COMPACT PHASE GRATING INTERFERENCE SENSOR FOR MICRO-DISPLACEMENT

On the basis of existing techniques, a compact micro-displacement sensor of phase grating interference （PGI） is described, which adopts cylindrical hologram diffraction grating as the calibration standard. The optical principle of the sensor is explained, and the relation between the grating motion displacement and the phase shift of interference stripes is deduced. The improvement of the integral structure and the method of photoelectric signal processing are described in detail. With the software system based on the virtual instrument development platform Labwindows/CVI and other hardwares such as the precision displacement worktable, the surfaces of typical parts are measured and the characterization results are given. The sensor has wide measuring range and high resolution, its sensitivity and resolution being independent of the wavelength of the incident light. The vertical measuring range is 0-6 mm, and the vertical resolution is 0.005μm. The experimental results show that the sensor can be used to measure and characterize the surface topography parameters of the plane and curved surface.

Recent Progress on Flexible Room-Temperature Gas Sensors Based on Metal Oxide Semiconductor

With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.

Influences of semiconductor laser on fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer

This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.

X-ray detection based on complementary metal-oxide-semiconductor sensors

Complementary metal-oxide-semiconductor(CMOS) sensors can convert X-rays into detectable signals; therefore, they are powerful tools in X-ray detection applications. Herein, we explore the physics behind X-ray detection performed using CMOS sensors. X-ray measurements were obtained using a simulated positioner based on a CMOS sensor, while the X-ray energy was modified by changing the voltage, current, and radiation time. A monitoring control unit collected video data of the detected X-rays. The video images were framed and filtered to detect the effective pixel points(radiation spots).The histograms of the images prove there is a linear relationship between the pixel points and X-ray energy. The relationships between the image pixel points, voltage, and current were quantified, and the resultant correlations were observed to obey some physical laws.

金属氧化物半导体MEMS气体传感器研究进展

随着物联网的快速发展,各领域对气体监测的需求越来越大,基于先进微机电系统(Micro-electro-mechanical systems, MEMS)技术的金属氧化物半导体(Metal oxide semiconductor, MOS)气体传感器在过去几十年里取得了很大发展。MEMS微热板的多样化设计、MOSs纳米结构的多样化以及机器学习算法的出现为MEMS的传感性能以及智能传感系统的构建提供了很大助力。本文从MEMS气体传感器的分类、制备和应用以及传感器阵列的构建等方面综述了金属氧化物半导体MEMS气体传感器的最新研究进展,并对MEMS基气体传感器的发展前景进行了总结和展望。

针对半导体气体传感器的电信号采集装置

针对半导体气体传感器对环境敏感、电阻跨度大的特性,设计了一种针对半导体气体传感器灵敏度高、体积小、适用性广的电信号采集装置。采用多档位分压法实现对欧姆(Ω)至吉欧姆(GΩ)范围的电阻测量,通过滤波与温湿度补偿消除物理、温湿度干扰;同时装置具有本地报警、上位机报警、气室等设计。本文装置实现了半导体气体传感器的精确测量,同时设计集成电路,将传感器封装为可实际应用系统,采用国产EDA与核心芯片设计,有效填补了该领域的空白。

氢气传感器在电解制氧系统中的应用研究

针对电解制氧系统中氢气浓度测量受环境因素影响大、测量准确性低等问题,选取了半导体型、催化燃烧型、热导型三类不同原理的氢气传感器,对其在电解制氧系统中的应用进行了试验验证,并对试验结果进行了讨论,分析了各类氢气传感器的使用局限性。

基于二维半导体的图像传感器

图像传感器作为获取视觉信息的重要器件,可将感知到的光信号转换为电信号进行输出。目前,基于互补型金属氧化物半导体构建的图像传感器制造技术已相当成熟。然而,在某些特定的应用场景下,对微型化和多功能的图像传感器的需求仍待解决。面对此挑战,结合二维半导体丰富的材料体系及优异的光电特性,以及器件向微型化和多功能化发展的趋势,基于二维半导体的图像传感器在微型化和高集成度方面显示出巨大潜力,为图像传感器领域的发展带来了新机遇。本文首先介绍了二维半导体的带隙特性及其对应的光谱响应波段范围,展示了基于二维半导体的单像素成像技术;接着,阐述了如何利用二维半导体原子排布呈面内各向异性的特征,成功构筑了偏振敏感的图像传感器;最后,探讨了随着大面积二维半导体材料生长技术的不断成熟,如何进一步实现基于二维半导体像素阵列图像传感器的构筑。

