This article presents a new design concept of a glucose oxidase (GOD) electrode as an anode for a biofuel cell based on plasma-polymerized thin film (PPF) of dimethylaminomethylferrocene (DMAMF), which plays a role as an electron transfer mediator between the active site of the enzyme and anodic electrode. The configuration of the anode is a multilayer mixture of DMAMF-PPF and GOD, in which a nano-thin DMAMF-PPF containing a redox mediator was plasma-deposited directly onto a GOD-physisorbed electrode. The optimized biofuel cell with bioanode, in a 20 mM phosphate buffer solution of pH 7.4 containing 10 mM glucose, exhibited a maximum power density of 2.7 µW/cm2 at 20. The film deposition was performed using microfabrication-compatible organic plasma, which therefore suggests this fabrication process has significant potential for enabling high throughput production of micro biofuel cells.
Yuki YAI Shigeki MIYABE Hiroshi SARUWATARI Kiyohiro SHIKANO Yosuke TATEKURA
In this paper, we propose a computationally efficient method of compensating temperature for the transaural stereo. The conventional method can be used to estimate the change in impulse responses caused by the fluctuation of temperature with high accuracy. However, the large amount of computation required makes real-time implementation difficult. Focusing on the fact that the amount of compensation depends on the length of the impulse response, we reduce the computation required by segmenting the impulse response. We segment the impulse responses in the time domain and estimate the effect of temperature fluctuation for each of the segments. By joining the processed segments, we obtain the compensated impulse response of the whole length. Experimental results show that the proposed method can reduce the computation required by a factor of nine without degradation of the accuracy.
Shinya KAJIYAMA Ken'ichiro SONODA Kazuo OTSUGA Hideaki KURATA Kiyoshi ISHIKAWA
A design methodology optimizing constant-charge-injection programming (CCIP) for assist-gate (AG)-AND flash memories is proposed. Transient circuit simulations using an array-level model including lucky electron model (LEM) current source describing hot electron physics enables a concept design over the whole memory-string in advance of wafer manufacturing. The dynamic programming behaviors of various CCIP sequences, obtained by circuit simulations using the model is verified with the measurement results of 90-nm AG-AND flash memory, and we confirmed that the simulation results sufficiently agree with the measurement, considering the simulation results give optimum bias AG voltage approximately within 0.2 V error. Then, we have applied the model to a conceptual design and have obtained optimum bit line capacitance value and CCIP sequence those are the most important issues involved in high-throughput programming for an AG-AND array.
Kamugisha KAZAURA Kazunori OMAE Toshiji SUZUKI Mitsuji MATSUMOTO Edward MUTAFUNGWA Tadaaki MURAKAMI Koichi TAKAHASHI Hideki MATSUMOTO Kazuhiko WAKAMORI Yoshinori ARIMOTO
Free-space optical communication systems can provide high-speed, improved capacity, cost effective and easy to deploy wireless networks. Experimental investigation on the next generation free-space optical (FSO) communication system utilizing seamless connection of free-space and optical fiber links is presented. A compact antenna which utilizes a miniature fine positioning mirror (FPM) for high-speed beam control and steering is described. The effect of atmospheric turbulence on the beam angle-of-arrival (AOA) fluctuations is shown. The FPM is able to mitigate the power fluctuations at the fiber coupling port caused by this beam angle-of-arrival fluctuations. Experimental results of the FSO system capable of offering stable performance in terms of measured bit-error-rate (BER) showing error free transmission at 2.5 Gbps over extended period of time and improved fiber received power are presented. Also presented are performance results showing stable operation when increasing the FSO communication system data rate from 2.5 Gbps to 10 Gbps as well as WDM experiments.
