A 1/2-in. CCD image sensor overlaid with a hydrogenated amorphous silicon

A half-inch size CCD image sensor overlaid with a hydrogen-erated amorphous silicon (α-Si:H) as a photodetector has been developed. The array consists of 506V × 404H picture elements. The glow-discharged α-Si:H film has high quantum efficiency of 0.75-0.8 in the visible wavelength range and low dark current of 0.2 nA/cm²and is formed on the CCD scanner with vertical overflow drain. This CCD image sensor has a sensitivity of 0.014 µA/lx (3200 K)and a S/N ratio of 73 and 68 dB for fixed-pattern noise and random noise, respectively. Smearing signal is suppressed to below 5 percent at incident light intensity of 1000 times saturation exposure. The blooming and highlight lag are completely suppressed by the vertical overflow drain structure.     

CMOS器件光学特性的测量

介绍了一种测量CMOS像感器调制传递函数(modulation transfer function,MTF)的方法,分别构造了可用于MTF和光谱量子效率测量的实验系统.并利用上述实验系统对1024×1024的CMOS像感器的MTF和量子效率进行了测量,获得了令人满意的结果.     

紫外可见NMOS线阵图像传感器量子效率的定标研究

作为一种新型紫外可见线阵图像传感器,紫外可见NMOS已经应用于国外的空间遥感探测中,但是目前在国内相关研究甚少。在紫外可见波段针对NMOS的重要光电性能参量量子效率进行了定标研究,为NMOS线阵图像传感器在紫外空间遥感探测的应用奠定了基础。基于美国标准技术研究院(NIST)标定的标准探测器,构建了一套NMOS量子效率高精度定标系统。在250~700 nm波段范围内,通过直接标定NMOS入射窗口处接收到的光子数,结合NMOS信号处理及读出单元得到NMOS的响应电子数,标定其量子效率。结果表明NMOS线阵图像传感器的量子效率在紫外波段达到34%@275 nm,在可见波段达到80%@550 nm。通过不确定度分析,量子效率的测量不确定度为2.5%。     

Characteristics of pH sensors fabricated by using protein-mediated CdSe/ZnS quantum dots

The pH sensors using protein-mediated CdSe/ZnS quantum dots in an electrolyte-insulator-semiconductor (EIS) structure have been investigated. The hydrophobic cylindrical cavity of the chaperonin (GroEL) protein template was used to trap CdSe/ZnS quantum dots on hydrophobically treated SiO₂ surface. The CdSe/ZnS quantum dot with a small diameter of 3.98 nm is observed by atomic force microscope. A fair pH response with a sensitivity of 39 mV/pH and a linearity of 99.48% are obtained by using CdSe/ZnS quantum dot based EIS sensor, while those values are found to be 53 mV/pH and 99.95% for bare SiO₂ based EIS pH sensors. The pH response and linearity of CdSe/ZnS based quantum dot sensors are inferior (slightly) as compared to the bare SiO₂ sensors owing to the initial negative charges of CdSe quantum dots membrane, which has been explained by energy band diagrams. It is expected that this kind of quantum dot membrane can be useful in future bio-molecule detections.     

一种新型的WSN量子加密系统

目前无线传感器网络越来越普及,在不久的将来无线传感器网络的服务将会遍布全球。由于无线传感器网络在用户数据方面并没有IPSec的安全策略,因此具有一定程度的安全风险。我们在此设计了一种量子加密机制。这种应用于无线传感器网络的加密机制试图不仅使用类似于IPSec的策略,而且使用新型的量子加密技术。这种系统将有助于改善无线传感器网络的安全性。     

Novel Reversible Design of Advanced Encryption Standard Cryptographic Algorithm for Wireless Sensor Networks

