研究者詳細 - 大野　雄高

論文 - 大野　雄高

分割表示 339 件中 21 - 40 件目／全件表示 >>

Fabrication of Carbon Nanotube Thin Films for Flexible Transistors by Using a Cross-Linked Amine Polymer 査読有り国際誌

Matsumoto Kaisei, Ueno Kazuki, Hirotani Jun, Ohno Yutaka, Omachi Haruka

CHEMISTRY-A EUROPEAN JOURNAL 26 巻 ( 28 ) 頁： 6118 - 6121 2020年5月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemistry - A European Journal

Owing to their remarkable properties, single-walled carbon nanotube thin-film transistors (SWCNT-TFTs) are expected to be used in various flexible electronics applications. To fabricate SWCNT channel layers for TFTs, solution-based film formation on a self-assembled monolayer (SAM) covered with amino groups is commonly used. However, this method uses highly oxidized surfaces, which is not suitable for flexible polymeric substrates. In this work, a solution-based SWCNT film fabrication using methoxycarbonyl polyallylamine (Moc-PAA) is reported. The NH2-terminated surface of the cross-linked Moc-PAA layer enables the formation of highly dense and uniform SWCNT networks on both rigid and flexible substrates. TFTs that use the fabricated SWCNT thin film exhibited excellent performance with small variations. The presented simple method to access SWCNT thin film accelerates the realization of flexible nanoelectronics.

DOI： 10.1002/chem.202000228

High output voltage generation of over 5 V from liquid motion on single-layer MoS2 査読有り国際誌

Aji Adha Sukma, Nishi Ryohei, Ago Hiroki, Ohno Yutaka

NANO ENERGY 68 巻 2020年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nano Energy

Water stores a large amount of clean energy in its dynamic forms. Owing to the wide availability of water and the rising demand for clean energy sources, the direct electricity generation from liquid motion by low-dimensional materials such as graphene has gained much interest. Electricity generation is induced by the motion of an electric double layer at the interface between the liquid droplet and solid surface. However, the output voltage with materials such as graphene is still limited to several hundred millivolts. In this report, we present a large-area single-layer MoS2 film grown by chemical vapor deposition as a nanogenerator, which is capable of generating a large output voltage of more than 5 V from the motion of an aqueous NaCl droplet. Our findings indicate that the high shunt resistance of MoS2 results in a large generated voltage. Furthermore, we demonstrate the possibility to scale up the MoS2 nanogenerator by arranging them in series and parallel connections, which respectively increase the output voltage and current, with a three-times increase with an array of three MoS2 nanogenerators. Our work opens the application of single-layer MoS2 for harvesting electricity from the dynamic movement of liquid, such as the capability to harvest ocean wave energy, which is also demonstrated here.

DOI： 10.1016/j.nanoen.2019.104370

High-output, transparent, stretchable triboelectric nanogenerator based on carbon nanotube thin film toward wearable energy harvesters

Matsunaga Masahiro, Hirotani Jun, Kishimoto Shigeru, Ohno Yutaka

NANO ENERGY 67 巻 2020年1月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nano Energy

Self-powered electronics can improve wearable health monitoring systems. Triboelectric generation, a type of energy harvesting technology, is a promising candidate as power source for wearable devices by generating electricity from body motion. For wearable energy harvesters, stretching is required for adaptation to dynamic three-dimensional body motions, and sufficient output power should be delivered for driving electronic devices. However, the currently demonstrated output power remains insufficient for using stretchable triboelectric generation in practice. We propose high-output (8 W/m2), stretchable triboelectric generators based on transparent carbon nanotube thin films. We realize high output by the surface treatment with fluorine plasma as well as stretchability by scalable and cost-effective spray coated carbon nanotube thin films. The carbon nanotube films also provide excellent scalability, optical transparency (95% transmittance), and durability under large deformations of tensile strain up to 80%. We also demonstrate applications to self-powered optical wireless communication sheets and gloves, where blue light emitting diodes are embedded in the triboelectric nanogenerator sheet and wired using stretchable carbon nanotube films. Our stretchable energy harvesting sheets can contribute to solve major problems in wearable electronics (i.e., power source limitations) at low cost.

