A novel micromixer with three‐dimensionally cross‐linked capillary array structure fabricated by deep X‐ray lithography

A novel micromixer was proposed, fabricated and verified. The new concept of the micromixer is to cross‐link many capillaries in a three‐dimensional structure. The characteristic flow behaviors were simulated by using the “FLUENT” computational fluid dynamics (CFD) software. The results of the CFD showed unique mixing behavior in three‐dimensionally cross‐linked capillaries. The mixing performance of the micromixer is strongly influenced by controlling the three‐dimensional crossing conditions. The micromixer was fabricated by deep X‐ray lithography with multistep exposure. The cross‐linked capillary structures were successfully fabricated while controlling the cross‐link conditions. The performance of the micromixer was evaluated by using an enzyme reaction. By comparing the mixtures produced with a cross‐linked fluid filter and with a fluid filter without cross‐linked capillaries, we found that the reaction was accelerated by using the new micromixer. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 26–31, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21157     

Cellular neural networks with opposite‐sign templates for image thinning

This paper presents image thinning algorithms using cellular neural networks (CNNs) with one‐ or two‐dimensional opposite‐sign templates (OSTs) as well as non‐unity gain output functions. Two four‐layer CNN systems with one‐dimensional (1‐D) OSTs are proposed for image thinning with 4‐ or 8‐connectivity, respectively. A CNN system, which consists of an eight‐layer CNN with two‐dimensional (2‐D) OSTs followed by another four‐layer CNN with 2‐D OSTs, is constructed for image thinning with 8‐connectivity, in which designs of B‐ and I‐templates are simpler than in CNNs with 1‐D OSTs. In the aforementioned designs, parameter values of 1‐D OSTs are chosen to make CNNs operate with thinning‐like property 1 (TL‐1), and those of 2‐D OSTs with 2‐D thinning‐like property (2‐DTL). Simulation studies show that these CNN systems have a good image thinning performance. Copyright © 1999 John Wiley & Sons, Ltd.     

Size‐reduced two‐dimensional integrated magnetic sensor fabricated in 0.18‐μm CMOS process

Two‐dimensional integrated magnetic sensors have been investigated in order to reduce their size for use in a magnetic self‐levitation motor. The two‐dimensional integrated magnetic sensor investigated in this paper is composed of a 16 × 16 array of Hall sensors and fabricated by a 0.18‐μm complementary metal–oxide–semiconductor (CMOS) standard process. The sizes of the Hall elements are 1 × 1, 2 × 2, 3 × 3, and 6 × 6 μm². Hall element of dimension 1 × 1 μm²was the minimum size in the fabrication process rule. The dimension of one pixel in which the Hall element was embedded was 20 × 20 μm². The average sensitivity of the arrayed Hall sensors at four sizes was about 0.140 mV/mT with a DC magnetic field. The product sensitivity at four sizes of Hall sensors was about 0.089 mV/(mA·mT), which is better than that of our previous work. Degradation of the product sensitivity was not seen in reduced‐size Hall elements. These results reveal that a Hall element of size 1 × 1 μm² has enough sensitivity for sensing the impeller position of a magnetically suspended motor. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A novel MOSFET with vertical signal‐transfer capability for 3D‐structured CMOS image sensors

We have developed a novel MOSFET that can transfer signals vertically without through‐silicon vias but by using a fully depleted silicon‐on‐insulator (FDSOI) structure with its source region connected to the back electrodes as well as the front ones. A prototype MOSFET fabricated using the backside anisotropic wet etching technique has confirmed that the electrical characteristics measured from the front and the back electrodes are identical. The subthreshold factor S of the prototype was found to be 64.5 mV/decade, suggesting a good switching performance. Since the double‐sided MOSFET has vertical signal‐transfer capability and excellent operating characteristics, it is expected to contribute to developing a More‐than‐Moore type device of three‐dimensional integration such as pixel‐parallel image sensors. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Characteristics of a two‐dimensional integrated magnetic sensor for position sensing and motor control

