96 results on '"Tsunaki Takahashi"'
Search Results
2. Face-selective tungstate ions drive zinc oxide nanowire growth direction and dopant incorporation
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Jiangyang Liu, Kazuki Nagashima, Hiroki Yamashita, Wataru Mizukami, Jun Uzuhashi, Takuro Hosomi, Masaki Kanai, Xixi Zhao, Yoshinori Miura, Guozhu Zhang, Tsunaki Takahashi, Masaru Suzuki, Daiki Sakai, Benjarong Samransuksamer, Yong He, Tadakatsu Ohkubo, Takao Yasui, Yuriko Aoki, Johnny C. Ho, Yoshinobu Baba, and Takeshi Yanagida
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Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Controlling the growth processes of nanowires is vital for tailoring their properties. Here, the presence of tungstate ions on specific surface planes of zinc oxide nanowires causes nanowire growth and chemical doping along specific crystal planes.
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- 2020
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3. Water–Organic Cosolvent Effect on Nucleation of Solution-Synthesized ZnO Nanowires
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Yuya Akihiro, Kazuki Nagashima, Takuro Hosomi, Masaki Kanai, Hiroshi Anzai, Tsunaki Takahashi, Guozhu Zhang, Takao Yasui, Yoshinobu Baba, and Takeshi Yanagida
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Chemistry ,QD1-999 - Published
- 2019
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4. Fabrication of a Robust In2O3 Nanolines FET Device as a Biosensor Platform
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Zetao Zhu, Takao Yasui, Quanli Liu, Kazuki Nagashima, Tsunaki Takahashi, Taisuke Shimada, Takeshi Yanagida, and Yoshinobu Baba
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In2O3 nanolines ,robust ,field effect transistor ,biosensor platform ,Mechanical engineering and machinery ,TJ1-1570 - Abstract
Field-effect transistors (FETs) are attractive biosensor platforms for rapid and accurate detection of various analytes through surface immobilization of specific bio-receptors. Since it is difficult to maintain the electrical stability of semiconductors of sensing channel under physiological conditions for long periods, passivation by a stable metal oxide dielectric layer, such as Al2O3 or HfO2, is currently used as a common method to prevent damage. However, protecting the sensing channel by passivation has the disadvantage that the distance between the target and the conductive channel increases, and the sensing signal will be degraded by Debye shielding. Even though many efforts use semiconductor materials directly as channels for biosensors, the electrical stability of semiconductors in the physiological environments has rarely been studied. In this work, an In2O3 nanolines FET device with high robustness in artificial physiological solution of phosphate buffered saline (PBS) was fabricated and used as a platform for biosensors without employing passivation on the sensing channel. The FET device demonstrated reproducibility with an average threshold voltage (VTH) of 5.235 V and a standard deviation (SD) of 0.382 V. We tested the robustness of the In2O3 nanolines FET device in PBS solution and found that the device had a long-term electrical stability in PBS with more than 9 days’ exposure. Finally, we demonstrated its applicability as a biosensor platform by testing the biosensing performance towards miR-21 targets after immobilizing the phosphonic acid terminated DNA probes. Since the surface immobilization of multiple bioreceptors is feasible, we demonstrate that the robust In2O3 FET device can be an excellent biosensor platform for biosensors.
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- 2021
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5. Metal–Oxide Nanowire Molecular Sensors and Their Promises
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Hao Zeng, Guozhu Zhang, Kazuki Nagashima, Tsunaki Takahashi, Takuro Hosomi, and Takeshi Yanagida
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nanowire ,oxide ,gas sensor ,device ,1D nanostructure ,sensing mechanism ,Biochemistry ,QD415-436 - Abstract
During the past two decades, one–dimensional (1D) metal–oxide nanowire (NW)-based molecular sensors have been witnessed as promising candidates to electrically detect volatile organic compounds (VOCs) due to their high surface to volume ratio, single crystallinity, and well-defined crystal orientations. Furthermore, these unique physical/chemical features allow the integrated sensor electronics to work with a long-term stability, ultra-low power consumption, and miniature device size, which promote the fast development of “trillion sensor electronics” for Internet of things (IoT) applications. This review gives a comprehensive overview of the recent studies and achievements in 1D metal–oxide nanowire synthesis, sensor device fabrication, sensing material functionalization, and sensing mechanisms. In addition, some critical issues that impede the practical application of the 1D metal–oxide nanowire-based sensor electronics, including selectivity, long-term stability, and low power consumption, will be highlighted. Finally, we give a prospective account of the remaining issues toward the laboratory-to-market transformation of the 1D nanostructure-based sensor electronics.
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- 2021
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6. Experimental Study on Deformation Potential ( ${D}_{{{ac}}}$ ) in MOSFETs: Demonstration of Increased ${D}_{{{ac}}}$ at MOS Interfaces and Its Impact on Electron Mobility
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Teruyuki Ohashi, Takahisa Tanaka, Tsunaki Takahashi, Shunri Oda, and Ken Uchida
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Deformation potential ,low-field mobility ,acoustic phonon scattering ,SOI ,MOSFETs ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
Deformation potential (Dac), which is one of the most important parameters determining the rate of electron-acoustic phonon scattering, in Si around MOS interfaces is thoroughly studied with regard to the dependences on surface carrier densities, back-gate biases, and device structures. It is demonstrated that Dac increases sharply at the MOS interface. To investigate the impact of the increased Dac on μe, thick body-channel SOI MOSFETs, where drain current flows in the entire SOI layers, was fabricated. The carrier transport experiments reveal that μe of greater than 1100 cm2 V-1 s-1 is obtained in body-channel SOI MOSFETs with the SOI thickness of greater than 70 nm. By taking into account the Dac profile around the MOS interface, experimental μe of SOI MOSFETs is numerically reproduced over a wide range of SOI thicknesses. μe of the body-channel SOI MOSFETs is also well reproduced using the same Dac profile. Thus, it is concluded that Dac increases sharply at the Si/SiO2 interface. The accurate modeling of the increased Dac around the Si/SiO2 interface is indispensable for designing high-performance and/or low-power 3-D MOSFETs including FinFETs, extremely thin SOI MOSFETs, and nanowire MOSFETs, because these types of MOSFETs have greater interface-to-volume ratios.
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- 2016
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7. Direct Evaluation of Self-Heating Effects in Bulk and Ultra-Thin BOX SOI MOSFETs Using Four-Terminal Gate Resistance Technique
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Tsunaki Takahashi, Takeo Matsuki, Takahiro Shinada, Yasuo Inoue, and Ken Uchida
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Self-heating effect ,ultra-thin BOX ,four-terminal gate resistance technique ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 - Abstract
We demonstrate clear self-heating effects (SHEs) of bulk and silicon-on-insulator (SOI) MOSFETs for various SOI/buried oxide (BOX) thicknesses including ultra-thin 6 nm BOX, which was not detected by the ac conductance method, using the four-terminal gate resistance technique. We clarify that the SHE in bulk MOSFETs originates from the degradation of thermal conductivity in a heavily doped well region. The strong chip-temperature dependence of the SHE was observed only in bulk MOSFETs. As results of the chip temperature-dependent SHE of bulk devices and the SHE suppression by BOX thinning, the device temperature of ultra-thin BOX SOI MOSFETs is close to that of bulk MOSFETs at an elevated chip temperature, which suggests the thermal advantage of extremely thin BOX structures.