SF_(6)分解组分的气体传感器检测方法综述

填充六氟化硫(SF_(6))的电气设备内部存在绝缘缺陷时可能发生过热或放电,迫使SF_(6)分解产生一些特定的气体副产物。通过检测这些副产物的种类和浓度,可以判断电气设备中是否存在绝缘缺陷以及缺陷的类型和严重程度。气体传感器作为气体检测的重要工具,在绝缘缺陷的气体检测法中受到了越来越多的关注。本文重点回顾了使用气体传感器检测SF_(6)分解产物的方法,介绍了SF_(6)解离过程和特征气体的生成路径,详细阐述了用于SF_(6)分解特征气体检测的传感器气敏原理和优缺点;重点讨论了利用特征气体信息诊断绝缘缺陷的算法,并展望了通过传感器检测气体分解组分方法诊断绝缘缺陷的发展方向。

激光供电脉冲电场传感器设计

为应对高电压电力系统中瞬变电场强度的测量难题,并确保直流输电系统的安全稳定运行,本研究设计并构建了一种由激光光电池供电的脉冲电场传感器。该传感器包括激光光电池供电模块、电光信号转换模块和单极子天线。此外,还在设计中采用恒流源电路作为半导体激光器的供电系统,它能将特定波长的激光能量转换为电能,为传感器或其他负载提供远距离非接触式供能。为确保传感器的精确度,本研究开发了一套系统标定装置,用于在控制空间内产生标准测试电场,并通过部署的传感器阵列来测量产生的电场、磁场及被测物体内部的其他数据,实现对动态系统电场强度的即时校准。实验测试表明,所研制的脉冲电场传感器具有20kHz至500MHz的3 dB带宽,100V/m至60kV/mm的动态范围,125Ω的负载阻抗,优于10%的线性度,以及上升沿小于3.5ns的瞬态响应性能,验证了其在强电磁干扰环境下仍具备良好的快速响应速度。

Highly sensitive and fast response strain sensor based on evanescently coupled micro/nanofibers

Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.

Semiconductor Optical Amplifier (SOA)-Fiber Ring Laser and Its Application to Stress Sensing

We have developed a novel optical fiber ring laser using a semiconductor optical amplifier (SOA) as the gain medium, and taking advantage of polarization anisotropy of its gain. The frequency difference of the bi-directional laser is controlled by birefringence which is introduced in the ring laser cavity. The beat frequency generated by combining two counter-propagating oscillations is proportional to the birefringence, the fiber ring laser of the present study is, therefore, applicable to the fiber sensor. The sensing signal is obtained in a frequency domain with the material which causes the retardation change by a physical phenomenon to be measured. For the application to stress sensing, the present laser was investigated with a photoelastic material.

Magnetoresistive sensors with hybrid Co/insulator/ZnO:Co junctions

Magnetic tunnel junctions （MTJs）, as the seminal spintronic devices, are expected for applications in magne- toresistive sensors due to their large magnetoresistance （MR） and high field sensitivity. Two hybrid Co/insulator/ZnO：Co junctions were fabricated with two different barriers to investigate the magneto-transport properties. Experimental results indicate that, both Co/MgO/ZnO：Co and Co/ZnO/ZnO：Co junctions show the positive and nearly linear MR, and their tunnel magnetoresistances （TMR） are 21.8% and 13.6%, respectively, when the current is applied perpendicular to the film plane under the magnetic field of 2 T at 4 K. The nonlinearity of MR is less than 1% within the magnetic field （H） of 1 kOe 〈 H 〈 12 kOe at low temperature, making them attractive as magnetoresistive sensors. The higher MR of Co/MgO/ZnO：Co junctions is due to the superior spin filtering effect and larger effective barrier height of the MgO barrier. This linear MR characteristic of Co/insulator/ZnO：Co structures shows a promising future on the applications of diluted magnetic semiconductors in magnetoresistive sensors.

Simple point contact WO_3 sensor for NO_2 sensing and relevant impedance analysis

A simple and new point contact tungsten trioxide （WO3） sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration （ppm level） environmental pollutants such as NO2. X-ray diffraction （XRD） and field emission scanning electron microscopy （FE-SEM） were applied to characterize the phase and the microstructure of the samples, respec-tively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor （W-WO3-W） showed rectifying characteristics and an ideal sensing performance of about 110 C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy （EIS） at a relatively low temperature of 150 C but faded away above 200 C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.

Difference in electron-and gamma-irradiation effects on output characteristic of color CMOS digital image sensors

Changes of the average brightness and non-uniformity of dark output images,and quality of pictures captured under natural lighting for the color CMOS digital image sensorsirradiated at different electron doses have been studied in comparison to those from theγ-irradiated sensors. For the electron-irradiated sensors, the non-uniformity increases obviouslyand a small bright region on the dark image appears at the dose of 0.4 kGy. The average brightnessincreases at 0.4 kGy, increases sharply at 0.5 kGy. The picture is very blurry only at 0.6 kGy,showing the sensor undergoes severe performance degradation. Electron radiation damage is much moresevere than γ radiation damage for the CMOS image sensors. A possible explanation is presented inthis paper.

