NANOSENSORS, BIOSENSORS, INFO-TECH SENSORS AND 3D SYSTEMS 2017 10167 巻 2017年

記述言語：英語出版者・発行元：Proceedings of SPIE - The International Society for Optical Engineering

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