DOI： 10.1016/j.nanoen.2019.104297

Fast and Ultraclean Approach for Measuring the Transport Properties of Carbon Nanotubes

Wei Nan, Laiho Patrik, Khan Abu Taher, Hussain Aqeel, Lyuleeva Alina, Ahmed Saeed, Zhang Qiang, Liao Yongping, Tian Ying, Ding Er-Xiong, Ohno Yutaka, Kauppinen Esko I.

ADVANCED FUNCTIONAL MATERIALS 30 巻 ( 5 ) 2020年1月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Advanced Functional Materials

In this work, a fast approach for the fabrication of hundreds of ultraclean field-effect transistors (FETs) is introduced, using single-walled carbon nanotubes (SWCNTs). The synthesis of the nanomaterial is performed by floating-catalyst chemical vapor deposition, which is employed to fabricate high-performance thin-film transistors. Combined with palladium metal bottom contacts, the transport properties of individual SWCNTs are directly unveiled. The resulting SWCNT-based FETs exhibit a mean field-effect mobility, which is 3.3 times higher than that of high-quality solution-processed CNTs. This demonstrates that the hereby used SWCNTs are superior to comparable materials in terms of their transport properties. In particular, the on–off current ratios reach over 30 million. Thus, this method enables a fast, detailed, and reliable characterization of intrinsic properties of nanomaterials. The obtained ultraclean SWCNT-based FETs shed light on further study of contamination-free SWCNTs on various metal contacts and substrates.

DOI： 10.1002/adfm.201907150

Dependence of enhancement factor on electrode size for field emission current from carbon nanotube on silicon wafer

Funayama Keita, Tanaka Hiroya, Hirotani Jun, Shimaoka Keiichi, Ohno Yutaka, Tadokoro Yukihiro

NANOTECHNOLOGY 30 巻 ( 42 ) 頁： 425201 2019年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Nanotechnology

This work studies the enhancement factor associated with a current emitted from a multi-wall carbon nanotube to an extremely small counter electrode. The experimental data show that the field enhancement factor increases by 1.15 times when the width of the counter electrode increases from 50 to 200 nm. To better understand this enhancement effect, field intensities at the emitter surface are numerically simulated. The experimental work and simulations demonstrate that the observed field enhancement results from increases in the capacitance between the emitter and counter electrode. In addition, corrugated counter electrodes are found to greatly affect both the capacitance and enhancement factor. This is because the corrugation of the anode surface raises the capacitance and thus provides a higher current. We experimentally show that an effective surface area enlargement of 1.67 times due to the corrugation provides a 1.06-fold increase of the enhancement factor. These results should assist in the future development of field emission devices based on semiconductor fabrication processes.

DOI： 10.1088/1361-6528/ab33c8

Aqueous two-phase extraction of semiconducting single-wall carbon nanotubes with isomaltodextrin and thin-film transistor applications

Omachi Haruka, Komuro Tomohiko, Matsumoto Kaisei, Nakajima Minako, Watanabe Hikaru, Hirotani Jun, Ohno Yutaka, Shinohara Hisanori

APPLIED PHYSICS EXPRESS 12 巻 ( 9 ) 2019年9月

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

Semiconducting single-wall carbon nanotubes (s-SWCNTs) are promising materials with potential applications in thin-film transistors (TFTs). However, separation techniques are required to obtain highly enriched s-SWCNTs since conventional as-grown SWCNTs are a mixture of 70% semiconducting and 30% metallic SWCNTs. Here, we developed a rapid single-step aqueous two-phase extraction of high-purity s-SWCNTs using isomaltodextrin, which is a cost-effective polysaccharide that contains a large amount of α-1,6-glucosidic linkages. We also succeeded in fabricating high-density uniform films directly from the high-purity s-SWCNT extract. Fabricated TFTs exhibited an excellent on/off ratio, carrier mobility, and on-current density.

