自适应光学系统MEMS微变形镜的研究

指出了传统变形镜研究所面临的瓶颈，以及采用MEMS技术研究微变形镜的优点．介绍了利用静电力驱动的平板电容式分立式微变形镜．分析结果表明它具有比传统变形镜更优越的性能．指出了进一步研究与发展MEMS微变形镜还需要解决的若干重要问题．     

人字脊蛇形通道微混合器性能的研究北大核心CSCD

微混合器是微芯片集成系统中重要的组成部分,广泛应用于生物分析,化学合成等领域。为了提高被动式微混合器在低雷诺数层流条件下的混合效率,本文设计了一种人字脊蛇形通道微混合器并对其混合结构和流体参数展开分析研究。在人字脊高度和角度对流体混合作用研究的基础上,取人字脊角度θ=45°,d/H为1/2时,分析流量大小对混合效果的影响。同时,选用PBS溶液和台盼蓝染色液进行实验测试,综合评估微混合器混合性能。结果表明:在一定结构参数取值范围内,人字脊高度与通道高度之比越大,流体混合越充分,最佳人字脊角度在40°~50°之间;流体流动速度越小,混合质量越高。模拟和实验平均误差不超过10%,具有良好的一致性。本研究为被动式微混合器混合效率的提升提供参考。     

一种新型电磁驱动无阀微泵的研究

介绍了一种适用于微流体系统的电磁驱动无阀微泵.该微泵的泵腔以及扩散口和喷口都采用微机电系统(MEMS)技术进行制备,利用扁平振动马达作为驱动部件,以弹性模量较小的聚二甲基硅氧烷(PDMS)作为振动膜,研制出一个尺寸为12mm×12mm×5mm的微泵.对微泵的振动频率和输出流量进行了测试,结果显示:电压对频率和流量均有显...     

基于光流技术MEMS平面微运动特性的测量

实现MEMS动态测试技术中平面微运动特性的测量，关键是记录MEMS运动过程中的瞬间运动状态，并恢复MEMS面内的运动历程．为此，介绍了光流技术，并提出利用邻域优化法进行微结构运动的光流计算．组建了基于频闪成像的MEMS平面运动测试系统，通过该系统获得MEMS谐振器周期运动不同相位下的清晰图像序列．利用邻域优化计算该图像序列的光流，选取合适的邻域大小和阈值，得到了MEMS谐振器在特定驱动频率下的运动幅度-相位图及其拟合曲线，从而获得微谐振器在此驱动频率下的运动幅度值为2．12μm．实验结果表明，该方法是准确有效的．     

通道式微混合器的设计及性能

利用计算流体力学和数字图像处理技术,研究"Y"型通道式微混合器的结构及混合性能,分析了混合器结构尺寸和流动条件对混合过程的影响.数值模拟结果表明,在混合通道入口夹角为60°、通道宽度为200μm、注入速度为0.02 m/s的流动条件下,可以取得比较满意的混合效果.利用数值模拟对比了扭曲通道混合器、导流块和直通道结构对混合过程的影响,结果表明使用导流块可以显著提高混合效果.依照模拟计算结果,设计并用MEMS工艺制作了双侧壁有内肋块的通道式微混合器,并进行了流体混合实验,观测了混合过程.拍摄混合实验图像,对比标准浓度-图像灰度关系曲线后识别出拍摄点混合指数.识别计算的结果也证实了所设计混合器性能上的优越性.最后对实验结果误差进行了分析,说明了误差来源并给出了相应的改进措施.     

PZT厚膜的气雾化湿法减薄制备技术

锆钛酸铅（PZT）厚膜的制备技术是制作基于PZT厚膜的微传感器和微驱动器的关键技术之一．传统的制备方法难以兼顾厚膜制备中对厚度、性能、工艺复杂度以及成本等方面的要求,因此,提出了一种新的利用气雾化湿法减薄体材料制备PZT厚膜的技术．该技术结合传统的PZT湿法化学刻蚀方法和刻蚀雾滴的物理轰击效应,在反应中实时去除化学反应残留物,在减薄前后样品厚度均匀性几乎不变的情况下,平均刻蚀速率可达3．3μm/min,且工艺过程简单,成本低廉．实验结果表明,用该技术制备的PZT厚膜可满足微机电系统（MEMS）领域中微传感器和微致动器对于厚膜具备较高灵敏度和较大驱动能力的性能要求,     

