Multiwell micromechanical cantilever array reader for biotechnology

We use a multiwell micromechanical cantilever sensor (MCS) device to measure surface stress changes induced by specific adsorption of molecules. A multiplexed assay format facilitates the monitoring of the bending of 16 MCSs in parallel. The 16 MCSs are grouped within four separate wells. Each well can be addressed independently by different analyte liquids. This enables functionalization of MCS separately by flowing different solutions through each well. In addition, each well contains a fixed reference mirror which allows measuring the absolute bending of MCS. In addition, the mirror can be used to follow refractive index changes upon mixing of different solutions. The effect of the flow rate on the MCS bending change was found to be dependent on the absolute bending value of MCS. Experiments and finite element simulations of solution exchange in wells were performed. Both revealed that one solution can be exchanged by another one after 200 microl volume has flown through. Using this device, the adsorption of thiolated DNA molecules and 6-mercapto-1-hexanol on gold surfaces was performed to test the nanomechanical response of MCS.     

基于无线声阵列传感器网络的实时多目标跟踪平台设计及实验

介绍了一套自主开发和实现的无线声阵列传感器网络多目标跟踪平台.在相关的多目标跟踪技术的基础上,结合无线声阵列传感器网络的特点,对系统平台的工作流程进行了整体设计并实现了相关算法模块,并在该平台下进行了多目标跟踪实验.实验中利用随机部署在实验区域中的多个声阵列传感器实现了对多个目标实时跟踪,同时还根据实验数据的分析建立了多目标下声阵列传感器的量测模型,并展示了平台下多目标跟踪实验的总体效果及各支撑模块的性能分析.实验表明该平台的设计达到预期要求,是无线声阵列传感器网络在多目标跟踪领域的前沿研究和实践.     

Shape effects of micromechanical cantilever sensor

Microcantilever has been increasingly used as microsensor thanks to its fast response, low cost and parallel implementation in large quantity. The principle of sensing lies in the positive correlation between the resonant frequency of microcantilever and the target mass loading. The shape of cantilever determines the resonant frequency. Therefore it plays a vital role in microsensing. In the present study three basic geometric shapes (rectangle, triangle and half-ellipse) with innovative inner cut are investigated. The micro-cantilever beams are cut to external aspect ratios of 0.5, 1, and 2, and inner cut at aspect ratios of 0, 0.5, 1, and 2, with equal sensing area. Both numerical and experimental analysis indicates that the low-aspect-ratio cantilever with high-aspect-ratio inner cut achieved high sensitivity. The half-ellipse being the highest followed by the rectangle. The results are useful for optimal shape design of a micromechanical cantilever sensor.     

Fabrication and characterization of a new MEMS fluxgate sensor with nanocrystalline magnetic core

This paper presents a new MEMS fluxgate sensor with a Fe-based nanocrystalline ribbon magnetic core and 3D micro-solenoid coils. The excitation coils were placed vertically to the sensing coil on the chip plane. Second harmonic operation principle was adopted in this fluxgate sensor. The total size of the fluxgate sensor was 6.25 mm × 4.85 mm × 120 μm. A simple testing system was established to characterize the fabricated devices. A band pass filter was used to pick up the second harmonic signals in the sensing coils. When excitation rms current of 120 mA and the operational frequency of 200 kHz were selected for the testing of the fabricated devices, the sensitivity of the developed fluxgate sensor was 1005 V/T in the linear range of −500 μT to +500 μT. Due to the combination of the 3D structure coils with the nanocrystalline core, relatively low sensor noise was achieved. The noise power density was 544 pT/Hz^0.5@1 Hz and the noise rms level was 9.68 nT in the frequency range of 25 mHz-10 Hz.     

High-throughput characterization of stresses in thin film materials libraries using Si cantilever array wafers and digital holographic microscopy

We report the development of an advanced high-throughput stress characterization method for thin film materials libraries sputter-deposited on micro-machined cantilever arrays consisting of around 1500 cantilevers on 4-inch silicon-on-insulator wafers. A low-cost custom-designed digital holographic microscope (DHM) is employed to simultaneously monitor the thin film thickness, the surface topography and the curvature of each of the cantilevers before and after deposition. The variation in stress state across the thin film materials library is then calculated by Stoney's equation based on the obtained radii of curvature of the cantilevers and film thicknesses. DHM with nanometer-scale out-of-plane resolution allows stress measurements in a wide range, at least from several MPa to several GPa. By using an automatic x-y translation stage, the local stresses within a 4-inch materials library are mapped with high accuracy within 10 min. The speed of measurement is greatly improved compared with the prior laser scanning approach that needs more than an hour of measuring time. A high-throughput stress measurement of an as-deposited Fe-Pd-W materials library was evaluated for demonstration. The fast characterization method is expected to accelerate the development of (functional) thin films, e.g., (magnetic) shape memory materials, whose functionality is greatly stress dependent.     