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- 2016
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8. Rational Strategy for Space-Confined Atomic Layer Deposition
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Ryoma Kamei, Takuro Hosomi, Masaki Kanai, Eisuke Kanao, Jiangyang Liu, Tsunaki Takahashi, Wenjun Li, Wataru Tanaka, Kazuki Nagashima, Katsuya Nakano, Koji Otsuka, Takuya Kubo, and Takeshi Yanagida
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General Materials Science - Published
- 2023
9. Thermal-aware CMOS: Challenges for future technology and design evolutions.
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Ken Uchida and Tsunaki Takahashi
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- 2016
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10. Interfacial Molecular Compatibility for Programming Organic–Metal Oxide Superlattices
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Takeshi Ono, Sae Mitamura, Takuro Hosomi, Hikaru Saito, Midori Ikeuchi, Jiangyang Liu, Kazuki Nagashima, Tsunaki Takahashi, Wataru Tanaka, Masaki Kanai, and Takeshi Yanagida
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General Materials Science - Published
- 2023
11. Core-shell Metal Oxide Nanowire Array to Analyze Adsorption Behaviors of Volatile Molecules
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Wenjun Li, Kazuki Nagashima, Takuro Hosomi, Jiangyang Liu, Tsunaki Takahashi, Guozhu Zhang, Wataru Tanaka, Masaki Kanai, and Takeshi Yanagida
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General Chemistry - Published
- 2022
12. Edge-Topological Regulation for in Situ Fabrication of Bridging Nanosensors
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Jiangyang Liu, Hao Zeng, Guozhu Zhang, Wenjun Li, Kazuki Nagashima, Tsunaki Takahashi, Takuro Hosomi, Wataru Tanaka, Masaki Kanai, and Takeshi Yanagida
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Mechanical Engineering ,General Materials Science ,Bioengineering ,General Chemistry ,Condensed Matter Physics - Published
- 2022
13. Low-Power and ppm-Level Detection of Gas Molecules by Integrated Metal Nanosheets.
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Takahisa Tanaka, K. Tabuchi, Kohei Tatehora, Yohsuke Shiiki, S. Nakagawa, Tsunaki Takahashi, R. Shimizu, Hiroki Ishikuro, Tadahiro Kuroda, T. Yanagida, and Ken Uchida
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- 2019
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14. Water-Selective Nanostructured Dehumidifiers for Molecular Sensing Spaces
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Jiangyang Liu, Kazuki Nagashima, Takuro Hosomi, Wenjin Lei, Guozhu Zhang, Tsunaki Takahashi, Xixi Zhao, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Wataru Tanaka, Hikaru Saito, Masaki Kanai, Taisuke Shimada, Takao Yasui, Yoshinobu Baba, and Takeshi Yanagida
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Fluid Flow and Transfer Processes ,Calcium Chloride ,Nanowires ,Process Chemistry and Technology ,Water ,Humidity ,Bioengineering ,Zinc Oxide ,Instrumentation - Abstract
Humidity and moisture effects, frequently called water poisoning, in surroundings are inevitable for various molecular sensing devices, strongly affecting their sensing characteristics. Here, we demonstrate a water-selective nanostructured dehumidifier composed of ZnO/TiO
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- 2022
15. Impact of Lateral SnO2 Nanofilm Channel Geometry on a 1024 Crossbar Chemical Sensor Array
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Haruka Honda, Tsunaki Takahashi, Yohsuke Shiiki, Hao Zeng, Kentaro Nakamura, Shintaro Nagata, Takuro Hosomi, Wataru Tanaka, Guozhu Zhang, Masaki Kanai, Kazuki Nagashima, Hiroki Ishikuro, and Takeshi Yanagida
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Fluid Flow and Transfer Processes ,Process Chemistry and Technology ,Bioengineering ,Instrumentation - Published
- 2022
16. Compact model of a metal oxide molecule sensor for self-heating control
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Yohsuke Shiiki, Shintaro Nagata, Tsunaki Takahashi, Takeshi Yanagida, and Hiroki Ishikuro
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Materials Chemistry ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2023
17. Robust and Electrically Conductive ZnO Thin Films and Nanostructures: Their Applications in Thermally and Chemically Harsh Environments
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Guozhu Zhang, Kazuki Nagashima, Tsunaki Takahashi, Ruolin Yan, Hao Zeng, Takuro Hosomi, Masaki Kanai, and Takeshi Yanagida
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Nanostructure ,Materials science ,Materials Chemistry ,Electrochemistry ,Electrically conductive ,Nanotechnology ,Thin film ,Electronic, Optical and Magnetic Materials - Published
- 2021
18. Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning
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Chaiyanut Jirayupat, Kazuki Nagashima, Takuro Hosomi, Tsunaki Takahashi, Benjarong Samransuksamer, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Jiangyang Liu, Guozhu Zhang, Wataru Tanaka, Masaki Kanai, Takao Yasui, Yoshinobu Baba, and Takeshi Yanagida
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Machine Learning ,Odorants ,Materials Chemistry ,Metals and Alloys ,Ceramics and Composites ,Reproducibility of Results ,General Chemistry ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
Breath odor sensing-based individual authentication was conducted for the first time using an artificial olfactory sensor system. Using a 16-channel chemiresistive sensor array and machine learning, a mean accuracy of97% was successfully achieved. The impact of the number of sensors on the accuracy and reproducibility was also demonstrated.
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- 2022
19. Maximizing Conversion of Surface Click Reactions for Versatile Molecular Modification on Metal Oxide Nanowires
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Hiroshi Masai, Masaya Otani, Tsunaki Takahashi, Kazuki Nagashima, Jun Terao, Masaki Kanai, Rimon Yamaguchi, Takuro Hosomi, Takeshi Yanagida, and Guozhu Zhang
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Materials science ,Nanostructure ,Nanowire ,Oxide ,02 engineering and technology ,Surfaces and Interfaces ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Photochemistry ,01 natural sciences ,Cycloaddition ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Covalent bond ,Monolayer ,Electrochemistry ,General Materials Science ,Azide ,0210 nano-technology ,Spectroscopy - Abstract
Click reactions (e.g., Huisgen cycloaddition) on metal oxide nanostructures offer a versatile and robust surface molecular modification for various applications because they form strong covalent bonds in a wide range of molecular substrates. This study reports a rational strategy to maximize the conversion rate of surface click reactions on single-crystalline ZnO nanowires by monitoring the reaction progress. p-Polarized multiple-angle incidence resolution spectrometry (pMAIRS) and Fourier-transformed infrared (FT-IR) spectroscopy were employed to monitor the reaction progress of an azide-terminated self-assembled monolayer (SAM) on single-crystalline ZnO nanowires. Although various reaction parameters including the concentration of Cu(I) catalysts, triazolyl ligands, solvents, and target alkynes were systematically examined for the surface click reactions, 10-30% of terminal azide on the nanowire surface remained unreacted. Temperature-dependent FT-IR measurements revealed that such unreacted residual azides deteriorate the thermal stability of the nanowire molecular layer. To overcome this observed conversion limitation of click reactions on nanostructure surfaces, we considered the steric hindrance around the closely packed SAM reaction points, then experimented with dispersing the azide moiety into a methyl-terminated SAM. The mixed-SAM method significantly improved the azide conversion rate to almost 100%. This reaction method enables the construction of spatially patterned molecular surface modifications on metal oxide nanowire arrays without detrimental unreacted azide groups.