DOI： 10.7567/1882-0786/ab369e

Effects of HLA mismatch on cytomegalovirus reactivation in cord blood transplantation

Yokoyama H., Kanda J., Kato S., Kondo E., Maeda Y., Saji H., Takahashi S., Onizuka M., Onishi Y., Ozawa Y., Kanamori H., Ishikawa J., Ohno Y., Ichinohe T., Takanashi M., Kato K., Atsuta Y., Kanda Y.

Bone Marrow Transplantation 54 巻 ( 7 ) 頁： 1004 - 1012 2019年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Bone Marrow Transplantation

Although human leukocyte antigen (HLA) mismatch is often thought to be associated with a high incidence of cytomegalovirus (CMV) reactivation, it is not clear whether this process is mediated by HLA mismatch or other factors, such as acute graft-versus-host disease (aGVHD). Here we focused on cord blood transplantation (CBT) and examined the effects of HLA mismatch on the incidence of CMV reactivation while minimizing the effects of aGVHD. In a multivariate analysis considering aGVHD as a time-dependent covariate, a significant effect on the incidence of CMV reactivation was noted for HLA disparity (hazard ratio [HR]: 0.54 for 8/8 match compared with 3-allele mismatch) and development of aGVHD (HR: 1.26). Next, in an analysis excluding cases that developed aGVHD, the incidences of CMV reactivation for 8/8 match and 1-allele mismatch were low compared with those for other mismatches. These findings were supported by the multivariate analysis (HR: 0.49 for 8/8 match and 0.64 for 1-allele mismatch compared with 3-allele mismatch). Together, these results suggested that HLA mismatch was involved in CMV reactivation and was associated with high morbidity of opportunistic infection after CBT.

DOI： 10.1038/s41409-018-0369-0

Electrical property measurement of two-dimensional hole-gas layer on hydrogen-terminated diamond surface in vacuum-gap-gate structure

Inaba Masafumi, Kawarada Hiroshi, Ohno Yutaka

APPLIED PHYSICS LETTERS 114 巻 ( 25 ) 頁： 253504 2019年6月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Publishing

Hydrogen-terminated diamond metal-insulator-semiconductor field-effect transistors are candidates for power devices that require a high breakdown field and stable, high-frequency operation. A two-dimensional hole-gas layer can form on H-terminated diamond surfaces. To understand the electrical properties of bare H-terminated diamond surfaces, we investigate the surface impurities on a H-terminated diamond surface in a vacuum-gap gate structure, which uses a H-terminated diamond channel and a vacuum gap as gate dielectrics. To obtain a bare surface without surface adsorbate, the device is annealed in a vacuum. The transconductance is increased by removing adsorbates. The mobility and interface-state density at the H-terminated diamond surface with no adsorbates are 25 cm2 V-1 s-1 and 1 × 1012 cm-2 eV-1, respectively.

DOI： 10.1063/1.5099395

Operando Analysis of Electron Devices Using Nanodiamond Thin Films Containing Nitrogen-Vacancy Centers

Uchiyama Haruki, Saijo Soya, Kishimoto Shigeru, Ishi-Hayase Junko, Ohno Yutaka

ACS OMEGA 4 巻 ( 4 ) 頁： 7459 - 7466 2019年4月

記述言語：日本語出版者・発行元：ACS Omega

Operando analysis of electron devices provides key information regarding their performance enhancement, reliability, thermal management, etc. For versatile operando analysis of devices, the nitrogen-vacancy (NV) centers in diamonds are potentially useful media owing to their excellent sensitivity to multiple physical parameters. However, in single crystal diamond substrates often used for sensing applications, placing NV centers in contiguity with the active channel is difficult. This study proposes an operando analysis method using a nanodiamond thin film that can be directly formed onto various electron devices by a simple solution-based process. The results of noise analysis of luminescence of the NV centers in nanodiamonds show that the signal-to-noise ratio in optically detected magnetic resonance can be drastically improved by excluding the large 1/f noise of nanodiamonds. Consequently, the magnetic field and increase in temperature caused by the device current could be simultaneously measured in a lithographically fabricated metal microwire as a test device. Moreover, the spatial mapping measurement is demonstrated and shows a similar profile with the numerical calculation.