Two‐dimensional integrated magnetic sensors for position sensing were designed and fabricated with the standard 0.35‐µm CMOS process on silicon. One such type is the n‐type Hall sensor that uses an inversion layer under the gate oxide of the MOSFET. The Hall sensors were arrayed (64 × 64), and the control digital circuits and output amplifier were also integrated into the same chip. ‘One pixel’ was 50 × 50 µm, and the entire chip was 4.9 × 4.9 mm. The sensitivity of one of these sensors was 2.7 mV/(mA·kG). The two‐dimensional magnetic flux distribution was measured from the 5‐mm diameter Nd–Fe–B rare‐earth permanent magnet. About 42 s was required to measure one frame. The position of the magnet could be detected with the fabricated sensors. Magnetic sensors using an inversion layer in MOSFETs are useful for position sensing systems, but their noise characteristics, such as poor sensitivity, should be improved. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Dual‐camera acquisition for accurate measurement of three‐dimensional eye movements

In this paper, we suggest a new approach for accurate measurement of three‐dimensional eye movements employing dual‐camera acquisition. Two calibrated mini CCD cameras are used to capture two simultaneous images of one eye. Center‐of‐mass and template‐matching algorithms are utilized to obtain two‐dimensional coordinates of the center of pupil and iris striation. Instead of asking each subject to fulfill intricate calibration steps, a novel and simpler technique to solve geometric distortion is presented by utilizing direct linear transformation (DLT) algorithm which requires only one preliminary calibration procedure for each camera without changing any camera installation. The DLT algorithm is then used to extract three‐dimensional coordinates of the center of the pupil and iris striation from prior two‐dimensional coordinates, allowing the three‐dimensional angular positions of the eye to be computed. Real‐time eyeball visualization based on tracking results is incorporated to help clinicians diagnose eye movements. Experimental results show that our system has high accuracy, as the average errors in the horizontal, vertical, and torsional angular positions were confined to 0.15°, 0.14°, and 0.20°, respectively. Real‐time implementation demonstrates that our system can be used in clinical routines to observe either voluntary or involuntary human eye movements. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Mode‐matching analysis of a spit‐circular cavity resonator for measurement of the dielectric constant for film on a substrate

In this paper, we apply the mode‐matching technique (eigenmode expansion) to formulate an analytical model for a split cylindrical cavity resonator with a thick ceramic film layer sandwiched between two‐layer alumina substrates. We then compute the resonant frequencies with the TE₀₁₁ mode with an eigenvalue problem approach using the model formula. The quality factor (Q ‐factor) of the resonator is also calculated by applying the perturbation method to the analytical model. The validity of the proposed analytical technique is confirmed by applying this method to the estimation of permittivity of thick films as an inverse problem. Ceramic films (2 µm thickness) were synthesized using a chemical solution method onto 200‐µm‐thick, 50‐mm‐diameter alumina substrates. The complex permittivity of the films was then determined using the TE₀₁₁ mode split cylindrical cavity resonator in the 10‐GHz band. The extent of the edge effect at a sample insertion space was evaluated by comparing the estimated results through TE wave analysis using the mode‐matching method when the transverse resonance technique and the perturbation method were applied to calculate the resonant frequency and the dielectric Q ‐factor. The results obtained indicate that a difference of 0.153% in the permittivity of the alumina substrate causes differences of 6.10 and 3.75% in the measured permittivity and loss tangent, respectively, of 2‐µm‐thick ceramic film with a permittivity of ∼50. Differences in permittivity and loss tangent were more pronounced with thinner films. It was also confirmed that the estimated results for permittivity and the loss tangent values of these ceramic films were affected by the estimated permittivity value of the alumina substrate. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

