纳升级生物样品核磁共振微检测高信噪比平面螺旋微线圈的设计

论述了纳升(nL)级生物样品核磁共振微检测技术中,高信噪比平面螺旋微线圈的设计方法及结果,介绍了这种检测技术的优点与缺点,并提出了改进方法。论述了核磁共振平面螺旋微线圈检测方法的理论基础,推导出自由感应衰减信号的信噪比与线圈几何参数的数学关系,利用MATLAB软件对信噪比进行了仿真,得到了最优信噪比条件下的线圈几何参数值,同时计算出相应的品质因数。最后,概括了平面螺旋形微线圈几何参数设计的一般原则。     

三维微弹簧型MEMS探卡的设计和制备

随着IC器件上的I/O尺寸减小和密度增加,与之通过接触来进行电性能测试的探卡密度也要相应增加,传统手工制作的环氧树脂针形探卡难以满足使用要求,使用MEMS技术制作探卡成为发展的趋势,但是当前MEMS探卡的主要问题是不能承受和产生破坏焊垫表面氧化层和污染层所需的应力.本文提出了一种简支梁结构、通过多次电镀工艺制作的三维弹性MEMS探卡,这种探卡可以承受更大应力,并且具有较小的自身电阻.针对间距为250 μm阵列排布的器件I/O,使用ANSYS有限元方法对弹簧型探卡进行了结构分析和设计,采用UV-LIGA工艺制备探卡,最后对探卡的力学性能进行了测试.     

阵列细胞微培养腔的设计与制造

采用光刻成型技术、"多次光刻、一次显影"工艺以及热键合工艺制备了基于三层、具有阀控开关和浓度梯度的PDMS微阵列细胞微培养腔,重点研究了浓度梯度、细胞培养腔结构的设计.研究表明浓度梯度的形成主要受芯片管道结构影响;在低雷诺数、被动混合方式情况下,采用简单结构进行混合的效率会很低;在本课题中,将瓦片状结构与管道复合起来提高混合效率,实验结果表明:即使在高流速情况下,也能得很高的混合效率并使各管道间浓度呈很好的线性分布;同时,对细胞培养腔的结构进行了设计;此外,将有限元分析软件COMSOL应用到混合管道及培养腔内流体、流态进行了分析,进一步利用分析结果优化了结构设计.     

Co‐design of a filtering antenna based on multilayer structure

In this paper, a co‐design of filtering antenna based on multilayer structure is proposed for modern wireless communication systems. The filtering antenna system consists of a filtering network partly designed on two dielectric substrates and a Г‐shaped antenna, which performs as both a radiator and the last order of the filter. An effective co‐design method based on parameter extraction for impedance matching can significantly reduce the optimization time. Furthermore, a slot is grooved on the common ground, which is shared by the antenna and the filter to realize the feeding of the resonator. A prototype of the filtering antenna was fabricated and measured, and a good agreement is achieved. The tested results show that the filtering antenna features a 2.7% bandwidth, 2.2 dBi gain at 2.6 GHz and ?20 dB out of band rejection at 5 × f ₀ . The size of the design is 0.29λ _g × 0.23λ _g .     

基于双焦点设计的平面波束扫描透镜天线研究

为了提升平面透镜天线的扫描性能,以实现波束扫描或多波束应用,首先研究设计了单焦点平面透镜天线,针对单焦点平面透镜天线在大角度扫描时增益降低太快的问题,引入了反射阵和传统介质透镜的双焦点设计方法。基于阵列天线合成理论,计算了双焦点透镜天线的辐射特性。采用多层金属孔阵列单元,建模了平面透镜天线模型,仿真对比了单焦点透镜和双焦点透镜天线的扫描辐射特性。结果表明,在扫描范围（0°-27°）内,双焦点透镜天线的最低增益相对于单焦点透镜天线有明显提升,而且大角度扫描方向图形状也有改善,证明了双焦点的设计方法有效提升了平面透镜的扫描性能。     

Design and fabrication of a silicon probe for surface profilers

A micromachining probe for surface profilers is reported in this paper. This probe employs single crystal silicon double-ended tuning forks (DETFs) as the sensitive unit to achieve high resolution and frequency read-out. The frequency shift of the DETFs caused by the induced axial stress is directly proportional to the undulation of the measured surface. Moreover, one-stage and two-stage microleverage amplification mechanisms are respectively implemented to improve the probe performance. The silicon on glass (SOG) process which can provide high aspect ratio single crystal silicon structures has been adopted to enhance the performance of the probes. The testing results indicate that the probe with two-stage mechanical amplifiers has a frequency-displacement sensitivity of 257.1 Hz/μm with a nominal frequency 27.3 kHz at room temperature in atmosphere, which is in close agreement with the simulation results.     