以溶胶-凝胶法PZT薄膜为驱动的微泵研制

采用溶胶-凝胶法(sol-gel)制备技术制作了Pb(Zr,Ti)O3(PZT)压电薄膜,并以PZT薄膜为驱动制作了微泵.采用了V型微阀的微泵主要利用PZT的压电效应.针对微泵的关键结构--复合驱动膜,探索了一种Si/SiO2/Ti/Au/PZT/Cr/Au多层驱动膜结构制备方法,解决了在硅基底上制备PZT薄膜的问题,同时探讨并解决了硅各向异性刻蚀微泵的微驱动腔、单向阀的工艺问题,并通过SEM照片对V型阀和多层驱动膜进行了表征.研究结果表明,采用MEMS技术成功地完成了微驱动器的研制,得到的驱动腔硅杯平坦均匀.在V型阀微泵整体设计中需要的硅片数目少,降低了器件的复杂性,可以满足功耗低、小型化和批量生产的要求.     

一种新型无阀微泵的研究

研究了一种适用于微流体系统的新型无阀微泵.以单晶硅片为材料并采用微机电系统(MEMS)技术制备微泵的泵腔以及扩散口和喷口,选用弹性模量较小的聚二甲基硅氧烷(PDMS)作为泵膜,利用扁平振动马达作为驱动部件,研制出一个尺寸为12 mm×12 mm× 6 mm的无阀微泵.分别对微泵的振动频率和输出流量进行了测试,结果显示:...     

基于MEMS的静电微泵建模与仿真

对MEMS中应用广泛的静电微泵进行有限元建模分析．对于涉及多能量域下多场耦合的静电微泵建模,在仿真过程中进行了合理简化．其中在静态分析中,利用圆型薄板的小挠度变形理论和微机电系统中的静电力驱动理论来模拟静电-结构耦合过程;在泵膜的模态分析、谐响应分析以及非线性瞬态分析中,把腔内的流体当作附加质量作用在泵膜上,近似代替流场对泵膜的影响,从而减小计算量,提高了仿真效率．     

基于聚吡咯/氧化石墨烯电极的MEMS微电容的性能研究

MEMS微电容具有高比容量、高储能密度和抗高过载等特点,在微电源系统、引信系统以及物联网等技术领域具有广泛的应用前景。设计制作了一种三维结构的聚吡咯/氧化石墨烯电极的MEMS微电容。该微电容由三维结构集流体、功能薄膜、凝胶电解质和BCB封装构成,其三维结构集流体是基于RIE刻蚀等微加工工艺加工实现的,而功能薄膜是通过电化学沉积工艺在集流体表面沉积聚吡咯/氧化石墨烯制备而成的,具有阻抗低、容量高、循环性能好的优点。电极的结构表征表明,聚吡咯中充分掺杂了氧化石墨烯,功能材料微观结构规整。器件电化学测试结果表明,放电电流为3mA时,MEMS微电容具有30μF的电容值,比容量达到7mF/cm2,在4000次充放电循环后,器件比容量仍保持在90%,电容量无明显衰减,具有稳定的电容性能和良好的循环性能。     

Digital microfluidic operations on micro-electrode dot array architecture

As digital microfluidics-based biochips find more applications, their complexity is expected to increase significantly owing to the trend of multiple and concurrent assays on the chip. There is a pressing need to deliver a top-down design methodology that the biochip designer can leverage the same level of computer-aided design support as the semi-conductor industry now does. Moreover, as microelectronics fabrication technology is scaling up and integrated device performance is improving, it is expected that these microfluidic biochips will be integrated with microelectronic components in next-generation system-on-chip designs. This study presents the analysis and experiments of digital microfluidic operations on a novel electrowetting-on-dielectric-based 'micro-electrode dot array architecture' that fosters a development path for hierarchical top-down design approach for digital microfluidics. The proposed architecture allows dynamic configurations and activations of identical basic microfluidic unit called 'micro-electrode cells' to design microfluidic components, layouts, routing, microfluidic operations and applications of the biochip hierarchically. Fundamental microfluidic operations have been successfully performed by the architecture. In addition, this novel architecture demonstrates a number of advantages and flexibilities over the conventional digital microfluidics in performing advanced microfluidic operations.     

