Novel portable electrical detection system for DNA SENSOR application

A novel, portable, electrical detection system was constructed for DNA sensor application to detect DNA hybridisation. The read-out circuit consists of an analogue circuit and a digital circuit. The analogue circuit with an IC MAX038 generates a sine wave with a constant frequency (10?kHz), which serves as the input for the DNA sensor. The DNA sensor consists of active and reference sensors. DNA hybridisation between the DNA probe and the target sequences causes changes in the conductance of the conductive membrane (DNA/MWCNTs) on the sensor surface, which lead to changes in the amplitude of the sine wave from the sensor output compared with that of the reference signal output (input sine wave). We used a digital circuit with a microprocessor (PIC33FJ256MC710) to determine the change in the amplitude of the sine wave signal of the sensor. From these digital data, the difference in the amplitudes of the active and reference sensors was calculated and displayed on the liquid crystal display. Measurement results show that the portable electrical detection system can detect DNA target concentrations as low as 0.16?µM. The detection of the amplified polymerase chain reaction sample and the reproducibility of the DNA sensor results were also determined using the designed readout circuit. The proposed electrical detection system is suitable for DNA sensor application.     

Rapid analyte recognition in a device based on optical sensors and the olfactory system

We report here the development of a new vapor sensing device that is designed as an array of optically based chemosensors providing input to a pattern recognition system incorporating artificial neural networks. Distributed sensors providing inputs to an integrative circuit is a principle derived from studies of the vertebrate olfactory system. In the present device, primary chemosensing input is provided by an array of fiber-optic sensors. The individual fiber sensors, which are broadly yet differentially responsive, were constructed by immobilizing molecules of the fluorescent indicator dye Nile Red in polymer matrices of varying polarity, hydrophobicity, pore size, elasticity, and swelling tendency, creating unique sensing regions that interact differently with vapor molecules. The fluorescent signals obtained from each fiber sensor in response to 2-s applications of different analyte vapors have unique temporal characteristics. Using signals from the fiber array as inputs, artificial neural networks were trained to identify both single analytes and binary mixtures, as well as relative concentrations. Networks trained with integrated response data from the array or with temporal data from a single fiber made numerous errors in analyte identification across concentrations. However, when trained with temporal information from the fiber array, networks using "name" or "characteristic" output codes performed well in identifying test analytes.     

基于MEMS技术可植入微压力传感器的检测电路设计（英文）

为实现体内压力（如：血压、颅内压等）的实时监测,采用微机电系统（MEMS）技术制造出植入式微压力传感器.由于它是电容式传感器,在信号读取系统中,首先通过集成电路CAV414将电容信号转换为电压信号.通过理论计算和实际试验测试,微压力传感器初始电容值为15 pF.CAV414检测范围是10 pF~2 nF,检测精度为电容初始值的5%,因此在该系统中可检测到的电容最小变化量为0.75 pF,其输出电压范围为0~5 V,该电压信号可以直接作为模拟/数字转换器（ADC）的输入信号.选用ADC0809实现模拟信号向数字信号的转换.ADC0809为一款8通道8位模数转换器,通过FPGA实现对ADC0809的驱动控制.ADC0809的8位输出信号直接作为数字信号的输入,在本文试验中数字信号处理通过FPGA编程实现.     

一种便携式角速度传感器

角速度是旋转系统或传动装置进行状态监测的重要参数。设计了一种新结构、无旋转部件的便携式瞬时角速度传感器。该传感器的工作原理是永磁磁钢建立恒定磁通,被测旋转装置的转动部件切割该恒定磁场后形成涡流,涡流产生的磁场与传感器的霍尔元件相互作用产生霍尔电势,该霍尔电势的幅值与被测旋转装置的角速度成正比。根据磁路的基本定律推导出传感器的输出特性,并对输出特性进行了实际的测定,结果表明:传感器的灵敏度为16.8mV·s/rad,非线性误差为1.24%。     