Optimal design of planar frames based on structural performance criteria

The aim of this study is to present a new approach, nearer to engineer's point of view, for optimizing the structures, in particular for the planar frames. As a means of improving the overall stability of the structure the objective function chosen to be maximized is the eigenvalues of the buckling modes. The optimization process involves two stages: a preliminary design when a prescribed value for the natural fundamental vibration period is the main constraint and a second stage in which the usual stress, displacement, and side constraints are taken into account. The algorithm used for optimization is based on a classical optimality criteria approach. The steps of the algorithm are illustrated by some examples which demonstrate the effectiveness of the proposed procedure in improving design.     

Optimal experiment design based on local model networks and multilayer perceptron networks

This paper addresses the topic of model based design of experiments for the identification of nonlinear dynamic systems. Data driven modeling decisively depends on informative input and output data obtained from experiments. Design of experiments is targeted to generate informative data and to reduce the experimentation effort as much as possible. Furthermore, design of experiments has to comply with constraints on the system inputs and the system output, in order to prevent damage to the real system and to provide stable operational conditions during the experiment. For that purpose a model based approach is chosen for the optimization of excitation signals in this paper. Two different modeling architectures, namely multilayer perceptron networks and local model networks are chosen and the experiment design is based on the optimization of the Fisher information matrix of the associated model architecture. The paper presents and discusses feasible problem formulations and solution approaches for the constrained dynamic design of experiments. In this context the effects of the Fisher information matrix in the static and the dynamic configurations are discussed. The effectiveness of the proposed method is demonstrated on a complex nonlinear dynamic engine simulation model and an analysis as well as a comparison of the presented model architectures for model based experiment design is given.     

A planar approach for manufacturing cardiac stents: design, fabrication, and mechanical evaluation

A new approach that uses planar batch manufacturing technologies is presented for the design and fabrication of coronary artery stents. Stent samples with different wall patterns have been fabricated from 50-/spl mu/m-thick stainless steel foil using microelectrodischarge machining. Stents have been expanded to tubular shapes by using angioplasty balloons, both inside mock arteries and without external confinement (i.e., free-standing). Free-standing stents exhibit diameter variations of 相似文献   

基于受控拉格朗日函数的垂直起降飞机控制器设计

本文将单欠驱动度力学系统基于受控拉格朗日函数(CL)的控制器设计技术应用到具有输入耦合的垂直起降(PVTOL)飞机的控制问题中. 在显式陀螺力的匹配条件下, 得到的光滑反馈控制律保证了系统几乎全局渐近稳定. 与现有同类方法所得到的结果相比, 该匹配控制器形式更简单而收敛性能得到保持.     

The design and fabrication of polymerase chain reaction platform

Thermalcycler was extensively used machine for amplify DNA sample. One of the major problems in the working time was that it spent most of time for cooling and heating. In order to improve the efficient, the study presented a novel method for amplify DNA sample. For this concept, the DNA sample in the silicon chamber which was pushed by a tappet through the three temperature regions around a center and then the DNA segments could be amplified rapidly after 30 cycles. The polymerase chain reaction (PCR) platform was composed of the thin-film heaters, Cu plates, DC powers, and temperature controllers. The photolithography and bulk etching technologies were utilized to construct the thin-film heater and DNA reaction chambers. Finally, 1 μl 100 bp DNA segment of Escherichia coli K12 was amplified successfully within 36 min on this PCR platform.     

基于PDMS的微流量计的研制

通过检测透皮抽取出的人体细胞间液中葡萄糖浓度来预测血糖浓度是一种重要的微创血糖检测技术。但由于抽取出的细胞间液量很少,需要进行稀释以便输送和收集,然后根据稀释后的体积来计算稀释前的细胞间液浓度。设计和加工了一种微流量计用以测量稀释后细胞间液的体积,并搭建了性能测试实验平台,测试了流量计测量结果的重复性和线性相关性。实验表明:流量计测量范围为4～16μL;对15μL的样品10次测量的变异系数为6.2%;13个不同体积样品的测量结果相关系数为0.988。微流量计能够满足测量要求。     

基于CMOS工艺钨微测辐射热计阵列集成芯片的设计与制作

采用0.5μm标准CMOS工艺和微机械加工工艺,设计并制作了低成本4×4钨微测辐射热计阵列集成芯片。阵列中每个钨微测辐射热计均由微悬桥结构和钨热敏电阻组成,CMOS读出电路集成在阵列下方。微悬桥结构由表面牺牲层技术实现,不需要任何的光刻工艺。钨微测辐射热计像元尺寸为100μm×100μm,填充因子为20%。测试结果表明,在真空环境下,钨微测辐射热计等效热导为1.31×10-4W/K,等效热容为1.74×10-7J/K,热时间常数为1.33 ms。当红外光源的斩波频率为10 Hz时,钨微测辐射热计的电压响应率为1.91×103V/W,探测率为1.88×107cm·Hz1/2/W。     

