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.     

An intelligent pressure sensor using neural networks

In this paper, we propose a scheme of an intelligent capacitive pressure sensor (CPS) using an artificial neural network (ANN). A switched-capacitor circuit (SCC) converts the change in capacitance of the pressure-sensor into an equivalent voltage. The effect of change in environmental conditions on the CPS and subsequently upon the output of the SCC is nonlinear in nature. Especially, change in ambient temperature causes response characteristics of the CPS to become highly nonlinear, and complex signal processing may be required to obtain correct readout. The proposed ANN-based scheme incorporates intelligence into the sensor. It is revealed from the simulation studies that this CPS model can provide correct pressure readout within ±1% error (full scale) over a range of temperature variations from -20°C to 70°C. Two ANN schemes, direct modeling and inverse modeling of a CPS, are reported. The former modeling technique enables an estimate of the nonlinear sensor characteristics, whereas the latter technique estimates the applied pressure which is used for direct digital readout. When there is a change in ambient temperature, the ANN automatically compensates for this change based on the distributive information stored in its weights     

A Digital Instantaneous Frequency Meter

A basic instrument is described which produces a parallel digital output proportional to frequency once per cycle, i.e., instantaneously. This is achieved by means of a reciprocal time generator which continuously generates digitally the reciprocal of the time elapsed between successive incoming pulses and the output of which is sampled and held at the end of each cycle. The meter is a 12-bit instrument having an accuracy of ±1 count plus clock stability. An analog output and a digital readout can be readily obtained. The range of the instrument is from zero to fc × 2-12 Hz, where fc is the clock frequency in hertz. Thus the range can be varied by appropriate adjustment of fc. An additional circuit to provide an analog output proportional to rate of change of frequency, also on a cycle-to-cycle basis, is suggested.     

A switched-capacitor interface for capacitive pressure sensors

A switched-capacitor interface for a capacitive pressure sensor is developed which provides a linear digital output. It consists basically of a sample/hold circuit followed by a charge-balancing analog-to-digital converter. The sensor capacitance changes hyperbolically with an applied pressure. To convert the nonlinear capacitance change into the linear digital output, two linearization methods are investigated. In either method, a linear digital output with an accuracy higher than 8-b is obtained. Because of its high-accuracy capability and compatible fabrication process, the interface described is best suited for a smart silicon capacitive pressure sensor     

X-Ray Detection Using a Two-Transistor Active Pixel Sensor Array Coupled to an a-Se X-Ray Photoconductor

A direct-conversion X-ray sensor array using amorphous silicon (a-Si) thin-film transistor (TFT) based active pixel sensor (APS) readout circuit coupled with a stabilized amorphous selenium (a-Se) photoconductor for large-area digital imaging applications is presented. The pixel readout circuit employs a novel two-transistor (2T) active/passive pixel architecture that enables a compact pixel circuit for high-resolution sensor arrays with high large-area fabrication reliability. The X-ray detector consists of an in-house fabricated 150 $mu$m pixel pitch 2-TFT pixel coated with an 80 $mu$m thick a-Se photoconductor. A detector dark current of 110 pA/cm$^{2}$ at 10 V/$mu$ m electric field, and a controllable pixel conversion gain up to 8.4 nA/mR with a quantum efficiency of 60% was measured. Capabilities such as voltage programmable gain and dynamic range control, as well as nondestructive readout during X-ray exposure are demonstrated. The detector in this work represents a highly promising technology for high-resolution X-ray digital imaging, adaptable to a wide range of applications owing to its gain and dynamic range programmability.      

X-Ray Imaging Using LEKIDs

We present the detection of 5.9 keV X-rays in a silicon wafer utilising an array of frequency multiplexed Kinetic Inductance Detectors. The readout electronics consists of a programmable digital electronics with an integrated 12-bit ADC, operating with a maximum frequency of 100 MHz. We implement a lumped element geometry, realising pixels as small as possible in order to achieve better position resolution. The whole system allows the simultaneous readout of 14 pixels with a bandwidth of 300 kHz, but it is easily scalable up to 100 pixels. A higher bandwidth detection, with less pixels, allows the reconstruction of the photon absorption position in the substrate up to hundreds of microns. This technological development could be applied in the next future to large area X-Ray Imaging. A better understanding of high energy photon and particle detection is also crucial for the space implementation of LEKIDs for mm-astronomy, where data loss due to Cosmic particles could be a major issue.     