The quantum of power consumption in wireless sensor nodes plays a vital role in power management since more number of functional elements are integrated in a smaller space and operated at very high frequencies. In addition, the variations in the power consumption pave the way for power analysis attacks in which the attacker gains control of the secret parameters involved in the cryptographic implementation embedded in the wireless sensor nodes. Hence, a strong countermeasure is required to provide adequate security in these systems. Traditional digital logic gates are used to build the circuits in wireless sensor nodes and the primary reason for its power consumption is the absence of reversibility property in those gates. These irreversible logic gates consume power as heat due to the loss of per bit information. In order to minimize the power consumption and in turn to circumvent the issues related to power analysis attacks, reversible logic gates can be used in wireless sensor nodes. This shifts the focus from power-hungry irreversible gates to potentially powerful circuits based on controllable quantum systems. Reversible logic gates theoretically consume zero power and have accurate quantum circuit model for practical realization such as quantum computers and implementations based on quantum dot cellular automata. One of the key components in wireless sensor nodes is the cryptographic algorithm implementation which is used to secure the information collected by the sensor nodes. In this work, a novel reversible gate design of 128-bit Advanced Encryption Standard (AES) cryptographic algorithm is presented. The complete structure of AES algorithm is designed by using combinational logic circuits and further they are mapped to reversible logic circuits. The proposed architectures make use of Toffoli family of reversible gates. The performance metrics such as gate count and quantum cost of the proposed designs are rigorously analyzed with respect to the existing designs and are properly tabulated. Our proposed reversible design of AES algorithm shows considerable improvements in the performance metrics when compared to existing designs.     

基于量子遗传粒子滤波的WSN目标跟踪算法

粒子滤波器是解决非线性非高斯运动跟踪的一种有效方法,很适合于无线传感器网络的目标跟踪.但是粒子滤波算法存在严重的退化现象.常规的重采样方法虽可解决退化问题,但容易导致粒子耗尽.本文针对此问题,将量子遗传算法引入粒子滤波,提出了基于量子遗传粒子滤波的无线传感器网络目标跟踪算法.通过量子遗传算法的编码方式增加粒子集的多样性...     

Integrated Ambient Light Sensor With Nanocrystalline Silicon on a Low-Temperature Polysilicon Display Panel

A novel integrated ambient light sensor using nanocrystalline silicon fabricated using low-temperature polysilicon technology has been developed on a display panel. The photosensing structure of the silicon nanocrystals embedded in a dielectric film sandwiched between the bottom metal and top indium-thin-oxide electrodes perfectly eliminates backlight noise, which is a problem typical of conventional p-i-n photodiodes integrated into a liquid-crystal display. Experimental results indicate that the Si-nanocrystal photosensor has better performances in dark current and quantum efficiency than those of the p-i-n diode. The Si-nanocrystal photosensor also exhibited response linearity and speed comparable to the p-i-n diode. In terms of long-term operation and reliability, the lifetime of the Si-nanocrystal photosensor is roughly two orders longer than that of the p-i-n diode. The Si-nanocrystal ambient light sensor has considerable flexibility in the design of spectrum, geometry, and the readout circuit, which is achieved by adjusting the nanocrystal size and applying a vertical stacking structure. The Si-nanocrystal photosensor can be a promising low-cost PMOS-only solution for various photosensing applications on display panels.      

Design and calibration of a microfabricated floating-elementshear-stress sensor

A microfabricated floating-element shear-stress sensor for measurements in turbulent boundary-layers is reported. Using surface micromachining of polyimide, a 500-μm×500-μm probe has been fabricated incorporating a differential-capacitor readout circuit. A model for the sensor response is described and is used for the design of an element to measure shear stresses of 1 Pa in air. The sensor is packaged for calibration in laminar flow, and electrical results obtained match the expected response     

A scalable sensor network using a polar coordinate system

Due to the quick development of chip design and antenna manufacturing techniques, wireless facilities, such as wireless sensors, have become significantly smaller and cheaper than before. Their usage has also consequently been widely enriched, such as in the areas of healthcare and forest monitoring. A wireless sensor network (WSN) is often used to monitor a specific environment for a specific purpose. However, how to effectively utilize the limited resources in a sensor, also in a WSN, is crucial. In a WSN, geographical information is usually employed to locate a node and its surroundings. In this article, we propose a system, named relative position for sensor routing using polar-coordinates (RP²), that deploys a polar coordinate system to identify sensor positions and route network packets. A sensor ID that carries geographical metadata can be helpful in positioning a sensor.     

