三维微小凹图式的加工及其与人神经母细胞瘤细胞的复合

采用紫外光光刻、硅蚀刻及软光刻技术分别制备了阴性光刻胶SU-8和聚乳酸及聚羟基乙酸共聚物(PLGA)微小凹图式.以人神经母细胞瘤细胞SH-SY5Y与三维微结构进行复合,采用扫描电子显微镜、光学显微镜及caicein荧光染色评价所加工图式的结构形态及细胞的生长行为.实验制备出名义直径约100/μm、高纵横比(接近或大于1)并可叠加微通道连接的SU-8及PLGA三维微小凹图式.所加工的图式透明,符合三维细胞生物传感器的光学检测的需要.细胞培养结果表明,该结构尺寸的图式能引导在三维环境神经细胞的排布、神经突起延伸及形态分化.     

星形胶质细胞膜电位门控钙离子通道调控神经元癫痫放电

细胞外空间钾离子的大量积累会导致星形胶质细胞膜去极化,星形胶质细胞膜电位变化引起的电压门控钙离子通道(VGCCs)电流内流会增加星形胶质细胞内钙离子浓度的振荡幅值,从而增强星形胶质细胞对神经元的正反馈作用。考虑星形胶质细胞VGCCs的钙离子内流,本文构建了一种包含多种离子浓度动力学行为的神经元-胶质细胞耦合模型。数值模拟结果发现,VGCCs的钙离子内流是影响星形胶质细胞内Ca^2+浓度升高的一个主要因素;VGCCs电流增强会诱发神经元产生自发性癫痫放电活动实验现象的内在机理。本文研究结果可以为星形胶质细胞钙离子代谢紊乱诱发神经系统自发性癫痫放电提供一种解释。     

基于分割的三维网格模型可展结构设计

随着柔性制造和精密器械的高速发展,基于三维网格模型的拉胀连杆等可展结构逼近技术已成为研究热点.可拉伸的负泊松比可展结构,可通过弯曲拉伸等几何变换改变外形,实现二维平面结构与三维空间结构之间的转换.针对目前可展结构设计不适用三维封闭模型、不能实现模型边界形状匹配等不足,提出基于分割的三维网格模型可展结构设计方法.首先,对封闭的三维网格模型做分割预处理;其次,以固定边界映射代替重新网格化,作为构造初始连杆结构的基础,并基于边界形状匹配约束构造边界;然后,构造非线性约束优化问题,得到可收缩的三维展开连杆结构,通过投影边长等约束优化二维连杆结构,得到紧凑的二维收缩连杆结构;边界匹配扭曲失真等实验结果表明,文中方法能够有效地实现与盘同胚的、封闭的三维网格模型可展结构设计,并在边界形状匹配和二维收缩连杆紧凑性等方面具有显著优势.     

基于区域分割的零件三维模型检索方法

为了满足大规模零件库的实时检索要求和零件模型以结构单元重用特点,提出一种基于区域分割的零件三维模型检索方法.该方法将平面划分为边界凸平面、边界凹平面和混合边界平面;利用边界邻域曲率、垂直边界曲率和沿边界曲率定义曲面在该边界的表面边界凹凸性,提出了马鞍面在区域凹凸性分析时计为凹、凸和平表面的约定条件.根据两表面合并后区域凹凸性是否保持不变,提出了边分类规范;通过外部边闭合规范、待定边转换规范和表面平区域合并规范,实现零件三维模型的区域分割.通过表面区域编码规范对分割区域编码,利用区域结构码实现相似结构零件的检索.实验结果表明,区域分割后零件整体相似结构检索更加有效,局部相似结构检索可以通过二元邻接区域结构求交集实现.     

