一种圆形横截面PDMS微血管模型的构建

基于软刻工艺发展的微血管模型为体外研究微循环系统疾病病理生理学机制提供了新思路,然而标准的软刻工艺加工的微通道呈矩形截面,不能真实地反映体内微血管管腔的圆形截面特征.本文介绍了一种简易的构建具有圆形截面特征聚二甲基硅氧烷(PDMS)微血管模型的方法.该方法以圆形截面微不锈钢丝作为模具,采用"微丝模塑抽除"软刻技术加工出具有圆形截面特征的微通道;优化微通道内细胞外基质蛋白修饰,并在修饰后的通道内进行血管内皮细胞EA.hy926灌流式培养.结果发现:纤维连接蛋白具有最佳的促进细胞黏附的效果,细胞在培养96 h后开始融合,细胞沿微通道内壁生长,保持生物活性且能承受高达2.5×10-4N/cm2的流体剪切力.本文介绍的圆形截面PDMS微血管模型加工的方法具有快速、简易的优点,可用于微循环疾病病理生理学机制的体外研究.     

一种用电晕放电仪实现PDMS改性与键合方法

聚二甲基硅氧烷(PDMS)的表面改性与键合是微流控芯片制作中的关键技术之一。本文比较分析了PDMS常用表面改性方法的优缺点,利用电晕放电仪在常温环境下产生的氧等离子体实现了对PDMS表面改性及不可逆键合,优化了电晕放电仪的表面处理参数,重点测试了PDMS分别与PDMS和PMMA之间的键合强度。并与紫外照射、表面活化剂等表面改性方法得到的键合进行了强度比较。键合强度测试结果表明:常温下氧等离子体表面改性效果略逊于真空环境中的氧等离子体表面处理,但是其键合强度达到700KPa,高于其它表面改性方法的键合强度。     

Surface characterization of plasma-treated and PEG-grafted PDMS for micro fluidic applications

The contact angle measurements have shown that polydimethyl siloxane (PDMS) surfaces treated by air plasma can recover up to about 40% of its hydrophobic nature in less than 20 min of air exposure. Therefore, poly(ethylene glycol) (PEG) silane was grafted after plasma treatment to permanently change the PDMS surface as hydrophilic in nature for micro fluidic application. The surface chemistry of plasma-treated and PEG-grafted PDMS substrate has been studied using X-ray photoelectron spectroscopy (XPS). The proportion of carbon atoms as C-Si and hydrocarbon decreased for both plasma-treated as well as PEG-grafted PDMS surfaces. The plasma treatment had increased the proportion of carbon atoms as CO and C(O)OX in C1s, whereas grafting of PEG silane decreased the proportion of C(O)OX and an increase in C-OX and CO functionalities. This is due to the interaction of OCH₃ on Si (in PEG silane) with C-OX and C(O)OX on plasma-treated PDMS by covalent bonding. Therefore, an increase in CO and C-OX functionalities and relative decrease in C(O)OX is expected. The plasma treatment of micro channels had increased the fluid velocity by a factor or four and similar measurements were observed in PEG grafted micro channel in PDMS chip. This indicates that the fluid velocity depends on the hydrophilic nature of substrate. The effect of nature of fluids on the fluid velocity in PDMS-based micro channel was also studied. It was observed that the fluid velocity was decreased with decreasing the pH values of the fluid.     

PDMS微/毫流控芯片的简易快速制备及其疏水性研究

将玻璃片/管、锡箔等材料进行组装、通道搭建制备出带有管路图案的容器,再将聚二甲基硅氧烷(PDMS)预聚体浇注到该容器中固化成型,之后通过模具拆卸、切割制备出整体式PDMS微/毫流控芯片.该法可获取各种微通道尺寸保真性好的整体式芯片,其通道截面圆形度与由热压法制备的微流控芯片相比有明显提高.另将获得的PDMS芯片经过30 min紫外改性后,其疏水性得到明显改善,与H2O的接触角由钝角变为了锐角,并在室温下静置能维持1 h左右的改性,完全能够满足液滴成型实验的时间要求.另外将该法制备的PDMS整体式芯片用于单分散液滴、双重液滴制备时,可在较宽的流速范围(4 mL/h~36 mL/h)内得到粒径可控的液滴,并且液滴在芯片通道中不易破乳,表现出良好的稳定性.这对于靶球制备、功能材料合成、活性成分保持等应用有重要意义.     