DOI： 10.1021/acsomega.9b00344

Graft-versus-MDS effect after unrelated cord blood transplantation: a retrospective analysis of 752 patients registered at the Japanese Data Center for Hematopoietic Cell Transplantation

Ishiyama K., Aoki J., Itonaga H., Uchida N., Takahashi S., Ohno Y., Matsuhashi Y., Sakura T., Onizuka M., Miyakoshi S., Takanashi M., Fukuda T., Atsuta Y., Nakao S., Miyazaki Y.

Blood Cancer Journal 9 巻 ( 3 ) 2019年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Blood Cancer Journal

Allogeneic hematopoietic stem cell transplantation is the sole curative therapy for myelodysplastic syndrome (MDS). However, there is concern regarding graft failure and relapse in patients who undergo cord blood transplantation (CBT). We conducted a retrospective study of the CBT outcomes in MDS patients using the Japanese Data Center for Hematopoietic Cell Transplantation database. Seven hundred fifty-two de novo MDS patients of ≥18 years of age (median, 58 years) undergoing their first CBT between 2001 and 2015 were examined. Two-thirds of the patients were male, and were RAEB. The cumulative incidences of neutrophil and platelet engraftment at day 100 were 77 and 59%, respectively. The 3-year overall survival (OS) was 41% and the median survival of the patients was 1.25 years. A multivariate analysis of pre-transplant variables showed that the age, gender, cytogenetic subgroups, number of RBC transfusions, HCT-CI and year of CBT significantly influenced the outcome. The cumulative incidence of acute graft-versus-host disease (aGVHD) and chronic GVHD (cGVHD) was 32 and 21%, respectively. A survival benefit was observed in patients who developed cGVHD, but not aGVHD. Our results suggest that CBT is an acceptable alternative graft and that a graft-versus-MDS effect can be expected, especially in patients who develop cGVHD.

DOI： 10.1038/s41408-019-0192-x

Highly Uniform, Flexible Microelectrodes Based on the Clean Single-Walled Carbon Nanotube Thin Film with High Electrochemical Activity

Nguyen Xuan Viet, Kishimoto Shigeru, Ohno Yutaka

ACS APPLIED MATERIALS & INTERFACES 11 巻 ( 6 ) 頁： 6389 - 6395 2019年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：ACS Applied Materials and Interfaces

Electrochemical sensors based on carbon nanotubes (CNTs) have great potential for use in wearable or implantable biomedical sensor applications because of their excellent mechanical flexibility and biocompatibility. However, the main challenge associated with CNT-based sensors is their uniform and reproducible fabrication on the flexible plastic film. Here, we introduce and demonstrate a highly reliable technique to fabricate flexible CNT microelectrodes on a plastic film. The technique involves a process whereby the CNT film is formed by the dry transfer process based on the floating-catalyst chemical vapor deposition. An oxide protection layer, which is used to cover the CNT thin film during the fabrication process, minimizes contamination of the surface. The fabricated flexible CNT microelectrodes show almost ideal electrochemical characteristics for microelectrodes with the average value of the quartile potentials, ΔE = |E 3/4 - E 1/4 |, being 60.4 ± 2.9 mV for the 28 electrodes, while the ideal value of ΔE = 56.4 mV. The CNT microelectrodes also showed enhanced resistance to surface fouling during dopamine oxidation in comparison to carbon fiber and gold microelectrodes; the degradation of the oxidation current after 10 consecutive cycles were 1.8, 8.3, and 13.9% for CNT, carbon fiber, and gold microelectrodes, respectively. The high-sensitivity detection of dopamine is also demonstrated with differential-pulse voltammetry, with a resulting limit of detection of ∼50 nM. The reliability, uniformity, and sensitivity of the present CNT microelectrodes provide a platform for flexible electrochemical sensors.

