A Magnetically Controlled Wireless Optical Oxygen Sensor for Intraocular Measurements

The influence of oxygen on various ophthalmological complications is not completely understood and intraocular oxygen measurements are essential for better diagnosis and treatment. A magnetically controlled wireless sensor device is proposed for minimally invasive intraocular oxygen concentration measurements. This device will make it possible to make measurements at locations that are currently too invasive for human intervention by integrating a luminescence optical sensor and a magnetic steering system. The sensor works based on quenching of luminescence in the presence of oxygen. A novel iridium phosphorescent complex is designed and synthesized for this system. A frequency-domain lifetime measurement approach is employed because of the intrinsic nature of the lifetime of luminescence. Experimental results of the oxygen sensor together with magnetic and hydrodynamic characterization of the sensor platform are presented to demonstrate the concept. In order to use this sensor for in vivo intraocular applications, the size of the sensor must be reduced, which will require an improved signal-to-noise ratio.     

Compact dielectric resonator antenna for microwave breast cancer detection

A compact stair-shaped dielectric resonator antenna (DRA) is designed and fabricated for microwave breast cancer detection. A quarter-wavelength choke was incorporated to reduce the finite ground plane size. A more than 40% return loss of 10 dB centred at 6.5 GHz is achieved with a 50 Ω coaxial port. Parametric studies are carried out to provide practical insights into sensor design. The design is performed numerically and confirmed experimentally. A simple model for the tissue is considered and the interaction of the sensor with the tissue is investigated. Good matching is retained without adding any matching medium or lumped loads when the sensor is in contact with the tissue. A two-element sensor array is investigated numerically. A dipole antenna and a circular ultra-wideband dipole antenna are compared with the stair-shaped DRA with a choked ground plane. Preliminary results are obtained for the cases with different tumour locations. The DRA type of sensor reveals good potential for frequency-domain detection.     

Multicomponent lifetime-based pH sensors utilizing constant-lifetime probes

A multicomponent luminescent sensor system is described that uses probe species with constant lifetimes to generate an analyte-dependent change in the apparent sensor lifetime. This new sensing scheme not only allows for lifetime-based measurement techniques to be applied to sensors that employ static quenching interactions but also provides the ability to vary the sensitivity of the sensor system with simple changes in instrumental parameters. A model for the multicomponent sensor is presented, followed by data measured using a prototype pH sensor based on the model.     

Mass transfer and gas-phase calibration of implanted oxygen sensors

A protocol is described for validation of implanted oxygen sensors, in which sensors are calibrated in the gas phase where concentration boundary layers are absent. Calibration prior to sensor implantation and confirmation after sensor explantation allows separation of tissue mass transfer effects from sensor variance and drift. A model is given here that describes the oxygen-dependent signal current in terms of oxygen mass transfer to the sensor, permeability of the sensor membrane, and electrode area. The parameter used in the model to describe mass transfer to implanted sensors is consistent with experimental observations and allows comparisons with nonimplanted sensors. This method provides a bridge between the complementary approaches of empirical calibration and model-based calculation for determining oxygen concentration from the sensor response.     

Optical-fiber sensor using tailored porous sol-gel fiber core

A new concept in optical-fiber chemical sensors, the active fiber core optical sensor (AFCOS), is presented. In this sensor, the fiber core acts as a transducer. The sensitivity of an AFCOS sensor is compared with that of an active coating [evanescent wave (EW)] based optical-fiber sensor. Requirements for a fiber core to act as a chemical sensor are discussed. Novel techniques for making a porous sol-gel silica fiber, doping chemical reagents into the fiber, and constructing a chemical sensor using the porous fiber as a transducer have been developed. The microstructure of the fabricated sol-gel silica fiber and the effect of the fiber's microstructure on the capability of the porous sol-gel silica fiber for guiding light are discussed. A humidity sensor employing a CoCl/sub 2/-doped porous sol-gel fiber as a transducer has been constructed as an example. The test results for the humidity sensor verified a theoretical analysis indicating that an optical-fiber chemical sensor using an active fiber core as a transducer has a much higher sensitivity than that of an EW-based sensor.     

A Wide-Dynamic-Range CMOS Image Sensor Based on Multiple Short Exposure-Time Readout With Multiple-Resolution Column-Parallel ADC

A wide-dynamic-range CMOS image sensor based on synthesis of one long and multiple short exposure-time signals is proposed. A high-speed, high-resolution column-parallel integration type analog-to-digital converter (ADC) with a nonlinear slope is crucial for this purpose. A prototype wide-dynamic-range CMOS image sensor that captures one long and three short exposure-time signals has been developed using 0.25-mum 1-poly 4-metal CMOS image sensor technology. The dynamic range of the prototype sensor is expanded by a factor of 121.5, compared with the case of a single long exposure time. The maximum DNL of the ADC is 0.3 least significant bits (LSB) for the single-resolution mode and 0.7 LSB for the multiresolution mode     

Sensor for Monitoring the Moisture in Porous Materials

A new principle of a sensor for monitoring of moisture in porous materials is presented. The sensor utilizes changes of the thermal conductivity of a porous structure when pores are filled with the air/vapor, water, or ice depending on thermodynamic conditions. A hot-ball method is used for measuring the thermal conductivity. The moisture sensor is made of the cylindrical core drilled from the parent material. The signal of the sensor is not sensitive to ionic radicals of the pore medium. The method of sensor calibration is presented, as well. Then the moisture sensor (hot ball) is inserted back into the drilled hole of the material to ensure that the porous structure of both the sensor and the investigated material are identical. Sensors can be made of porous materials in the range of porosities from 0.3 % up to 70 %. A simple device is constructed that allows monitoring of moisture in real conditions.     