A Frequency Modulation Based System Using Bilayer Thin-Film Displacement Sensors

A novel method has been used for accurately measuring low voltage signals (~10^-4 V) associated with inductance changes of bilayer thin-film sensors under bending stress. In this paper the architecture of the system is first presented, and then the design ideas and key technologies are followed. Initially, the frequency modulated signals were simulated with superimposed noise signals to test the demodulation performance of the written program. From the results, the expected output of the program was confirmed. Following this, the frequency modulation technique was used with actual sensor signals to measure the displacement of a bilayer thin film sensor. The results from the acquisition were compared with a previously developed amplitude modulation based setup, and it proved that the frequency modulation system provided a robust and accurate solution to evaluate magnetostrictive materials and their application in magnetic sensors     

A High-Resolution MEMS Piezoelectric Strain Sensor for Structural Vibration Detection

This paper presents the modeling, fabrication, and testing of a high-performance dynamic strain sensor. Using microelectromechanical systems (MEMS) technology, ZnO piezoelectric microsensors are directly fabricated on silicon and steel substrates. The sensors are intended to be used as point sensors for vibration sensing without putting an extra burden on the host structures. A model that incorporates piezoelectric effects into an RC circuit, representing the sensor architecture, is developed to describe the voltage output characteristics of the piezoelectric microsensors. It is shown that the sensitivity of microplanar piezoelectric sensors that utilize the $e_{31}$ effect is linearly proportional to sensor thickness but unrelated to sensor area. Sensor characterization was performed on a cantilever beam cut from a fabricated silicon wafer. The experimental data indicate that the overall sensor and circuit system is capable of resolving better than 40.3 nanostrain time domain signal at frequencies above 2 kHz. The corresponding noise floor is lower than 200 femto-strain per root hertz and the sensitivity, defined as the sensor voltage output over strain input, is calculated to be 340 V/$varepsilon$ . Micro ZnO piezoelectric sensors fabricated on steel hard disk drive suspensions also show excellent results. The sensor not only has a better signal-to-noise ratio but also detects more vibration information than the combination of two laser-doppler-vibrometer measurements in different directions.      

Gas concentration monitoring system for small and medium sized coal mines based on gas sensing detection and single chip control

This paper is aimed at the actual conditions of disaster caused by gas in small and medium-sized coal mines. A new gas concentration monitoring system for coal mines is developed on the basis of gas-sensing detection and single-chip control. The monitoring system uses the tin oxide as the main material of N-type semiconductor gas sensors, because it has good sensitive characteristics for the flammable and explosive gas (such as methane, carbon monoxide). The QM-N5-semiconductor gas sensor is adopted to detect the output values of the resistance under the different gas concentrations. The system, designedly, takes the AT89C51 digital chip as the core of the circuit processing hardware structure to analyze and judge the input values of the resistance, and then achieve the control and alarm for going beyond the limit of gas concentration. The gas concentration monitoring system has many advantages including simple in structure, fast response time, stable performance and low cost. Thus, it can be widely used to monitor gas concentration and provide early warnings in small and medium-sized coal mines.     

Internet-Based Distributed Data Acquisition System for Fiber-Optic Sensors

This paper describes an internet-based distributed data-acquisition system for fiber-optic pressure sensors. There is a great need in industry to coordinate remote resources to perform a common task. The architecture described is based on remote access, via the internet, to a large number of fiber-optic pressure sensors located in different geographical areas. Distribution is done with server applications, which schedule requests for service and control the actual sensor device. Servers also detect conflicts between new requests and their current schedules. Client applications act as virtual instrument panels that dispatch measurement tasks for servers. The architecture supports multiple sensors, which can be added/removed from the system dynamically. As well, there can be multiple clients attempting to access servers simultaneously. Thus, the sensors in question are publicly shared among the various active client applications     

Novel concept of a single-mass adaptively controlled triaxial angular rate sensor

