阵列细胞微培养腔的设计与制造

采用光刻成型技术、"多次光刻、一次显影"工艺以及热键合工艺制备了基于三层、具有阀控开关和浓度梯度的PDMS微阵列细胞微培养腔,重点研究了浓度梯度、细胞培养腔结构的设计.研究表明浓度梯度的形成主要受芯片管道结构影响;在低雷诺数、被动混合方式情况下,采用简单结构进行混合的效率会很低;在本课题中,将瓦片状结构与管道复合起来提高混合效率,实验结果表明:即使在高流速情况下,也能得很高的混合效率并使各管道间浓度呈很好的线性分布;同时,对细胞培养腔的结构进行了设计;此外,将有限元分析软件COMSOL应用到混合管道及培养腔内流体、流态进行了分析,进一步利用分析结果优化了结构设计.     

Design and fabrication of a flexible three-axial tactile sensor array based on polyimide micromachining

This paper describes the design and fabrication of a flexible three-axial tactile sensor array using advanced polyimide micromachining technologies. The tactile sensor array is comprised of sixteen micro force sensors and it measures 13 mm × 18 mm. Each micro force sensor has a square membrane and four strain gauges, and its force capacity is 0.6 N in the three-axial directions. The optimal positions of the strain gauges are determined by the strain distribution obtained form finite element analysis (FEA). The normal and shear forces are detected by combining responses from four thin-film metal strain gauges embedded in a polyimide membrane. In order to acquire force signals from individual micro force sensors, we fabricated a PCB based on a multiplexer, operational amplifier and microprocessor with CAN network function. The sensor array is tested from the evaluation system with a three-component load cell. The developed sensor array can be applied in robots’ fingertips, as well as to other electronic applications with three-axial force measurement and flexibility keyword requirements.     

Gold nanoparticles-coated eggshell membrane with immobilized glucose oxidase for fabrication of glucose biosensor

This work reports the fabrication and application of a glucose biosensor based on the catalytic effect of gold nanoparticles (AuNPs) on enzymatic reaction for blood glucose determination. AuNPs were initially in situ synthesized on the surface of an eggshell membrane (ESM) which was subsequently immobilized with glucose oxidase (GO_x) to produce a GO_x-AuNPs/ESM. The GO_x-AuNPs/ESM was positioned on the surface of an oxygen electrode to form a GO_x-AuNPs/ESM glucose biosensor. The effects of pH, concentration of phosphate buffer solution and amount of GO_x on the response of the GO_x-AuNPs/ESM glucose biosensor were studied in detail. AuNPs on GO_x/ESM can improve the calibration sensitivity (30% higher than GO_x/ESM without AuNPs), stability (87.3% of its initial response to glucose after 10-week storage) and shortens the response time (<30 s) of the glucose biosensor. The linear working range for the GO_x-AuNPs/ESM glucose biosensor is 8.33 μM to 0.966 mM glucose with a detection limit of 3.50 μM (S/N = 3). The biosensor has been successfully applied to determine the glucose in human blood serum samples and the results compared well to a standard spectrophotometric method commonly used in hospitals. Our work demonstrates that the developed GO_x-AuNPs/ESM glucose biosensor has potential in biomedical analysis.     

基于压缩后缀数组的近似字符串匹配算法

近似字符串匹配是模式匹配研究领域中的一个重要研究方向。压缩后缀数组是字符串匹配、数据压缩等领域广泛使用的索引结构,具有检索速度快和适用广泛的优点。利用压缩后缀数组,提出了适合近似字符串匹配搜索算法的数据结构,并在此基础上提出了一种匹配搜索算法。实验结果表明,相对于现有的算法,提出的算法在小字母表的情况下具有计算优势。     

基于石英和载玻片的微电极制备工艺研究

研究以石英片和载玻片为基底的微电极制备工艺,以较常见的叉指型电极为例,基于光刻工艺中各工艺参数要求,重点研究曝光和显影时间对微电极的影响。制得的2种不同基底的电极,采用对比度、精度等关键参数进行分析,最终确定选用载玻片作为芯片基底并获得其最佳工艺参数;制作带电极的PDMS—玻璃微流控芯片,通过实验,成功观察到酵母菌细胞的正、负介电泳现象。     

一种低成本压电无阀微泵的研制

提出了一种低成本的由压电材料驱动的平面扩张/收缩管无阀微泵的制作工艺.通过数值模拟确定了扩张/收缩管扩张角的最优值,在此基础上,采用光刻和湿法刻蚀工艺,刻蚀了300μm深的泵腔基片和100 μm深的盖片;使用等离子体清洗技术将其与PDMS薄膜键合,完成了可以实现单向泵送的压电无阀微泵样机制作.研究了该压电无阀微泵样机的...     