Analysis of proton and γ-ray radiation effects on CMOS active pixel sensors

Radiation effects on complementary metal-oxide-semiconductor（CMOS） active pixel sensors（APS） induced by proton and γ-ray are presented. The samples are manufactured with the standards of 0.35 μm CMOS technology. Two samples have been irradiated un-biased by 23 MeV protons with fluences of 1.43 × 10^11 protons/cm^2 and 2.14 × 10^11 protons/cm-2,respectively, while another sample has been exposed un-biased to 65 krad（Si） ^60Co γ-ray. The influences of radiation on the dark current, fixed-pattern noise under illumination, quantum efficiency, and conversion gain of the samples are investigated. The dark current, which increases drastically, is obtained by the theory based on thermal generation and the trap induced upon the irradiation. Both γ-ray and proton irradiation increase the non-uniformity of the signal, but the nonuniformity induced by protons is even worse. The degradation mechanisms of CMOS APS image sensors are analyzed,especially for the interaction induced by proton displacement damage and total ion dose（TID） damage.

Ultra-Low Power 1 Volt Small Size 2.4 GHz CMOS RF Transceiver Design for Wireless Sensor Node

Ultra-low power transceiver design is proposed for wireless sensor node used in the wireless sensor network（WSN）.Typically,each sensor node contains a transceiver so it is required that both hardware and software designs of WSN node must take care of energy consumption during all modes of operation including active/sleep modes so that the operational life of each node can be increased in order to increase the lifetime of network.The current declared size of the wireless sensor node is of millimeter order,excluding the power source and crystal oscillator.We have proposed a new 2.4 GHz transceiver that has five blocks namely XO,PLL,PA,LNA and IF.The proposed transceiver incorporates less number of low-drop outs（LDOs）regulators.The size of the transceiver is reduced by decreasing the area of beneficiary components up to 0.41 mm;of core area in such a way that some functions are optimally distributed among other components.The proposed design is smaller in size and consumes less power,<1 mW,compared to other transceivers.The operating voltage has also been reduced to 1 V.This transceiver is most efficient and will be fruitful for the wireless networks as it has been designed by considering modern requirements.

Modelling and fabrication of wide temperature range Al_(0.24)Ga_(0.76)As/GaAs Hall magnetic sensors

Silicon Hall-effect sensors have been widely used in industry and research fields due to their straightforward fabrication process and CMOS compatibility.However,as their material property limitations,technicians usually implement complex CMOS circuits to improve the sensors’performance including temperature drift and offset compensation for fitting tough situation,but it is no doubt that it increases the design complexity and the sensor area.Gallium arsenide(GaAs)is a superior material of Hall-effect device because of its large mobility and stable temperature characteristics.Concerning there is no specified modelling of GaAs Hall-effect device,this paper investigated its modelling by using finite element method(FEM)software Silvaco TCAD®to help and guide GaAs Hall-effect device fabrication.The modeled sensor has been fabricated and its experimental results are in agreement with the simulation results.Comparing to our previous silicon Hall-effect sensor,the GaAs Hall-effect sensor demonstrates potential and reliable benchmark for the future Hall magnetic sensor developments.

Two-Mode Biomedical Sensor Build-up:Characterization of Optical Amplifier

Intracavity absorption spectroscopy is a strikingly sensitive technique that has been integrated with a two-wavelength setup to develop a sensor for human breath.Various factors are considered in such a scenario,out of which Relative Intensity Noise(RIN)has been exploited as an important parameter to characterize and calibrate the said setup.During the performance of an electrical based assessment arrangement which has been developed in the laboratory as an alternative to the expensive Agilent setup,the optical amplifier plays a pivotal role in its development and operation,along with other components and their significance.Therefore,the investigation and technical analysis of the amplifier in the system has been explored in detail.The algorithm developed for the automatic measurements of the system has been effectively deployed in terms of the laser’s performance.With this in perspective,a frequency dependent calibration has been pursued in depth with this scheme which enhances the sensor’s efficiency in terms of its sensitivity.In this way,our investigation helps us in a better understanding and implementation perspective of the proposed system,as the outcomes of our analysis adds to the precision and accuracy of the entire system.

Enabling Long-Term Operation of GaAs-Based Sensors

A coating scheme was developed for enabling the operation of a GaAs-based Molecular Controlled Semiconductor Resistor (MOCSER) under biological conditions. Usually GaAs is susceptible to etching in an aqueous environment. Several methods of protecting the semiconductor based devices were suggested previously. However, even when protected, it is very difficult to ensure the operation of a GaAs-based electronic sensor in aqua solution for long periods. We developed a new depositing scheme of (3-mercaptopropyl)-trimethoxysilane (MPTMS) on GaAs substrate consisting of two separate steps. The first involves chemisorption of a dense primary MPTMS layer on the substrate, whereas in the second, a thin MPTMS polymer layer is deposited on the already adsorbed layer, resulting in a 15 -?29 nm thick coating. We show that applying the new MPTMS deposition procedure to GaAs-based MOCSER devices allows up to 15 hours of continuous electrical measurements and stable performance of the sensing device in harsh biological environment. The new protection allows implementing GaAs technology in bioelectronics, particularly in biosensing.