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- 2021
20. Rational Strategy for Space-Confined Seeded Growth of ZnO Nanowires in Meter-Long Microtubes
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Kazuki Nagashima, Eisuke Kanao, Ryoma Kamei, Takao Yasui, Tsunaki Takahashi, Koji Otsuka, Takuro Hosomi, Takuya Kubo, Guozhu Zhang, Takeshi Yanagida, Masaki Kanai, Yoshinobu Baba, and Jun Terao
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Nanostructure ,Materials science ,chemistry.chemical_element ,Crystal growth ,02 engineering and technology ,Zinc ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Aspect ratio (image) ,Hydrothermal circulation ,0104 chemical sciences ,Crystal ,Chemical engineering ,chemistry ,General Materials Science ,0210 nano-technology ,Layer (electronics) ,Confined space - Abstract
Seeded crystal growths of nanostructures within confined spaces offer an interesting approach to design chemical reaction spaces with tailored inner surface properties. However, such crystal growth within confined spaces tends to be inherently difficult as the length increases as a result of confinement effects. Here, we demonstrate a space-confined seeded growth of ZnO nanowires within meter-long microtubes of 100 μm inner diameter with the aspect ratio of up to 10 000, which had been unattainable to previous methods of seeded crystal growths. ZnO nanowires could be grown via seeded hydrothermal crystal growth for relatively short microtubes below the length of 40 mm, while any ZnO nanostructures were not observable at all for longer microtubes above 60 mm with the aspect ratio of 600. Microstructural and mass spectrometric analysis revealed that a conventional seed layer formation using zinc acetate is unfeasible within the confined space of long microtubes as a result of the formation of detrimental residual Zn complex compounds. To overcome this space-confined issue, a flow-assisted seed layer formation is proposed. This flow-assisted method enables growth of spatially uniform ZnO nanowires via removing residual compounds even for 1 m long microtubes with the aspect ratio of up to 10 000. Finally, the applicably of ZnO-nanowire-decorated long microtubes for liquid-phase separations was demonstrated.
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- 2021
21. Enhancement of pH Tolerance in Conductive Al-Doped ZnO Nanofilms via Sequential Annealing
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Hao Zeng, Ruolin Yan, Masaki Kanai, Takeshi Yanagida, Takuro Hosomi, Guozhu Zhang, Kazuki Nagashima, and Tsunaki Takahashi
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Materials science ,Annealing (metallurgy) ,Doping ,Oxide ,Nanotechnology ,Electronic, Optical and Magnetic Materials ,Metal ,chemistry.chemical_compound ,chemistry ,visual_art ,Electrode ,Materials Chemistry ,Electrochemistry ,visual_art.visual_art_medium ,Chemical stability ,Electrical conductor ,Biosensor - Abstract
Chemically stable and electrically conductive metal oxide nanofilms are promising as robust electrodes for chemical/biosensors and for photoelectrochemical applications, which require harsh conditi...
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- 2021
22. A thermally robust and strongly oxidizing surface of WO3 hydrate nanowires for electrical aldehyde sensing with long-term stability
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Johnny C. Ho, Masaki Kanai, Takeharu Sugiyama, Wataru Mizukami, Takeshi Yanagida, Tsunaki Takahashi, Yoshinobu Baba, Takao Yasui, Guozhu Zhang, Takuro Hosomi, Yuriko Aoki, Jiangyang Liu, and Kazuki Nagashima
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Materials science ,Renewable Energy, Sustainability and the Environment ,Nonanal ,Nanowire ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Adsorption ,chemistry ,Chemical engineering ,Desorption ,Oxidizing agent ,General Materials Science ,Thermal stability ,0210 nano-technology ,Hydrate - Abstract
Electrical molecular nanosensors require two conflicting surface characteristics, which are catalytic activity for molecular selectivity and thermal stability for long-term data collection. Here, we show that a simple surface treatment using strong acids creates two such conflicting surface properties of WO3 hydrate nanowires, which enhance the electrical molecular sensing of aldehydes (nonanal, a biomarker). Mass-spectrometric measurements reveal that the surface treatment using strong acids substantially promotes both the oxidization of nonanal and the desorption of products, nonanoic acid, from the surfaces at a temperature of 50 °C, which is lower than the 300 °C required for untreated surfaces. Spectroscopic and structural measurements combined with numerical simulations identify two different adsorption structures of carbonyl groups on the surface, where molecules directly bound to coordinatively unsaturated surface tungsten preferentially proceed to the catalytic oxidization reaction and the subsequent desorption process. Furthermore, we confirm the thermal durability (over 10 years) of the catalytic activity on acid-treated WO3 hydrate nanowire surfaces up to 300 °C, which enables us to demonstrate the long-term stable sensor operations with the sensitivity (4 orders of magnitude) remaining for years.
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- 2021
23. The impact of surface Cu2+ of ZnO/(Cu1−xZnx)O heterostructured nanowires on the adsorption and chemical transformation of carbonyl compounds
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Chen Wang, Kazuki Nagashima, Jiangyang Liu, Guozhu Zhang, Hikaru Saito, Takeshi Yanagida, Masaki Kanai, Takao Yasui, Wataru Mizukami, Tsunaki Takahashi, Yoshinobu Baba, Yuki Nagamatsu, Benjarong Samransuksamer, and Takuro Hosomi
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Materials science ,Nonanal ,Nanowire ,chemistry.chemical_element ,General Chemistry ,Copper ,Catalysis ,Metal ,Chemistry ,chemistry.chemical_compound ,Adsorption ,Chemical engineering ,chemistry ,visual_art ,visual_art.visual_art_medium ,Molecule ,Aldol condensation - Abstract
The surface cation composition of nanoscale metal oxides critically determines the properties of various functional chemical processes including inhomogeneous catalysts and molecular sensors. Here we employ a gradual modulation of cation composition on a ZnO/(Cu1−xZnx)O heterostructured nanowire surface to study the effect of surface cation composition (Cu/Zn) on the adsorption and chemical transformation behaviors of volatile carbonyl compounds (nonanal: biomarker). Controlling cation diffusion at the ZnO(core)/CuO(shell) nanowire interface allows us to continuously manipulate the surface Cu/Zn ratio of ZnO/(Cu1−xZnx)O heterostructured nanowires, while keeping the nanowire morphology. We found that surface exposed copper significantly suppresses the adsorption of nonanal, which is not consistent with our initial expectation since the Lewis acidity of Cu2+ is strong enough and comparable to that of Zn2+. In addition, an increase of the Cu/Zn ratio on the nanowire surface suppresses the aldol condensation reaction of nonanal. Surface spectroscopic analysis and theoretical simulations reveal that the nonanal molecules adsorbed at surface Cu2+ sites are not activated, and a coordination-saturated in-plane square geometry of surface Cu2+ is responsible for the observed weak molecular adsorption behaviors. This inactive surface Cu2+ well explains the mechanism of suppressed surface aldol condensation reactions by preventing the neighboring of activated nonanal molecules. We apply this tailored cation composition surface for electrical molecular sensing of nonanal and successfully demonstrate the improvements of durability and recovery time as a consequence of controlled surface molecular behaviors., Unexpected features of surface Cu2+ on ZnO/(Cu1−xZnx)O nanowires for molecular transformation and electrical sensing of carbonyl compounds were found.
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- 2021
24. Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano-Micro-Macro Trans-Scale Design
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Hirotaka Koga, Kazuki Nagashima, Koichi Suematsu, Tsunaki Takahashi, Luting Zhu, Daiki Fukushima, Yintong Huang, Ryo Nakagawa, Jiangyang Liu, Kojiro Uetani, Masaya Nogi, Takeshi Yanagida, and Yuta Nishina
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customized 3D network structures ,General Engineering ,trans-scale structural design ,General Physics and Astronomy ,tunable electrical property ,General Materials Science ,semiconductor ,paper electronics ,nanocellulose - Abstract
Koga H., Nagashima K., Suematsu K., et al. Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano-Micro-Macro Trans-Scale Design. ACS Nano, 16(6), 8630-8640, 2022. https://doi.org/10.1021/acsnano.1c10728., Semiconducting nanomaterials with 3D network structures exhibit various fascinating properties such as electrical conduction, high permeability, and large surface areas, which are beneficial for adsorption, separation, and sensing applications. However, research on these materials is substantially restricted by the limited trans-scalability of their structural design and tunability of electrical conductivity. To overcome this challenge, a pyrolyzed cellulose nanofiber paper (CNP) semiconductor with a 3D network structure is proposed. Its nano-micro-macro trans-scale structural design is achieved by a combination of iodine-mediated morphology-retaining pyrolysis with spatially controlled drying of a cellulose nanofiber dispersion and paper-crafting techniques, such as microembossing, origami, and kirigami. The electrical conduction of this semiconductor is widely and systematically tuned, via the temperature-controlled progressive pyrolysis of CNP, from insulating (1012 ω cm) to quasimetallic (10-2 ω cm), which considerably exceeds that attained in other previously reported nanomaterials with 3D networks. The pyrolyzed CNP semiconductor provides not only the tailorable functionality for applications ranging from water-vapor-selective sensors to enzymatic biofuel cell electrodes but also the designability of macroscopic device configurations for stretchable and wearable applications. This study provides a pathway to realize structurally and functionally designable semiconducting nanomaterials and all-nanocellulose semiconducting technology for diverse electronics.