空间三角网格曲面的补洞方法

由三维扫描仪对文物表面进行扫描得到网格数据后,先提取出破洞的边界,利用破洞边界三角形的法矢信息将破洞边界上的点投影到一个平面上,形成一个二维多边形;然后基于该二维多边形各内角及各边长度在多边形内插入新的离散点,再将多边形内离散点三角网格化;最后用移动最小二乘近似法将破洞附近的点拟和成曲面,以此求出插入点的高度值,这样就得到了在三维空间中的网格数据。     

空间三角网格曲面的补洞方法*

由三维扫描仪对文物表面进行扫描得到网格数据后,先提取出破洞的边界,利用破洞边界三角形的法矢信息将破洞边界上的点投影到一个平面上,形成一个二维多边形;然后基于该二维多边形各内角及各边长度在多边形内插入新的离散点, 再将多边形内离散点三角网格化;最后用移动最小二乘近似法将破洞附近的点拟和成曲面,以此求出插入点的高度值,这样就得到了在三维空间中的网格数据。     

基于B-Rep实体模型的IGES转换为STL

提出一种将IGES文件格式转换成STL文件格式的算法.根据IGES文件内容重构几何实体信息及其拓扑关系;将几何实体的三维曲面贴合为二维平面,并将曲面上的轮廓边界转换到平面上,在二维空间中根据封闭轮廓边界裁剪曲面;根据曲面上保留的特征点及轮廓边界上的顶点信息对面进行符合STL模型一致性规则的三角剖分,生成合法的STL文件.该算法的核心是保证面与面接合处的三角化的正确性.最后介绍了该算法的转换实例.     

基于UV贴图优化人体特征的行人重识别

现有行人重识别研究大多关注人体在二维平面的特征表示,而在现实社会中,人体以一种对称的三维结构存在,三维人体结构相较二维平面像素含有更多的体型、姿态等特征,仅研究二维平面上的行人特征限制了计算机对人体特征的理解。利用人体是一种三维对称的刚体结构这一先验事实,提出一种基于UV贴图优化人体特征的行人重识别方法。对图像底库进行数据预处理,通过数据增广方法生成更多的训练数据,对预处理后的图片进行特征提取,将特征矩阵解耦为姿态、色彩、形状以及视角参数,利用参数信息调整预定义的人体模型以得到重构后的三维人体模型。将重构后的三维人体模型转化为UV贴图,即将人体特征从三维空间映射到二维平面,同时对UV贴图进行优化从而丰富人体特征。使用UV贴图训练三维行人重识别网络模型,利用后处理的方法对输出结果做进一步优化,以得到最终的行人重识别结果。在Market-1501数据集上的实验结果表明,该方法的rank-1准确率和mAP分别达到94.76%和82.53%,相较OG-Net模型分别提升13.82%和22.56%。     

构造正六面体表面混沌吸引子的平面迭代映射

为了实现用二维迭代映射构造三维球面图形,提出用平面正方形格子上的迭代映射构造三维正六面体表面上连续排列的混沌吸引子的方法.首先提出用于构造正六面体上连续排列混沌吸引子的平面迭代映射在正方形格子上应满足的边界条件;其次用截断的傅里叶三角级数构造出满足边界条件的3个平面排列迭代映射;最后找到了2个基本绘图窗口,利用3个迭代映射在2个正方形格子边界上的对称特性完成混沌吸引子在平面上和正六面体上的连续排列图形的构造.实验结果表明,文中提出的基于正方形格子的二维平面排列迭代映射可以用于大量的自动生成三维正六面体上的连续混沌吸引子图形.     

三维表面与平面数据间的自适应配准

三维体数据与二维平面数据间的配准是手术导航的基础。与以往的思路有所不同,论文通过把三维表面投影到平面上,利用光照模型计算投影平面的灰度值,实现投影图像与实拍照片间的匹配,在匹配中调整投影参数使得两平面图像达到最佳相似,进而实现三维到二维的自适应配准。     

SU-8 microstructure for quasi-three-dimensional cell-based biosensing

A quasi-three-dimensional (quasi-3-D) cell-based biosensor platform microfabricated from SU-8 has been developed and characterized. In this work, SH-SY5Y human neuroblastoma cells were integrated with SU-8 microfabricated microwells with diameters of 100 μm. SH-SY5Y cells were differentiated with 1 mM dibutyryl cAMP and 2.5 μM 5-bromodeoxyuridine. Voltage-gated calcium channel (VGCC) function of SH-SY5Y cells cultured within the microwells (quasi-3-D) versus those cultured on the SU-8 planar substrates (2-D) was evaluated by confocal microscopy with a calcium fluorescent indicator, Calcium Green-1. In response to 50 mM high K⁺ depolarization, cells in microwells were less responsive in terms of increase in intracellular Ca²⁺ in comparison to cells on 2-D substrates. This study shows that VGCC function of cells within SU-8 microwells was indeed different from that of cells on planar SU-8 surfaces, suggesting that SU-8 microstructure did affect SH-SY5Y cell differentiation with respect to VGCC function and that high-aspect-ratio microstructures are not merely “folded” 2-D structures. Furthermore, these results are consistent with previous 2-D/3-D comparative studies carried out in polymer scaffolds and support the hypothesis that cell calcium dynamics on 2-D substrates may be exaggerated. Overall, this work is supportive of SU-8 micropattern as a viable platform for engineering a quasi-3-D cell culture system for cell-based biosensing against drugs for VGCCs.     

