基于视觉反馈的毫米级颗粒超声操控研究

声波具有良好的穿透性与较广的波长范围,能够突破传统光镊、磁镊、微流控技术的操控颗粒尺寸限制,因此非接触超声操控技术成为研究热点之一.为克服传统驻波声镊的应用局限性,深入探讨基于单面全息声镊系统实现的毫米级颗粒轨迹操控技术.根据Twin声阱模型提出求解相应相位矩阵的快速实现算法,以保证后续轨迹操控的实时性;根据被控颗粒受力模型及自平衡时长设定轨迹操控策略,以保证操控的稳定性;为确保声镊系统驱动信号的同步性,基于处理器FPGA设计相应复用电路;为提升实际轨迹的准确性,基于FPGA实时视觉测量功能实现闭环反馈.实验通过所设计的声镊系统成功完成直径3mm聚苯乙烯小球的正方形轨迹移动操控.结果表明,所提出系统声场生成和视觉检测计算效率高,轨迹操控快速同步,实时可靠,轨迹形状与目标轨迹一致性好.     

超快脉冲光束在激光光镊技术中的应用

光镊技术广泛应用物理、化学和生物等领域的非接触微粒操控,其基本原理是基于光场与微粒相互作用和感应线性极化。随着激光技术的发展,超快脉冲光束应用于光镊技术的研究越来越多。相比于连续激光,低功率高重复频率超快脉冲光束捕获微粒具有更高的捕获效率,不仅粒子所受的瞬时光力较大,而且较高的重复频率能够保证粒子被重复捕获。基于激光光镊技术的基本原理,阐述了光镊技术的研究进展,着重介绍了超快脉冲光束在光镊技术中的应用;基于超快脉冲光束与瑞利粒子相互作用过程中的理论,研究了光学力的计算方法,在理论上论证了超快脉冲光束用于捕获粒子的高效性,发展和完善了单粒子的光学表征技术,探讨了超快脉冲光束捕获粒子在生物光子学和超分辨成像等方面的应用。超快脉冲光束在光镊技术中的应用有利于研究光捕获动力学。     

液晶硅(LCOS)技术研究与应用

新型微显示技术--液晶硅显示技术LCOS是一种全新的数码成像技术,也称数字硅基反射液晶显示技术,具有大屏幕、高亮度、高分辨率、省电等诸多优势,用LCOS技术制作高分辨率光阀的方法逐渐在平板显示界占有一席之地.本文对LCOS的结构和原理以及发展趋势和市场走向以及应用作了较详细的分析.     

微/纳米冰镊操作器执行过程的数值模拟

冰镊是一种借助于针尖与作用对象之间形成的极微小冰晶来实现对物体灵巧操纵的微/纳米操作技术,应用该器件不仅可以实现如拾取、摆放等简单动作,更可以方便地实施如拉伸、旋转等复杂操作,且不受对象的形状、带电与否、重量、材料以及质地等限制,并可与其它机构结合,组成微观意义上的自动化设备.针对冰镊的工作原理,基于相应的流体力学及传热学数学模型,从数值计算角度对微纳米尺度下冰镊的执行过程进行了模拟,在此基础上可望更好地理解冰镊的工作状态及控制过程,从而有助于设计优化新的微/纳米冰镊器件.     

基于声表面波的微操控技术研究进展

微操控技术是指精确控制微纳米颗粒的运动状态,如对细胞、生物大分子、纳米药物等进行捕获、筛选、移 动、分类,其在生物医学、化学分析、材料科学等领域有着重要应用,近年来引起了各国学者的极大关注。声操控是利 用声波操控微粒,具有非接触、穿透性较好、无需对微粒进行化学生物修饰等优点。近年来随着微机电系统(MEMS)技 术和微流控芯片技术的迅速发展,基于声表面波(SAW)的微操控技术受到广泛关注和研究。声表面波芯片因其具有频率 较高、能量局域、易于集成等特点,能够基于显微技术直接观察细胞、微泡等生物微粒的操纵状态,是一个良好的微操 控工具。文章主要介绍基于声表面波的声流、声辐射力效应操控微粒的最新研究进展以及声操控的发展趋势。     

