Faculty Profiles - OHNO, Yutaka

Papers - OHNO, Yutaka

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（総説）ウェアラブルデバイスへの実装を目指した柔軟な摩擦帯電型エネルギーハーベスタ Invited Reviewed

松永正広，大野雄高

繊維機械学会誌「せんい」 Vol. 76 ( 9 ) page： 479 - 486 2023.9

Electrochemical reservoir computing based on surface-functionalized carbon nanotubes Reviewed International journal

T. Shingu, H. Uchiyama, T. Watanabe, and Y. Ohno

Carbon Vol. 214 page： 118344 2023.8

Artificial-intelligence-assisted mass fabrication of nanocantilevers from randomly positioned single carbon nanotubes Reviewed Open Access

Y. Tadokoro, K. Funayama, K. Kawano, A. Miura, J. Hirotani, Y. Ohno, and H. Tanaka

Microsyst. Nanoeng. Vol. 9 page： Art. No. 32 2023.3

Key factors for ultra-high on/off ratio thin-film transistors using as-grown carbon nanotube networks Reviewed International coauthorship Open Access

Y. Sun, P. Li, E. I. Kauppinen, D.-M. Sun, and Y. Ohno

RSC Advances Vol. 12 page： 16291 - 16295 2022.6

In situ monitoring of the electrical property of carbon nanotube thin film in floating catalyst chemical vapor deposition Reviewed Open Access

Oshima H., Iwase K., Ohno Y.

Japanese Journal of Applied Physics Vol. 61 ( 3 ) 2022.3

Authorship：Last author Language：English Publisher：Japanese Journal of Applied Physics

In floating catalyst chemical vapor deposition (FCCVD), when a carbon nanotube (CNT) network film is produced by filter collection, the film thickness is adjusted by controlling the collection time. However, even with consistent synthesis parameters, the synthesis condition in FCCVD changes constantly depending on the carbon and catalyst adhesion to the inner wall of the reaction tube. Thus, the rate of synthesis changes, making it difficult to obtain the target film thickness repeatedly and stably. We propose a method of monitoring CNT film thickness and percolation threshold by the in situ measurement of the electrical impedance during the deposition. The time evolution of the measured impedance is reproducible by an equivalent electrical circuit simulation.

DOI： 10.35848/1347-4065/ac4a5e

Open Access

Scopus

PMMA/Al<inf>2</inf>O<inf>3</inf>bilayer passivation for suppression of hysteresis in chemically doped carbon nanotube thin-film transistors Reviewed

Tan F.W., Hirotani J., Kishimoto S., Ohno Y.

Japanese Journal of Applied Physics Vol. 61 ( 3 ) 2022.3

Authorship：Last author,　Corresponding author Language：English Publisher：Japanese Journal of Applied Physics

Hysteresis is usually present in carbon nanotube thin-film transistors exposed to air due to adsorbed water and oxygen molecules. Thus, it is desirable to passivate the device from these environmental effects and provide an air-stable platform for chemical doping to tune the threshold voltages. Here, we demonstrate p- and n-doped carbon nanotube transistors with suppressed hysteresis using bilayer stacking of poly(methyl methacrylate) and aluminum oxide (Al2O3) passivation layers using a low-temperature process suitable for flexible substrates. The results show that the bilayer passivation layers achieved reduced hysteresis to be 2.25% of applied gate voltage at low operation voltage as 2 V.

DOI： 10.35848/1347-4065/ac5264

Scopus

Temperature dependence of Raman shift in defective single-walled carbon nanotubes Reviewed

Endo Masanori, Uchiyama Haruki, Ohno Yutaka, Hirotani Jun

APPLIED PHYSICS EXPRESS Vol. 15 ( 2 ) 2022.2

Authorship：Corresponding author Language：English Publisher：Applied Physics Express

Raman scatterings of both pristine and defective single-walled carbon nanotubes were measured. Defects on carbon nanotubes (CNTs) were induced by UV/O3 treatment, and the correlation between the temperature dependence of the Raman shift of the G-band and the crystallinity of CNTs was investigated. In the temperature range of 250-600 K, a gradual negative change in the slope was observed; the linear shift of the Raman G-band frequency with respect to temperature increased as the crystallinity deteriorated. This phenomenon is attributed to the increase in the fourth-order phonon-phonon scattering interaction resulting from the induced defects.

