Design and Characterization of Nano-Displacement Sensor with High-Frequency Oscillators

The circuitry of a capacitive nanometer displacement sensor using the ring oscillator has been analyzed and characterized. We focus on the sensitivity of the sensor to detect the nanometer displacement or strain. The displaced target object must be conductive and the medium around the target object must be an insulator or a vacuum. The sensitivity in the range of L < 1 μm is enhanced with decreases in the size of the sensor electrode, and using a higher free-running oscillation frequency can increase sensitivity. The proposed sensor, which converts the displacement of the target object to the oscillation frequency, was fabricated with CMOS 350 nm technology, and the sensitivity was estimated at 8.16 kHz/nm. The results of our study indicated that the presented sensor has enough sensitivity to detect the nanometer displacement of the target object at a distance within 1 μm from the surface of the sensor electrode

Wireless Moisture Sensor Using a Microstrip Antenna

A wireless moisture sensor has been developed on the basis of the backscatter characteristic of the microstrip antenna, which works in the far field without a battery. This study aims to develop a wireless sensor with a long communication distance and to apply the wireless applications, such as monitoring the moisture in the wrapped products and surface adsorption of hydrogen peroxide in the biological isolation systems. The dropwise addition of the distilled water on the cleaning tissue is clearly detected by the measurement of the backscattered power from the sensor at the frequencies of 0.954 GHz and 2.45 GHz. The ratio of the backscattered power in two frequency bands can be used as an index to measure moisture

Circuit implementation, operation, and simulation of multivalued nonvolatile static random access memory using a resistivity change device

We proposed and computationally analyzed a multivalued, nonvolatile SRAM using a ReRAM. Two reference resistors and a programmable resistor are connected to the storage nodes of a standard SRAM cell. The proposed 9T3R MNV-SRAM cell can store 2 bits of memory. In the storing operation, the recall operation and the successive decision operation of whether or not write pulse is required can be performed simultaneously. Therefore, the duration of the decision operation and the circuit are not required when using the proposed scheme. In order to realize a stable recall operation, a certain current (or voltage) is applied to the cell before the power supply is turned on. To investigate the process variation tolerance and the accuracy of programmed resistance, we simulated the effect of variations in the width of the transistor of the proposed MNV-SRAM cell, the resistance of the programmable resistor, and the power supply voltage with 180 nm 3.3 V CMOS HSPICE device models. © 2013 Kazuya Nakayama and Akio Kitagawa.© 2013 K. Nakayama and A. Kitagawa

Transient phases and their transition temperatures of a-Si in non-isothermal processes

The heating rate dependence of the phase transition temperature was formulated based on the temperature dependence of nucleation of a new phase. The glass transition temperature of a-Si was explained in terms of van der Waals fluid of a-Si pseudo-molecules which are produced by the fragmentation of continuous random networks of Si atoms. Transient phases and their transition temperatures as a function of the heating rate are summarized in the phase diagram

Micro-textures of Hematite in the Liesegang Rocks, Found in Pyrophyllite Deposits, Shobara District, Southwest Japan.

Characteristic micro-textures of hematite found commonly in the Liesegang rocks collected from pyrophyllite ore deposits, Shobara district, southwest Japan were investigated. Detailed observations of the Liesegang rocks under the high magnification reflection microscope with oil immersion lens reveal that almost all of opaque grains are composed of needle-shaped very fine crystals with less than few microns in width and 5-10 microns in length. Moreover, doughnut-like texture, which is characteristic in the Liesegang rock (Yamashita et al., 1996), is mainly composed of the needle-shaped fine crystals. In many cases, the rings are composed of radiated aggregates of the needle-shaped hematite crystals. The size of the most predominant rings is less than 10µm in diameter, and double, triple and multi rings are also common. The optical properties of these opaque crystals under the reflection microscope are almost similar to those of ordinary hematite, i.e., weak but noticeable bireflectance and distinct anisotropism (e.g., Uytenbogaardt, 1971). X-ray powder diffraction data indicate that most of the opaque minerals are hematite with small amount of goethite. However, under the reflection microscope, distinguishment of the two minerals is not possible

微小物体可視化センサLSIの設計

金沢大学大学院自然科学研究科情報システム金沢大学工学

疑似的な不規則画素配置をもつ方向特異性のない撮像・表示素子構成の基礎検討 (論文小特集 画像の処理と符号化)

