A novel optical waveguide microcantilever sensor for the detection of nanomechanical forces

This study presents a novel generic multipurpose probe based on an array of 20 waveguide channels with microcantilevers acting as optical waveguides operated in the visible range. The principle of operation is based on the sensitivity of energy transfer between two butt-coupled waveguides to their misalignment with respect to each other. The technique can be considered an alternative to the known methods used for the readout of the nanomechanical response of microcantilevers to the external force exerted on them. The cantilever displacement can be detected with a resolution of 18 fm//spl radic/Hz. The limit is generally defined by the shot noise of a conventional photodetector used for the readout of the output signal. Real-time parallel monitoring of several channels can be realized. In contrast to devices based on the atomic force microscope detection principle, no preliminary alignment or adjustment, except for light coupling, is required. The detection of the cantilever deflection at subnanometer range was demonstrated experimentally.     

A CMOS, fully integrated sensor for electronic detection of DNA hybridization

An integrated field-effect device for fully electronic deoxyribonucleic acid (DNA) detection was realized in a standard CMOS process. The device is composed of a floating-gate MOS transistor, a control-capacitor acting as integrated counterelectrode, and an exposed active area for DNA immobilization. The drain-current of the transistor is modulated by the electric charge carried by the DNA molecules. After DNA hybridization, this charge increases and a change in the output current is measured. Experimental results are provided. Full compatibility with a standard CMOS process opens the way to the realization of low-cost large-scale integration of fast electronic DNA detectors.     

A novel intrinsic multimode fiber-optic sensor for the detection or monitoring of microwave power

A graded-index silica multimode fiber with an acrylate primary coating has been shown to act as an intrinsic sensor of microwave power. When under the influence of a microwave field, the fiber absorbs a small fraction of microwave energy and this alters the propagation condition for transmitted laser light (632.8 nm). This alteration is manifested in the speckle pattern which is projected, after transmission, from the cut end of the fiber, and is recorded either by an optical detector or by visual observation. The rate of change of the speckle pattern is the important feature. The sensitivity of the effect increases as the microwave power increases, as the fiber length increases, and when the fiber is coated with conducting silver paint. Microwave powers, transmitted at 2.45 GHz in a rectangular waveguide is in the range 0.07-700 W were detected with an accuracy of better than 2 dB. These power levels correspond to electric field levels of2.8 times 10^{2}V . m^-1and2.8 times 10^{4}V . m^-1at the position of the fiber. The results are briefly compared with recent similar observations using a silica single-mode fiber as the sensor and an interferometer as detector. Discussions relate to use of the speckle pattern for detection and to possible applications.     

A novel semiconductor capacitive sensor for a single-chipfingerprint sensor/identifier LSI

We describe a new semiconductor capacitive sensor structure and the fabrication process for a single-chip fingerprint sensor/identifier LSI in which the sensor is stacked on a 0.5-μm CMOS LSI. To ascertain the influence of the fabrication process and normal usage on the underlying LSI, sensor chips were subjected to an electrostatic discharge (ESD) test, mechanical stress test, and unsaturated pressure cooker test (USPCT). ESD tolerance is obtained at the value of ±3.0 kV. To investigate mechanical stress, we carried out a tapping test. The sensor is immune to mechanical stress under the condition of 10⁴ taps with the strength of 1 MPa. A multilayer passivation film consisting SiN under polyimide film provides protection against contamination such as water. Thus, under USPCT conditions of 130°C, 80% humidity, and 48 h, the chips were not degraded. The tests confirm that the proposed sensor has sufficient reliability for normal identification usage     

A novel airflow sensor for miniature mobile robots

A novel airflow sensor has been developed for applications involving miniature chemical sensing robots. Information about air movement is essential for robots when they are searching for the sources of chemical plumes. The airflow sensor described here measures both wind direction and velocity at airflow rates commonly encountered in an indoor environment. Measurements are made by rotating a small paddle in the airflow. The varying speed of the paddle is analysed to determine both wind speed and direction. Low power consumption and rugged construction make the sensor well suited to robotic applications. The prototype sensor is small enough to fit on a mobile robot measuring only 10 cm in diameter. This paper presents the sensor operating principle, construction and some experimental results.     