Simulation, implementation, and analysis of an optical fiber bundle distance sensor with single mode illumination

A simulation model for an optical fiber bundle distance sensor with a single mode fiber as the illumination fiber and a multimode fiber as the receiving fiber is presented. Approximating the illumination light exiting the single mode fiber as having a Gaussian intensity profile, a closed-form solution of the reflected light coupled into the receiving fiber was derived. A distance sensor was implemented and the measured sensor outputs were compared with the simulation data to verify the theoretical model. The performance of the distance sensor with different design parameters was analyzed. Design guidelines for achieving desired sensor performances are suggested.     

一种新型霍尔式角度传感器的研究

设计了一种新型霍尔式角度传感器,详细阐述了传感器的机械结构和工作原理,根据磁路定律和霍尔效应推导了传感器的输出特性,表明传感器工作时能够直接输出与旋转角度成正比的霍尔电势。由于霍尔传感器的输出采用差动式连接,不存在零点剩余电压。建立了传感器的有限元模型,对其工作时的磁场情况进行了仿真,验证了传感器测量原理的正确性。最后对传感器样机进行了特性测定,实验结果表明传感器的灵敏度约为105 mV/(°),线性误差约为0.12%,重复性误差约为0.19%。     

基于概率模型的光纤光栅传感网络优化布置

光纤光栅传感器相比与传统传感器,其特有的轴向敏感性决定了它的探测距离在传感器的不同方向上是有差异的,因此光纤光栅传感器的布置角度对于传感器网络的性能具有很大的影响。基于传统传感器的概率探测模型,本文提出了一种贴合光纤布拉格光栅传感器实际特点的探测模型,并通过实验验证了其正确性,继而利用这一模型,采用粒子群优化算法进行了光纤光栅传感网络的优化布置。最后,同不考虑布置角度的优化布置方法进行了比较,结果表明,在实际应用中考虑布置角度对于传感网络性能具有很大的提升。     

Airborne bacterial endospores detected by use of an impinger containing aqueous terbium chloride

An experimental investigation is described of a terbium luminescence sensor for continuous collection and detection of bacterial endospores suspended in the atmosphere. A sensor is presented that continuously monitors and rapidly detects small concentrations of aerosolized bacterial endospores. The aerosol particles are collected by an impinger from which terbium dipicolinate photoluminescence is measured. A preliminary test of the sensor is described with Bacillus globigii endospores that were dispersed in an aerosol chamber. Another experiment is described showing that evaporation of water from the impinger limits operation time of the sensor to a few hours.     

Composite Optical Bend Loss Sensor for Pressure and Shear Measurement

A composite optical bend loss sensor for measuring 3-D forces has been developed. The sensor is composed of two optic fiber meshes which are embedded into a polydimethylsiloxane (PDMS) slab. The sensor consists of an array of optical fibers lying in perpendicular rows and columns sandwiched inside an elastomeric pad. A map of normal and shear stress is constructed based on observed macrobending through the intensity attenuation from physical deformation of two adjacent perpendicular fibers. Due to the new addition of the composite design and acrylic holder, the stability of the present sensor is found to be significantly better than our previously reported microfabricated optical bend loss sensor. In this paper, we will report the results of an optical bend loss simulation using the beam propagation method based on a series of images captured by a CCD camera on the fiber's bending curvatures. The result from the simulation will be compared with the results obtained from the experiment. Other results include vertical force and shear measurements at a single pressure point of the sensor. A force image algorithm is used to map the force distribution detected by the sensor. Here, we will present the results of six different shape patterns and two force magnitudes on each shape using a neural network system. We will also present a radio frequency sensor module, which we developed for the composite optical bend loss sensor for remote sensing.     

大型硅晶片平面度精密纳米计量技术

描述了一种基于斜率传感器的大型硅晶片平面度扫描测量系统．采用二维斜率传感器对晶片表面扫描，以获得表面绕X和Y轴的倾斜度．斜率传感器装在X向滑板上，而晶片固定在可绕Z轴转动的主轴上．对斜率传感器Y向的输出积分，得到晶片表面各个同心圆上轮廓截面高度．对斜率传感器X向的输出积分，得到晶片表面沿X向的截面轮廓，从而获得各同心圆轮廓之间的关系．构建了一个包括基于自准直原理的小型斜率传感器、气浮主轴、气浮导轨的实验系统，提出一种斜率传感器现场标定方法，用此系统测量了直径300mm的硅晶片平面度。     