DOI： 10.1021/acsami.8b19252

Enhancement of the electron transfer rate in carbon nanotube flexible electrochemical sensors by surface functionalization

Nishimura Keita, Ushiyama Takuya, Viet Nguyen Xuan, Inaba Masafumi, Kishimoto Shigeru, Ohno Yutaka

ELECTROCHIMICA ACTA 295 巻頁： 157 - 163 2019年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Electrochimica Acta

Thin films of single-walled carbon nanotubes (SWNTs) possess high potential for use in flexible electrochemical sensors in wearable medical devices. However, the electrochemical activity of such materials is not yet fully understood. We studied the enhancement in electrochemical activity of SWNT-based flexible electrochemical sensors. To exclude the effect of surface contaminations from the fabrication processes on the electrochemical activity, we introduced the dry process for high-quality and clean SWNT film formation and the clean device fabrication process with a protective layer. So-fabricated SWNT electrodes exhibited a low electron transfer rate. Electrochemical functionalization with an H2SO4 solution successfully enhanced the electrochemical activity of the SWNT electrode for the inner sphere probes such as [Fe(CN)6]4−/3−. This method is quite gentle and controllable, but also effective at increasing the electron transfer rate without either degrading the potential window. We found out that there was a correlation between the electron transfer rate and the amount of defects evaluated from Raman scattering spectroscopy. XPS analysis showed that the functionalization process introduced C–O and C[dbnd]O species, suggesting that these species constituted active sites for inner sphere probes. The electrochemical functionalization was also effective for enhancing the limit of detection in dopamine detection with the flexible SWNT electrode. The limit of detection was ∼100 nM for functionalized electrode whereas it was ∼1 μM for as-fabricated electrodes.

DOI： 10.1016/j.electacta.2018.10.147

Origins of the variability of the electrical characteristics of solution-processed carbon nanotube thin-film transistors and integrated circuits

Hirotani Jun, Kishimoto Shigeru, Ohno Yutaka

NANOSCALE ADVANCES 1 巻 ( 2 ) 頁： 636 - 642 2019年2月

記述言語：日本語出版者・発行元：Nanoscale Advances

Carbon nanotube (CNT) thin-film transistors based on solution processing have great potential for use in future flexible and wearable device technologies. However, the considerable variability of their electrical characteristics remains a significant obstacle to their practical use. In this work, we investigated the origins of the variability of these electrical characteristics by performing statistical analysis based on spatial autocorrelation and Monte Carlo simulation. The spatial autocorrelation of the on-current decreased with increasing distance on the order of millimetres, showing that macroscopic non-uniformity of the CNT density was one of the causes of the characteristic variability. In addition, even in the local regime where the macroscopic variability is negligible, the variability was greater than that expected based on the Monte Carlo simulation. The CNT aggregation could be attributed to microscopic variability. We also investigated the variability of the properties of integrated circuits such as inverters and ring oscillators fabricated on flexible plastic film. All of the inverters worked well, and their threshold voltage variations were fairly small. As the number of stages in the ring oscillator increased, the yield decreased, although the oscillation frequency variability improved.

DOI： 10.1039/c8na00184g

Carbon Nanotube Thin Films for High-Performance Flexible Electronics Applications

Hirotani Jun, Ohno Yutaka

TOPICS IN CURRENT CHEMISTRY 377 巻 ( 1 ) 頁： 3 2019年2月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Topics in Current Chemistry

Carbon nanotube thin films have attracted considerable attention because of their potential use in flexible/stretchable electronics applications, such as flexible displays and wearable health monitoring devices. Due to recent progress in the post-purification processes of carbon nanotubes, high-purity semiconducting carbon nanotubes can be obtained for thin-film transistor applications. One of the key challenges for the practical use of carbon nanotube thin-film transistors is the thin-film formation technology, which is required for achieving not only high performance but also uniform device characteristics. In this paper, after describing the fundamental thin-film formation techniques, we review the recent progress of thin-film formation technologies for carbon nanotube-based flexible electronics.