介电泳操控纳米材料及其在微纳传感器中的应用

要将纳米结构作为功能元件应用在微纳传感器、纳米电路等系统中,首先要解决材料的定位操作问题.在自行设计的几种电极的基础上,采用介电泳技术对SiO2微纳米材料进行操控,可以实现材料的沿电场方向的排布和电极间的跨接,为解决纳米结构的定位操作做了有益的尝试.初步测试了采用介电泳技术操控自行生长的ZnO纳米结构制作而成的湿度传感器的基本特性并取得很好的响应,表明介电泳技术可以很好得实现纳米材料在传感器领域中的应用.     

一种基于SOI的集成光波导耦合系统的设计与制备

根据锥形光纤与平面环型微腔耦合原理,使用L-Edit版图设计软件设计并优化了锥形光波导与微腔耦合系统。利用MEMS工艺对SOI圆晶片进行加工,从而实现了锥形光波导与跑道型以及环型光波导微腔的集成。其中,光波导以及微腔通过ICP刻蚀顶层硅而成,矩形槽通过RIE刻蚀衬底硅而成。光波导两侧的矩形凹槽可方便光纤接人以及对出射光...     

惯性微流体的应用与发展

近年来惯性微流体已经成为操纵颗粒和细胞的重要工具,在医学诊断,材料合成以及生化反应领域有着重要应用。微流体的惯性效应能够实现颗粒高通量下的精确操控。惯性升力会驱动颗粒在微通道内发生侧向迁移,通过改变微通道尺寸,入口流速等条件来调控颗粒的运动,实现不同尺寸颗粒的聚焦。非直微通道中迪恩曳力和离心力在颗粒的迁移过程中也起到了重要作用,这两种力的加入有助于提高聚焦效率。综述了多种类型的直通道和弯曲通道中颗粒惯性迁移的最新研究进展,详细阐述了各类型通道中颗粒迁移的原理及应用实例,总结发展现状并对惯性微流体在未来发展中需要解决的问题进行讨论。     

微机电系统(MEMS)技术的应用:微结构气敏传感器

硅和硅基微机电系统技术是微机电系统技术的主流,本文主要介绍用这种技术制造的各种微结构气敏传感器。     

基于集成光波导的超快光子微积分运算研究进展

为了克服电子计算的速率瓶颈,采用全光计算可以有效释放光子的巨大带宽资源,同时全光计算在全光通信网络中有着举足轻重的作用,集成光波导器件以其尺寸小、质量轻、功率代价小等优势已经成为最受关注的光子计算芯片资源之一。光子微积分运算是指在光域中直接对输入信号进行微积分数学运算。本文回顾了几种 常见的硅基光波导器件用于光子微积分运算的实现方案,包括高阶光子微分运算、分数阶微分运算、高阶常系数微分方程求解、可重构的一阶常系数微分方程求解,分别采用的硅基集成光子器件包括级联马赫增德尔干涉仪、掺杂型马赫增德尔干涉仪、级联微环谐振器和掺杂型微环谐振器。本文指出利用集成光波导器件来实现光子微积分器势必会成为光子微积分运算的重要发展方向。     

Dynamics simulation of positioning and assembling multi-microparticles utilizing optoelectronic tweezers