This paper presents a novel concept for an adaptively controlled triaxial angular rate (AR) sensor device that is able to detect rotation in three orthogonal axes, using a single vibrating mass. Pedestrian navigation is presented as an example demonstrating the suitability of the proposed device to the requirements of emerging applications. The adaptive controller performs various functions. It updates estimates of all stiffness error, damping and input rotation parameters in real time, removing the need for any offline calibration stages. The parameter estimates are used in feedforward control to cancel out their otherwise erroneous effects, including zero-rate output. The controller also drives the mass along a controlled oscillation trajectory, removing the need for additional drive control. Finally, the output of the device is simply an estimate of input rotation, removing the need for additional demodulation normally used for vibratory AR sensors. To enable all unknown parameter estimates to converge to their true values, the necessary model trajectory is shown to be a three-dimensional Lissajous pattern. A modified trajectory algorithm is presented that aims to reduce errors due to discretization of the continuous time system. Simulation results are presented to verify the operation of the adaptive controller. A finite-element modal analysis of a preliminary structural design is presented. It shows a micro electro mechanical systems realizable design having modal shapes and frequencies suitable for implementing the presented adaptive controller.     

Oscillator-based interface for measurand-plus-temperature readoutfrom resistive bridge sensors

A signal conditioning circuit based on a relaxation oscillator is proposed for use with resistive bridge sensors. The circuit provides a rectangular-wave output whose frequency is related to the bridge unbalance, and duty-cycle is a function of the overall sensor bridge resistance, hence of the sensor operating temperature. In this way, two measurement values are simultaneously and independently carried on the same output signal. The circuit makes use of a constant current bridge excitation which enables the connection of remote sensors without accuracy degradation, and moreover, for silicon piezoresistive sensors, provides a first-order temperature compensation. A frequency-doubling output stage significantly reduces the nonlinearity due to switching delay times, at the parity of output center frequency and span. Experimental results are reported on the characterization of both the circuit alone and interfaced to a silicon pressure sensor     

基于任意波形发生器的高压短路试验测量系统校准方法和装置的研究

提出了一种将标准短路试验波形注入多通道任意波形发生器,来产生模拟实际的校准波形,进而对测量系统进行校准的方法。校准装置使用现场可编程门阵列(FPGA)、直接数字频率合成器(DDS)等器件。对装置的检定结果表明:在10 Hz^200 kHz频率范围内,输出频率、输出电压最大误差分别为2.1×10^-6、3×10^-3。重复输出10次,输出幅值的最大相对标准偏差为5.7×10^-4,1年内幅值变化的最大相对标准偏差为1.9×10^-4。通过将该装置用于实际高压短路试验测试系统的校准,验证了试验波形的噪声、零漂及带宽均会对测量系统的准确度产生显著影响。     

An arrayed waveguide grating based multiplexer and interrogator for Fabry-Perot sensors

In this paper, we propose an interrogation system capable of multiplexing four identical Fabry-Perot (FP) interferometric sensors using two wavelength-division multiplexing devices. One is a 40-channel DWDM channel monitor, the other a four-channel CWDM device. The sensors are connected to the output channels of the CWDM device in order to assign a portion of the spectrum to each sensor. The reflected spectra are then analyzed using the DWDM channel monitor. By monitoring the power incident on each of the DWDM channels, the four sensor reflection spectra can be reconstructed in software and information relating to the measurand obtained. Based on software simulations and previous laboratory experiments with single sensors, it is predicted that this system would be capable of interrogating four EFPI strain sensors simultaneously at frequencies greater than 5 kHz with a resolution of approximately 2 /spl mu//spl epsiv/ and a range of 3000 /spl mu//spl epsiv/.     

Phase and amplitude modulation of elliptic polarization states by nonabsorbing anisotropic elements: application to liquid-crystal devices

We study the modulation of programmable birefringent devices when they are illuminated by elliptically polarized light. We apply the theory to liquid-crystal display panels (LCDs). We consider the setups at the input and the output sides of the LCD as polarization-state generators (PSGs) or detectors (PSDs). We demonstrate that once the programmable birefringent device is described by a physical model, the amplitude and phase modulation depend only on the polarization state at the input of the device and on the output state detected behind it. This permits optimization of the modulation response only in terms of the input and the output states and the physical model of the device. The procedure to find the PSG and PSD configurations is detailed by using a geometrical interpretation of the states and the plates on the Poincaré sphere.     

冲击加速度传感器频域校准技术研究

为获得更为真实的传感器频响特性,利用激光干涉仪对传感器进行动态校准,在传感器输入和输出数据的基础上,确定系统模型结构、阶次,基于输出误差模型,采用系统辨识实验法,辨识传感器模型的各项参数,从而建立被校冲击加速度传感器的数学等价模型,进而将模型方程转换为传递函数,并绘制出传感器的幅频、相频特性曲线,最终实现被校传感器的冲...     