Masahiro OZAKI Tohru OKABAYASHI Teppei ISHIMARU Nobuhiko YAMASHITA Masuo NAKAGAWA
A novel sensing system for glucose in aqueous solution based on cataluminescence(CTL) is proposed. CTL is a kind of chemiluminescence emitted in a course of catalytic oxidation of combustible substances. A sensing system consisting of a CTL-based chemical-sensor made of the γ-Al2O3 catalyst activated with Tb and an ultrasonic nebulizer is developed. CTL is emitted by injection of air containing mist of a glucose solution prepared by the nebulizer on the catalyst. The CTL intensity measured by a photomultiplier is reproducible for the repeated injection of the mist, and the system can measure glucose concentration in a range of 1-200 mg/dl.
Hitoshi MUGURUMA Hideyuki UEHARA
An electron transfer mediated amperometric enzyme biosensor based on a plasma-polymerized thin film of dimethylaminomethylferrocene (DMAMFc) is reported. A nanoscale thin polymer film containing a redox mediator was plasma-deposited directly onto an electrode with physisorbed glucose oxidase (GOD). Since the redox sites were introduced in the vicinity of the reaction centers of GOD, a highly efficient electron transfer system was formed in which almost all the reaction centers of GOD were connected to redox sites of the polymer matrix. The advantages of this strategy were: no need for prior or further chemical modification of the enzyme molecules, and simplicity of design compared with the use of a conventional polymer matrix. Moreover, the fact that the film deposition was performed using a microfabrication-compatible organic plasma promised great potential for high-throughput production of bioelectronic devices.
Hiroshi SHIMAMORI Teruhiko KOHAMA Tamotsu NINOMIYA
Paralleled converter system with synchronous rectifiers (SRs) causes several problems such as surge voltage, inhalation current and circulating current. Generally, the system stops operation of the SRs in light load to avoid these problems. However, simultaneously, large voltage fluctuations in the output of the modules are occurred due to forward voltage drop of diode. The fluctuations cause serious faults to the semiconductor devices working in very low voltage such as CPU and VLSI. Moreover, the voltage fluctuations generate unstable current fluctuations in the paralleled converter system with current-sharing control. This paper proposes new switching control methods for rectifiers to reduce the voltage and current fluctuations. The effectiveness of the proposed methods is confirmed by computer simulation and experimental results.
Tae-Woo KIM Tae-Kyung CHO Byoung-Soo PARK
Radio frequency (RF) microwave can be used to predict glucose concentration in a sample. This paper presents preliminary results in determining the concentration by measuring relative permittivity in the solutions of distilled water, saline, human serum, and human blood containing glucose. In the experiments, sensitivity for detecting glucose concentration in blood solutions was almost 57 mg/dl at the frequency of approximately 5.8 GHz.
Let us introduce n ( 2) nonlinear mappings fi (i = 1,2,,n) defined on complete linear metric spaces (Xi-1,ρ) (i = 1,2,,n), respectively, and let fi:Xi-1 Xi be completely continuous on bounded convex closed subsets Xi-1, (i = 1,2,,n 0), such that fi() . Moreover, let us introduce n fuzzy-set-valued nonlinear mappings Fi:Xi-1Xi {a family of all non-empty closed compact fuzzy subsets of Xi}. Here, by introducing arbitrary constant βi (0,1], for every integer i (i = 1,2,,n 0), separately, we have a fixed point theorem on the recurrent system of βi -level fuzzy-set-valued mapping equations: xi Fiβi(xi-1, fi(xi-1)), (i = 1,2,,n 0), where the fuzzy set Fi is characterized by a membership function µFi(xi):Xi [0,1], and the βi -level set Fiβi of the fuzzy set Fi is defined as Fiβi {ξi Xi |µFi (ξi) βi}, for any constant βi (0,1]. This theorem can be applied immediately to discussion for characteristics of ring nonlinear network systems disturbed by undesirable uncertain fluctuations and to extremely fine estimation of available behaviors of those disturbed systems. In this paper, its mathematical situation and proof are discussed, in detail.