Optoelectronic tweezer (OET) has become a powerful and versatile technique for manipulating microparticles and cells using real-time reconfigurable optical patterns. However, detailed research in the dynamics of particles in an OET device is still scarce, and the multiple-particle interactions still need further quantitative investigation. In this study, a dynamics simulation model coupling optically induced dielectrophoretic force, interaction forces between particles, and hydrodynamic and sedimentary forces is established and numerically solved by utilizing a finite element method and a dynamics simulation frame for multi-microparticles’ positioning and assembling in a typical OET device. The spatial distributions of particles in the energized OET device before optically projecting are simulated first and the condition for particle chain formation is discussed. Then, the most representative ring-shaped optical pattern is applied, and the influences of optical-ring tweezer’ dimensions of inner radius R _e and width d _e on positioning and assembling effect are dynamically simulated and discussed for 5- and 2-μm radius particles. The simulation results indicate the particles inside and outside optical ring both undergo negative DEP and are distributed centre-symmetrically under the action of ring virtual tweezers. Average distance between the particle and center of ring (ADPC) at equilibrium and the system equilibrium time characterizing particle positioning effect dramatically increase for both 5- and 2-μm radius particles while R _e increases from 35 to 55?μm. Specially, the captured particles will pile up and immediately form a three-dimensional micropyramid structure when R _e approximately equals 25?μm for the 5-μm radius particle. Moreover, ADPC decreases very slowly for both two particle-sizes and the system equilibrium time of 2-μm radius particle vary more obviously than that of 5-μm radius particle with d _e increasing from 10 to 30?μm. And the system equilibrium time for 2-μm radius particle is always larger than that for 5-μm radius particle. The primary simulation results are in good agreement with experimental observations; hence this dynamics simulation model can truly predict the particle-moving trajectory and equilibrium positions in an OET device. Moreover, this dynamics simulation holds promise for designing and optimizing optical patterns for accuracy in assembling particles in order to form a specific microstructure.     

Fabrication and property analysis of a MEMS micro-gripper for robotic micro-manipulation

The micro-gripper is an essential device in micro-manipulation. A new micro-gripper fabrication process using MEMS technology is developed for a robotic micro-manipulation system. The mechanical stiffness of this gripper is analyzed with the Pseudo-Rigid Body Model to estimate the grip force of these micro-grippers of various scales and materials. The validity of the proposed model is verified by simulations and experiments. An experimental robotic micro-manipulation system consisting of this micro-gripper and a precision manipulator is implemented, and an actual gripping test is conducted to evaluate the robotic manipulation system.     

Miniaturized flow cytometer with 3D hydrodynamic particle focusing and integrated optical elements applying silicon photodiodes

In this study, the design, realization and measurement results of a novel optofluidic system capable of performing absorbance-based flow cytometric analysis is presented. This miniaturized laboratory platform, fabricated using SU-8 on a silicon substrate, comprises integrated polymer-based waveguides for light guiding and a biconcave cylindrical lens for incident light focusing. The optical structures are detached from the microfluidic sample channel resulting in a significant increase in optical sensitivity. This allows the application of standard solid-state laser and standard silicon-based photodiodes operated by lock-in-amplification resulting in a highly practical and effective detection system. The easy-to-fabricate single-layer microfluidic structure enables independently adjustable 3D hydrodynamic sample focusing to an arbitrary position in the channel. To confirm the fluid dynamics and raytracing simulations and to characterize the system, different sets of microparticles and T-lymphocyte cells (Jurkat cell line) for vital staining were investigated by detecting the extinction (axial light loss) signal. The analytical classification via signal peak height/width demonstrates the high sensitivity and sample discrimination capability of this compact low-cost/low-power microflow cytometer.     

Preliminary scanning fluorescence detection of a minute particle running along a waveguide implemented microfluidic channel using a light switching mechanism

It has long been thought that an optical sensor, such as a light waveguide implemented total analysis system (TAS), is one of the functional components that will be needed to realize a “ubiquitous human healthcare system” in the near future. We have already proposed the fundamental structure for a light waveguide capable of illuminating a living cell or particle running along a microfluidic channel, as well as of detecting fluorescence even from the extremely weak power of such a minute particle. In order to develop novel functions to detect the internal structure of living cells quickly, an angular scanning method that sequentially changes the direction of illumination of the minute cell or particle may be crucial. In this paper, we investigate fluorescence detection from moving particles by switching the laser power delivery path of plural light waveguides as a preliminary experiment toward this novel method. To construct an experimental system able to incorporate a switching light source mechanism cost effectively, we utilized a conventional TAS chip with plural waveguide pairs arranged in parallel, and a forced vibration mechanism on an optical fiber tip by a piezoelectric actuator. With this system, we performed an experiment to detect extremely weak fluorescence using micro particles with a fluorescent substance attached and an optical TAS chip that incorporated a microfluidic channel and three pairs of laser-power-delivering light waveguide cores. We successfully obtained clear, quasi-triangular-shaped pulses in fluorescent signals from resin particles running across the intersection under three different conditions: (1) a particle with approximately the same velocity as that of a forced-vibrated optical fiber tip of approximately 700 mm/s, (2) a particle with velocity 1 digit smaller than that of an optical fiber tip, and (3) a particle with velocity approximately 1/20 that of an optical fiber tip.     