Small optical magnetic-field sensor that uses rare-Earth iron garnet films based on the faraday effect

Highly accurate optical magnetic-field probe sensors that use iron garnet films have been developed. New probe-type sensors were designed with a confocal optical system. A new garnet composition, Bi(0.98)Gd(0.92)La(0.03)Y(1.07)Fe(4.72)Ga(0.28)O(12), was found that shows high temperature stability for a sensitivity of less than 2.0% from -20 to +80 degrees C. The linearity error of the sensor output was within 1.0% for alternating magnetic fields from 0.3 to 42 mT. An optical current transformer that uses the proposed sensor has an ac linearity of 1.0% for input current up to nearly 300 A. The sensor realized high performance in actual use.     

压电式力传感器连续加载的校准方法

针对压电式力传感器连续加载的校准方法进行初步探索。使用高精度应变式力传感器作为标准力传感器,在叠加式力标准装置上对压电式力传感器施加类似三角波式的连续载荷,利用数据采集系统采集标准力传感器和被校压电式力传感器的输出,记录整个加载过程,对输出曲线进行分析处理。提出了在连续加载曲线上选择校准点的方法,通过实验数据验证该校准方法的可行性,并对影响校准结果的各种因素进行了初步的分析。     

High-speed Josephson integrated circuit technology

The author describes recent progress in high-speed integrated circuits using niobium junctions. He briefly describes the circuit fabrication process and then introduces the modified variable threshold logic (MVTL) gate family. The lowest experimentally obtained MVTL OR-gate delay was only 2.5 ps with a power consumption of 17 μW/gate. This gate family is used in various high-speed logic circuits, such as 8-bit shift registers, 16-bit ALUs (arithmetic logic units), and 4-bit microprocessors. The author confirmed the high-speed operation of less than 10 ps per gate on average for these circuits. A novel high-sensitivity magnetic sensor using a SQUID (superconducting quantum interference device) was also developed. It is called a single-chip SQUID magnetometer because the feedback circuit, which is operated at room temperature is a conventional SQUID system, has been integrated on the same chip as the SQUID sensor itself     

A "Fail-safe" circuit principle in semiconductor and solid-state systems

This paper deals with the problem of securing greater safety from shock hazard due to leakage to ground in installations involving portable tools, swimming-pool wiring, and hydrotherapy equipment, and proposals for "built-in" protective systems. Criticism has been directed at the use of transistors on grounds of reliability, and it has been required that such a system must "fail safe." The construction and performance of a compact test model, a protective element embodying magnetic amplifiers and a single diode, which fails safe if the diode fails either as open circuit or as short circuit, is described. This device will handle the starting current of a half-horsepower motor and will disconnect a load with leakage current to ground of less than two milliamperes.     

基于比例阀门的升降速度控制方法研究

提出了一种新的航空升降速度标准信号自动产生方法.从控制方面,采用硅压阻模拟、石英数字双传感器,分别作为过程控制传感器和基准压力传感器,保证系统升降速度的准确度.采用双闭环控制方案,模拟闭环采用电路设计实现,数字闭环通过计算机、数字传感器和软件实现.控制执行部件采用一对比例电磁阀门.控制电路设计采用了模拟电路PID和数字PID控制结合的串级控制方案,对实现升降速度和压力信号变化的微分电路进行了设计.实验证明,该装置升降速度的输出准确度优于0.2%F.S,控制范围为0～200 m/s.     

制动系统气压传感器测试平台研究

为满足实际应用要求,设计一种新的制动系统气压传感器测试平台。该平台以DSP系统为核心,包括气压传感器、制动系统气压模拟装置、汽车气压仪表以及上位机。DSP接受上位机的实验指令后,气压传感器通过调理电路送给DSP系统板以实时测量当前实际气压值,并传递给上位机进行同步显示。测试结果表明:该平台人机界面友好,操作简单方便,可应用于气压仪表及气压传感器的参数测试、标定及相关的培训教育等领域。