MTL‐based implementation of current‐mode CMOS RMS‐to‐DC converters

In this paper, systematic implementation of current‐mode RMS‐to‐DC converters based upon MOS translinear (MTL) principle, utilizing symmetric cascoded MTL cell (SCMC) is proposed. Theory of operation and mathematical analysis of both explicit (direct) and implicit (indirect) techniques for realization of SCMC‐based RMS‐to‐DC converters are discussed. The SCMC includes a folded MTL loop and realizes an MTL equation. MTL principle utilizes the square law characteristics of saturated MOS transistors to realize square‐root domain (SRD) functions. The SCMC is constructed by two connected cascoded current mirrors and has a compact, symmetric, and multi‐purpose structure, with capability of implementing the circuits into the programmable and configurable structures. The proposed RMS‐to‐DC converters utilize the SCMC along with a configurable current mirror array. The required squaring and square‐rooting functions are realized using the SCMC, after proper configuration of the current mirror array. The proposed circuits have been implemented using a reconfigurable architecture fabricated in a 0.5 µm CMOS technology. Copyright © 2014 John Wiley & Sons, Ltd.     

Potential‐based threshold voltage and subthreshold swing models for junctionless double‐gate metal‐oxide‐semiconductor field‐effect transistor with dual‐material gate

On the basis of quasi‐two‐dimensional solution of Poisson's equation, an analytical threshold voltage model for junctionless dual‐material double‐gate (JLDMDG) metal‐oxide‐semiconductor field‐effect transistor (MOSFET) is developed for the first time. The advantages of JLDMDG MOSFET are proved by comparing the central electrostatic potential and electric field distribution with those of junctionless single‐material double‐gate (JLSMDG) MOSFET. The proposed model explicitly shows how the device parameters (such as the silicon thickness, oxide thickness, and doping concentration) affect the threshold voltage. In addition, the variations of threshold voltage roll‐off, drain‐induced barrier lowering (DIBL), and subthreshold swing with the channel length are investigated. It is proved that the device performance for JLDMDG MOSFET can be changed flexibly by adjusting the length ratios of control gate and screen gate. The model is verified by comparing its calculated results with those obtained from three‐dimensional numerical device simulator ISE. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimum design approach for low‐speed,high‐torque permanent magnet motors

This paper presents an optimum design approach for low‐speed, high‐torque permanent magnet motors. The approach is divided into two steps: the first consists of the rough estimation of torque by linear analysis, and the second the optimization of the motor configuration by nonlinear FEM analysis. Under restricted dimensional specifications and electrical requirements, a 16‐pole, 18‐coil permanent magnet motor with a rating of 600 Nm and 300 rpm was designed and constructed. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 52–63, 2001     

Single‐layer perceptron and dynamic neuron implementing linearly non‐separable Boolean functions

This paper presents a single‐layer perceptron (SLP) scheme with an impulse activation function (IAF) and a dynamic neuron (DN) with a trapezoidal activation function (TAF). Combining with some interesting properties of the offset levels, it is shown that many linearly non‐separable Boolean functions can be realized by using only one SLPwIAF or one DNwTAF. In the present work, a few appropriate IAF and TAF are adopted, and the inverse offset level method is used for the design of the SLPwIAF synaptic weights and the DNwTAF templates. The XOR and NXOR Boolean operations with two inputs and all 152 non‐separable Boolean functions with three inputs can be easily implemented by one SLPwIAF or one DNwTAF. Finally, the entire set of 152 DNwTAF templates associated with 152 non‐separable Boolean functions of three inputs is completely listed. Copyright © 2008 John Wiley & Sons, Ltd.     