This paper describes an analysis of IP-network traffic in terms of the time variation of self-similarity. To get a comprehensive view in analyzing the degree of long-range dependence (LRD) of IP-network traffic, this paper used a self-organizing map, which provides a way to map high-dimensional data onto a low-dimensional domain. Also, in the LRD-based analysis, this paper employed detrended fluctuation analysis (DFA), which is applicable to the analysis of long-range power-law correlations or LRD in non-stationary time-series signals. In applying this method to traffic analysis, this paper performed two kinds of traffic measurement: one based on IP-network traffic flowing into NTT Musashino R&D center (Tokyo, Japan) from the Internet and the other based on IP-network traffic flowing through at an interface point between an access provider (Tokyo, Japan) and the Internet. Based on sequential measurements of IP-network traffic, this paper derived corresponding values for the LRD-related parameter α of measured traffic. As a result, we found that the characteristic of self-similarity seen in the measured traffic fluctuated over time, with different time variation patterns for two measurement locations. In training the self-organizing map, this paper used three parameters: two α values for different plot ranges, and Shannon-based entropy, which reflects the degree of concentration of measured time-series data. We visually confirmed that the traffic data could be projected onto the map in accordance with the traffic properties, resulting in a combined depiction of the effects of the degree of LRD and network utilization rates. The proposed method can deal with multi-dimensional parameters, projecting its results onto a two-dimensional space in which the projected data positions give us an effective depiction of network conditions at different times.
Yoshihiro KASE Hitoshi MUGURUMA Atsunori HIRATSUKA Isao KARUBE
An amperometric thin-film glucose biosensor based on a plasma-polymerized film using hexamethyldisiloxane as the monomer is presented. The plasma-polymerized film, achieved in plasma in the vapor phase, offers a new alternative for use in the design of the electrode-enzyme interface of biosensors. The film shows promise of high sensor performance; namely, rapid sensor response, low noise, a wide dynamic range, reproducibility, and reduction in the effects of interfering materials such as ascorbic acid. In this study, we examined the usefulness of the hexamethyldisiloxane plasma-polymerized film and investigated how the thickness of the plasma-polymerized film on a platinum electrode affected sensor characteristics: the selectivity for hydrogen peroxide versus interfering agents, the sensor response due to enzymatic reaction, and oxygen depletion.
An optical fiber biosensor using adsorption LB films has been investigated for the application to the glucose detection in blood. The adsorption LB film containing glucose oxidase (GOD: the enzyme in human body) was deposited on the core portion of optical fiber and the variation of absorption spectra due to the reactions of GOD, glucose, and hemoglobin was measured. The relatively high response time of 60 s and glucose sensitivity as low as 20 mg/dl were obtained. The results demonstrate that the optical fiber bio-sensor using adsorption LB film can be used as a glucose sensor.
Kenichi OKADA Kento YAMAOKA Hidetoshi ONODERA
This paper proposes a model to calculate statistical gate-delay variation caused by intra-chip and inter-chip variabilities. The variation of each gate delay directly influences the circuit-delay variation, so it is important to characterize each gate-delay variation accurately. Every transistor in a gate affects transient characteristics of the gate, so it is indispensable to consider an intra-gate variability for the modeling of gate-delay variation. This effect is not captured in a statistical delay analysis reported so far. Our model considers the intra-gate variability by sensitivity constants. We evaluate our modeling accuracy, and we show some simulated results of a circuit delay variation.
Let us introduce n ( 2) nonlinear mappings fi (i = 1,2,,n) defined on complete linear metric spaces (Xi-1,ρ) (i = 1,2,,n), respectively, and let fi: Xi-1 Xi be completely continuous on bounded convex closed subsets Xi-1,(i = 1,2,,n 0), such that fi() . Moreover, let us introduce n fuzzy-set-valued nonlinear mappings Fi: Xi-1 Xi {a family of all non-empty closed compact fuzzy subsets of Xi}. Here, we have a fixed point theorem on the recurrent system of β-level fuzzy-set-valued mapping equations: xi Fiβ(xi-1,fi(xi-1)), (i = 1,2,,n 0), where the fuzzy set Fi is characterized by a membership function µFi(xi): Xi [0,1], and the β-level set Fiβ of the fuzzy set Fi is defined as Fiβ {ξi Xi | µFi(ξi) β}, for any constant β (0,1]. This theorem can be applied immediately to discussion for characteristics of ring nonlinear network systems disturbed by undesirable uncertain fluctuations and to fine estimation of available behaviors of those disturbed systems. In this paper, its mathematical situation and proof are discussed, in detail.