Art‐on‐a‐Chip: Preserving Microfluidic Chips for Visualization and Permanent Display

“After a certain high level of technical skill is achieved, science and art tend to coalesce in aesthetics, plasticity, and form. The greatest scientists are always artists as well.” said Albert Einstein. Currently, photographic images bridge the gap between microfluidic/lab‐on‐a‐chip devices and art. However, the microfluidic chip itself should be a form of art. Here, novel vibrant epoxy dyes are presented in combination with a simple process to fill and preserve microfluidic chips, to produce microfluidic art or art‐on‐a‐chip. In addition, this process can be used to produce epoxy dye patterned substrates that preserve the geometry of the microfluidic channels—height within 10% of the mold master. This simple approach for preserving microfluidic chips with vibrant, colorful, and long‐lasting epoxy dyes creates microfluidic chips that can easily be visualized and photographed repeatedly, for at least 11 years, and hence enabling researchers to showcase their microfluidic chips to potential graduate students, investors, and collaborators.     

微流控芯片制作及电特性研究

采用热压和键合的方法制作玻璃和有机聚合物(PMMA)芯片,对玻璃和PMMA芯片在高压直流电场作用下的伏安特性进行了研究和分析。实验表明,玻璃芯片的伏安线性区域为1100V,PMMA芯片为700V,由于玻璃的导热性能优于PMMA,所以玻璃芯片的伏安线性区域大于PMMA芯片。在此线性段内,根据基尔霍夫电流定律将芯片简化为等效电阻模型,研究了分离电压以及分离焦耳热对芯片分离效果的影响因素,为微流控芯片的优化设计提供了理论依据。     

Recent Progress of Microfluidic Devices for Hemodialysis

Microfluidic hemodialysis techniques have recently attracted great attention in the treatment of kidney disease due to their advantages of portability and wearability as well as their great potential for replacing clinical hospital‐centered blood purification with continuous in‐home hemodialysis. This Review summarizes the recent progress in microfluidic devices for hemodialysis. First, the history of kidney‐inspired hemodialysis is introduced. Then, recent achievements in the preparation of microfluidic devices and hemodialysis nanoporous membrane materials are presented and categorized. Subsequently, attention is drawn to the recent progress of nanoporous membrane‐based microfluidic devices for hemodialysis. Finally, the challenges and opportunities of hemodialysis microfluidic devices in the future are also discussed. This Review is expected to provide a comprehensive guide for the design of hemodialysis microfluidic devices that are closely related to clinical applications.     

Transport, location, and quantal release monitoring of single cells on a microfluidic device

A novel microfluidic device has been developed for on-chip transport, location, and quantal release monitoring of single cells. The microfluidic device consists of a plate of PDMS containing channels for introducing cells and stimulants and a glass substrate into which a cell micro-chamber was etched. The two tightly reversibly sealed plates can be separated for respective cleaning, which significantly extends the lifetime of the microchip that is frequently clogged in cell analysis experiments. Using hydraulic pressure, single cells were transported and located on the microfluidic chip. After location of a single PC12 cell on the microfluidic chip, the cell was stimulated by nicotine that was also introduced through the micro-channels, and the quantum release of dopamine from the cell was amperometricly detected with our designed carbon fiber microelectrode. The results have demonstrated the convenience and efficiency of using the microfluidic chip for monitoring of quantal release from single cells and have offered a facile method for the analysis of single cells on microfluidic devices.     

塑料微流控芯片的注塑成型

有别于传统的微流控芯片压塑成型方法,本文提出注塑成型加工塑料微流控芯片的新工艺.采用UV-LIGA技术制作成型微通道的型芯,设计制造了微流控芯片注塑模具.充模试验表明,如何使微通道复制完全是微流控芯片注塑成型的主要技术难点.模拟与理论分析表明,熔体在微通道处出现滞流现象是复制不完全的主要原因;搭建了可视化装置对此加以试验验证.利用正交试验方法进行充模试验,研究各工艺参数对微通道复制度的影响.试验表明模具温度对提高微通道复制度起决定性作用;注射速度和熔体温度是次要因素,而注射压力相对其他因素影响力较差,但必须保持在一个较高的水平.依此形成塑料微流控芯片的注塑成型工艺,对于宽80μm、深50μm截面的微通道而言,可使微通道复制度由70%提高到90%,满足使用要求.     