Numerical simulation of blow‐down closed‐cycle disk MHD generator

Numerical simulations of the closed‐cycle disk MHD generation experiment with Tokyo Institute of Technology's Fuji‐1 blow‐down facility are performed. In the calculations, the r–z two‐dimensional time‐dependent simulation code developed by the authors that can take the effect of water contamination into account is used, and the experimental conditions of Run A4109 operated by Disk‐F4 generator are selected as the numerical conditions. When the water contamination is the lowest level realized in the experiments, the simulation results coincide with the experimental results reasonably well, though there exist some discrepancies caused by inaccuracy of used basic plasma parameters, limitations of the two‐dimensional approximation, and so on. The voltage–current curve is almost linear, indicating that the MHD interaction is relatively weak and the flow field is mainly determined by the back‐pressure. The increase of the water contamination level results in decreased seed ionization rate at the generator channel inlet, leading to the steep deterioration of the generator performance. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 46–54, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10335     

A study of three‐dimensional observation of prebreakdown phenomena in dielectric liquids

This paper presents a new method which visualizes the high‐speed three‐dimensional images of prebreakdown streamers in dielectric liquids. A new optical system, having two crossed light axes to observe the needle tip from different directions, was designed. The shadowgraphic images from these two directions were combined through a beam splitter and focused on the photo‐cathode of an image converter camera. The photograph taken by this high‐speed shadowgraph system was reconstructed to three‐dimensional images using an image scanner and a computer. Using this system, the growth and decay processes of the streamer in cyclohexane were investigated. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 9–15, 1999     

Design of A Soft X‐ray Source with Periodic Microstructure Using Resonance Transition Radiation for Tabletop Synchrotron

A soft X‐ray source with a periodic aluminum multilayer structure with vacuum layers in between for tabletop synchrotrons with low‐energy electrons was designed, and the dependence of radiation performance on structural parameters was clarified using a theoretical calculation of the resonance transition radiation. A photon density of 1 keV pr incident electron was calculated by optimizing the thickness of the aluminum and vacuum layers. Furthermore, the designed structure was fabricated by a microfabrication technique. The effects of dimensional error on the photon density are discussed on the basis of the calculated results and the prototype structure of a 6‐MeV synchrotron. It is clarified that dimensional errors of 1.5% in Al layers and of plus or minus a few dozen nanometers in the vacuum layers are negligible in obtaining a photon density of more than 90% of the maximum value. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Efficient optimization‐oriented design methodology of high‐order 3‐D filters using 2‐D and 3‐D electromagnetic simulators

This paper proposes a computationally highly efficient interface between two‐dimensional (2‐D) and three‐dimensional (3‐D) electromagnetic (EM) simulators for the optimization‐oriented design of high‐order 3‐D filters. In a first step, the novel optimization‐oriented design methodology aligns the 3‐D EM simulator response with the 2‐D EM simulator response of a low‐order 3‐D filter by using an inverse linear space mapping optimization technique. Then, a second mapping performs a calibration with the optimal 2‐D and 3‐D design parameters obtained from the first mapping. The optimization of high‐order filters is carried out using only the efficient 2‐D EM simulator, and the calibration equations directly give the design parameters of the 3‐D filter. The potential and the effectiveness of the proposed optimization‐oriented design methodology are demonstrated through the design of C‐band 3‐D evanescent rectangular waveguide bandpass filters with increasing orders from three to eight. Copyright © 2014 John Wiley & Sons, Ltd.     

A portable class of 3‐transistor current references with low‐power sub‐0.5 V operation

This work proposes a new class of current references based on only 3 transistors that allows sub‐0.5 V operation. The circuit consists of a 2‐transistor block that generates a proportional‐to‐absolute‐temperature or a complementary‐to‐absolute‐temperature voltage and a load transistor. The idea of a 3T current reference is validated by circuit simulations for different complementary metal‐oxide‐semiconductor technologies and by experimental measurements on a large set of test chips fabricated with a commercial 0.18 μm complementary metal‐oxide‐semiconductor process. As compared to the state‐of‐art competitors, the 3T current reference exhibits competitive performance in terms of temperature coefficient (578 ppm/°C), line sensitivity (3.9%/V), and power consumption (213 nW) and presents a reduction by a factor of 2 to 3 in terms of minimum operating voltage (0.45 V) and an improvement of 1 to 2 orders of magnitude in terms of area occupation (750 μm²). In spite of the extremely reduced silicon area, the fabricated chips exhibit low‐process sensitivity (2.7%). A digital trimming solution to significantly reduce the process sensitivity is also presented and validated by simulations.     