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- 2022
25. Face-Selective Crystal Growth of Hydrothermal Tungsten Oxide Nanowires for Sensing Volatile Molecules
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Takuro Hosomi, Tsunaki Takahashi, Kentaro Nakamura, Kazuki Nagashima, Sho Nekita, Masaki Kanai, Tetsuya Okuyama, Guozhu Zhang, Qianli Wang, and Takeshi Yanagida
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Materials science ,Nanowire ,Anisotropic crystal ,chemistry.chemical_element ,Tungsten oxide ,Crystal growth ,Tungsten ,equipment and supplies ,Hydrothermal circulation ,Chemical engineering ,chemistry ,Hydrothermal synthesis ,Molecule ,General Materials Science - Abstract
Here, we demonstrate the impact of tungsten precursor concentration on anisotropic crystal growth of hydrothermal tungsten oxide (WO3) nanowires. When varying the tungsten precursor concentration, ...
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- 2020
26. Facile Synthesis of Zinc Titanate Nanotubes via Reaction-byproduct Etching
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Yong He, Takeshi Yanagida, Jiangyang Liu, Guozhu Zhang, Masaki Kanai, Takuro Hosomi, Kazuki Nagashima, Hideto Yoshida, and Tsunaki Takahashi
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chemistry.chemical_compound ,chemistry ,Chemical engineering ,Etching (microfabrication) ,General Chemistry ,Zinc titanate ,Isotropic etching - Abstract
A facile methodology to create zinc titanate nanotubes via reaction-byproduct etching is demonstrated. The chemical etching by the sol-gel reaction byproduct—hydrochloric acid (HCl) allows us to cr...
- Published
- 2020
27. Perovskite Core–Shell Nanowire Transistors: Interfacial Transfer Doping and Surface Passivation
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Takeshi Yanagida, Johnny C. Ho, Wei Wang, Fangzhou Li, You Meng, Quan Quan, Fei Wang, Jian Lu, Yan Bao, Kazuki Nagashima, Tsunaki Takahashi, Zhengxun Lai, SenPo Yip, Takuro Hosomi, and Xiuming Bu
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Electron mobility ,Materials science ,Passivation ,business.industry ,Doping ,General Engineering ,Nanowire ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Molybdenum trioxide ,chemistry.chemical_compound ,chemistry ,Optoelectronics ,Surface modification ,General Materials Science ,Quantum efficiency ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
While halide perovskite electronics are rapidly developing, they are greatly limited by the inferior charge transport and poor stability. In this work, effective surface charge transfer doping of vapor-liquid-solid (VLS)-grown single-crystalline cesium lead bromide perovskite (CsPbBr3) nanowires (NWs) via molybdenum trioxide (MoO3) surface functionalization is achieved. Once fabricated into NW devices, due to the efficient interfacial charge transfer and reduced impurity scattering, a 15× increase in the field-effect hole mobility (μh) from 1.5 to 23.3 cm2/(V s) is accomplished after depositing the 10 nm thick MoO3 shell. This enhanced mobility is already better than any mobility value reported for perovskite field-effect transistors (FETs) to date. The photodetection performance of these CsPbBr3/MoO3 core-shell NWs is also investigated to yield a superior responsivity (R) up to 2.36 × 103 A/W and an external quantum efficiency (EQE) of over 5.48 × 105% toward the 532 nm regime. Importantly, the MoO3 shell can provide excellent surface passivation to the CsPbBr3 NW core that minimizes the diffusion of detrimental water and oxygen molecules, improving the air stability of CsPbBr3/MoO3 core-shell NW devices. All these findings evidently demonstrate the surface doping as an enabling technology to realize high-mobility and air-stable low-dimensional halide perovskite devices.
- Published
- 2020
28. Phosphonic Acid Modified ZnO Nanowire Sensors: Directing Reaction Pathway of Volatile Carbonyl Compounds
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Kazuki Nagashima, Takeshi Yanagida, Takuro Hosomi, Masaki Kanai, Guozhu Zhang, Hideto Yoshida, Tsunaki Takahashi, and Chen Wang
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Materials science ,Nonanal ,010401 analytical chemistry ,Molecular sensor ,Nanowire ,Oxide ,Rational design ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,General Materials Science ,Aldol condensation ,0210 nano-technology ,Methylphosphonic acid - Abstract
Surface molecular transformations on nanoscale metal oxides are inherently complex, and directing those reaction pathways is still challenging but important for designing their various applications, including molecular sensing, catalysts, and others. Here, a rational strategy to direct a reaction pathway of volatile carbonyl compounds (nonanal: biomarker) on single-crystalline ZnO nanowire surfaces via molecular modification is demonstrated. The introduction of a methylphosphonic acid modification on the ZnO nanowire surface significantly alters the surface reaction pathway of nonanal via suppressing the detrimental aldol condensation reaction. This is directed by intentionally decreasing the probability of two neighboring molecular activations on the nanowire surface. Spectrometric measurements reveal the correlation between the suppression of the aldol condensation surface reaction and the improvement in the sensor performance. This tailored surface reaction pathway effectively reduces the operating temperature from 200 to 100 °C while maintaining the sensitivity. This is because the aldol condensation product ((E)-2-heptyl-2-undecenal) requires a higher temperature to desorb from the surface. Thus, the proposed facile strategy offers an interesting approach not only for the rational design of metal oxide sensors for numerous volatile carbonyl compounds but also for tailoring various surface reaction pathways on complex nanoscale metal oxides.
- Published
- 2020
29. Face-selective tungstate ions drive zinc oxide nanowire growth direction and dopant incorporation
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Hiroki Yamashita, Xixi Zhao, Yoshinobu Baba, Kazuki Nagashima, Jun Uzuhashi, Jiangyang Liu, Yoshinori Miura, Masaki Kanai, Masaru Suzuki, Johnny C. Ho, Takeshi Yanagida, Daiki Sakai, Benjarong Samransuksamer, Tsunaki Takahashi, Tadakatsu Ohkubo, Takuro Hosomi, Wataru Mizukami, Guozhu Zhang, Takao Yasui, Yong He, and Yuriko Aoki
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Materials science ,Dopant ,Doping ,Nucleation ,Nanowire ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Ion ,Crystal ,chemistry.chemical_compound ,Crystallography ,Tungstate ,chemistry ,Mechanics of Materials ,TA401-492 ,General Materials Science ,0210 nano-technology ,Materials of engineering and construction. Mechanics of materials - Abstract
Tailoring the elemental doping of inorganic nanowires remains an important challenge due to complex dopant incorporation pathways. Here we report that the face-selectivity of tungstate ions controls growth direction and dopant incorporation of hydrothermal zinc oxide nanowires. The introduction of tungstate ions on nanowire surface during synthesis unexpectedly enhances nucleation at sidewall $$\left\{ {10\bar 10} \right\}$$ 10 1 ¯ 0 planes, while dopant incorporation occurs only on (0001) planes. This conflicting face-selective behavior leads to inhomogeneous dopant distribution. Density functional theory calculations reveal that the face-selective behavior can be interpreted in terms of the effect of coordination structure of the tungstate ions on each zinc oxide crystal plane. In addition, we demonstrate a rational strategy to control the morphology and the elemental doping of tungsten-doped zinc oxide nanowires.