DOI： 10.1007/s41061-018-0227-y

Noise Modeling in Field Emission and Evaluation of the Nano-Receiver in Terms of Temperature

Funayama Keita, Tanaka Hiroya, Hirotani Jun, Shimaoka Keiichi, Ohno Yutaka, Tadokoro Yukihiro

IEEE ACCESS 7 巻頁： 57820 - 57828 2019年

記述言語：日本語出版者・発行元：IEEE Access

The field-emission phenomenon is exploited in a broad variety of applications and systems. Previous studies have reported that the current induced by field emission strongly and inherently depend on the temperature. This dependence enhances the noise in the current, which results in performance degradation in, for example, signal detection and communications in nanoscale receivers. In this paper, a mathematical model is presented for the suppression of the noise based on its probability density. Our experiment and analysis revealed that the density follows a Gaussian distribution, and the dependence on temperature is observed to be exponential. This result is intriguing because in the field of signal processing and communication, the influence of temperature is often considered with a noiseerature model, namely, linear dependence. Using our derived model, we theoretically evaluated the communication performance of a nanoscale receiver; owing to the exponential dependence on temperature, severe performance degradation was found with increasing temperature. This means that, as field-emission technology continues to be developed, the temperature should be kept low, for example, at room temperature, to secure the reliability of nanoscale communication devices.

DOI： 10.1109/ACCESS.2019.2913692

Stochastic Optimal Control to Minimize the Impact of Manufacturing Variations on Nanomechanical Systems

Ito Yuji, Funayama Keita, Hirotani Jun, Ohno Yutaka, Tadokoro Yukihiro

IEEE ACCESS 7 巻頁： 171195 - 171205 2019年

記述言語：日本語出版者・発行元：IEEE Access

This paper presents a control method intended to suppress the effects of manufacturing variations on nanomechanical systems. Often, the resonance characteristics of nanoscale devices are inconsistent, due to unavoidable variations in the fabrication process. This is important because resonant vibrations enhance the sensitivities of the devices. As such, the sensitivities of these systems can be degraded if the device characteristics are not identified. To address this fundamental problem, this paper presents a multidisciplinary method based on control theory, nanotechnology, and communication technology. A stochastic optimal feedback controller is employed to enhance an average sensitivity by regarding the variations as stochastic parameters. This method is applied to nanoscale receivers that detect transmitted binary data based on binary phase-shift keying in communication systems. The proposed method controls the vibrations of carbon nanotubes (CNTs) that serve as the antennas of the receiver. The proposed method is demonstrated via a numerical simulation using nanoscale receivers with the manufacturing variation. The simulation based on experimental data obtained from CNTs shows that the average performance of the devices is enhanced.

DOI： 10.1109/ACCESS.2019.2955697

An interdigitated electrode with dense carbon nanotube forests on conductive supports for electrochemical biosensors

Sugime Hisashi, Ushiyama Takuya, Nishimura Keita, Ohno Yutaka, Noda Suguru

ANALYST 143 巻 ( 15 ) 頁： 3635 - 3642 2018年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Analyst

A highly sensitive interdigitated electrode (IDE) with vertically aligned dense carbon nanotube forests directly grown on conductive supports was demonstrated by combining UV lithography and a low temperature chemical vapor deposition process (470 °C). The cyclic voltammetry (CV) measurements of K4[Fe(CN)6] showed that the redox current of the IDE with CNT forests (CNTF-IDE) reached the steady state much more quickly compared to that of conventional gold IDE (Au-IDE). The performance of the CNTF-IDE largely depended on the geometry of the electrodes (e.g. width and gap). With the optimum three-dimensional electrode structure, the anodic current was amplified by a factor of ∼18 and ∼67 in the CV and the chronoamperometry measurements, respectively. The collection efficiency, defined as the ratio of the cathodic current to the anodic current at steady state, was improved up to 97.3%. The selective detection of dopamine (DA) under the coexistence of l-ascorbic acid with high concentration (100 μM) was achieved with a linear range of 100 nM-100 μM, a sensitivity of 14.3 mA mol-1 L, and a limit of detection (LOD, S/N = 3) of 42 nM. Compared to the conventional carbon electrodes, the CNTF-IDE showed superior anti-fouling property, which is of significant importance for practical applications, with a negligible shift of the half-wave potential (ΔE1/2 < 1.4 mV) for repeated CV measurements of DA at high concentration (100 μM).

