电泳微芯片进样口与微沟道形状的优化设计

基于电渗流场的理论,建立电泳芯片的不同结构模型,以计算流体力学(CFD)方法来模拟不同设计参数和电压组合下的电泳微芯片微沟道中流体流动现象.最终优化基本型毛细管微沟道交叉口形状为矩形,微沟道宽度为20 μm,进样与分离场强为200～250V/cm.为在有限芯片面积下增加有效分离距离,设计螺旋形沟道电泳芯片模式.     

新型半填充微气相色谱柱芯片研究

基于微机电系统(MEMS)技术设计制造了新型半填充微气相色谱柱(μGCC)芯片,芯片的微沟道内设计有排列整齐的椭圆微柱阵列。与现有半填充μGCC相比,新型μGCC的微沟道具有更大的表面积和更均匀的流速场分布,对芯片分离度和柱效的提高起着至关重要的作用。设计的芯片成功分离了重烃类混合气体组分和苯系物,理论塔板数最高可达到9 246 plates/m。     

用于血样前处理的BioMEMS微流控芯片

基于BioMEMS技术,研制成三种血液样品前处理微流控芯片,分别介绍了血样前处理微流控芯片的原理、结构、制备技术以及样品前处理效果.基于错流过滤原理,设计了用于血细胞分离的错流过滤微结构,采用深刻蚀技术在硅片上刻蚀出直径为20μm,高度为50 μm的圆柱阵列;基于化学法破裂细胞,设计了用于血细胞破裂的夹流式微沟道,采用湿法腐蚀技术在硅片上腐蚀出深度约为80μm的微沟道;基于固相萃取原理,设计了用于DNA提纯的介孔固相载体,采用电化学阳极腐蚀技术在硅微沟道内表面制得表面积为300m2/g的介孔层.分别在芯片上实现了血细胞的分离、血细胞的破裂以及DNA的提纯.     

PDMS用加窗方式快速复制微结构

提出了一种微流控芯片中的制作方法,此方法可以复制现有芯片的任意结构,可用于实验室原有芯片的修复和整合.用窗口的方法提取结构,可排除芯片上相邻结构的干扰,得到表面光滑整齐的新芯片.特别适用于复制目前软光刻工艺尚未达到的特微结构和三维结构芯片.实验制作出的聚二甲基硅氧烷(PDMS)芯片沟道长30μm,宽5μm,深5μm,显微镜下观察芯片表面光滑,窗口内沟道性质复制良好,窗口边缘与表面之间具有明显的陡变.     

集成微流体测控芯片的研制

设计、研制了集成有微泵、微沟道、微流量传感器、温度传感器的微流体测控芯片.采用有限元软件ANSYS模拟分析了将其作为冷却芯片时微沟道的散热作用,分析确定了芯片上各元件的结构.该集成芯片为硅-玻璃结构,在硅片上,利用ICP法刻蚀无阀微泵泵体和微沟道;在7740玻璃片上,以溅射、剥离法制作微流量和温度传感器;图形精确对准后硅/玻璃以静电键合方法封接.无阀微泵采用压电元件驱动.测试结果表明:集成芯片具有冷却功能,循环水的流速最大可达25.4mm/s.     

自热式连续流PCR芯片的模拟与设计

介绍了一种连续流式的聚合酶链式反应(PCR)芯片,采取主动加热、被动冷却的方式,可实现DNA片断的倍增。用ANSYS有限元分析软件对器件进行温场分布仿真及分析,在此基础上, 设计了一种基于玻璃-玻璃的PCR芯片,芯片上分布着宽90μm,深40μm的迂回微沟道。通过单侧局部区域加热的方法,即可形成3个较宽的恒温区(95, 72, 60℃)与PCR反应相对应,且恒温区内温差在5℃以内,可以满足PCR反应的需要。     

聚二甲基硅氧烷微流控芯片的制备

采用印刷电路板技术加工出芯片模具,以聚二甲基硅氧烷(PDMS)为材料制作出微流控芯片。该芯片由基片和盖片组成,微流控沟道位于基片上,深度和宽度分别为75μm和100μm,由盖片对其进行密封。考察了有绝缘漆模具和无绝缘漆模具制作的芯片的电泳分离情况。在该PDMS微流控芯片上对用异硫氰酸酯荧光素标记的氨基酸进行了电泳分离,当信噪比S/N=3时,最小检测浓度达到0.8×10-11mol/L。     

基于交流电场驱动的微流体运动特性模拟研究

为研究在交流电场驱动下微沟道中流体的运动特性,采用有限元的方法建立了非对称电极驱动流体的数学模型.微管道高为40μm,出口在交流微电极以后100μm处,通过多物理场耦合软件研究了交流微电极对数、驱动电压、频率与微沟道出口平均速度之间的关系,其中交流微电极对数、驱动电压与出口速度成正比,对于几何尺寸一定的微管道,在特定频率下可以得到最大出口速度.实例中微管道在1V电压下,最佳驱动频率为3500 Hz,可获得的最大出口速度为9.6×10-8 m/s.     