Design and fabrication of a micromachined planar patch-clamp substrate with integrated microfluidics for single-cell measurements

We have designed, fabricated, tested, and integrated microfabricated planar patch-clamp substrates and poly(dimethylsiloxane) (PDMS) microfluidic components. Substrates with cell-patch-site aperture diameters ranging from 300nm to 12 /spl mu/m were produced using standard MEMS-fabrication techniques. The resistance of the cell-patch sites and substrate capacitance were measured using impedance spectroscopy. The resistance of the microfabricated apertures ranged from 200 k/spl Omega/ to 47 M/spl Omega/ for apertures ranging from 12 /spl mu/m to 750 nm, respectively. The substrate capacitance was 17.2 pF per mm/sup 2/ of fluid contact area for substrates with a 2-/spl mu/m-thick layer of silicon dioxide. In addition, the ability of the planar patch-clamp substrates to form high-resistance seals in excess of 1 G/spl Omega/ has been confirmed using Chinese hamster ovary cells (CHO-K1). Testing shows that the microfluidic components are appropriate for driving human embryonic kidney cells (HEK 293) to patch apertures, for trapping cells on patch apertures, and for exchanging the extracellular fluid environment.     

The design of a planar robotic manipulator for optimum performance of prescribed tasks

The application of a general optimization methodology, previously proposed by the authors, is extended here to the design of a three link revolute-joint planar manipulator performing more practical and complicated prescribed tasks. In particular a tool moving task and a spray painting task are considered. Both the minimization of average torque and energy usage required for execution of the tasks are addressed and the optimization is carried out with the link lengths and base coordinates taken as the five design variables. In addition to simple physical bounds placed on the variables, the maximum deliverable torques of the driving motors represent further constraints on the system. Joint angle constraints, not previously considered but of great practical importance, are also imposed in this study. This results in significantly more challenging optimization problems than those previously tackled. The complications arising from lock-up and nonassembly are handled by specially devised procedures. The optimization is carried out via penalty function formulations of the constrained problems to which the Snyman unconstrained trajectory optimization algorithm is applied in a special way. For both tasks and for both objective functions, with the full complement of constraints imposed, feasible designs with low objective function values are obtained by using, in each case, four different infeasible designs as starting points for the algorithm.     

基于VR+AR技术的电缆接头制作虚拟培训系统设计

设计了一种基于VR+AR技术的电缆接头制作虚拟培训系统.首先通过VR虚拟现实和AR增强现实技术模拟电缆接头制作场景,并在场景中添加电缆接头组件和工具箱供制作人员操作和使用;其次通过深度学习方法捕捉和识别制作人员手部动作,并与标准动作进行对比来判别其动作规范性,从而可以对受训人员进行考核,完成反馈互动.整个系统包括理论学...     

The design and fabrication of autonomous polymer-based surface tension-confined microfluidic platforms

A one-step thick film printing process has been established for patterning hydrophobic polyvinyl chloride (PVC) substrate materials with hydrophilic cellulose acetate. The opposing patterned substrate materials are brought within close proximity utilizing spacer material of defined thickness. The parallel-plate configured devices are capable of supporting autonomous fluid transport through capillarity. Minimum attainable path widths of 313.3 ± 17.9 μm can be achieved utilizing an affordable personal printer for photomask generation. In addition, a theoretical model for this system predicting meniscus position as a function of time and system architecture is posed along with experimental data which is found to be in good agreement with the model. Lastly, the curvature of the surface is approximated and exploited for the determination of the true pressure jump across the curved surface at the gas–liquid interface at all points on a discretized surface. The curvature associated pressure jump results are found to be consistent with the Laplace pressure approximation.

超导接收机中低射频低温低噪声放大器的研制

提出了分别工作于低温和常温下级联使用的两级低射频低温低噪声放大器的设计方案,给出了改善电路条件稳定和便于调谐的具体方法。测试结果表明,此两级低射频低温低噪声放大器完全满足高性能高温超导接收机的指标要求。     

Structural optimization as a harmony of design, fabrication and economy

The main requirements of load-carrying engineering structures are safety, producibility and economy. The role and importance of fabrication constraints and costs is shown in the case of a compression tubular strut, a tubular truss of parallel chords and a welded stiffened square plate. The evaluation of optimal versions of these structures shows that, neglecting the fabrication constraints and costs, the design cannot result in up-to-date solutions.