A dielectrophoresis-based microdevice coated with nanostructured TiO2 for separation of particles and cells

In this study, we present a microdevice coated with titanium dioxide for cells and particles separation and handling. The microsystem consists of a pair of planar interdigitated gold micro-electrode arrays on a quartz substrate able to generate a traveling electric completed with a microfabricated three-dimensional glass structure for cell confinement. Dielectrophoretic forces were exploited for both vertical and lateral cell motions. In order to provide a biocompatible passivation layer to the electrodes a highly biocompatible nanostructured titanium dioxide film was deposited by supersonic cluster beam deposition (SCBD) on the electrode array. The dielectrophoretic effects of the chip were initially tested using polystyrene beads. To test the biocompatibility and capability of dielectrophoretic cell movement of the device, four cell lines (NIH3T3, SH-SY5Y, MDCK, and PC12) were used. Separation of beads from SH-SY5Y cells was also obtained.     

阵列型微拓扑结构基底的制备及其对神经细胞电生物物理特性的影响

以紫外光光刻、硅蚀刻及软光刻技术制备了微柱阵列型细胞培养基底.实验发现,在4μm的结构高度下,当微柱特征尺寸大于或等于4 μm时,该法能制备结构规整清晰的聚二甲基硅氧烷微柱阵列型基底.特征尺寸为2μm的基底已经接近该法的极限加工能力,所加工的微柱阵列出现倒伏或缺失.采用一种简单的倾斜角法可以制备一种聚苯乙烯微球致密阵列...     

Fabrication of three-dimensional microstructures byelectrochemically welding structures formed by microcontact printing onplanar and curved substrates

This paper describes two convenient techniques for the fabrication of three-dimensional (3-D) structures with micron-sized features. The methods use microcontact printing (μCP) to define patterns with feature sizes as small as 20 μm both on planar substrates and on cylinders (diameter ~2 mm). Electrodeposition serves as a micron-scale tool for metal deposition and welding that transforms these patterned surfaces and cylinders into metallic complex 3-D microstructures (e.g., tetrahedra). Final tetrahedra (~2-cm sides) have feature sizes as small as 50 μm     

Three-dimensional thin-film Li-ion microbatteries for autonomous MEMS

Autonomous MEMS require similarly miniaturized power sources. In this paper, we present the first working three-dimensional (3-D) rechargeable Li-ion thin-film microbattery technology that is compatible with MEMS requirements. The technology has been developed, and full 3-D cells have been manufactured on both glass and silicon substrates. Our 3-D microbatteries have a sandwich-like structure of conformal thin-film electrodes, electrolyte and current collectors. The films are deposited sequentially on all available surfaces of a perforated substrate (e.g., silicon or a glass microchannel plate or "MCP") using wet chemistry. The substrate has thousands of high-aspect ratio holes per square cm, thereby providing more than an order of magnitude increase in surface area per given footprint (original 2-D substrate area). The full 3-D cell consists of a Ni cathode current collector, a MoO/sub y/S/sub z/ cathode, a hybrid polymer electrolyte (HPE) and a lithiated graphite anode that also serves as anode current collector. One 3-D cell with a roughly 1-/spl mu/m-thick cathode ran at C/10 to 2C charge/discharge rates and room temperature for 200 cycles with 0.2% per cycle capacity loss and about 100% Faradaic efficiency. The cell exhibited a capacity of 2 mAh/cm/sup 2/, about 30times higher than the capacity of a similarly built planar (2-D) cell with the same footprint and same cathode thickness.     