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- 2020
30. Unusual Sequential Annealing Effect in Achieving High Thermal Stability of Conductive Al-Doped ZnO Nanofilms
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Ruolin Yan, Kazuki Nagashima, Takeshi Yanagida, Masaki Kanai, Takuro Hosomi, Guozhu Zhang, and Tsunaki Takahashi
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Materials science ,business.industry ,Annealing (metallurgy) ,Doping ,Oxide ,Electronic, Optical and Magnetic Materials ,Metal ,chemistry.chemical_compound ,chemistry ,Electrical resistivity and conductivity ,visual_art ,Electrode ,Materials Chemistry ,Electrochemistry ,visual_art.visual_art_medium ,Optoelectronics ,Thermal stability ,business ,Electrical conductor - Abstract
Emerging interactive sensor electronics requires metal oxide electrodes that possess long-term atmospheric stability and electrical conductivity to function under harsh conditions (e.g., high tempe...
- Published
- 2020
31. Monovalent sulfur oxoanions enable millimeter-long single-crystalline h-WO3 nanowire synthesis
- Author
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Hideto Yoshida, Tsunaki Takahashi, Yuriko Aoki, Masaki Kanai, Wataru Mizukami, Chen Wang, Kazuki Nagashima, Kentaro Nakamura, Takao Yasui, Yoshinobu Baba, Guozhu Zhang, Takuro Hosomi, and Takeshi Yanagida
- Subjects
chemistry.chemical_classification ,Materials science ,Ab initio ,Nanowire ,chemistry.chemical_element ,Electronic structure ,Sulfur ,Divalent ,Ion ,chemistry ,Chemical engineering ,Molecule ,General Materials Science ,Hydration energy - Abstract
Here, we discuss a misunderstanding regarding chemical capping, which has intrinsically hindered the extension of the length of hexagonal (h)-WO3 nanowires in previous studies. Although divalent sulfate ions (SO42−) have been strongly believed to be efficient capping ions for directing anisotropic h-WO3 nanowire growth, we have found that the presence of SO42− is highly detrimental to the anisotropic crystal growth of the h-WO3 nanowires, and a monovalent sulfur oxoanion (HSO4−) rather than SO42− only substantially promotes the anisotropic h-WO3 nanowire growth. Ab initio electronic structure simulations revealed that the monovalent sulfur oxoanions were preferentially able to cap the sidewall plane (100) of the h-WO3 nanowires due to the lower hydration energy when compared with SO42−. Based on this capping strategy, using the monovalent sulfur oxoanion (CH3SO3−), which cannot generate divalent sulfur oxoanions, we have successfully fabricated ultra-long h-WO3 nanowires up to the millimeter range (1.2 mm) for a wider range of precursor concentrations. We have demonstrated the feasibility of these millimeter-long h-WO3 nanowires for the electrical sensing of molecules (lung cancer biomarker: nonanal) on flexible substrates, which can be operated at room temperature with mechanical flexibility with bending cycles up to 104 times due to the enhanced textile effect.
- Published
- 2020
32. Synthesis of Monodispersedly Sized ZnO Nanowires from Randomly Sized Seeds
- Author
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Takuro Hosomi, Xixi Zhao, Takao Yasui, Yoshinobu Baba, Kazuki Nagashima, Gang Meng, Yuriko Aoki, Masaki Kanai, Takeshi Yanagida, Benjarong Samransuksamer, Masaru Suzuki, Hideto Yoshida, Guozhu Zhang, Yuya Akihiro, Tsunaki Takahashi, Zetao Zhu, and Wataru Mizukami
- Subjects
Materials science ,Mechanical Engineering ,Dispersity ,Oxide ,Zno nanowires ,Nanowire ,Nucleation ,chemistry.chemical_element ,Bioengineering ,02 engineering and technology ,General Chemistry ,Zinc ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Hydrothermal circulation ,Metal ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,visual_art ,visual_art.visual_art_medium ,General Materials Science ,0210 nano-technology - Abstract
We demonstrate the facile, rational synthesis of monodispersedly sized zinc oxide (ZnO) nanowires from randomly sized seeds by hydrothermal growth. Uniformly shaped nanowire tips constructed in ammonia-dominated alkaline conditions serve as a foundation for the subsequent formation of the monodisperse nanowires. By precisely controlling the sharp tip formation and the nucleation, our method substantially narrows the distribution of ZnO nanowire diameters from σ = 13.5 nm down to σ = 1.3 nm and controls their diameter by a completely bottom-up method, even initiating from randomly sized seeds. The proposed concept of sharp tip based monodisperse nanowires growth can be applied to the growth of diverse metal oxide nanowires and thus paves the way for bottom-up grown metal oxide nanowires-integrated nanodevices with a reliable performance.
- Published
- 2019
33. Low-Power and ppm-Level Multimolecule Detection by Integration of Self-Heated Metal Nanosheet Sensors
- Author
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Hiroki Ishikuro, Ryota Shimizu, Kenta Tabuchi, Yohsuke Shiiki, Tsunaki Takahashi, Kohei Tatehora, Ken Uchida, Takahisa Tanaka, Shuya Nakagawa, Takeshi Yanagida, and Tadahiro Kuroda
- Subjects
010302 applied physics ,Materials science ,business.industry ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Power (physics) ,Metal ,Power consumption ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Optoelectronics ,Electrical and Electronic Engineering ,Self heating ,business ,Scaling ,Electronic circuit ,Nanosheet - Abstract
H2 and NH3 detection with low power consumption was demonstrated by integrated chemiresistive Pt and PtRh nanosheet sensors on glass substrates. The self-heating effects realized low power and local heating of metal nanosheet sensors, enabling the integration of sensors with different operating temperatures. Based on different resistance changes in Pt and PtRh nanosheets toward H2 and NH3, the concentration of each gas was detected from a gas mixture by consuming around 1-mW power. For decreasing the power consumption and further integration of sensors, sensor scaling and pulsed operations were numerically and experimentally studied. In addition to good connectivity of metal nanosheet sensors to large-scale integration (LSI) circuits, improvements of the power consumption by sensor scaling were proven. The pulsed operations required for integrated sensor arrays maintained a sensor response, or a resistance change, of approximately 60%, even when the power consumption was reduced by 20%.
- Published
- 2019
34. Mechanistic Approach for Long-Term Stability of a Polyethylene Glycol-Carbon Black Nanocomposite Sensor
- Author
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Guozhu Zhang, Wenjun Li, Tsunaki Takahashi, Kazuki Nagashima, Chen Wang, Jiangyang Liu, Takuro Hosomi, Masaki Kanai, Yosuke Hanai, Atsushi Shunori, Wataru Tanaka, Takeshi Yanagida, and Atsuo Nakao
- Subjects
Fluid Flow and Transfer Processes ,chemistry.chemical_classification ,Nanocomposite ,Materials science ,Polymers ,Process Chemistry and Technology ,technology, industry, and agriculture ,Infrared spectroscopy ,Bioengineering ,Polymer ,Polyethylene glycol ,Carbon black ,Ascorbic acid ,Carbon ,Nanocomposites ,Polyethylene Glycols ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Soot ,PEG ratio ,Degradation (geology) ,Instrumentation - Abstract
Polymer-carbon nanocomposite sensor is a promising molecular sensing device for electronic nose (e-nose) due to its printability, variety of polymer materials, and low operation temperature; however, the lack of stability in an air environment has been an inevitable issue. Here, we demonstrate a design concept for realizing long-term stability in a polyethylene glycol (PEG)-carbon black (CB) nanocomposite sensor by understanding the underlying phenomena that cause sensor degradation. Comparison of the sensing properties and infrared spectroscopy on the same device revealed that the oxidation-induced consumption of PEG is a crucial factor for the sensor degradation. According to the mechanism, we introduced an antioxidizing agent (i.e., ascorbic acid) into the PEG-CB nanocomposite sensor to suppress the PEG oxidation and successfully demonstrated the long-term stability of sensing properties under an air environment for 30 days, which had been difficult in conventional polymer-carbon nanocomposite sensors.