A CMOS active pixel sensor based DNA micro-array with nano-metallic particles detection protocol

A DNA micro-array (DMA) for DNA detection is reported. The DMA combines a standard CMOS active pixel image sensor with a DNA detection protocol utilizing the binding of DNA targets and probes functionalized with gold nano-particles that can modify the opaqueness at the detection site. The DMA has been fabricated using a 0.5 μm CMOS process together with on-chip timing control and correlated double sampling. Experimental results show that the system can detect DNA samples with extremely low concentration down to 10 pM using ordinary light source.     

Design and characterization of novel read-out systems for a capacitive DNA sensor

This paper presents novel read-out electronic systems for a fast DNA label-less detection. The capacitive shift due to the hybridization effect is monitored by means of a charge sensitive amplifier and a differential stage. The systems provide an A/D conversion and an evaluation of the capacitive shift amount with a resolution of 11 bit. The read-out solutions demonstrate the ability to identify a 0.01% variation on the capacitive value of the sensor. The investigated techniques are suitable for monolithic systems or for a micro-fabricated array of sensors.     

A novel wavelet transform-based transient current analysis for fault detection and localization

Transient current (IDD) testing has been often cited and investigated as an alternative and/or supplement to quiescent current (IDDQ) testing. In this correspondence, we present a novel integrated method for fault detection and localization using wavelet transform-based IDD waveform analysis. The time-frequency resolution property of wavelet transform helps us detect as well as localize faults in digital CMOS circuits. Experiments performed on measured data from a fabricated 8-bit shift register, and simulation data from more complex circuits show promising results for both detection and localization. Wavelet-based detection method shows better sensitivity than spectral and time-domain methods. Effectiveness of the localization method in presence of complex power supply network, measurement noise, and process variation is also addressed.     

Efficient deployment quality analysis for intrusion detection in wireless sensor networks

The intrusion detection in a Wireless Sensor Network is defined as a mechanism to monitor and detect any intruder in a sensing area. The sensor deployment quality is a critical issue since it reflects the cost and detection capability of a wireless sensor network. The quality of deterministic deployment can be determined sufficiently by a rigorous analysis before the deployment. However, when random deployment is required, determining the deployment quality becomes challenging. In the intrusion detection application, it is necessary to define more precise measures of sensing range, transmission range, and node density that impact overall system performance. The major question is centred around the quality of intrusion detection in WSN, how we can guarantee that each point of the sensing area is covered by at least one sensor node, and what a sufficient condition to guarantee the network connectivity? In this paper, we propose an appropriate probabilistic model which provides the coverage and connectivity in k-sensing detection of a wireless sensor network. We have proved the capability of our approach using a geometric analysis and a probabilistic model.     

A novel structure for the intrinsic Fabry-Perot fiber-optictemperature sensor

A novel structure of the intrinsic Fabry-Perot interference (IFPI) fiber temperature sensor is presented. The sensor uses two different core diameter fibers and produces a reflective mirror by fusing uncoated bare fibers. This procedure not only solves the problem of controlling thickness and reflectance of the thin film but also provides easier and cheaper technologies for IFPI fiber sensors. Theoretical and experimental aspects of the intrinsic Fabry-Perot cavity are described. Both theoretical and experimental results from this novel structure show good agreement with those from the traditional Fabry-Perot fiber sensor     

A novel mathematical model for coverage in wireless sensor network

1 Introduction With the development of the sensor, wireless communication, and computer science, many researches have been focused on the development of a novel wireless network named wireless Ad-hoc sensor networks. This network can be defined as a network that can be self-organized in Ad-hoc fashion. This includes many sensor nodes and its objective is to sense, collect, and process the information collected by the individual sensor nodes via their cooperation [2]. Because of its high pract…     

A novel approach for void avoidance in wireless sensor networks

We propose a novel approach to treat the problem of void avoidance in sensor networks. In our approach, the choice of the forwarding region around a discovered void is oriented by the locations of (i) the sender node, (ii) the void center and (iii) the destination node. Three void‐avoidance schemes are described which use the same void‐discovery algorithm. Based on an oriented face routing, the first scheme is used by the boundary nodes to prevent packets from dropping. The second scheme is used by sender nodes located n‐hops away from the void boundary to launch a preventive rerouting. The third scheme tends to protect packets from both the concave zones and the boundaries nodes of voids. Proposed schemes are simple to implement. They save network resources and could be easily associated with existing geographic routing protocols. Simulation results show the efficiency of the proposed approach. Copyright © 2009 John Wiley & Sons, Ltd.     