Magnetic lithography for servowriting applications using flexible magnetic masks nanofabricated on plastic substrates

Magnetic lithography (ML) is a process qualitatively analogous to contact optical lithography which transfers information from a nanopatterned magnetic mask (analog of optical photomask) to magnetic media (analog of photoresist), and is interesting for applications in instantaneous parallel magnetic recording, in particular for servowriting applications. The magnetic mask consists of nanopatterned magnetically soft material (FeNiCo, FeCo) on a thin flexible plastic substrate, typically Polyethylene teraphtalate (PET) or polyimide. When uniformly magnetized media is brought into intimate contact with the magnetic mask, an externally applied magnetic field selectively changes the magnetic orientation in the areas not covered with the soft magnetic material. Flexible substrate of the magnetic mask offers superior compliance to magnetic media which is likely to have imperfect flatness and surface particulate contamination. We discuss nanofabrication challenges of magnetic masks on plastic substrates, including electron beam lithography, electroplating and lift-off processing on the nanometer scale, adhesion of metal thin films on PET and polyimide substrates, and release of plastic films from rigid substrates used during the processing. We present results on fabricated magnetic masks, magnetic force microscopy images of the magnetic transition patterns and disk spinstand tests of servowritten patterns.     

Three-dimensional effects in multi-element high lift computations

In an effort to discover the causes for disagreement between previous two-dimensional (2-D) computations and nominally 2-D experiment for flow over the three-element McDonnell Douglas 30P-30N airfoil configuration at high lift, a combined experimental/CFD investigation is described. The experiment explores several different side-wall boundary layer control venting patterns, documents venting mass flow rates, and looks at corner surface flow patterns. The experimental angle of attack at maximum lift is found to be sensitive to the side-wall venting pattern: a particular pattern increases the angle of attack at maximum lift by at least 2°. A significant amount of spanwise pressure variation is present at angles of attack near maximum lift. A CFD study using three-dimensional (3-D) structured-grid computations, which includes the modeling of side-wall venting, is employed to investigate 3-D effects on the flow. Side-wall suction strength is found to affect the angle at which maximum lift is predicted. Maximum lift in the CFD is shown to be limited by the growth of an off-body corner flow vortex and consequent increase in spanwise pressure variation and decrease in circulation. The 3-D computations with and without wall venting predict similar trends to experiment at low angles of attack, but either stall too early or else overpredict lift levels near maximum lift by as much as 5%. Unstructured-grid computations demonstrate that mounting brackets lower the lift levels near maximum lift conditions.     

On the recognition of properties of three-dimensional pictures

This correspondence proposes one-pass algorithms that compute the numbers of objects, cavities, and holes in three-dimensional (3-D) digital pictures. Also, it is shown that a one-way, 3-D parallel/sequential acceptor cannot accept the class of 3-D binary arrays in which the set of 1's is connected, unlike the situation in the two-dimensional (2-D) case; but it can do so if multipasses are allowed.     

The electromechanical response of multilayered piezoelectric structures

The constitutive equations of multilayered piezoelectric structures are derived in a new form. In this form, the electromechanical coupling is presented as an additional stiffness matrix. This matrix is a true property of the piezoelectric structure and is independent of specific mechanical boundary conditions that may apply to the structure. A novel model of the electromechanical response of such structures is presented. This model accounts for the three-dimensional (3-D) kinematics of the structure deformation. Solution of example problems using the new model shows excellent agreement with full 3-D finite element simulations. These solutions are also compared to the results of previous two-dimensional (2-D) model approximations presented in literature, and the inaccuracies associated with these previous models are discussed.     

Three-Dimensional Image Reconstruction Procedure for Food Microstructure Evaluation

Confocal laser scanning microscopy (CLSM) is a noninvasive technique for evaluating the microstructure of foods and other materials. CLSM provides several sequential subsurface layers of two-dimensional (2-D) images. An image processing algorithm was developed to reconstruct these 2-D layers into a three-dimensional (3-D) network. Microstructure of fat globules in cheese was used as an example application. The validity of the image reconstruction algorithm was evaluated by processing several layered digital images of known shape and size. Differences between the original and reconstructed images were 2–5% in terms of object size and 1–8% in terms of shape.