基于集成参比电极的多参数水质监测微传感器阵列研制

研究了一种基于MEMS工艺制备的集成微电极型传感器,并用电化学修饰方法将Ag/AgCl参比电极集成在传感器上,用于水体中温度、电导率和氧化还原电位的测定.Pt温度传感器的电阻与温度的线性关系良好,满足温度测量精度的需求;比较法确定电导率传感器的电极常数为2.723,可以对一般水体的电导率进行测定;氧化还原电位传感器的标...     

基于模式分类的图像区域作伪检测

为了鉴别一幅数字图像是否存在作伪的区域,提出一种利用改进的图像特征进行区域作伪检测的算法.基于模式分类的思想,该方法把图像分割成适当大小的块,从图像块中提取特征数据,用SVM分类器训练数据并得到支持向量机模型,利用该模型检测嫌疑图片是否存在作伪.该算法从噪声相关性、残差噪声、图像质量、小波域等方面分析相机图片的特点,获取每种的统计特征,形成特征集.实验结果表明,该方法能有效地检测出图像的具体作伪区域.     

基于新型间谍技术的半监督自训练正例无标记学习

正例无标记（PU）学习中的间谍技术极易受噪声和离群点干扰，导致划分的可靠正例不纯，且在初始正例中随机选择间谍样本的机制极易造成划分可靠负例时效率低下，针对这些问题提出一种结合新型间谍技术和半监督自训练的PU学习框架。首先，该框架对初始有标记样本进行聚类并选取离聚类中心较近的样本来取代间谍样本，这些样本能有效地映射出无标记样本的分布结构，从而更好地辅助选取可靠负例；然后对间谍技术划分后的可靠正例进行自训练提纯，采用二次训练的方式取回被误分为正例样本的可靠负例。该框架有效地解决了传统间谍技术在PU学习中分类效率易受数据分布干扰以及随机间谍样本影响的问题。通过9个标准数据集上的仿真实验结果表明，所提框架的平均分类准确率和F-值均高于基本PU学习算法（Basic_PU）、基于间谍技术的PU学习算法（SPY）、基于朴素贝叶斯的自训练PU学习算法（NBST）和基于迭代剪枝的PU学习算法（Pruning）。     

基于正负效用划分的高效用模式挖掘方法综述

高效用模式挖掘（HUPM）是新兴的数据科学研究内容之一,通过考虑事务数据库中项的单位利润和数量,以提取出更有用的信息。传统的HUPM方法假定所有项的效用值均为正,但是在实际应用中,某些数据项的效用值可能为负（如商品因产生亏损而导致利润值为负）,含负项的模式挖掘与仅含正项的模式挖掘同样重要。首先,阐述了HUPM的相关概念,并分别给出相应正负效用的实例;然后,以正与负角度划分了HUPM方法,其中带有正效用的模式挖掘方法进一步以动态与静态的数据库新颖角度划分,带有负效用的模式挖掘方法中包括了基于先验、基于树、基于效用列表和基于数组等关键技术,并从不同方面对这些方法进行了讨论和总结;最后,给出了现有HUPM方法的不足和下一步研究方向。     

Rapid prototyping of magnetic valve based on nanocomposite Co/PDMS membrane

In this study, a new type of active membrane based on magnetic elastomer composite is manufactured, characterized and integrated into a simple valve. The simple and low-cost fabrication process combined with large displacement capability of the membrane is favorable for use in disposable fluidic devices. Passivated ferromagnetic cobalt nanoparticles (~37 nm) synthesized by the chemical route were embedded in polydimethylsiloxane (PDMS) to fabricate nano-composite flexible membranes. Magneto-mechanical and mechanical properties of the PDMS composite elastomeric membrane loaded with various concentrations of cobalt (Co) nanoparticles (between 15 and 75 % by weight) were studied. Dynamic mechanical analysis (DMA) measurements of the nano-composite membranes were conducted as a function of the applied frequency (between 0.1 and 56 Hz). With higher concentration (50-wt%) of Co nanoparticles in PDMS, the elastic modulus was increased by 3–4 times as compared with that of membranes with lower concentrations of nanoparticles. Shore hardness was maximum for the nano-composite membrane loaded with 50-wt% of Co nanoparticles. A fluidic actuator with 400 μm thick PDMS membrane of 18 mm free diameter loaded with 50-wt% Co nanoparticles was manufactured and tested under external magnetic field. In the region where the magnetic field gradient is highest, high deflection of the membrane could be obtained (0.68 mm for 1 Tesla). However some hysteresis of the membrane deflection could be observed, even at very low frequency. Loading of PDMS with Co nanoparticles allowed a wider range of control of the wetting properties of PDMS surfaces under oxygen plasma treatment, from hydrophobic to hydrophilic to super-hydrophilic. Tunability in hydrophilicity could be achieved by varying the process parameters as verified by contact angles and Fourier transforms infrared (FTIR) spectra before and after plasma treatment. Under certain conditions, 50 % Cobalt-PDMS membrane surfaces exhibited a super-hydrophilic behavior (contact angle ~5°).     