Performance analysis of a color CMOS photogate image sensor

The performance of a color CMOS photogate image sensor is reported. It is shown that by using two levels of correlated-double sampling it is possible to effectively cancel all fixed-pattern noise due to read-out circuit mismatch. Instead the fixed-pattern noise performance of the sensor is limited by dark current nonuniformity at low signal levels, and conversion gain nonuniformity at high signal levels. It is further shown that the imaging performance of the sensor is comparable to low-end CCD sensors but inferior to that reported for high-end CCD sensors due to low quantum efficiency, high dark current, and pixel cross-talk. As such the performance of CMOS sensors is limited at the device level rather than at the architectural level. If the imaging performance issues can be addressed at the fabrication process level without increasing cost or degrading transistor performance, CMOS has the potential to seriously challenge CCD as the solid-state imaging technology of choice due to low power dissipation and compatibility with camera system integration     

Monte Carlo modeling for implantable fluorescent analyte sensors

A Monte Carlo simulation of photon propagation through human skin and interaction with a subcutaneous fluorescent sensing layer is presented. The algorithm will facilitate design of an optical probe for an implantable fluorescent sensor, which holds potential for monitoring many parameters of biomedical interest. Results are analyzed with respect to output light intensity as a function of radial distance from source, angle of exit for escaping photons, and sensor fluorescence (SF) relative to tissue autofluorescence (AF). A sensitivity study was performed to elucidate the effects on the output due to changes in optical properties, thickness of tissue layers, thickness of the sensor layer, and both tissue and sensor quantum yields. The optical properties as well as the thickness of the stratum corneum, epidermis, (tissue layers through which photons must pass to reach the sensor) and the papillary dermis (tissue distal to sensor) are highly influential. The spatial emission profile of the SF is broad compared that of the tissue fluorescence and the ratio of sensor to tissue fluorescence increases with distance from the source. The angular distribution of escaping photons is more concentrated around the normal for SF than for tissue AF. The information gained from these simulations will be helpful in designing appropriate optics for collection of the signal of interest.     

基于移动sink的无线传感器网络数据采集方案

对无线传感器网络的数据采集问题进行了研究,提出了一种基于可移动sink节点的数据采集方案DCSR。DCSR包括2个阶段,第1个阶段根据传感器节点的分布情况确定一批采集点,第2个阶段使用量子遗传算法求解出经过采集点的最短回路。计算完之后,sink沿着这条回路运动,周期性进行数据采集。理论分析和仿真实验表明,DCSR的性能较好,采集的数据量也更多。     

Capture of charge carriers and output power of a quantum well laser

The effect of noninstantaneous carrier capture by a nanoscale active region on the power characteristics of a semiconductor laser is studied. A laser structure based on a single quantum well is considered. It is shown that delayed carrier capture by the quantum well results in a decrease in the internal differential quantum efficiency and sublinearity of the light-current characteristic of the laser. The main parameter of the developed theoretical model is the velocity of carrier capture from the bulk (waveguide) region to the two-dimensional region (quantum well). The effect of the capture velocity on the dependence of the following laser characteristics on the pump current density is studied: the output optical power, internal quantum efficiency of stimulated emission, current of stimulated recombination in the quantum well, current of spontaneous recombination in the optical confinement layer, and carrier concentration in the optical confinement layer. A decrease in the carrier capture velocity results in a larger sublinearity of the light-current characteristic, which results from an increase in the injection current fraction expended to parasitic spontaneous recombination in the optical confinement layer and, hence, a decrease in the injection current fraction expended to stimulated recombination in the quantum well. A comparison of calculated and experimental light-current characteristics for a structure considered as an example shows that good agreement between them (up to a very high injection current density of 45 kA/cm²) is attained at a capture velocity of 2 × 10⁶ cm/s. The results of this study can be used to optimize quantum well lasers for generating high optical powers.     

