MOEMS扫描微镜的测试实验与分析

针对集成角度传感器微镜在实际使用过程中的要求,在分析研究MOEMS扫描微镜结构与工作原理的基础上,进行了MOEMS扫描微镜最大偏转角度、驱动电压、谐振频率和传感器输出参数的测试.并且为了提高数据的可靠性,利用几何光学理论和误差理论的方法对该测试系统进行了详细分析,以此作为测试的系统误差与测试随机误差进行了误差合成.误差分析表明,该微镜在驱动电压为0.7 V时,最大偏转角为±8.704 15°,测试误差为±0.045 605°.此外,还对测试过程中扫描微镜谐响应频率随扫描模式及扫描电压而变化的现象进行了分析.     

互易法校准压电型声发射传感器的研究与实现

声发射传感器的校准是实现声发射定量技术的前提,依据电声换能器互易原理,在计算互易常数的基础 上,建立了适用于压电型声发射传感器表面波和纵波互易的校准系统。通过设置特定的激励信号波形,依据接收 电压信号与激励电流信号之间的时间延迟,准确获取电流信号与电压信号对应的特征值,实现了声发射传感器的表面波和纵波互易校准。由于传感器的尺寸效应,传感器在高频时的表面波速度灵敏度低于纵波灵敏度,不确定度评定结果表明,声发射传感器速度灵敏度的互易法校准不确定度为1. 2 dB。     

A Monolithic CMOS Autocompensated Sensor Transducer for Capacitive Measuring Systems

In this paper, a monolithic complimentary metal-oxide-semiconductor (CMOS) autocompensated sensor transducer for capacitive measuring systems is newly presented. The proposed converter is compact and robust to integrate in capacitive measuring systems. The proposed autocompensated sensor transducer is attractive due to the fact that a digitized signal is produced without realizing the analog-to-digital converter. Hence, the hardware cost could be reduced. Furthermore, the output signal of the proposed transducer is a pulse stream; it could be easily sent over a wide range of transmission media, such as package switch networks (PSNs), radios, and optical, infrared (IR), and ultrasonic media. Another innovation is that the proposed automatic compensation circuits enhance and compensate the linear relation between the variable capacitance of the detected sensor and the output digital frequency over a wide dynamic frequency range. Measurement results have successfully verified the functions and the performance of the proposed autocompensated sensor transducer and confirmed that it is possible to apply it to the air pressure sensor. The area of this chip is 940 times 1080 mum², and the power consumption is 6.4 mW. The proposed transducer is not only suitable for capacitive measuring systems but also practical for application in the front-end systems of the wireless sensor network.     

Hydrogel-based piezoresistive pH sensors: investigations using FT-IR attenuated total reflection spectroscopic imaging

The strong swelling ability of the pH-responsive poly(acrylic acid)/poly(vinyl alcohol) (PAA/PVA) hydrogel makes the development of a new type of sensor possible, which combines piezoresistive-responsive elements as mechanoelectrical transducers and the phase transition behavior of hydrogels as a chemomechanical transducer. The sensor consists of a pH-responsive PAA/PVA hydrogel and a standard pressure sensor chip. However, a time-dependent sensor output voltage mirrors only the physical swelling process of the hydrogel but not the corresponding chemical reactions. Therefore, an investigation of the swelling behavior of this hydrogel is essential for the optimization of sensor design. In this work, Fourier transform infrared (FT-IR) spectroscopic imaging was used to study the swelling of the hydrogel under in situ conditions. In particular, laterally and time-resolved FT-IR images were obtained in the attenuated total reflection mode and the entire data set of more than 80,000 FT-IR spectra was evaluated by principal component analysis (PCA). The first and third principal components (PCs) indicate the swelling process. Molecular changes within the carboxyl groups were observed in the second and fourth PC and identified as key processes for the swelling behavior. It was found that time-dependent molecular changes are similar to the electrical sensor output signal. The results of the FT-IR spectroscopic images render an improved chemical sensor possible and demonstrate that in situ FT-IR imaging is a powerful method for the characterization of molecular processes within chemical-sensitive materials.     

Ultrasonic density sensor for liquids

This paper presents an ultrasonic density sensor for liquids that unifies high accuracy with high durability and is suitable for on-line measurements in a wide range of tube diameters. The sensor consists of a transducer with a piezoceramic disk mounted between two reference rods of quartz glass. Additionally, a second transducer is used as a sound receiver. The density is obtained from the reflection coefficient of ultrasound at the interface between the quartz glass rod and the liquid and the transit time of sound between this interface and the second transducer. Parameters, such as high long-term stability and accuracy of +/-0.1% of full scale, were obtained by an internal acoustic reference measurement. The reference signal is generated using the sound radiated from the rear side of the piezoceramic disk. Design aspects such as sensor materials and signal-to-noise ratio are discussed, and experimental results are given in this paper. Applications of the sensor include concentration measurement, and ultrasonic mass flow measurement.     