Readout of micromechanical cantilever sensor arrays by Fabry-Perot interferometry

The increasing use of micromechanical cantilevers in sensing applications causes a need for reliable readout techniques of micromechanical cantilever sensor (MCS) bending. Current optical beam deflection techniques suffer from drawbacks such as artifacts due to changes in the refraction index upon exchange of media. Here, an adaptation of the Fabry-Perot interferometer is presented that allows simultaneous determination of MCS bending and changes in the refraction index of media. Calibration of the instrument with liquids of known refraction index provides an avenue to direct measurement of bending with nanometer precision. Versatile construction of flow cells in combination with alignment features for substrate chips allows simultaneous measurement of two MCS situated either on the same, or on two different support chips. The performance of the instrument is demonstrate in several sensing applications, including adsorption experiments of alkanethioles on MCS gold surfaces, and measurement of humidity changes in air.     

Wireless resonant sensor array for high-throughput screening of materials

Screening of materials arrays for their viscoelastic, gas-sorbing, and dielectric properties is important in a wide variety of combinatorial materials science applications. Impedance analysis is an attractive approach to analyze these materials properties and to generate the required new knowledge. Often, these measurements are performed by applying a material onto a suitable sensor and monitoring the changes in materials properties. However, when such a sensor is positioned into a test cell, a direct-wired connection to the analyzer becomes complicated. These complications further increase dramatically when a whole array of sensors is being tested in the test cell. To eliminate these complications, we developed a wireless proximity resonant sensor array system. In the developed system, tested materials are applied onto an array of thickness-shear mode (TSM) resonators operating at 10 MHz and arranged for performance testing in a test chamber. Each TSM resonator is coupled to a receiver coil (antenna). An array of these coils is read with a single scanning transmitter coil or an array of transmitter coils. This high-throughput screening approach of sensing materials permits their evaluation in complex environments where additional wiring is not desirable or adds a prohibitively complex design. We demonstrated the applicability of the wireless sensor materials screening approach for the rapid evaluation of the effects of conditioning of polymeric sensing films at different temperatures on the vapor-response patterns to several vapors of industrial, health, law enforcement, and security interest (ethanol, acetonitrile, and water vapors).     

柔性触觉传感阵列力觉标定及加载系统

为解决现有触觉力标定系统不易实现对柔性触觉传感阵列中任意触觉单元进行标定,且存在精度低、不易操作等弊端,设计并研制了一种柔性触觉传感阵列力觉标定及加载系统。利用STM32F103VET6高性能微处理器控制步进电机以联动S型高精度压力传感器实现二维力的精确加载与标定,并将标定信息于上位机实时图形化显示。介绍了标定平台的结构特点、工作原理及系统软硬件设计,通过对系统误差分析及平台标定测试,可实现二维力加载范围0~50 N,法向与切向精确度为0.18%FS。触觉力加载应用实验表明,该加载平台具有较高的测量精度和较强的实用性,为不同结构单元的柔性触觉传感阵列二维力标定及加载提供了便利。     

Design and fabrication of a micro PZT cantilever array actuator for applications in fluidic systems

In this article, a micro cantilever array actuated byPZT films is designed and fabricated for micro fluidic systems. The design features for maximizing tip deflections and minimizing fluid leakage are described. The governing equation of the composite PZT cantilever is derived and the actuating behavior predicted. The calculated value of the tip deflection was 15 μm at 5 V. The fabrication process from SIMOX (Separation by oxygen ion implantation) wafer is presented in detail with the PZT film deposition process. The PZT films are characterized by investigating the ferroelectric properties, dielectric constant, and dielectric loss. Tip deflections of 12 μm at 5 V are measured, which agreed well with the predicted value. The 18 μ1/s leakage rate of air was observed at a pressure difference of 1000 Pa. Micro cooler is introduced, and its possible application to micro compressor is discussed.     