DOI： 10.35848/1882-0786/ac4678

Web of Science

Scopus

In-plane dual-electrode triboelectric nanogenerator based on differential surface functionalization Reviewed

Matsunaga M., Hirotani J., Ohno Y.

Applied Physics Express Vol. 15 ( 2 ) 2022.2

Authorship：Last author,　Corresponding author Language：English Publisher：Applied Physics Express

Stretchable triboelectric nanogenerators (s-TENGs) are promising power sources for self-powered wearable electronics. Conventional single-electrode s-TENGs require an external ground electrode to form a closed circuit. We propose an in-plane dual-electrode s-TENG based on differential surface functionalization to eliminate the external ground electrode. The s-TENG comprises fully stretchable materials such as carbon nanotube thin films and elastomers. The top surface of the elastomer was functionalized to produce a difference in electronegativity between the two electrode regions. A high output power density of 3.5 W m-2 was obtained by tapping the two electrode regions by hand.

DOI： 10.35848/1882-0786/ac4d07

Scopus

Carbon Nanotube-Based Nanomechanical Receiver for Digital Data Transfer Reviewed Open Access

Funayama K., Tanaka H., Hirotani J., Shimaoka K., Ohno Y., Tadokoro Y.

ACS Applied Nano Materials Vol. 4 ( 12 ) 2021.12

Language：English Publisher：ACS Applied Nano Materials

The evolution of carbon nanomaterials can provide tremendous advantages in sensing, computation, and functional materials. A carbon nanotube (CNT) has outstanding thermal and electrical conductivity features and is one of the most promising nanoscale carbon materials. It has a hardness of up to 1 TPa. Exploiting these features, nanomechanical systems with CNTs have been reported to achieve ultrasensitive sensors for mass, force, and electromagnetic waves owing to their outstanding elastic and electric properties. Some research groups have attempted to achieve digital data transfer in potential nanoscale wireless terminals with carbon nanomaterials. Although conceptual demonstrations have been reported, the fundamental capability of the transfer, particularly in the presence of noise, is yet to be explained. Here, we experimentally demonstrate for the first time that an ultrasmall digital receiver with a nanomechanical nanoantenna can transfer a vast amount of digital data, up to 1 Mbit, even in the presence of noise. We successfully transfer a digital image data with 393 216 bits. This demonstration proves that the data-transfer capability is close to the theoretical limit established in information theory and channel capacity. This small but robust nanomechanical receiver will contribute to the forthcoming data-oriented age of Internet of things (IoT)- and artificial intelligence (AI)-based systems.

DOI： 10.1021/acsanm.1c02563

Scopus

Stretchable triboelectric nanogenerator based on carbon nanotubes Invited Reviewed

MATSUNAGA Masahiro, KAWAGUCHI Atsushi, OHNO Yutaka

Oyo Buturi Vol. 90 ( 11 ) page： 684 - 688 2021.11

Authorship：Last author,　Corresponding author Language：Japanese Publisher：The Japan Society of Applied Physics

<p>Triboelectric energy harvesters are expected as a power source for self-powered wearable devices since they can generate electricity from the low-frequency motion of the human body. For wearable device applications, high stretchability is required to follow the dynamic three-dimensional surface of the human body. We have realized a stretchable sheet-shaped triboelectric energy harvester with a high output and elasticity. The high output has been achieved by a fluorine plasma treatment for the surface of the dielectric layer. We demonstrate a self-powered signal transmitter and LED-embedded gloves, exploiting the characteristics of the harvester. Furthermore, we propose a highly efficient intermittent operation circuit to drive electronic devices, using a small amount of power generated by the harvester. Our study can contribute to solve the problem of power source limitations in wearable electronics.</p>

DOI： 10.11470/oubutsu.90.11_684

CiNii Research

Dynamic Range Enhancement via Linearized Output in Nanoelectromechanical Systems by Combining High-Order Harmonics Reviewed International journal

K. Funayama, H. Tanaka, J. Hirotani, K. Shimaoka, Y. Ohno, and Y. Tadokoro

IEEE Trans. on Circuits and Systems II Vol. 68 ( 10 ) page： 3251 - 3255 2021.10