Acoustic Emission Sensor Calibration for Absolute Source Measurements

This paper describes sensor calibration and signal analysis techniques applicable to the method of acoustic emission (AE) and ultrasonic testing. They are particularly useful for obtaining absolute measurements of AE wave amplitude and shape, which can be used to constrain the physics and mechanics of the AE source. We illustrate how to perform calibration tests on a thick plate and how to implement two different mechanical calibration sources: ball impact and glass capillary fracture. In this way, the instrument response function can be estimated from theory, without the need for a reference transducer. We demonstrate the methodology by comparing calibration results for four different piezoelectric acoustic emission sensors: Physical Acoustics (PAC) PAC R15, PAC NANO30, DigitalWave B1025, and the Glaser-type conical sensor. From the results of these tests, sensor aperture effects are quantified and the accuracy of calibration source models is verified. Finally, this paper describes how the effects of the sensor can be modeled using an autoregressive-moving average (ARMA) model, and how this technique can be used to effectively remove sensor-induced distortion so that a displacement time history can be retrieved from recorded signals.     

压电加速度传感器输出信号可变增益控制

针对压电加速度传感器信号调理电路中标定过程繁琐、标定效率低下、系统在运行过程中输出信号增益不能改变的问题,提出了在电荷放大器之后由微控制器控制数字电位器组成可调增益的电压放大电路,实现加速度计输出信号的自动标定和增益的可变控制.分析压电式加速度计的信号调理电路,在电压放大电路中选择使用数字电位器的方法实现可变增益控制,...     

新型光纤电流传感器的研制

光纤电流传感器运用Faraday效应,将光纤绕在电流母线上可以方便地测得电流母线中的电流,但光纤电流传感器的信号受环境振动、温度变化的影响严重,从而限制了其应用。本文从分析振动、温度变化的干扰机理出发,提出一种新型的在线校正方法来抑制干扰的影响,并进行了原理性实验。研究结果表明,用这种方法实现的光纤电流传感器在40～400A之间有良好的线性度和精度。     

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.     

一种电感式位移传感器的电路系统设计

介绍了一种电感式位移传感器的电路系统.该系统以一片AD698芯片为信号调整电路的核心,将位移量输出信号转换为相应的直流电压值,并结合其它一系列电路模块实现了测头位移量测量.通过对测头的标定试验证明该系统精度高、线性测量范围大.     

基于SYSTEM Ⅱ的新型微波中功率计量系统

SYSTEMⅡ功率传递系统是微波小功率计量领域内应用比较广泛的测试系统之一,通过对传统中功率计量方法的分析研究,提出了利用SYSTEMⅡ功率传递系统实现中功率计量的构建方案。采用低反射系数等效信号源结构,构成反射系数小、输出稳定、输出电平可调的中功率等效信号源;采用中功率衰减器和SYSTEMⅡ功率传递系统中含有的高精度终端式小功率座构成中功率传递标准,通过交替比较法,实现微波中功率计的高精度自动校准。     

Electrochemical DNAzyme sensor for lead based on amplification of DNA-Au bio-bar codes

An electrochemical DNAzyme sensor for sensitive and selective detection of lead ion (Pb(2+)) has been developed, taking advantage of catalytic reactions of a DNAzyme upon its binding to Pb(2+) and the use of DNA-Au bio-bar codes to achieve signal enhancement. A specific DNAzyme for Pb(2+) is immobilized onto an Au electrode surface via a thiol-Au interaction. The DNAzyme hybridizes to a specially designed complementary substrate strand that has an overhang, which in turn hybridizes to the DNA-Au bio-bar code (short oligonucleotides attached to 13 nm gold nanoparticles). A redox mediator, Ru(NH3)6(3+), which can bind to the anionic phosphate of DNA through electrostatic interactions, serves as the electrochemical signal transducer. Upon binding of Pb(2+) to the DNAzyme, the DNAzyme catalyzes the hydrolytic cleavage of the substrate, resulting in the removal of the substrate strand along with the DNA bio-bar code and the bound Ru(NH3)6(3+) from the Au electrode surface. The release of Ru(NH3)6(3+) results in lower electrochemical signal of Ru(NH3)6(3+) confined on the electrode surface. Differential pulse voltammetry (DPV) signals of Ru(NH3)6(3+) provides quantitative measures of the concentrations of Pb(2+), with a linear calibration ranging from 5 nM to 0.1 microM. Because each nanoparticle carries a large number of DNA strands that bind to the signal transducer molecule Ru(NH3)6(3+), the use of DNA-Au bio-bar codes enhances the detection sensitivity by five times, enabling the detection of Pb(2+) at a very low level (1 nM). The DPV signal response of the DNAzyme sensor is negligible for other divalent metal ions, indicating that the sensor is highly selective for Pb(2+). Although this DNAzyme sensor is demonstrated for the detection of Pb(2+), it has the potential to serve as a general platform for design sensors for other small molecules and heavy metal ions.     