Design of reactive power optimization control for electromechanical system based on fuzzy particle swarm optimization algorithm

Due to low precision and premature tendency of traditional particle swarm optimization, the reactive power optimization control of electromechanical system based on fuzzy particle swarm optimization algorithm was designed. The premise is to meet the constraints of operation conditions. The active network loss was reduced and the static reactive power optimization mathematical model of electromechanical system was constructed by changing the voltage and reactive power distribution of system. Meanwhile, the voltage did not exceed the limit, and the discrete control variables were limited by the maximum allowable action times, so that the dynamic reactive power optimization mathematical model of electromechanical system was built by minimizing the sum of network loss in twenty-four hours of a day. The particle swarm algorithm was optimized by adaptive adjustment strategy, and then the particle position of particle swarm optimization algorithm was updated. Moreover, the static and dynamic reactive power optimization mathematical model of electromechanical system was solved. Finally, the reactive power optimization control of the electromechanical system is realized. Experimental results show that the proposed method has high convergence performance, so it is able to realize the precise control of reactive power optimization for electromechanical system and eliminate the voltage exceeding specified limits of electromechanical system. In this way, the node voltage can always be within the specified range.     

Simulation of an optical sensing system for automatic object tracking

An optical guiding system is modeled and the signal processing and its operation are studied. Our model is based on the principle that two moving objects are considered, in which one is the moving robot, and the other one is the sought object. The reported system is capable of detecting and measuring the relative motion of the target, and, in response generating electrical signal capable of directing and guiding the vehicle on the shop floor. In this way, the respected robot or vehicle using such a device can maintain its aim on the related target scene at all times. The proposed system offers a higher degree of accuracy and reliability since it considers the state-of-art electronic and optical components for signal processing. A software package (ORCAD 9) is used to simulate signal processing of such an optical tracking system and the results are reported.     

Illumination and scattered light detection using a light source consisting of sub-micrometer defect arrays formed on a extremely flat light waveguide core

We have previously argued that an optical sensor combined total analysis system (TAS) is one of the indispensable functional components needed to realize a “ubiquitous human healthcare” system. To achieve this goal, we have proposed a fundamental structure for illuminating a minute cell or particle running along a microfluidic channel using a flat waveguide construction. It is desirable that the TAS light source should be arranged as close to the specimen flow as possible in order to acquire the necessary optical properties; hence, artificial defects formed on the surface of a flat light waveguide are considered to be a promising candidate for realizing the arbitrary-shaped light source for a highly functional optical TAS structure. Based on this idea, we fabricated a structure, constructing a flat and square light source consisting of rectangular solids, sub-micrometer in size, with a 1-μm thick and a 12-μm wide light waveguide core. We successfully trial-manufactured an optical TAS chip with a fluidic channel containing a 14 × 10-μm cross section, and an extremely flat light waveguide core. We repeatedly confirmed that the defect array could function as an approximately square light source when a 650-nm wavelength laser power was carefully introduced. Furthermore, we developed a hybrid numerical calculation method base on the finite-difference, time-domain method together with the beam propagation method. Utilizing this hybrid method, we evaluated the optical response when a particle runs across the light source while changing the aperture length of a shading mask to obtain signals with both higher intensity and shorter full width at half maximum. The numerical results were compared with experimental results obtained using an image acquisition system, and demonstrated good qualitative accord.     

基于六维微位移传感器的并联微操作台全闭环控制

以一种新型的6-PSS并联微操作台为对象,将六维微位移传感器应用于微操作台的终端运动平台,设计了一种全闭环的控制系统。介绍了系统各部分的结构组成和工作原理,包括6-PSS微操作台结构及其运动学分析、六维微位移传感器组成与原理。由开闭环下的实验结论比较得知,通过基于六维微位移传感器的全闭环控制,系统定位精度得到提高,实现了终端运动平台六维位姿的精确控制。