金沢大学大学院自然科学研究科情報システム金沢大学工学部Conventional image display devices and image acquisition devices consist of regularly located pixels. The pixels are located in a matrix for ease of implementation. Matrix placement of pixels intrinsically has directional singularity in the representation of images. The clarity of represented images is significantly dependent on the directions that objects in the image, such as lines, are facing. For example, horizontal lines are perfectly represented by matrix pixels, while the slanted lines have the jagged edges. We developed a pseudorandom pixel placement architecture that has no directional singularity in the representation of images, and we evaluated its characteristics and layout implementation

圧電材料を用いた新しい平面型トンネリングデバイスの製作法および動作特性の研究

金沢大学理工研究域電子情報通信学系1.素子構造の提案圧電材料の上に電子トンネリングを起こすための1対の電極を形成し、もう1対の電極に印加した電圧によりトンネル電流を変調するタイプの新しい論理デバイスを提案した。電極配置により相補的な2種類の入出力特性を持つデバイスを構成する事が可能である事が分かった。2.圧電性基板基板圧電材料として、チタン酸バリウムやニオブ酸鉛などほとんどの強誘電体が使用可能であることが分かった。実用化のためには、単結晶で薄膜化出来る材料が望ましい。チタン酸バリウムの圧電定数テンソルを用い、自発分極を考慮して外部電界の1次と2次の項を持つトンネルギャップ対入力端子間電界強度の関係式を得た。3.直流特性出力電極間のトンネル電流の大きさを弾性トンネリング確率より計算した。トンネリング確率の計算では、高電界下のFN電流の影響が大きく、有効質量の変化を考慮したシュレディンガー方程式を直接数値積分する必要があることが分かった。電極端形状を考慮した3次元トンネリング確率の計算およびその電子波数空間での積分は実質上不可能であっため、電極の無限平面近似を仮定した上で、デバイスの出力特性を算出するためのシミュレーションプログラムを作成した。以上の圧電性およびトンネル電流のデータより、本研究により提案するデバイスの直流特性が予想される。特に、入出力利得の大きさを表す相互コンダクタンスは、従来の半導体素子に比べて巨大な値が得られた。しかし、この値については、現在、材料の疲労や破壊を起こさない電圧範囲についての考察を行っているところであり、さらに研究を深める必要がある。4.製造方法の検討と応用これまでの研究で得られた知見をもとに、素子の試作を行うために必要な設備について調査したところ、まだ製造技術としての実用段階には入っていないが、電子ビームリソグラフィや走査型プローブ顕微鏡技術を用いてデバイスの製作ができる可能性があることが分かった。また、本デバイスを用いた巨大集積回路のための機能ブロックの構成法について現在検討中である。研究課題/領域番号:08750356, 研究期間(年度):1996出典：研究課題「圧電材料を用いた新しい平面型トンネリングデバイスの製作法および動作特性の研究」課題番号08750356（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-08750356/）を加工して作

Model for the glass transition in amorphous solids based on fragmentation

A model for the glass transition in a heating process has been proposed. In the model, noncrystalline solids are assumed to be assemblies of pseudomolecules or structural units. When the noncrystalline solid is heated, a bond breaking process becomes dominant compared with a rebinding process of broken bonds. At high temperature, successive bond breaking causes the fragmentation of the solid and the fragment size becomes smaller as the temperature further increases. Consequently, the solid begins to show some viscous behavior when the fragment size reaches a critical value. To construct mathematical expressions for the fragmentation model, we employed a simple rate equation for the bond breaking process first and then obtained the temperature dependence of dangling bond density in a noncrystalline solid. Second, the expressions for the fragment density and size as a function of temperature were obtained based on the following assumptions: (1) bond breaking takes place mainly at the boundaries between pseudomolecules, (2) once buds of microcracks are generated, successive bond breaking occurs mostly at the tip of the microcracks, and (3) the fragments are Voronoy polyhedra. Finally, the diffusion coefficient in the system was obtained by assuming the vacancy mechanism in solids and then the temperature dependence of viscosity was derived through Stokes-Einstein relation. To examine the present model, applications of the model to the phase changes of α-Si in heating processes are carried out and the results were discussed