- Published
- 2021
35. Image Processing and Machine Learning for Automated Identification of Chemo-/Biomarkers in Chromatography-Mass Spectrometry
- Author
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Takuro Hosomi, Chaiyanut Jirayupat, Kazuki Nagashima, Masaki Kanai, Guozhu Zhang, Jiangyang Liu, Wataru Tanaka, Tsunaki Takahashi, Takeshi Yanagida, and Benjarong Samransuksamer
- Subjects
Data processing ,Analyte ,Chemistry ,business.industry ,Reproducibility of Results ,Image processing ,Machine learning ,computer.software_genre ,Mass spectrometry ,Mass Spectrometry ,Analytical Chemistry ,Chemometrics ,Machine Learning ,Identification (information) ,Open source ,Metabolomics ,Humans ,Artificial intelligence ,business ,computer ,Biomarkers ,Software ,Chromatography, Liquid - Abstract
We present a method named NPFimg, which automatically identifies multivariate chemo-/biomarker features of analytes in chromatography-mass spectrometry (MS) data by combining image processing and machine learning. NPFimg processes a two-dimensional MS map (m/z vs retention time) to discriminate analytes and identify and visualize the marker features. Our approach allows us to comprehensively characterize the signals in MS data without the conventional peak picking process, which suffers from false peak detections. The feasibility of marker identification is successfully demonstrated in case studies of aroma odor and human breath on gas chromatography-mass spectrometry (GC-MS) even at the parts per billion level. Comparison with the widely used XCMS shows the excellent reliability of NPFimg, in that it has lower error rates of signal acquisition and marker identification. In addition, we show the potential applicability of NPFimg to the untargeted metabolomics of human breath. While this study shows the limited applications, NPFimg is potentially applicable to data processing in diverse metabolomics/chemometrics using GC-MS and liquid chromatography-MS. NPFimg is available as open source on GitHub (http://github.com/poomcj/NPFimg) under the MIT license.
- Published
- 2021
36. Redox-Inactive CO2 Determines Atmospheric Stability of Electrical Properties of ZnO Nanowire Devices through a Room-Temperature Surface Reaction
- Author
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Naoya Shibata, Guozhu Zhang, Takuro Hosomi, Kazuki Nagashima, Takehito Seki, Kentaro Nakamura, Tsunaki Takahashi, Takeshi Yanagida, and Masaki Kanai
- Subjects
Materials science ,Nanostructure ,business.industry ,Contact resistance ,Nanowire ,Oxide ,02 engineering and technology ,Semiconductor device ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,chemistry ,Scanning transmission electron microscopy ,Thermal ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business - Abstract
Emerging interactive electronics for the Internet of Things era inherently require the long-term stability of semiconductor devices exposed to air. Nanostructured metal oxides are promising options for such atmospherically stable semiconductor devices owing to their inherent stability in air. Among various oxide nanostructures, ZnO nanowires have been the most intensively studied for electrical and optical device applications. Here, we demonstrate a strategy for achieving the atmospheric electrical stability of ZnO nanowire devices. Although the chemically active oxygen and water in air are strong candidates for affecting the electrical stability of nanoscale metal oxides, we found that the ppm-level redox-inactive CO2 in air critically determines the atmospheric electrical stability of hydrothermally grown single-crystalline ZnO nanowires. A series of analyses using atmosphere-controlled electrical characterization of single nanowire devices, Fourier transform infrared spectroscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy consistently revealed that atmospheric CO2 reacts substantially with the ZnO nanowire surfaces, even at room temperature, to form an electrically insulative zinc carbonate thin layer. The formation of this layer essentially limits the atmospheric electrical stability of the ZnO nanowire devices. Based on this surface carbonation mechanism, we propose a strategy to suppress the detrimental surface reaction, which is based on (1) reducing the density of surface hydroxyl groups and (2) improving the nanowire crystallinity by thermal pretreatment. This approach improves the atmospheric electrical stability to at least 40 days in air.
- Published
- 2019
37. Water–Organic Cosolvent Effect on Nucleation of Solution-Synthesized ZnO Nanowires
- Author
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Guozhu Zhang, Yuya Akihiro, Yoshinobu Baba, Takao Yasui, Takeshi Yanagida, Kazuki Nagashima, Takuro Hosomi, Hiroshi Anzai, Masaki Kanai, and Tsunaki Takahashi
- Subjects
Materials science ,General Chemical Engineering ,Nucleation ,Anisotropic crystal ,Zno nanowires ,Alcohol ,General Chemistry ,Article ,lcsh:Chemistry ,chemistry.chemical_compound ,lcsh:QD1-999 ,chemistry ,Chemical engineering ,Acetone - Abstract
Here, we show the effect of water–organic (acetone, tert-butyl alcohol, and isopropanol) cosolvents on nucleation and anisotropic crystal growth of solution-synthesized ZnO nanowires. The addition of organic solution does not alter the face-selective crystal growth nature but significantly promotes the crystal growth of both length and diameter of the nanowires. Systematic investigations reveal that a variation of the relative dielectric constant in the cosolvent can rigorously explain the observed effect of the water–organic cosolvent on the ZnO nanowire growth via the degree of supersaturation for the nucleation. The difference between acetone, tert-butyl alcohol, and isopropanol on the cosolvent effect can be interpreted in terms of a local solvent-sorting effect.
- Published
- 2019
38. Paper-Based Disposable Molecular Sensor Constructed from Oxide Nanowires, Cellulose Nanofibers, and Pencil-Drawn Electrodes
- Author
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Masaki Kanai, Akihide Inoue, Chen Wang, Yintong Huang, Kojiro Uetani, Hong Yan, Guozhu Zhang, Hirotaka Koga, Takeshi Yanagida, Tsunaki Takahashi, Kazuki Nagashima, Yong He, and Masaya Nogi
- Subjects
Cellulose nanofiber ,Materials science ,Nanowire ,Oxide ,Nanotechnology ,02 engineering and technology ,01 natural sciences ,NO2 sensor ,chemistry.chemical_compound ,Paper electronics ,Hardware_GENERAL ,0103 physical sciences ,Hardware_INTEGRATEDCIRCUITS ,General Materials Science ,010302 applied physics ,Nanocomposite ,Molecular sensor ,021001 nanoscience & nanotechnology ,Electrical contacts ,Oxide nanowire ,chemistry ,Nanofiber ,Electrode ,0210 nano-technology ,Wireless sensor network - Abstract
This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acsami.9b01287., Progress toward the concept of "a trillion sensor universe" requires sensor devices to become more abundant, ubiquitous, and be potentially disposable. Here, we report a paper-based disposable molecular sensor device constructed from a nanowire sensor based on common zinc oxide (ZnO), a wood-derived biodegradable cellulose nanofiber paper substrate, and a low-cost graphite electrode. The ZnO nanowire/cellulose nanofiber composite structure is embedded in the surface of the cellulose nanofiber paper substrate via a two-step papermaking process. This structure provides a mechanically robust and efficiently bridged network for the nanowire sensor, while ensuring efficient access to target molecules and allowing reliable electrical contact with electrodes. The as-fabricated paper sensor device with pencil-drawn graphite electrodes exhibits efficient resistance change-based molecular sensing of NO2 as a model gas. The performance of our device is comparable to that of noble metal electrodes. Furthermore, we demonstrate cut-and-paste usability and easy disposal of the sensor device with its uniform in-plane sensing properties. Our strategy offers a disposable molecular sensing platform for use in future sensor network technologies.