PDMS有机硅膜的制备及其渗透汽化脱硫的研究

以聚二甲基硅氧烷(PDMS)为原料,正庚烷为溶剂,正硅酸乙酯为交联剂,二月桂酸二丁基锡为催化剂,聚丙烯腈为基膜,制得聚二甲基硅氧烷／聚丙烯腈复合膜．采用红外谱图和扫描电镜对膜的物理及化学结构进行了分析和表征．所得膜用于辛烷中噻吩的脱除,研究了硫化温度、料液温度等因素对膜性能的影响．结果表明:在同一料液温度下,硫化温度越高,交联硫化越完全,膜对辛烷中噻吩的选择性越高,渗透通量下降;在相同硫化温度下,料液温度升高,渗透通量增加,膜对噻吩的选择性下降．对硫化温度50℃的膜,在料液温度为30℃时,膜的渗透通量370 g／(m2·h),膜对噻吩的选择系数为5．212．     

Design and analysis of single-cell capture microfluidic device

The aim of our study was to develop microfluidic devices using microchannel technology with the capability of capturing single cells. We analyzed and compared the cell-capturing efficiencies of series-loop microchannel and parallel-loop microchannel devices that were produced using polydimethylsiloxane (PDMS). Each set of microchannels was composed of a main flow channel and several branch channels with capturing zones. The microfluidic devices were designed to use the differences in flow rates between the main flow channel and the branch channels as a means of capturing single cells based on size and sequestering them within the microstructure of multiple capture zones. The data indicated that the flow medium encountered significant resistance in the series-loop microchannel device, which resulted in an inability to hold the captured cells within any of the capture zones. Flow resistance was, however, greatly reduced in the parallel-loop microchannel device compared to the series-loop device, and single cells were captured in all the capturing zones of the device. Our data suggest that the parallel-loop microchannel technology has significant potential for development toward high-throughput platforms capable of capturing single cells for physiological analyses at the single-cell level.     

PDMS/PVDF复合膜分离VOC/N2的性能研究

采用涂布法制备了聚二甲基硅氧烷/聚偏氟乙烯(PDMS/PVDF)复合膜,并用于VOC/N2体系(正已烷/N2、环己烷/N2、正庚烷/N2二元混合气体)的分离,系统地考察了原料气浓度、原料气流速、操作温度对PDMS/PVDF复合膜分离性能的影响.结果表明,随着原料气浓度的升高、流速的增大,VOC的渗透率及选择性均增大,而随着操作温度的升高,VOC的渗透率和选择性有所降低.连续运行三个月,膜分离性能稳定,正庚烷的渗透率为1.2×10-6 mol/(s·m2·Pa),选择性可达145.     

聚合物多层微流控芯片超声波键合界面温度研究

针对聚合物多层微流控芯片键合,采用热辅助超声波键合方法实现了4层微流控芯片的键合,搭建了多界面温度测试装置,采用埋置热电偶的方法测试了三个被封接界面的温度场,研究了单独超声波作用和热辅助超声波键合法中各界面的温度并进行了比对.温度测试实验结果表明,在顶层热辅助温度70℃、6μm振幅、30kHz频率、100N超声波焊接压力和25s超声波作用时间下,基于热辅助的多层超声波键合方法可以使各键合界面的温度基本一致,从而实现多层微流控器件的多个界面键合质量一致.本文的研究为聚合物微流控器件的超声波多层键合机理研究提供了有益借鉴.     