超晶格中浅杂质能带与光吸收

超晶格BEST模式像传感器是近几年来发展的非常有潜力的红外探测器件。本文结合这种器件计算和讨论了超晶格中浅杂质能谱和光吸收,给出了:杂质能带;杂质离化能;杂质能带的带宽和能态密度;杂质基态与第一束缚子能带基态间光跃迁:量子化极限尺寸以及其它性质。这不但具有一定物理意义,并对于BEST模式红外传感器件的光吸收有一定参考价值。     

Broad-band emission from a multiple asymmetric quantum-well light-emitting diode

The authors demonstrate broadband light-emitting diode (LED) emission, with a full-width-at-half-maximum (FWHM) values >100 nm, based on concurrent multiple-state transitions in a single active layer containing two asymmetric quantum wells in the GaAs/AlGaAs material system. This spectral width is much broader (by a factor of 2.5) than that for commercial edge-emitting LEDs in the GaAs/AlGaAs system. The LED device is well suited for broadband source applications in wavelength-multiplexing-based, fibre-optic sensor network systems.<>     

Proposal of a new structural thermal vacuum sensor with diode-thermistors combined with a micro-air-bridge heater

New structural Pirani gauge-type thermal vacuum sensor with a microheater and two pn junction diodes, Th-A and Th-B, as a high-sensitive temperature sensor working like a thermistor formed on a micro-air-bridge (MAB) is proposed. The MAB is separated into two regions of A and B. The Th-A and the Th-B can measure temperatures of the region A and the region B connected to the region A with thermal resistance, respectively. The microheater is formed in the region A and can maintain its temperature by feedback control. The diode-thermistor, Th-C, formed on the SOI substrate is provided to measure the ambient temperature T_c. Principle of this Pirani gauge-type thermal vacuum sensor is based on the measurement of the pressure-dependent thermal conductivity of gaseous media due to the heat exchange between the heated MAB (suspended film) and surrounding gas in vacuum. This has more than two orders of magnitude measurable pressure range (2×10⁻³-1×10⁵ Pa) compared with traditional Pirani vacuum sensor, and has very fast response and low power consumption.     

Junction CCD optical line sensor

An optical line sensor based on a junction CCD is presented. The expected good quantum efficiency of a junction CCD appears to be better than 0.8. In addition, this type of CCD has excellent blooming suppression. The resolution is 49.5 ?m and the sensor is driven by a 3-phase clock.     

Deadbeat controller design for a soft-switched high-frequencyresonant rectifier

In this paper, a deadbeat controller design technique is developed for a quantum boost series resonant rectifier (QBSRR) to achieve the fast dynamic responses of the output voltage in the presence of any load variations, and in order to monitor the load information without employing the current sensor, the load estimation method is also derived. By using the information of the load estimation method, the proposed controller gain is automatically adjusted to have the system always keep the very fast dynamic responses. To verify these superior performances, the simulation and experiment are carried out     

基于量子遗传算法的无线视频传感网络优化覆盖算法

针对智慧城市无线视频传感网络建设需要,提出一种基于量子遗传算法的网络优化覆盖算法。算法面向复杂的监视区场景,监视区中存在形状各异的障碍物,各区域的重要程度不同。以二维离散网格模型描述监视区场景,用编码描述矩阵表示监视区域,用七元组描述有向无线视频传感器。通过严格的数学推导得出了问题的数学规划模型。优化覆盖算法由IntialDeployment算法和OptimizedDeployment算法2部分组成,以获得最大有效覆盖率的网络部署方案为求解目标。采用量子遗传算法搜索解空间,通过合理编码染色体,优化量子旋转门参数,使算法的运算速度快,收敛性好。引入理想覆盖率和理想加权覆盖率2个极限值,采用相对比较法评判算法优劣。仿真实验和数据分析表明,算法获得的方案能很好地逼近理想极限值。在传感器节点数给定的情况下,算法能获得最大的覆盖率。