- Published
- 2019
39. Oxygen-Induced Reversible Sn-Dopant Deactivation between Indium Tin Oxide and Single-Crystalline Oxide Nanowire Leading to Interfacial Switching
- Author
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Kazuki Nagashima, Masaki Kanai, Naoya Shibata, Guozhu Zhang, Tsunaki Takahashi, Takeshi Yanagida, Hao Zeng, Takuro Hosomi, and Takehito Seki
- Subjects
Materials science ,Dopant ,business.industry ,Nanowire ,Oxide ,02 engineering and technology ,Dopant Activation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Indium tin oxide ,chemistry.chemical_compound ,Semiconductor ,Electrical resistance and conductance ,Chemical engineering ,chemistry ,Electrode ,General Materials Science ,sense organs ,0210 nano-technology ,business - Abstract
An impurity doping in semiconductors is an important irreversible process of manipulating the electrical properties of advanced electron devices. Here, we report an unusual reversible dopant activation/deactivation phenomenon, which emerges at an interface between indium tin oxide (ITO) and single-crystalline oxide channel. We found that the interface electrical resistance between ITO electrodes and single-crystalline oxide nanowire channel can be repeatedly switched between a metallic state and a near-insulative state by applying thermal treatments in air or vacuum. Interestingly, this electrical switching phenomenon disappears when the oxide nanowire changes from the single-crystalline structure to the lithography-defined polycrystalline structure. Atmosphere-controlled annealing experiments reveal that atmospheric oxygen induces repeatable change in the interfacial electrical resistance. Systematic investigations on metal cation species and channel crystallinity demonstrate that the observed electrical switching is related to an interface-specific reversible Sn-dopant activation/deactivation of ITO electrode in contact with a single-crystalline oxide channel.
- Published
- 2020
40. Self-Anti-Stacking 2D Metal Phosphide Loop-Sheet Heterostructures by Edge-Topological Regulation for Highly Efficient Water Oxidation
- Author
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Xiuming Bu, Takuro Hosomi, Tsunaki Takahashi, Zhengxun Lai, Yan Bao, Chuntai Liu, Johnny C. Ho, Jian Lu, Kazuki Nagashima, Quan Quan, Wei Wang, You Meng, and Takeshi Yanagida
- Subjects
Tafel equation ,Materials science ,Phosphide ,Alkaline water electrolysis ,Stacking ,02 engineering and technology ,General Chemistry ,Overpotential ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,0104 chemical sciences ,Anode ,law.invention ,Biomaterials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,law ,Water splitting ,General Materials Science ,0210 nano-technology ,Biotechnology - Abstract
2D metal phosphide loop-sheet heterostructures are controllably synthesized by edge-topological regulation, where Ni2 P nanosheets are edge-confined by the N-doped carbon loop, containing ultrafine NiFeP nanocrystals (denoted as NiFeP@NC/Ni2 P). This loop-sheet feature with lifted-edges prevents the stacking of nanosheets and induces accessible open channels for catalytic site exposure and gas bubble release. Importantly, these NiFeP@NC/Ni2 P hybrids exhibit a remarkable oxygen evolution activity with an overpotential of 223 mV at 20 mA cm-2 and a Tafel slope of 46.1 mV dec-1 , constituting the record-high performance among reported metal phosphide electrocatalysts. The NiFeP@NC/Ni2 P hybrids are also employed as both anode and cathode to achieve an alkaline electrolyzer for overall water splitting, delivering a current density of 10 mA cm-2 with a voltage of 1.57 V, comparable to that of the commercial Pt/C||RuO2 couple (1.56 V). Moreover, a photovoltaic-electrolysis coupling system can as well be effectively established for robust overall water splitting. Evidently, this ingenious protocol would expand the toolbox for designing efficient 2D nanomaterials for practical applications.
- Published
- 2020
41. Monovalent sulfur oxoanions enable millimeter-long single-crystalline h-WO
- Author
-
Guozhu, Zhang, Chen, Wang, Wataru, Mizukami, Takuro, Hosomi, Kazuki, Nagashima, Hideto, Yoshida, Kentaro, Nakamura, Tsunaki, Takahashi, Masaki, Kanai, Takao, Yasui, Yuriko, Aoki, Yoshinobu, Baba, and Takeshi, Yanagida
- Abstract
Here, we discuss a misunderstanding regarding chemical capping, which has intrinsically hindered the extension of the length of hexagonal (h)-WO
- Published
- 2020
42. Correction: Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning
- Author
-
Chaiyanut Jirayupat, Kazuki Nagashima, Takuro Hosomi, Tsunaki Takahashi, Benjarong Samransuksamer, Yosuke Hanai, Atsuo Nakao, Masaya Nakatani, Jiangyang Liu, Guozhu Zhang, Wataru Tanaka, Masaki Kanai, Takao Yasui, Yoshinobu Baba, and Takeshi Yanagida
- Subjects
Materials Chemistry ,Metals and Alloys ,Ceramics and Composites ,General Chemistry ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
Correction for ‘Breath odor-based individual authentication by an artificial olfactory sensor system and machine learning’ by Chaiyanut Jirayupat et al., Chem. Commun., 2022, DOI: https://doi.org/10.1039/D1CC06384G.
- Published
- 2022
43. Nanoscale Pt thin film sensor for accurate detection of ppm level hydrogen in air at high humidity
- Author
-
Ken Uchida, Shinsuke Hoshino, Tsunaki Takahashi, and Takahisa Tanaka
- Subjects
010302 applied physics ,Materials science ,Hydrogen ,Metals and Alloys ,Analytical chemistry ,Humidity ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Oxygen ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Adsorption ,chemistry ,Desorption ,0103 physical sciences ,Materials Chemistry ,Relative humidity ,Electrical and Electronic Engineering ,Thin film ,0210 nano-technology ,Platinum ,Instrumentation - Abstract
Hydrogen is an important biomarker for the human digestive system. However, accurate detection of ppm-level hydrogen in breath is difficult due to the competing detection of high concentration water. We fabricated Pt thin films that respond to hydrogen in air at concentrations as low as 500 ppb. In both dry and humid air, these films have almost identical response to hydrogen, i.e., their resistance decreases linearly with increasing hydrogen concentration regardless of relative humidity. Even at high relative humidity, these Pt thin films can detect ppm-level hydrogen. Furthermore, it was strongly suggested that these films can be applied to low-level hydrogen in the air expired by a healthy human. Based on the chemical kinetics, namely the adsorption and desorption of hydrogen and oxygen, the sensor response is quantitatively described by relating the hydrogen surface coverage to the magnitude of electron scattering at the Pt surface. The proposed model successfully reproduces the effects of hydrogen concentration and time on the sensor response, particularly at hydrogen concentrations below 20 ppm. Based on this model, these Pt thin film sensors have the potential to detect 1 ppm hydrogen in expired air within 30 s.
- Published
- 2018
44. Long-Term Stability of Oxide Nanowire Sensors via Heavily Doped Oxide Contact
- Author
-
Hao Zeng, Takeshi Yanagida, Yong He, Guozhu Zhang, Tsunaki Takahashi, Kazuki Nagashima, and Masaki Kanai
- Subjects
Antimony ,Hot Temperature ,Materials science ,Ultraviolet Rays ,Nitrogen Dioxide ,Nanowire ,Oxide ,Bioengineering ,Nanotechnology ,02 engineering and technology ,Naphthalenes ,010402 general chemistry ,01 natural sciences ,Stability (probability) ,Metal ,chemistry.chemical_compound ,Electric Impedance ,Instrumentation ,Titanium ,Fluid Flow and Transfer Processes ,Nanowires ,Process Chemistry and Technology ,Contact resistance ,Doping ,Oxides ,021001 nanoscience & nanotechnology ,Electrical contacts ,0104 chemical sciences ,chemistry ,visual_art ,visual_art.visual_art_medium ,Degradation (geology) ,Polyethylenes ,0210 nano-technology - Abstract
Long-term stability of a chemical sensor is an essential quality for long-term collection of data related to exhaled breath, environmental air, and other sources in the Internet of things (IoT) era. Although an oxide nanowire sensor has shown great potential as a chemical sensor, the long-term stability of sensitivity has not been realized yet due to electrical degradation under harsh sensing conditions. Here, we report a rational concept to accomplish long-term electrical stability of metal oxide nanowire sensors via introduction of a heavily doped metal oxide contact layer. Antimony-doped SnO2 (ATO) contacts on SnO2 nanowires show much more stable and lower electrical contact resistance than conventional Ti contacts for high temperature (200 °C) conditions, which are required to operate chemical sensors. The stable and low contact resistance of ATO was confirmed for at least 1960 h under 200 °C in open air. This heavily doped oxide contact enables us to realize the long-term stability of SnO2 nanowire s...