微机械陀螺ASIC接口电路设计

在分析微机械陀螺接口电路工作原理的基础上,采用中电集团第24研究所的3μm10 V P-well标准模拟CMOS工艺设计并制作了微机械陀螺ASIC接口电路.电路HSPICE仿真灵敏度为0.252 mV/aF.芯片面积为5.5 mm×4.4 mm,在此工艺流片并进行了芯片测试.结果表明,在10 V电源电压下,其功耗为49.3 mW,输出摆幅为4.85±3.1 V,输出节点的零点偏离为0.15 V.此芯片具有微陀螺驱动及信号检测功能,可实现与微陀螺敏感结构的双片集成.     

微型自吸氧直接甲醇燃料电池的阳极极板设计研究

在体积微型化条件下,极板流场图形的设计对燃料电池的性能优化,尤其是提高面积比功率,具有极其重要的意义.本文设计了不同沟道和沟脊宽度的阳极极板,测试了相应微型自吸氧燃料电池的性能变化.实验结果表明,在沟脊宽度小于沟道宽度的条件下,增加沟道或沟脊宽度都能改善微型燃料电池的性能,但改善幅度随宽度增加而趋缓.当沟道和沟脊宽度等比例变化时,性能随宽度的增加的最优值为600μm,其性能达到了2.87 mW/cm2,优于沟道和沟脊均为400μm和800μm的燃料电池的性能.     

Two-axis micro fluxgate sensor on single chip

We present a two-axis micro fluxgate sensor on single chip for electronic compassing function. To measure X- and Y-axis magnetic fields, functional two fluxgate sensors were perpendicularly aligned and connected each other. The fluxgate sensor was composed of square-ring shaped magnetic core and solenoid excitation and pick-up coils. The solenoid coils and magnetic core were separated by benzocyclobutane which had high insulation and good planarization characters. Copper coil patterns of 10 μm width and 6 μm thickness were electroplated on Ti (300 Å)/Cu (1,500 Å) seed layers. 3 μm thick Ni_0.8Fe_0.2 (permalloy) film for the magnetic core was also electroplated under 2,000 gauss. Excellent linear response over the range of ?100 μT to +100 μT was obtained with the sensitivity of ～280 V/T. Actual chip size was 3.1×3.1 mm². The sine and cosine signals of two-axis fluxgate sensor had a good function of azimuth compass.     

Swelling of SU-8 structure in Ni mold fabrication by UV-LIGA technique

UV-LIGA technique is used to fabricate hot embossing mold of PMMA microfluidic chip. Pre-polished Ni plate serves as electroforming substrate and the micro channel is the only structure to be electroformed in the fabricated mold. The precision of the micro channel strongly depends on the process parameters. Experiments show that the width of micro channel varies with the electroforming time. With the electroforming time of 108, 140 and 160 min, the width of micro channel reduces to 89, 86 and 82% of patterned SU-8 mold respectively, which is caused by swelling of SU-8 in acidic, high temperature electroforming solution. This swelling is the key answer to the slope of the sidewalls of the electroformed structure. This study is beneficial to optimizing microfluidic chip mold design.     

Fully‐integrated active matrix programmable UV and blue micro‐LED display system‐on‐panel (SoP)

High pixel per inch and high‐resolution micro‐LED displays are attracting more and more attentions. The increasing pixel number requires a large amount of bonding pads and brings huge difficulties to micro‐LED system design and lowers power efficiency as well. It is urgent to integrate row and column driving circuits onto the micro‐LED panel. Here, we report a fully integrated active matrix programmable micro‐LED system on panel (SoP) with ultraviolet and blue emission wavelengths. The micro‐LED SoP has a resolution of 60 × 60 and pixel pitch of 70 μm. The micro‐LED SoP was achieved by integrating micro‐LED arrays with silicon‐based p‐channel metal‐oxide semiconductor driving panel using fine‐toned flip‐chip bonding technology. With fully integrated scan and data circuits, the number of bonding pads was greatly reduced from 136 to 28, and large amount of metal interconnection lines were saved. The micro‐LED SoP panel was mounted on a periphery driving board, and representative characters were displayed successfully.     

Position detection method for microwell chip on microscope stage by photon multiplier tube

In this paper, we propose a position detection method for a microwell with manageable volume (MMV) chip on the stage of the inverted microscope. When the manipulation robot arm puts an MMV chip on the microscope stage, there is alignment error up to 500 μm. This error affects measurement accuracy of fluorescence from solution filled in a tiny hall of the MMV chip. Usually, CCD image processing is used for detecting a position. However, appending a CCD camera to our microscope increases the complexity of the optical system. Therefore, we used a photon multiplier tube which was already equipped for measuring fluorescence. In the result, the position of the MMV chips was detected by putting a pilot LED directly above the objective lens. The detection error was less than 10 μm. Although this method was devised for our system, we considered that it was available in other micro optics systems.     