Two‐dimensional recursive digital filters with nearly circular‐symmetric magnitude response and approximately linear phase

This paper presents a general structure using 1‐D and two‐dimensional (2‐D) recursive digital all‐pass filters (DAFs) for the design of 2‐D recursive circularly symmetric digital low‐pass filters (CS‐DLFs). The general structure is a cascade of two stages composed of all‐pass building blocks. The first stage is a parallel connection of a 2‐D recursive DAF with a symmetric half‐plane (SHP) support for its filter coefficients and a 2‐D pure delay block. The second stage composed of a parallel connection of a 1‐D recursive DAF and a 1‐D pure delay block is used for eliminating the unwanted pass‐band induced by the first stage. As a result, the design of a 2‐D CS‐DLF in either the least‐squares or the minimax sense can be formulated in a simple linear optimization problem in terms of the weighted‐phase response error for each DAF. Design results with nearly circularly symmetric magnitude response and approximately linear phase are also provided for illustration and comparison. Copyright © 2010 John Wiley & Sons, Ltd.     

Distribution on localized two‐dimensional magnetic properties of three‐phase induction motor core

Improving material characteristics and optimizing technical designs have been studied from the standpoint of efficiency improvement of electrical machinery and apparatus. Unfortunately, the local magnetic properties in actual cores are still not understood fully. On the other hand, there is understanding of the two‐dimensional magnetic property, that is, the relationship between the magnetic field strength vector H and the magnetic flux density vector B , which are not usually parallel but have a phase angle. Therefore, local magnetic properties in an actual constructed core should be measured as a vector relation. This paper presents the local magnetic properties in a three‐phase induction motor model core, which are measured with a two‐dimensional measurement sensor. © 2000 Scripta Technica, Electr Eng Jpn, 133(4): 34–40, 2000     

Novel fabrication method for long silicon microneedles with three‐dimensional sharp tips and complicated shank shapes by isotropic dry etching

This paper proposes a novel fabrication method for long solid microneedles made of silicon, which have a three‐dimensional sharp tip, by using isotropic dry etching. Since the fabrication is done in a direction parallel to the surface of the silicon substrate, there is no limit for the needle length. Also, the shank shape of this needle is freely designed three‐dimensionally by defining the mask on the silicon surface. For example, a jagged or harpoon shape is possible by using the proposed method, which may be effective for some medical applications. First, several three‐dimensional, complicated‐shaped needles with sharp tip angles were fabricated by changing the mask pattern. Second, a penetration experiment with them on an artificial skin was carried out, and easy penetration comparable with a conventional metal solid needle was confirmed. For an example of lancet application for diabetics, one of the needles was inserted into a human skin, and bleeding was confirmed. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Extending the enlarged cell and uniformly stable conformal techniques to modeling curved conductors in two‐dimensional high‐order finite‐difference time‐domain algorithms

The critical tool of modeling irregularly shaped perfect conductors is developed for the extended‐stencil high‐order two‐dimensional M24 variant of the finite‐difference time‐domain (FDTD) method. Two standard FDTD conformal approaches are analyzed and successfully extended to work accurately with M24. They both afford higher order convergence with respect to mesh density than a previously developed technique, which better matches M24's characteristics. Both approaches rely on borrowing weighted electromotive forces from nearby extended‐stencil cells to ensure accuracy and numerical stability while the overall algorithm is efficiently operated at the maximum allowable time steps by FDTD and M24 theories. Validation examples demonstrate that M24's amplitude and phase accuracies using coarse numerical meshes were not compromised. Copyright © 2012 John Wiley & Sons, Ltd.