Working-point control method for readout of dynamic phase changes in interferometric fiber-optic sensors by tuning the laser frequency

A simple but reliable method, namely the working-point control by tuning the laser frequency, for the dynamic phase shift measurement in a passive homodyne interferometric fiber-optic sensor is proposed. A dc voltage calculated from the photodetector output is applied to the light source to control the interferometer at the condition of maximum sensitivity. Then the signal's phase shift can be obtained from the components of zero and fundamental frequencies. To test the method, an all polarization-maintaining Mach-Zehnder interferometer with a piezoelectric ceramic (PbZrTiO(3), or PZT) cylinder in one arm is constructed. The experimental results show that the simulation signal's phase shift generated by the PZT cylinder can be read out correctly with the method. It has the advantages of simplicities of operation, no-active element in the sensing head, and large operating bandwidth. It can be used for readout of dynamic phase shifts in various interferometric fiber-optic sensors.     

A 1.2-V 0.25-/spl mu/m clock output pixel architecture with wide dynamic range and self-offset cancellation

A 10T/pixel CMOS digital pixel sensor with clock count output, ultra low supply voltage, and wide dynamic range is presented. The pixel fabricated by a standard 0.25-/spl mu/m CMOS logic process comprises a reset transistor, a photo-diode, a comparator, and an inverter with pixel size of 9.4/spl times/9.4 /spl mu/m/sup 2/ and 24% fill factor. The amplified logarithmic output response similar to the light response of human eye is demonstrated in this work. The pixel can operate at a supply voltage as low as 1.2 V without affecting its output characteristics. The dynamic range of this cell limited by either the subsequent analog-to-digital circuit resolution or the rising and falling time of output clock is higher than 90 dB with an 8-bit resolution.     

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.     

A Dual-Mode Conditioning Circuit for Differential Analog-to-Digital Converters

Several devices such as load cells and pressure sensors, among others, provide differential outputs. Given that present high-resolution analog-to-digital converters (ADCs) have differential inputs, fully differential (F-D) circuits are required to adapt the sensor output to the ADC input. This paper proposes an F-D conditioning circuit that allows adjusting both differential- and common-mode signals to the levels required by the ADC. A design example is presented, and a prototype was built and tested. It transforms a differential input signal of $pm$25 mV with a common-mode voltage of 5 V to a differential output signal of $pm$5 and 2.5 V, respectively. It shows an input-referenced peak-to-peak noise of 120 nV, which results in a 112-dB dynamic range (18.7-bit noise-free resolution) for a signal bandwidth of 10 Hz.      

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.     

High-accuracy circuits for on-chip capacitive ratio testing andsensor readout

This paper presents novel CMOS switched-capacitor circuits for high-accuracy, on-chip capacitive-ratio testing and sensor readout. Using sigma-delta and correlated-double-sampling (CDS) techniques, these circuits provide accurate digitized capacitive-ratio readout. Both single-ended and fully differential circuits are presented. Simulation results show that the resolution can be as fine as 100 aF for 10 pF capacitors. Single-ended circuit and fully-differential circuits were implemented and tested. The measured standard deviation was below 20 aF when 10 pF capacitors were tested     

CMOS microsystem for AC current measurement with galvanic isolation

In this paper, we present an integrated ac current sensor based on sensitivity-optimized horizontal Hall effect devices and a differential readout chain. This microsystem has been designed for 5-A rms nominal ac current measurement with 5-kV galvanic isolation and 0.5% accuracy after calibration from 250 mA to 5 A, over 1.5-kHz bandwidth, which allows up to 30th (25th) harmonic detection in 50-Hz (60-Hz) applications. This qualifies the current sensor microsystem for class 1 products according to international norms for energy meters (IEC44-1 and IEC1036). From the sensing element throughout the instrumental chain's output, the signal conditioning is exclusively performed by low-noise standard CMOS analog blocks. Moreover, the whole microsystem features a mixed-signal structure dedicated to auto-balancing.     

Digital and analog readout systems for fiber-optic strain sensors as applied to the monitoring of roller element bearing systems

A rotating machinery test rig was instrumented with fiber Fabry-Perot interferometer strain sensors for condition monitoring of rolling element bearings. Strain variations produced by ball passes were observed and analyzed in the time and frequency domain. Wavelength division multiplexing was utilized to simultaneously monitor the sensors with analog and digital readout systems--analog for high bandwidth and digital for high dynamic range and the monitoring of multiple sensors. The effects of imbalance on the shaft, changes in rotational speed, effects on the rotor system, and detection of bearing defects were investigated. Frequency peaks observed in the bearing sensor spectra closely matched predicted values. Imbalance and rotational speed tests showed good agreement with expected trends, and bearing defects were successfully detected.     