A combined theory of the micromagnetic and Monte Carlo simulations is established to analyze the thermal property of a nano-sized magnetic grain. The Langevin equation of a grain's magnetic moment is the Landau-Lifshitz equation augmented by a "random-field" term representing the thermal-agitated force. The angular distribution of the magnetic moment of the grain is studied via its time evolution process. The switching of the magnetic moment vector between two energy-minimum states is observed. A simple analytical expression is obtained for the simulated attempt frequency f0, which is related to the magnetic constant of the nano-grain, and agrees well with the phenomenological value.
Kenichi OKADA Hidetoshi ONODERA
The main purpose of our method is to obtain realistic worst-case delay in statistical timing analyses. This paper proposes a method of statistical delay calculation based on measured intra-chip and inter-chip variabilities. We present a modeling and extracting method of transistor characteristics for the intra-chip variability and the inter-chip variability. In the modeling of the intra-chip variability, it is important to consider a gate-size dependence by which the amount of intra-chip variation is affected. This effect is not captured in a statistical delay analysis reported so far. Our method proposes a method for modeling of the device variability and statistical delay calculation with consideration of the size dependence, and uses a response surface method (RSM) to calculate a delay variation with low processing cost. We evaluate the accuracy of our method, and we show some experimental results the variation of a circuit delay characterized by the measured variances of transistor currents.
Tatsuya EZAKI Takeo IKEZAWA Akio NOTSU Katsuhiko TANAKA Masami HANE
A realistic 3-D process/device simulation method was developed for investigating the fluctuation in device characteristics induced by the statistical nature of the number and position of discrete dopant atoms. Monte Carlo procedures are applied for both ion implantation and dopant diffusion/activation simulations. Atomistic potential profile for device simulation is calculated from discrete dopant atom positions by incorporating the long-range part of Coulomb potential. This simulation was used to investigate the variations in characteristics of sub-100 nm CMOS devices induced by realistic dopant fluctuations considering practical device fabrication processes. In particular, sensitivity analysis of the threshold voltage fluctuation was performed in terms of the independent dopant contribution, such as that of the dopant in the source/drain or channel region.
Scott T. DUNHAM Pavel FASTENKO Zudian QIN Milan DIEBEL
In this work, we review our recent efforts to make effective use of atomistic calculations for the advancement of VLSI process simulation. We focus on three example applications: the behavior of implanted fluorine, arsenic diffusion and activation, and the impact of charge interactions on doping fluctuations.
Yoshinori ODA Yasuyuki OHKURA Kaina SUZUKI Sanae ITO Hirotaka AMAKAWA Kenji NISHI
A new analysis method for random dopant induced threshold voltage fluctuations by using Monte Carlo ion implantation were presented. The method was applied to investigate Vt fluctuations due to statistical variation of pocket dopant profile in 0.1µm MOSFET's by 3D process-device simulation system. This method is very useful to analyze a statistical fluctuation in sub-100 nm MOSFET's efficiently.
Yosuke TATEKURA Hiroshi SARUWATARI Kiyohiro SHIKANO
We describe a method of compensating temperature fluctuation by a linear-time-warping processing in a sound reproduction system. This technique is applied to impulse responses of room transfer functions, to achieve a high-quality sound reproduction system, particularly one that treats high-frequency components. First, the impulse responses are measured before and after temperature fluctuation, and the former are converted to the latter by the proposed process. Next, we design inverse filters for the system, and evaluate the improvement of the reproduction accuracy and spectrum distortion. By the compensation method, we can improve the reproduction accuracy at any frequency. Moreover, we propose an adaptive algorithm for the estimation of a suitable warping ratio, using the observed signal of reproduced sound obtained at only one control point. Using the proposed algorithm, we can improve the reproduction accuracy at each control point by about 14 dB, in which a difference in temperature is 1.4.