无线传感网络中基于规则预设的集中式入侵检测系统

黑洞攻击和选择性转发攻击是威胁分簇无线传感器路由协议安全的主要攻击手段。提出一种基于规则预设的集中式入侵检测系统,预设两种攻击条件下网络的行为规则,一旦簇头通过收发控制分组检测到入侵节点,发现网络行为偏离预设规则,则判定网络遭受某种网络攻击。使用网络仿真软件(NS2)评估入侵检测系统。仿真实验结果证明,在节点能量受限的无线传感器网络应用场景下,集中式入侵检测系统具有优越的安全性能和节能特性。     

A distributed fiber optic sensor based on cladding fluorescence

The fiber for the sensor is formed by cladding fused silica during drawing with polydimethyl siloxane into which an organic fluorescent dye, 9, 10-diphenylanthracene, has been dissolved. Upon side illumination at a wavelength within the excitation range of the dye, the cladding fluoresces; some of this fluorescence is coupled into guided modes in the fiber core through the evanescent fields of these modes. In the presence of oxygen, fluorescent emission by the dye is diminished. For the sensor described, the rubbery liquidlike nature of the polydimethyl siloxane cladding allows rapid diffusion of gases, and the intensity of the guided fluorescence is observed to drop by 30% in less than 5 s when the ambient atmosphere changes from pure nitrogen to pure oxygen. The advantages of this sensing technique, and some of the possibilities for new sensors based on this principle, are discussed     

一种新颖的光纤光栅电流传感器

提出并验证了一种光纤光栅电流传感装置,该装置利用洛氏线圈把大电流转换为低电压,借助压电陶瓷的电致伸缩效应把低电压转换为光纤光栅布拉格波长的漂移,最后通过干涉解调技术把波长漂移信号转化为相移信号,由相移值确定待测电流的变化量.实验证明在0～400 A的范围内,电流传感灵敏度为0.0473 rad/A,与理论值0.0589 rad/A基本吻合.     

A novel adaptive logarithmic digital pixel sensor

A major problem associated with complementary metal-oxide-semiconductor and charge couple device imagers is their limited dynamic range (DR), typically 60-70 dB. This falls far short of covering the wide illumination ranges found in natural scenes (typically 120-140 dB). Biological retinas are known to feature adaptive, logarithmic-type responses enabling them to cover a very wide DR, without compromising the resolution. This letter presents a novel way to realize such an adaptive logarithmic response by combining a digital time domain vision sensor and a simple adaptive digital quantizer. This letter presents the theory and experimental results for an adaptive logarithmic response sensor featuring over 100-dB DR.     

A CMOS blood cancer detection sensor based on frequency deviation detection

This paper proposes a technique to detect Leukaemia (blood cancer) based on the frequency modulation of a relaxation oscillator by changes in the dielectric constant of blood cells. A novel 16-bit frequency detector with a digital output has been proposed to detect the frequency difference between two oscillators based on healthy blood and Leukaemic blood. A circuit has been designed, to operate on a 1.2 V supply, post layout simulations shows 0.35 mA current consumption. The chip Area including pads ~0.6 mm × 0.45 mm.     

基于量子点荧光淬灭技术的痕量Cu2+检测传感器研究

本文设计了一种可用于现场检测的痕量Cu2+传感器,运用自行研制的光学感知与信号处理模块实现痕量Cu2+的快速检测,达到了检测仪器的低成本、小型化的目的.实验结果表明,在Cu2+浓度50-1000nmol/L范围内传感器检测结果具有较好的线性关系,拟合后的直线方程为Y=0.11869* X+ 14.47268,线性度为0.99358,标准方差为4.63099,传感器响应时间为50秒,检测的可重复性较好,该传感器可以满足痕量Cu2+现场检测的需求.     

一种新型的CMOS集成湿度传感器

利用MEMS技术，对一种新型CMOS湿度传感器进行理论分析、模拟以及结果讨论。该湿度传感器采用标准CMOS工艺制造，采用梳状铝电极结构、梳状多晶硅加热结构，衬底接地，感湿介质采用聚酰亚胺，利用商业软件Coventor进行模拟绘制出敏感电容与相对湿度的曲线图。接口电路采用开关电容电路，输出可测电压信号，利用Microsim公司的Pspice模拟电路得到相对湿度与输出电压曲线关系。