Bio‐microfluidics: Biomaterials and Biomimetic Designs

Bio‐microfluidics applies biomaterials and biologically inspired structural designs (biomimetics) to microfluidic devices. Microfluidics, the techniques for constraining fluids on the micrometer and sub‐micrometer scale, offer applications ranging from lab‐on‐a‐chip to optofluidics. Despite this wealth of applications, the design of typical microfluidic devices imparts relatively simple, laminar behavior on fluids and is realized using materials and techniques from silicon planar fabrication. On the other hand, highly complex microfluidic behavior is commonplace in nature, where fluids with nonlinear rheology flow through chaotic vasculature composed from a range of biopolymers. In this Review, the current state of bio‐microfluidic materials, designs and applications are examined. Biopolymers enable bio‐microfluidic devices with versatile functionalization chemistries, flexibility in fabrication, and biocompatibility in vitro and in vivo. Polymeric materials such as alginate, collagen, chitosan, and silk are being explored as bulk and film materials for bio‐microfluidics. Hydrogels offer options for mechanically functional devices for microfluidic systems such as self‐regulating valves, microlens arrays and drug release systems, vital for integrated bio‐microfluidic devices. These devices including growth factor gradients to study cell responses, blood analysis, biomimetic capillary designs, and blood vessel tissue culture systems, as some recent examples of inroads in the field that should lead the way in a new generation of microfluidic devices for bio‐related needs and applications. Perhaps one of the most intriguing directions for the future will be fully implantable microfluidic devices that will also integrate with existing vasculature and slowly degrade to fully recapitulate native tissue structure and function, yet serve critical interim functions, such as tissue maintenance, drug release, mechanical support, and cell delivery.     

Computer-controlled microcirculatory support system for endothelial cell culture and shearing

Endothelial cells (ECs) lining the inner lumen of blood vessels are continuously subjected to hemodynamic shear stress, which is known to modify EC morphology and biological activity. This paper describes a self-contained microcirculatory EC culture system that efficiently studies such effects of shear stress on EC alignment and elongation in vitro. The culture system is composed of elastomeric microfluidic cell shearing chambers interfaced with computer-controlled movement of piezoelectric pins on a refreshable Braille display. The flow rate is varied by design of channels that allow for movement of different volumes of fluid per variable-speed pump stroke. The integrated microfluidic valving and pumping system allowed primary EC seeding and differential shearing in multiple compartments to be performed on a single chip. The microfluidic flows caused ECs to align and elongate significantly in the direction of flow according to their exposed levels of shear stress. This microfluidic system overcomes the small flow rates and the inefficiencies of previously described microfluidic and macroscopic systems respectively to conveniently perform parallel studies of EC response to shear stress.     

Optimization of microfluidic fuel cells using transport principles

Microfluidic fuel cells exploit the lack of convective mixing at low Reynolds number to eliminate the need for a physical membrane to separate the fuel from the oxidant. Slow transport of reactants in combination with high catalytic surface-to-volume ratios often inhibit the efficiency of a microfluidic fuel cell. The performance of microfluidic devices that rely on surface electrochemical reactions is controlled by the interplay between reaction kinetics and the rate of mass transfer to the reactive surfaces. This paper presents theoretical and experimental work to describe the role of flow rate, microchannel geometry, and location of electrodes within a microfluidic fuel cell on its performance. A transport model, based on the convective-diffusive flux of reactants, is developed that describes the optimal conditions for maximizing both the average current density and the percentage of fuel utilized. The results show that the performance can be improved when the design of the device includes electrodes smaller than a critical length. The results of this study advance current approaches to the design of microfluidic fuel cells and other electrochemically-coupled microfluidic devices.     

Construction of Microfluidic Chip Structure for Cell Migration Studies in Bioactive Ceramics

Cell migration is an essential bioactive ceramics property and critical for bone induction, clinical application, and mechanism research. Standardized cell migration detection methods have many limitations, including a lack of dynamic fluid circulation and the inability to simulate cell behavior in vivo. Microfluidic chip technology, which mimics the human microenvironment and provides controlled dynamic fluid cycling, has the potential to solve these questions and generate reliable models of cell migration in vitro. In this study, a microfluidic chip is reconstructed to integrate the bioactive ceramic into the microfluidic chip structure to constitute a ceramic microbridge microfluidic chip system. Migration differences in the chip system are measured. By combining conventional detection methods with new biotechnology to analyze the causes of cell migration differences, it is found that the concentration gradients of ions and proteins adsorbed on the microbridge materials are directly related to the occurrence of cell migration behavior, which is consistent with previous reports and demonstrates the effectiveness of the microfluidic chip model. This model provides in vivo environment simulation and controllability of input and output conditions superior to standardized cell migration detection methods. The microfluidic chip system provides a new approach to studying and evaluating bioactive ceramics.