粉尘颗粒阵列传感器灵敏度分析

为了更好的实现粉尘颗粒浓度的测量,对阵列式光学传感器的灵敏度场进行了数学建模和分析,对传感器权重系数进行了计算。分析了不同阵列结构传感器的灵敏度系数。最后根据数学模型使用C语言进行了编程计算,并对四种结构的传感器灵敏度进行了仿真分析与图形仿真。     

阵列式静电-电容传感器灵敏度特性研究

结合静电和电容传感技术各自的特点,提出了阵列式静电-电容传感器用于气固两相流中固相颗粒的局部速度、局部浓度以及局部流量测量。利用静电极片阵列与电容极片阵列获取管道内颗粒的速度分布与浓度分布,进而计算出颗粒的局部流量。该阵列式传感器参数测量的准确性直接取决于它的空间灵敏度分布特性。对静电极片阵列和电容极片阵列的灵敏度特性进行了研究。首先,建立了静电极片阵列的三维静电场模型,通过有限元法分析静电极片阵列的结构参数(电极长度、电极覆盖角等)对传感器灵敏度特性的影响;然后根据电磁场理论建立电容极片阵列的数学模型,并对其进行数值计算,研究管道厚度、管道介电常数、电极覆盖角等参数对传感器灵敏度特性的影响;最后搭建了传动带装置进行了实验研究,实验结果证实了模拟结果的准确性,为阵列式静电-电容传感器的优化设计提供理论依据。     

Design and analysis of micro-mass sensor based on I-shaped cross-section cantilever

压电式微质量传感器的测试精度直接依赖于结构频率对质量变化的灵敏程度.本文利用对称槽型梁和压电薄膜组成的对称敏感结构,提出了一种提高传感器灵敏度的结构设计方法,并设计了一种高精度谐振式微质量传感器.建立了结构频率变化对吸附质量敏感性的分析模型,并研究了槽型截面参数、自振频率及振动模态对灵敏度的影响.与矩形截面结构进行了仿真与实验对比,结果表明,相同几何尺寸参数下,槽型截面悬臂梁的一阶自振频率为1 851 Hz,矩形截面悬臂梁的一阶自振频率为1 610 Hz,相应的传感器灵敏度则分别为3.12×104 Hz/g和1.5×104 Hz/g,前者是后者的2倍.该项设计为提高微质量传感器灵敏度提供了一种新思路.     

Fabrication of multiple electrodes and their application for micro-holes array in ECM

In this study, a two-step composite processing technology combining the EDM process and electrochemical etching is introduced to fabricate a micro-electrodes array. Firstly, rectangular columns measuring 0.2×0.2 mm are machined by the wire-EDM (electrical discharge machining) machine tool, then electrochemical etching is used to erode the microelectrodes array into cylindrical columns. Results show that microelectrodes ranging from hundreds of micrometers to several millimeters could be prepared. Then the machined microelectrodes are used as a cathode tool for electrochemical drilling of micro-hole arrays in electrochemical micromachining (EMM). Furthermore, various parameters affecting the performance of EMM are discussed in detail. Results indicate that the production of EMM improves by using multiple microelectrodes. The pulse current shows strong localization in micro-hole drilling and improves the machining accuracy.     

微型柔性热敏传感器阵列应用研究

边界层分离点检测是实现分离流主动控制的前提和基础，也是气动控制灵巧蒙皮系统研究的重点和难点。以流体边界层分离点检测技术为研究对象，以流体边界层分离点判定的风洞实验为验证目标，设计制作微型热敏传感器与聚酰亚胺柔性衬底，并首次利用微装配技术集成分立敏感元件与柔性衬底形成热敏传感器阵列。首先，采用分立元件通过表面贴装工艺来实现柔性微型热膜传感器阵列的集成，并研究该传感器阵列中敏感元件、柔性衬底的设计及传感器的排布。然后，在低速风洞实验中对传感器阵列的性能和传感器阵列输出信号采用统计量算法的方式进行处理判断，判定圆柱翼型的流体分离点位置。最后，对实验的结果所作的分析表明，该微型柔性热敏传感器阵列满足流体分离检测系统实时性、动态性的要求。     