Ratiometric fluorescence sensor based on a pyrene derivative and quantification detection of heparin in aqueous solution and serum

A ratiometric fluorescence sensor based on pyrene was designed for selective detection of heparin in HEPES (N-(2-hydroxyethyl)piperazine-N'-ethanesulfonic acid) buffer and serum sample. Pyrene and long-chain alkanes were linked through bisquaternary functionality in the sensor which could interact with heparin via supramolecular assembly. A ratiometric fluorescent signal change of the sensor can be observed because of the specific monomer-excimer conversion of pyrene which is modulated by the supramolecular self-assembly of sensor and heparin. Upon addition of heparin, the excimer emission of the sensor at 489 nm is observed and the monomer emission intensity at 395 nm decreases concomitantly. Addition of heparin derivatives with very similar structure such as chondroitin 4-sulfate or hyaluronic acid to the same sensor solution only leads to very smaller changes in intensity ratios probably because of lower charge density and more distant spatial distribution of anions (or disadvantageous spatial orientation of anions) as compared to those of heparin. The novel sensor can effectively differentiate heparin from its derivatives with relatively low background interference and wide linear response in HEPES and serum. A linear calibration curve is obtained from 0 to 3.4 μM for heparin quantification in serum.     

SAW Sensor Network Fabricated on a Polyvinylidine Difluoride (PVDF) Substrate for Dynamic Surface Profile Sensing

A combination of two 2-D sensor networks is proposed as a dynamic surface profile sensor network for biomimicing applications. A surface acoustic wave device fabricated on a polyvinylidine difluoride substrate has been investigated as the elementary 1-D bending curvature sensor used in the network. The device was tested under an injected signal and it shows the variation in amplitude and phase angle of output signal with respect to the injected signal in response to the bending curvature. These dual outputs provide opportunity to make an intelligent sensor with self error limit determination capability. Finally, a network of such sensors is proposed as a dynamic surface profile sensor     

附加式压磁测力传感器在动态称重轨中的应用

根据剪力型动态称重轨的工作原理,对应用附加式压磁测力传感器动态称重进行了可行性研究。设计了一种三磁极压磁测力传感器,推导出这种传感器的输出方程,并分别在材料试验机与矿山有轨运输轨道上进行了静态特性标定试验和实试验。试验结果表明,这种传感器能够达到5mV／kN的测试灵敏度和小于2．7％的不重复精度。另外,这种传感器结构简单、安装方便、坚固耐用,将其应用动态称重轨是可行的。     

Thin-film sensor for emergency shutdown of electrochemical generator

A thin-film sensor for detection of emergency situations in fuel cells of electrochemical generators is proposed. Experimental results of emergency modeling are presented. It is shown that the thin-film sensor can function as a high-speed warning device. A system is proposed for emergency shutdown by means of a thermal pulse from the thin-film sensor. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 64–65, July, 2000.     

A study of the creep effect upon the response of a pressure sensor embedded in an ice sheet

A new numerical incremental analysis is presented for the viscoelastic bridging response of a pressure sensor embedded in an ice sheet. The analysis takes into account the effect of the time dependent creep response of both the ice sheet and pressure sensor upon the ratio between measured stress and undisturbed stress (called the registration ratio or inclusion factor). The effect of the sensor dimensions, sensor stiffness, elastic modulus of ice, creep properties of the sensor and ice, and rate of loading on the registration ratio is presented.A daily algorithm is also presented, which can be used to interpret the field data obtained using the pressure sensor by predicting the daily change in the base line (zero pressure) due to creep behaviour of the panel.     

共平面低功耗CO气体传感器的设计及制作

设计了一种新型的共平面微结构气体传感器,利用MEMS技术制作了传感器样品.实验测得该传感器对于体积分数为50×10~(-6)CO气体的灵敏度为8.6(R0/R),功耗为82mW,响应时间约5s,恢复时间约22s,该传感器的灵敏度是同种敏感材料烧结型传感器(测体积分数50×10~(-6) CO气体)的2.5倍,而功耗却是同种敏感材料烧结型传感器的1/2,是一种具备了体积小、重量轻、功耗低、灵敏度高、便于与其它器件集成等特点,而且制作工艺简单,成本较低的微结构CO气体传感器.     

A Cement-Based Piezoelectric Sensor for Civil Engineering Structure

A new aggregate-like sensor using piezoelectric ceramic as sensing element was designed, fabricated and tested. The sensor was made by bonding together two cuboids of hardened cement paste with a commercially available piezoelectric ceramic plate in between, which is the sensing element. A new adhesive was developed during the fabrication of the sensor. The sensor was tested on its basic performance with a charge amplifier measuring system. First, the frequency response of the sensor was investigated in the general frequency range of civil engineering structure, which is from 0.01 Hz to 40 Hz. Then the relationship between output and input of the sensor was tested. Finally, complex, random and square loads were applied to observe the performance of the sensors. The excellent compatibility with concrete and the good sensing performance enable the aggregate-like sensor to be easily embedded into concrete structures like a real aggregate and to reliably monitor the vibration of host structure. There is a good potential for such a sensor to be used in structural health monitoring.