A high accuracy, low power, reproducible temperature telemetrysystem

A low-power temperature telemetry system incorporating a miniature micropower temperature sensor/modulator and hand-held decoder with direct digital readout is described. The system is designed to avoid the need to calibrate and characterize individual units while guaranteeing an accuracy of ±0.25°C and a resolution of 0.1°C. The combined sensor and transmitter is constructed using thick-film technology and weighs less than 2.5 g without batteries. Developed principally for wild life tracking and monitoring, the system also has other applications where remote environmental monitoring is required     

Encrypted optical storage with angular multiplexing

We present the first, to our knowledge, demonstration of an encrypted optical storage based on double-random phase encoding by using angular multiplexing in a photorefractive material. Original two-dimensional data are encrypted by use of two random phase codes located in the input and the Fourier planes and are then stored holographically in a LiNbO(3):Fe crystal. The retrieval of the original data can be achieved with a phase-conjugated readout scheme. We demonstrate the encryption and the decryption of multiple frames of two-dimensional digital data by using angular multiplexing. We also evaluate numerically the influence of the bandwidth of the optical system on the decrypted digital data. The bit error rate as a function of the optical system bandwidth is presented.     

Liquid-phase chemical and biochemical detection using fully integrated magnetically actuated complementary metal oxide semiconductor resonant cantilever sensor systems

A novel resonant cantilever sensor system for liquid-phase applications is presented. The monolithic system consists of an array of four electromagnetically actuated cantilevers with transistor-based readout, an analog feedback circuit, and a digital interface. The biochemical sensor chip with a size of 3 mm x 4.5 mm is fabricated in an industrial complementary metal oxide semiconductor (CMOS) process with subsequent CMOS-compatible micromachining. A package, which protects the electrical components and the associated circuitry against liquid exposure, allows for a stable operation of the resonant cantilevers in liquid environments. The device is operated at the fundamental cantilever resonance frequency of approximately 200 kHz in water with a frequency stability better than 3 Hz. The use of the integrated CMOS resonant cantilever system as a chemical sensor for the detection of volatile organic compounds in liquid environments is demonstrated. Low concentrations of toluene, xylenes, and ethylbenzene in deionized water have been detected by coating the cantilevers with chemically sensitive polymers. The liquid-phase detection of analyte concentrations in the single-ppm range has been achieved. Furthermore, the application of this sensor system to the label-free detection of biomarkers, such as tumor markers, is shown. By functionalizing the cantilevers with anti-prostate-specific antigen antibody (anti-PSA), the corresponding antigen (PSA) has been detected at concentration levels as low as 10 ng/mL in a sample fluid.     

High-resolution of rotary encoder analog quadrature signals

The paper describes a software technique to provide high-resolution absolute angular measurements from the analog quadrature signals of a rotary encoder. The method uses digitized samples of the sinusoidal quadrature signals and the output of a divide-by-four counter circuit. Dynamic measurements on an external trigger signal are possible allowing instantaneous up-to-date angular readings even at high speed. The resolution and hysteresis errors are only dependent on the encoder itself and the bandwidth and resolution of the sampling circuitry. The scheme allows up to 135 degrees of counter hysteresis and delay without loss of precision, thus also affording excellent noise immunity. The theoretical resolution for a 12-bit digital conversion of the analog signals is 1/3360 of a pitch. Experimental results on an encoder built into a laser-tracking measurement system and using 81000 pitches show a unidirectional precision of 0.3 arcsec (rms), a mean bidirectional hysteresis of about 1 arcsec and a worst case variation for a stationary encoder shaft of 0.06 arcsec     

Shack-Hartmann sensor improvement using optical binning

We present a design improvement for a recently proposed type of Shack-Hartmann wavefront sensor that uses a cylindrical (lenticular) lenslet array. The improved sensor design uses optical binning and requires significantly fewer detector pixels than the corresponding conventional or cylindrical Shack-Hartmann sensor, and so detector readout noise causes less signal degradation. Additionally, detector readout time is significantly reduced, which reduces the latency for closed loop systems and data processing requirements. We provide simple analytical noise considerations and Monte Carlo simulations, we show that the optically binned Shack-Hartmann sensor can offer better performance than the conventional counterpart in most practical situations, and our design is particularly suited for use with astronomical adaptive optics systems.