Fabrication of a 2-D in-plane micro needle array integrated with microfluidic components using crystalline wet etching of (110) silicon

We propose a two-dimensional (2-D) in-plane micro-needle array with shaft sidewalls aligned parallel to the vertical (111) crystalline plane of (110) silicon. Six types of needle tips with various shapes and tapered angles were fabricated so as to maintain the tip sharpness. Two layers of micro needles (upper and bottom needle arrays) for the 2-D array were realized using simultaneous etching from the front and back sides of (110) silicon. In addition, microfluidic components were embedded in the micro-needle chip to inject or extract biochemical samples. The length of the micro needles was easily extended to 2200 μm, and the insertion forces of the single and arrayed micro needles were evaluated by pricking chicken breast flesh. In case of a micro needle having a tapered angle of 10° and tip end width of 1 μm, the insertion force per needle was as low as 15 mN, which is lower than those reported in previous studies.     

Design,fabrication and characterization of micro flow sensor inspired by biological hair cell

Design, fabrication and characterization of micro flow sensor were investigated based on the inspiration of biological hair cell in a nature. The micro scale artificial hair cell sensor was designed as considering two parts; first the high aspect ratio cilium structure which works as a hair cell of fish and second the mechanoreceptor structure where the drag force by flow are actually measured. Parameters of cilium structure were designed based on static modelling as follow: 300 μm diameter and 2 mm height. The high aspect ratio cilium structure was precisely fabricated using a hot embossing process with the developed separated micro mold system prepared by LIGA (from the German Lithographi, Galvanoformung, Abformung) process. The mechanoreceptor was formulated with a force sensitive resistor with four symmetric electrodes to analyze the direction and the magnitude of target flow. Performance of assembled sensor was characterized using the prepared water channel. Flow velocity was sensed with the magnitude of signal and the direction of flow was distinguished by analyzing the signals from four mechanoreceptors.     

Using an electro-spraying microfluidic chip to produce uniform emulsions under a direct-current electric field

An electro-spraying microfluidic chip was integrated with a parallel electrode and flow-focusing device to successfully generate uniform emulsions with an electric field. This approach utilizes a high electric field driven by a direct-current voltage to form a stable Taylor cone in the flow-focusing position. The Taylor cone can then generate stable and uniform emulsions that are less than 5?μm in diameter. The emulsion size is controlled by the surfactant concentration, the ratio of the water and oil phase flow rates and the strength of the electric field. When the strength of the electric field increases at a high surfactant concentration and low ratio of flow rates, the Taylor angle decreases, which causes the emulsion size to decrease. In this study, the water emulsion diameter ranged from 1 to 98?μm, and the poly(lactic-co-glycolic acid) (PLGA) emulsion size ranged from 7 to 70?μm. The microfluidic chip developed in this work has the advantages of actively controlling the emulsion size and generating uniform emulsions (the relative standard deviation was less than 10%) and represents a new emulsion generation process.     

Electronically controllable microvalves based on smart hydrogels: magnitudes and potential applications

Electronically controllable microvalves based on temperature sensitive hydrogels as actuators are described. A thermal-electronic interface was used for electronic control of the liquid flow. The hydrogel actuators were directly placed in a flow channel. They used the process medium as the swelling agent. Because of the direct placement into the channel the elastic properties of the hydrogel actuator were utilized to improve the pressure insensitivity, to achieve high particle tolerance and to avoid a leakage flow. The microvalves show an extremely simple structure. They can be fabricated using conventional micro technology within a few technical steps. The microvalves can also be miniaturized to a currently unrivalled extent of about 4 /spl mu/m/spl times/4 /spl mu/m/spl times/1/spl mu/m. Valves for "laboratory on chip" applications can already be obtained. The switching times of the electronically controllable microvalves based on hydrogels are 0.3 s to 10 s.     

基于SU-8的微流沟道的设计和制作

以SU—8作为结构材料,采用紫外光刻工艺,尤以斜曝光工艺为主,制造一种新型的、小型化的、低成本的、三维的、高深宽比的微流沟道,微流沟道的高度约为1100μm。初步确定出加工此微流沟道结构所需要的曝光计量、前烘时间、后烘时间和显影时间以及工艺方法,为加工其他尺寸的微流沟道提供参考。基于此方法加工的微流沟道可以应用在微型流式细胞仪上,来提供红细胞计数、血色素浓度、血小板计数和红细胞单元指数等参数。