低电压驱动微流控芯片二氧化硅绝缘薄膜的研究

采用电子束蒸发法在玻璃基底上制备了二氧化硅薄膜,利用原子力显微镜(AFM)、台阶仪、X射线衍射仪(XRD),分别对不同条件下制备的二氧化硅薄膜的表面形貌、膜厚、结构进行了表征,并采用金属/绝缘膜/金属(MIM)结构对薄膜的I-V电学特性进行了分析。结果表明玻璃基底温度在300℃条件下生长的4μm厚度的二氧化硅薄膜,其表面均匀平整,耐压能力>200V,能够承受500kV/cm以上的场强,满足作为低电压驱动微流控芯片绝缘薄膜的要求,并在样品驱动的应用中得到验证。     

三种检测微囊藻毒素的ELISA方法比较研究

建立了抗原抗体复合物酶联免疫法(anti-immune complex ELISA,ICELISA)、间接竞争酶联免疫法(Indirect cELISA)、直接竞争酶联免疫法(Direct cELISA)三种检测微囊藻毒素的酶联免疫方法,确定了每种方法的检测限、线性范围以及重现性。以三种方法分别对标准品、藻样、水样及水产品中微囊藻毒素进行了测定,并对三种分析方法进行了较为系统的比较研究,为微囊藻毒素ELISA试剂盒的研制奠定了基础。     

Computer-aided process planning for fabrication of three-dimensional microstructures for bioMEMS applications

In recent years, there has been increasing interest from both academies and industries in developing micro-electromechanical system (MEMS) technology for biological applications, known as bioMEMS or biochips. Targeting at high throughput biomolecule analysis, drug compound screening, and reduction of reagent and sample volume, today's bioMEMS devices come with miniaturised design and increased complexity of microstructures. Fabrication of such a complex bioMEMS structure involves a number of layer fabrication cycles. Moreover, a two-dimensional (2D) mask is required for each process. Thus, manually generating such a complex process plan has become a difficult task. With recent advances in material technology, polydimethylsiloxane (PDMS) silicone material has been widely applied in nowadays bioMEMS fabrication. This paper proposes a novel automated process planning approach for fabrication of three-dimensional (3D) microstructures in bioMEMS. This approach can handle both PDMS casting and traditional micro fabrication processes. It integrates a novel solid decomposition method and a feasibility search algorithm. Also, it can directly handle the solid model of an integrated microstructure with B-rep representation, and automatically generate the data of the fabrication process plan along with masks. A process planner prototype has been implemented. An application example is presented to demonstrate the functionality of the prototype.     

Mechanically tunable aspheric lenses via additive manufacture of hanging elastomeric droplets for microscopic applications

Abstract

Mechanically deformable lenses with dynamically tunable focal lengths have been developed in this work. The fabricated five types of aspheric polydimethylsiloxane (PDMS) lenses presented here have an initial focal length of 7.0, 7.8, 9.0, 10.0 and 10.2 mm. Incorporating two modes of operation in biconvex and concave–convex configurations, the focal lengths can be tuned dynamically as 5.2–10.2, 5.5–9.9, 6.6–11.9, 6.1–13.5 and 6.6–13.5 mm respectively. Additive manufacturing was utilized to fabricate these five types of aspheric lenses (APLs) via sequential layering of PDMS materials. Complex structures with three-dimensional features and shorter focal lengths can be successfully produced by repeatedly depositing, inverting and curing controlled PDMS volume onto previously cured PDMS droplets. From our experiments, we empirically found a direct dependence of the focal length of the lenses with the amount (volume) of deposited PDMS droplets. This new mouldless, low-cost, and flexible lens fabrication method is able to transform an ordinary commercial smartphone camera into a low-cost portable microscope. A few microscopic features can be readily visualized, such as wrinkles of ladybird pupa and printed circuit board. The fabrication technique by successively applying hanging droplet and facile mechanical focal-length-tuning set-up can be easily adopted in the development of high-performance optical lenses.     