非线性压力传感器静态性能校准方法探讨

指出利用非线性传感器的输出测量值进行校准的方法不能真实地反映其固有特性。正确的方法是:利用其输出测量值进行解算,得到相应的被测量,然后再按被测量对传感器的静态性能进行校准。     

Current sensor using heterodyne detection

Based on the Faraday effect for measuring ac current, we describe a fiber-optic sensor that uses laser-diode intensity modulation to perform heterodyne signal detection. The sensor output at the carrier frequency is used as a reference signal to normalize the results. The sensing element consists of a few coils low-birefringence fibers between polarizers. We built the current sensor described above and tested its performance-sensitivity and noise-as functions of the angle between polarizers.     

超声换能器的自易校准法及其在功率测量中的应用和它与辐射力法的关系(英文)

论述了电声互易原理和用于平面活塞型与球面聚焦换能器校准的自易法(Self Reciprocity Method,SRM)。介绍了一系列的定义和发送电压(电流)响应与电压灵敏度。阐述了SRM与辐射力天平(Radiation Force Balance,RFB)法之间的关系。在1~25 MHz频率范围内,对超声换能器校准和输出功率测量的实验显示,两种方法具有相近的准确度。SRM法比RFB法测量具有更高的信噪比和更好的稳定性。     

Microfluidic sensor for dynamic surface tension measurement

A novel microfluidic sensor for measuring dynamic gas-liquid interfacial tension is reported. The device consists of a microfluidic chip with a microchannel network and an optical detection system. The sample is introduced into a main channel, while air is injected through a T-junction. Owing to the fixed flow rate ratio used for the sensor, surface tension is the only parameter determining bubble formation frequency, which can be measured by optical detection. Although the bubble is represented by a pulse in the output signal, the formation frequency is simply the frequency of the output signal. Measurements were carried out for aqueous solutions with different concentrations of the ionic surfactant cetyl trimethyl ammonium bromide. Surface tensions of these solutions were calibrated with a commercial tensiometer. The measurement results show a clear relationship between surface tension and formation frequency. The sensor can be used to identify the critical micelle concentration of the surfactant. The sensor potentially allows the use of a minute amount of sample compared with the relatively large amount required for existing commercial systems.     

Mechanoluminescent pulse pressure sensors. Processing of output optical signal

The process of mechanoluminescence transformation of a pulse pressure sensor is considered. The process consists in excitation of emission under the action of mechanical loading. An algorithm for use in processing the output optical signal of the sensor that makes it possible to determine an input shock pulse is presented. __________ Translated from Izmeritel’naya Tekhnika, No. 10, pp. 28–31, October, 2007.     

Measurement of the Transfer Function of Hot-Wire and Hot-Film Turbulence Transducers

A microwave simulator for controlled variation of air-flow velocity in the dc to 500 kHz frequency range is described. The simulator serves for measurement of the transfer function of hot-wire and hot-film transducers used in turbulence research. The microwave simulator consists of an X-band power modulated klystron which delivers electromagnetic energy to the transducer, mounted in a small-size calibration wind-tunnel supplying the transducer mean flow velocity (in the 0 to 80 m/s range). Experimental results are given for the absolute value of the transfer function in a 60 dB range, of a hot-wire tungsten transducer (5 micron diameter X 1 mm long) and of a platinum-plated quartz hot-film transducer (25 micron diameter × 0.5 mm long).     

压阻式真空传感器校准技术研究

随着科学技术的发展,各种类型真空传感器在真空测量设备中得到广泛应用,日常测量和校准问题也日益得到相关计量部门的关注。通过对压阻式真空传感器使用原理的分析,采用比较法真空校准装置,获得真空变量与测量输出信号问的函数关系,对照测量误差是否在准确度等级范围内,准确判断测量结果与被测量真值的一致程度,解决该类型真空传感器的测量和校准问题。     

A Smart Translation From the Response of the Piezoelectric Transducer to a Real-Time Ventilating Signal for the Release of Cooking Fumes

Although the amount of cooking fumes can be estimated based on the output of the piezoelectric transducer, a proper translation from the response of the transducer to the exhaust rate remains to be implemented. In this paper, a smart translation method is used to generate a ventilating signal for the release of cooking fumes based on the output of a piezoelectric transducer. The start and end states of the fume release were computed according to the temporal variation of the output of the piezoelectric transducer, as determined with four successive samples. These detected states were mapped to a 1-bit digital ventilating signal, which then controlled the exhaust fan. Results from a demonstrated range hood system showed that the proposed method enhances the detection of cooking fumes and provides an effective control of the exhaust fan