基于STM32的膜材料完整性测试仪设计

针对现有完整性测试仪的弊端,设计了一种全自动膜材料完整性测试仪。该仪器通过检测压力和流量传感器的反馈信号,以STM32嵌入式系统芯片作为主控制器,采用闭环PI控制方法,驱动电磁阀开关阀和电磁调节阀动作,实现系统内压力和流量的精确控制。详细阐述了完整性测试理论和测试仪控制系统的软硬件实施方案。实验结果表明:该设计所测泡点压力介于高精度的扫描电子显微镜和孔径分析仪测试结果之间,结果精确,扩散流速可以通过流量传感器测得。     

Control of the microparticle position in the channel based on dielectrophoresis

We report here the control of the microparticles position within fluid flow based on its size by using dielectrophoresis (DEP) with a microelectrode array consisted of rectangular features with the different size of width and gap. 3 μm- and 10 μm-diameter particles were introduced into the channel with 300 μm height at 30 μl/min. An AC electric field (20 V peak–peak and 2 MHz) was then applied to microelectrode arrays to form dielectrophoretic fluid cage, resulting in a formation of flow paths with low electric fields on the arrays. The microparticles separately flow in line streams along the paths formed between the rectangular features of the arrays, the 3 μm-diameter particles mainly flow through the narrow path and 10 μm-diameter particles through the wide path. These results indicated that positions of two types of microparticles in the fluidic channel were easily separated and controlled using the n-DEP.     

基于膜计算的蝙蝠算法在云计算资源调度的研究

如何进一步实现云计算环境下的资源利用最大化是目前研究的热点.建立云计算环境下的资源分配模型,云计算资源调度使用蝙蝠算法,同时引入膜计算概念,提出一种基于膜计算的蝙蝠算法,将膜系统内部分解为主膜和辅助膜,在辅助膜内进行蝙蝠的个体局部寻优,将优化后的个体传送到主膜间进行全局优化,从而达到了云计算资源优化分配要求.通过CloudSim平台与其他算法进行仿真对比表明算法提高了云计算环境下的系统处理时间和效率,使得云计算环境下的资源分配更加合理.     

一个基于模式的快速查询构建系统

介绍了如何设计和实现一个基于模式的J2EE快速查询生成系统。系统主要有两种角色的使用人员,设计人员与用户。系统让设计人员定义面向用户的数据库信息,包括表、表的字段及其显示风格;系统允许用户从已设计好的界面模式中选择自己喜欢的界面风格,在用户定制完自己的查询内容后,系统采用广度优先搜索来判断查询的合理性,并用最短路径算法优化查询。系统极大地简化了基于Web的查询系统的开发和维护。     

膜系统下的一种多目标优化算法

提出一种基于膜优化理论的多目标优化算法,该算法受膜计算的启发,结合膜结构、多重集和反应规则来求解多目标优化问题。为了增强算法的适应能力,采用了遗传算法中的交叉与变异机制,同时在膜中引入外部档案集,并采用非支配排序和拥挤距离方法对外部档案集进行更新操作来提高搜索解的多样性。仿真实验采用标准的KUR和ZDT系列多目标问题对所提出的算法进行测试,通过该算法得出的非支配解集能够较好地逼近真实的Pareto前沿,说明所提算法在求解多目标优化问题上具有可行性和有效性。     

Improved results on stability of continuous-time switched positive linear systems

In this paper, the problems of stability for switched positive linear systems (SPLSs) under arbitrary switching are investigated in a continuous-time context. The so-called “copositive polynomial Lyapunov function” (CPLF) giving a generalization of copositive types of Lyapunov function is first proposed, which is formulated in a higher order form of the positive states of the underlying systems. It is illustrated in this paper that some classical types of Lyapunov functions can be seen as special cases of the proposed CPLF. Then, new stability conditions are developed by the new Lyapunov function approach. It is also proved that the conservativeness of the obtained criteria can be further reduced as the degree of the Lyapunov function increases. A numerical example is given to demonstrate the effectiveness and less conservativeness of the developed techniques.     

Rapid,simple and low cost fabrication of a microfluidic direct methanol fuel cell based on polydimethylsiloxane

In this paper a simple and rapid fabrication method for a microfluidic direct methanol fuel cell using polydimethylsiloxane (PDMS) as substrate is demonstrated. A gold layer on PDMS substrate as seed layer was obtained by chemical plating instead of conventional metal evaporation or sputtering. The morphology of the gold layer can be controlled by adjusting the ratio of curing agent to the PDMS monomer. The chemical properties of the gold films were examined. Then catalyst nanoparticles were grown on the films either by cyclic voltammetry or electrophoretic deposition. The microfluidic fuel cell was assembled by simple oxygen plasma bonding between two PDMS substrates. The cell operated at room temperature with a maximum power density around 6.28 mW cm^?2. Such a fuel cell is low-cost and easy to construct, and is convenient to be integrated with other devices because of the viscosity of the PDMS. This work will facilitate the development of miniature on-chip power sources for portable electronic devices.