A Hall sensor array for internal current profile constraint

Measurements of the internal distribution of B in magnetically confined plasmas are required to obtain current profiles via equilibrium reconstruction with sufficient accuracy to challenge stability theory. A 16-channel linear array of InSb Hall effect sensors with 7.5 mm spatial resolution has been constructed to directly measure internal B(z)(R,t) for determination of J(ψ,t) associated with edge-localized peeling mode instabilities in the Pegasus Toroidal Experiment. The diagnostic is mounted in an electrically isolated vacuum assembly which presents a slim, cylindrical profile (～1?cm outside diameter) to the plasma using graphite as a low-Z plasma facing component. Absolute calibration of the sensors is determined via in situ cross-calibration against existing magnetic pickup coils. Present channel sensitivities are of order of 0.25 mT. Internal measurements with bandwidth of ≤25?kHz have been obtained without measurable plasma perturbation. They resolve n=1 internal magnetohydrodynamics and indicate systematic variation in J(ψ) under different stability conditions.     

多层膜气体传感器研制与特性试验

针对粉末烧结型SnO2:基气体传感器功耗大、交叉敏感、工作温度高的问题,研制了多层复合薄膜型气体传感器,以抛光的耐热石英玻璃为基片,真空磁控溅射50～70 am厚度的SnO2薄膜,在SnO2薄膜上分别溅射不连续的ZnO、AI2O3、InO等薄膜,传感器背面溅射30 μm的Ni80Cr20电阻合金作为传感器加热电阻,用薄膜热电偶测量传感器工作温度.测试了不同的复合膜对传感器灵敏度和选择性的影响,并对传感器的吸附与解吸速度进行了测试,薄膜传感器达到相同灵敏度所需的工作温度比粉末烧结型传感器下降100～150℃,吸附解吸速度比粉末烧结型快.     

稀疏基阵水下声成像的压缩感知方法

声传感器基阵式成像是水下目标探测的主要方法之一。在保证成像质量的同时,采用稀疏基阵是降低系统复杂性的有效途径。另一方面,成像方法也是关键技术之一,其性能直接决定成像质量的优劣。在前期研究的稀疏阵基础上,提出了压缩感知成像方法用于水下成像。回波经传感器基阵接收并进行信号分离后,获得各虚拟通道信号,利用压缩感知方法进行成像。在提出的成像方法中,采用了自适应块贝叶斯算法,它能够在噪声环境下较为准确地恢复图像。此外,根据声信号特点设计字典,并按算法特性设计了数据排列规则。实验表明:通过自适应块贝叶斯算法的压缩感知成像能够可靠地对水下目标进行成像,目标的几何特征明显。     

基于Sagnac的分布式光纤传感声学传感器

介绍了一种基于Sagnac的分布式光纤声学传感器. 这种声学传感器通过光电探测器、 数据采集卡、 滤波器和音频放大将3×3耦合器处干涉的光信号转换为电信号且实现音频信号的还原. 为了研究此分布式光纤声学传感器的性能, 分析了基于零频点实验声源扰动定位的原理, 并运用快速傅立叶变换将时域信号转化为频域信号显示声源扰动产生的零频点. 实验结果表明, 基于Sagnac的分布式光纤声学传感系统可以很好地实现声音信号的还原和定位.     

基于DSP的面阵红外图像采集系统设计

为提高进口红外相机的视频信号输出帧率,以提升其性能并扩大应用范围,设计以DSP为控制芯片的面阵红外图像采集系统。通过对IRFPA输出串行数字视频信号的采集和分析,利用CPLD完成信号的解码和逻辑转换,在DSP的控制下利用两个DPRAM,分别实现图像信号的灰度转换和显示缓存,最后由显示芯片完成模拟视频的编码和输出显示。在黑暗环境下对不同热源进行采集实验,结果表明,系统能够对红外图像信号进行实时采集和显示,输出帧率得到大幅提升。     

环型空间阵列扭矩传感器设计及电磁分析

针对极端环境下机械转轴扭矩动态测量的难题,分析了交流电磁感应原理,采用特制的环型空间阵列和专用的磁电式检测器,组成一种新型的非接触式扭矩传感器.建立了其动态扭矩测量的数学模型,并利用ANSYS有限元分析软件对该传感器进行了建模及电磁分析,经初步实验验证可满足极端环境下机械转轴扭矩的动态测量要求.