DOI： 10.1039/c8an00528a

Non-coherent detection of digitally phase-modulated signals with carbon nanotube cantilever vibration

Tadokoro Y., Ohno Y., Tanaka H.

ELECTRONICS LETTERS 54 巻 ( 13 ) 頁： 840 - + 2018年6月

記述言語：日本語出版者・発行元：Electronics Letters

Towards the realisation of reliable communication systems using simple nanoscale transceivers, this Letter presents a method for the non-coherent detection of digitally phase-modulated signals. Without the synchronisation of the phases of the transmitted and received carrier signals, data transmission cannot be reliably achieved. To address this issue, the proposed method is developed using a nanoscale receiver that receives the binary phase-modulated signal through the mechanical vibration of a carbon nanotube cantilever. The present analysis reveals that this receiver has an interesting characteristic: the two decision statistics available in the receiver have a phase difference of p/2, which means that at least one of the statistics is fairly reliable regardless of the synchronisation error. Through the selection of the more reliable of the two statistics, the proposed method achieves low error in the estimation of the transmitted data even without carrier phase synchronisation. This Letter presents the derivation of the proposed rule for selecting the statistic and numerical results that demonstrate the effectiveness of the proposed method. This Letter is expected to contribute to the realisation of future communication applications using nanoscale transceivers.

DOI： 10.1049/el.2018.0475

Detection of Digitally Phase-Modulated Signals Utilizing Mechanical Vibration of CNT Cantilever

Tadokoro Yukihiro, Ohno Yutaka, Tanaka Hiroya

IEEE TRANSACTIONS ON NANOTECHNOLOGY 17 巻 ( 1 ) 頁： 84 - 92 2018年1月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Transactions on Nanotechnology

Communication between tiny sensor nodes is an important function in future sensing applications and services. This paper contributes to the design of both the front end and the demodulator of nanoscale receivers. A nanoscale phase detector is proposed that provides two important functions at nanoscale: Reception of an incoming carrier signal in the megahertz band, and detection of the carrier phase which contains the information of the transmitted digital data. These two functions are achieved by the mechanical vibration of the tip of a carbon nanotube. The proposed detector was theoretically analyzed in terms of its communication aspects; although a digitally phase-modulated signal could be detected in nanoscale, the effective received signal power showed to be strongly reduced in a key performance measure in communication systems, bit error rate. However, the present analysis reveals that the output of the proposed detector has two frequency components, which describe the transmitted data. To take the advantage of this characteristic, a demodulator using maximum-ratio combining is introduced in this paper. The optimal weights used to combine the components were analytically derived to improve the bit error rate performance. The effectiveness of the nanoscale phase detector is numerically demonstrated, and the gain relative to the demodulation achieved using a conventional simple correlator is established.

DOI： 10.1109/TNANO.2017.2765310

Phase shifter tuned by varying the spring constant of a nanomechanical cantilever

Tanaka H., Ozaki T., Ohno Y., Tadokoro Y.

JOURNAL OF APPLIED PHYSICS 122 巻 ( 23 ) 2017年12月

記述言語：日本語出版者・発行元：Journal of Applied Physics

This paper presents a theoretical study of an adaptive microwave phase shifter based on a nanomechanical resonator. The phase shifter can be tuned to provide an arbitrary phase rotation in the range between -90° and 90° by adjusting the bias voltage applied to the resonator. An analytical model is developed to reveal the underlying mechanism of the phase shifter. It is also analytically demonstrated that the operating frequency can be selected by adjusting the bias voltage. In addition, it is found that the bandwidth is tunable via the quality factor for the cantilever.

DOI： 10.1063/1.4992040

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17