- Published
- 2017
45. Impact of Lateral SnO2 Nanofilm Channel Geometry on a 1024 Crossbar Chemical Sensor Array.
- Author
-
Haruka Honda, Tsunaki Takahashi, Yohsuke Shiiki, Hao Zeng, Kentaro Nakamura, Shintaro Nagata, Takuro Hosomi, Wataru Tanaka, Guozhu Zhang, Masaki Kanai, Kazuki Nagashima, Hiroki Ishikuro, and Takeshi Yanagida
- Published
- 2022
- Full Text
- View/download PDF
46. Fabrication of a Robust In2O3 Nanolines FET Device as a Biosensor Platform
- Author
-
Kazuki Nagashima, Quanli Liu, Takeshi Yanagida, Zetao Zhu, Taisuke Shimada, Tsunaki Takahashi, Yoshinobu Baba, and Takao Yasui
- Subjects
Materials science ,Fabrication ,Passivation ,biosensor platform ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Signal ,law.invention ,robust ,field effect transistor ,law ,TJ1-1570 ,Mechanical engineering and machinery ,Electrical and Electronic Engineering ,In2O3 nanolines ,business.industry ,Mechanical Engineering ,Transistor ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Threshold voltage ,Semiconductor ,Control and Systems Engineering ,Optoelectronics ,Field-effect transistor ,0210 nano-technology ,business ,Biosensor - Abstract
Field-effect transistors (FETs) are attractive biosensor platforms for rapid and accurate detection of various analytes through surface immobilization of specific bio-receptors. Since it is difficult to maintain the electrical stability of semiconductors of sensing channel under physiological conditions for long periods, passivation by a stable metal oxide dielectric layer, such as Al2O3 or HfO2, is currently used as a common method to prevent damage. However, protecting the sensing channel by passivation has the disadvantage that the distance between the target and the conductive channel increases, and the sensing signal will be degraded by Debye shielding. Even though many efforts use semiconductor materials directly as channels for biosensors, the electrical stability of semiconductors in the physiological environments has rarely been studied. In this work, an In2O3 nanolines FET device with high robustness in artificial physiological solution of phosphate buffered saline (PBS) was fabricated and used as a platform for biosensors without employing passivation on the sensing channel. The FET device demonstrated reproducibility with an average threshold voltage (VTH) of 5.235 V and a standard deviation (SD) of 0.382 V. We tested the robustness of the In2O3 nanolines FET device in PBS solution and found that the device had a long-term electrical stability in PBS with more than 9 days’ exposure. Finally, we demonstrated its applicability as a biosensor platform by testing the biosensing performance towards miR-21 targets after immobilizing the phosphonic acid terminated DNA probes. Since the surface immobilization of multiple bioreceptors is feasible, we demonstrate that the robust In2O3 FET device can be an excellent biosensor platform for biosensors.
- Published
- 2021
47. True Vapor–Liquid–Solid Process Suppresses Unintentional Carrier Doping of Single Crystalline Metal Oxide Nanowires
- Author
-
Zetao Zhu, Takeshi Yanagida, Mickaël Boudot, Katsuichi Kanemoto, Kazuki Nagashima, Masaki Kanai, Tsunaki Takahashi, Masaru Suzuki, Yong He, Takehito Seki, Hiroshi Anzai, Naoya Shibata, and Guozhu Zhang
- Subjects
Materials science ,Oxide ,Nanowire ,Bioengineering ,Nanotechnology ,Crystal growth ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Electrical resistivity and conductivity ,General Materials Science ,Electrical measurements ,Vapor–liquid–solid method ,business.industry ,Mechanical Engineering ,Doping ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Semiconductor ,chemistry ,Optoelectronics ,0210 nano-technology ,business - Abstract
Single crystalline nanowires composed of semiconducting metal oxides formed via a vapor–liquid–solid (VLS) process exhibit an electrical conductivity even without an intentional carrier doping, although these stoichiometric metal oxides are ideally insulators. Suppressing this unintentional doping effect has been a challenging issue not only for metal oxide nanowires but also for various nanostructured metal oxides toward their semiconductor applications. Here we demonstrate that a pure VLS crystal growth, which occurs only at liquid–solid (LS) interface, substantially suppresses an unintentional doping of single crystalline SnO2 nanowires. By strictly tailoring the crystal growth interface of VLS process, we found the gigantic difference of electrical conduction (up to 7 orders of magnitude) between nanowires formed only at LS interface and those formed at both LS and vapor–solid (VS) interfaces. On the basis of investigations with spatially resolved single nanowire electrical measurements, plane-view el...
- Published
- 2017
48. Mechanistic Approach for Long-Term Stability of a Polyethylene Glycol-Carbon Black Nanocomposite Sensor.
- Author
-
Wenjun Li, Kazuki Nagashima, Takuro Hosomi, Chen Wang, Yosuke Hanai, Atsuo Nakao, Atsushi Shunori, Jiangyang Liu, Guozhu Zhang, Tsunaki Takahashi, Wataru Tanaka, Masaki Kanai, and Takeshi Yanagida
- Published
- 2022
- Full Text
- View/download PDF
49. Redox-Inactive CO
- Author
-
Kentaro, Nakamura, Tsunaki, Takahashi, Takuro, Hosomi, Takehito, Seki, Masaki, Kanai, Guozhu, Zhang, Kazuki, Nagashima, Naoya, Shibata, and Takeshi, Yanagida
- Abstract
Emerging interactive electronics for the Internet of Things era inherently require the long-term stability of semiconductor devices exposed to air. Nanostructured metal oxides are promising options for such atmospherically stable semiconductor devices owing to their inherent stability in air. Among various oxide nanostructures, ZnO nanowires have been the most intensively studied for electrical and optical device applications. Here, we demonstrate a strategy for achieving the atmospheric electrical stability of ZnO nanowire devices. Although the chemically active oxygen and water in air are strong candidates for affecting the electrical stability of nanoscale metal oxides, we found that the ppm-level redox-inactive CO
- Published
- 2019
50. Low-Power and ppm-Level Detection of Gas Molecules by Integrated Metal Nanosheets
- Author
-
Hiroki Ishikuro, Kohei Tatehora, Yohsuke Shiiki, Takeshi Yanagida, Tadahiro Kuroda, Ryota Shimizu, K. Tabuchi, Takahisa Tanaka, Shuya Nakagawa, Tsunaki Takahashi, and Ken Uchida
- Subjects
010302 applied physics ,Materials science ,Hydrogen ,business.industry ,chemistry.chemical_element ,01 natural sciences ,Catalysis ,Power (physics) ,Sensor array ,chemistry ,0103 physical sciences ,Optoelectronics ,Molecule ,business ,Joule heating ,Thermal energy ,Nanosheet - Abstract
Ppm-level hydrogen and ammonia in air were recognized by low-power, integrated sensors consisting of catalytic metal nanosheets. Thermal energy necessary for catalytic reactions were given by Joule heating not by external heaters. The ther-mal-aware design of sensors reduces the power consumption to 0.14 mW. The low-power and small-area properties enable large-scale, on-chip integration of molecular sensors, which will be useful in IoT era. A sensor array was successfully connected to a platform with wireless connectivity.
- Published
- 2019
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