动物组织中新霉素残留快速检测方法

以兔抗新霉素多抗为包被抗体,以新霉素-HRP连接物为标记物,TMB为显色底物,三氯乙酸提取法为样品前处理方法,建立了一种适用于动物组织中新霉素残留量的竞争性直接酶联免疫快速检测方法.该方法可测定新霉素残留的线性范围为0.6~50.0 ng/mL,线性方程为y=-0.412 7x+1.185 9,相关系数为0.993 6,半抑制率IC50为5.0 ng/mL,板内变异系数小于5.6%,板间变异系数小于5.3%,检出限为0.6 ng/mL,回收率在80%~120%之间.     

衍射微透镜列阵掩模制作软件的设计

研究了衍射微透镜列阵的设计方法及ＣＩＦ格式掩模数据的数据结构与生成方法,设计了一套产用软件,采用图形切割、跟踪计算等方法,解决了生成子孔径为矩形、六 方形及圆环扇形的衍射微透镜列阵掩模的问题,满足了实际系统对衍射微透镜列阵子孔径形状的各种需求。     

混合集成型光学拾音器的设计与制作

通过混合集成型结构光学拾音器的光学设计和芯片设计，制作了包含微光学棱镜，光电探测器和信号放大电路的混合集成型光学拾音器。经过测试，发现有较好的信号输出特性，表明混合集成型光学拾音器已基本研制成功。     

A titanium dioxide nanorod array as a high-affinity nano-bio interface of a microfluidic device for efficient capture of circulating tumor cells

Nanomaterials show promising opportunities to address clinical problems (such as insufficient capture of circulating tumor cells;CTCs) via the high surface area-to-volume ratio and high affinity for biological cells.However,how to apply these nanomaterials as a nano-bio interface in a microfluidic device for efficient CTC capture with high specificity remains a challenge.In the present work,we first found that a titanium dioxide (TiO2) nanorod array that can be conveniently prepared on multiple kinds of substrates has high affinity for tumor cells.Then,the TiO2 nanorod array was vertically grown on the surface of a microchannel with hexagonally patterned Si micropillars via a hydrothermal reaction,forming a new kind of a micro-nano 3D hierarchically structured microfluidic device.The vertically grown TiO2 nanorod array was used as a sensitive nano-bio interface of this 3D hierarchically structured microfluidic device,which showed high efficiency of CTC capture (76.7％ ± 7.1％) in an artificial whole-blood sample.     

PMMA微流控检测芯片的设计与制作

设计并制作了一种PMMA（polymethyl methacrylate）材料的微流控检测芯片,将外界气体驱动液体用于实际水样的分析和检测．利用精密加工的方法加工出芯片的整体尺寸为86mm×60mm×4．5mm．采用溶胶-凝胶的改性方法对微通道管路进行亲水处理,正硅酸乙酯的水解缩合生成了一层溶胶．凝胶覆盖在PMMA表面,从而大大提高了亲水性．在室温下对芯片进行键合,溶剂为二氯乙烷和无水乙醇按1：1混合的混合液．该方法避免了微通道的坍塌,有效防止了堵塞．实验证明,芯片接触紧密,且冲击强度能够满足要求．同时,芯片上集成了多个阀．阀膜选用0．5mm厚的硅胶膜,采用硅橡胶做黏合剂     

Experimental deformation analysis of an adhesively bonded multi-material joint for marine applications

The strength and deformation of full-scale adhesively bonded multi-material joints is studied in this paper. Four joints with a thick layer of methyl methacrylate adhesive (MMA) have been manufactured in shipyard conditions. In two specimens, cracks have been introduced at steel–adhesive and composite–adhesive interfaces. One cracked and one un-cracked specimen were subjected to quasi-static tensile testing; the two remaining specimens were stepwise loaded/unloaded with increasing load until failure. The strain in the adhesive layers was measured with digital image correlation (DIC). This showed a predominant shear deformation and dissimilar shear strain patterns for different bond lines. Fibre Bragg (FBG) sensors were used to monitor strains at steel and composite constituents and to detect the onset and evolution of damage in the un-cracked specimen. Strains measured by FBG sensors correspond well with DIC results at nearby regions. All specimens failed by delamination of the composite panel near the composite–adhesive interface.