微流控生物芯片的磁场仿真及实验对比

近年来,随着生物医学分析和MEMS技术的发展,基于纳米磁珠的微流控生物芯片得到了广泛关注和研究.芯片上的微流路内部集成了微磁场元件,可在外磁场的作用下产生局部梯度磁场,从而将具有特定生物活性的纳米磁殊流捕获,实现后续的生物医学分析.为了有效的捕获磁珠,微磁场元件的外形结构需精心设计,才能产生足够高的磁场强度和磁场梯度.本文利用仿真软件COMSOL(Femlab)对所设计的不同外形的微磁场元件的磁场分布情况进行了仿真分析,随后的在片实验结果与仿真结果吻合得很好.     

低成本聚合物微流控芯片加工技术综述

针对传统微流控芯片加工方法成本高昂、耗时长的问题,近年来出现了多种低成本的微流控芯片加工方法,在聚合物、纸等材料上加工、完成了能够满足其应用需求的微流控芯片。对当前各类基于聚合材料的低成本微流控芯片加工技术进行了梳理和总结,并对未来低成本微流控芯片的发展进行了展望。     

用于微流控PCR的TEC温控系统结构优化设计

为了实现微流控聚合酶链式反应(PCR)的快速升降温,设计了一种基于半导体制冷片(TEC)的温度控制系统.通过对控温对象微流控PCR芯片的热分析,确定了TEC的参数,并且研究了TEC效率与散热性能之间的关系.在此基础上,设计了一种热管鳍片式高性能散热器,对其传热机理、传热路线及热阻进行了深入分析,建立了有限元模型,并对该热管散热器进行了实验测试.实验结果表明:该温控系统的平均升降温速率达到7.48℃/s,为实现微流控PCR系统的快速精确升降温控制奠定了良好基础.     

基于分段式超前校正的微流控PCR温度控制器

根据微流控聚合酶链式反应(PCR)对温度控制的要求,设计了一种分段式超前校正温度控制器。针对被控对象的动态特性,采用了超前校正改善系统性能;根据温度误差大小调节控制参数,误差较大时快速升降温,误差较小时精确控温。实验结果表明:分段式超前校正温度控制器不仅提高了系统响应速度,还减小了稳态误差,平均升温速率为4.46℃/s,平均降温速率为4.36℃/s,稳态误差不大于0.5℃,已成功用于微流控PCR实验。     

具有单一热源的对流双温PCR微流控装置的研究

为了克服传统连续流动聚合酶链式反应(PCR)微系统经常需要多个加热源来获取PCR所需要的温度,且集成或者非集成的泵系统也需要用来驱动PCR溶液连续流动,从而实现PCR扩增的缺点,研究了一种具有单一热源的对流双温PCR微系统.通过复合肋片技术在沟槽铜片上形成对流双温PCR所需要的温度,由流体密度差形成的自然对流来驱动闭环...     

应用于肿瘤细胞基因表达水平分析的微流控芯片

近年来快速发展的微流控技术为单细胞基因诊断的基础研究提供了一个有力的平台,微流控芯片具有样品和试剂低消耗、快速实时、大量样本平行处理等优点,还可以使分析过程自动化、防止污染以及完成自动高效的重复实验。本文主要介绍一种用于高通量单细胞基因表达水平分析的微流控芯片技术平台。芯片集成了单细胞捕获、裂解、纯化、逆转录等生物样品处理单元,通过内置气动微阀实现细胞反应腔的独立寻址,从而实现单细胞处理与分析整个过程的自动化操控。实验结果显示了此平台可以实现基因表达水平稳定性的评估,具有应用于肿瘤早期诊断领域的潜力。     

面向数字微流控生物芯片的差分隐私方案

近年来,基于数字微流控生物芯片(Digital Microfluidic Biochip,DMFB)的分子诊断技术成为热点研究方向。与传统分子诊断技术相比,数字微流控生物芯片具有精准控制离散液滴、执行生化协议等优势。然而,作为网络物理系统的组成,生物芯片潜在的隐私安全问题日益突出,比如通信信道的窃听攻击,生化协议的篡改攻击,物理结构保护的版权攻击等。差分隐私作为传统数据隐私保护的常用技术可以融入生物芯片应用以保护用户隐私安全。然而,对隐私安全、生物芯片应用以及生物芯片安全三种技术的交叉研究较为少见。调研分析生物芯片应用的实现机制和威胁模型,包括生化协议、网络物理系统及增强隐私保护的DMFB用户数据安全平台,首先在DMFB用户数据平台上描述了拉普拉斯机制、高斯机制和随机响应机制的应用场景和保护方案,其次基于用户层级敏感度、路由权重集合和路由交叉点参数集合这三个策略提出参数安全发布算法,最后创建防篡改概率作为安全性指标,同时建立置信分数、校准度和累计误差率衡量数据可用性。仿真实验结果表明整体方案的隐私安全性可达98%,数据可用性平均可达93.3%,算法性能试验表明方案最佳的隐私预算为0.4,此外,对比同类算法,所提方案平均提高了12.09%隐私安全性和7.02%的数据可用性,因此该方案能够为DMFB执行生化协议安全有效的用户数据平台。     

微流控DNA计算的研究进展及展望

DNA计算机具有超强的并行运算能力和巨大的数据存储能力,被认为有望解决电子计算机所面临的瓶颈问题。微流控技术提供了一个可实现自动化操作、通用型DNA计算机的支持平台。借助于微流控技术,将DNA计算相关的生化反应有机地集成在芯片平台上加以实现,进一步提高了DNA计算的可靠性、减少了实验过程的手工操作和反应时间。在介绍DNA计算机的基本概念和微流控技术基础上,围绕微流控DNA计算机的原理、模型和应用等关键问题,分析了微流控DNA计算机的体系结构及设计方法,讨论了微流控DNA计算机未来可能的发展方向。     

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FPGA的微流控芯片电泳控制系统设计

设计一套基于FPGA的微流控芯片的电泳控制系统。该系统采用具有大量控制端口的FPGA作为系统的控制芯片,同时为了节约控制端口,选取串行控制的A／D与D／A芯片;采用USB2.0高速传输接口与上位机通信,满足了实施控制与数据上传的要求;采用VerilogHDL语言对芯片编程后,可同时对30个PCR芯片实施控制,另外还编写了基于Windows XP的驱动程序与控制软件。     

基于MEMS技术的PCR生物芯片的研究

聚合酶链式反应 (PCR)技术已在分子生物学、基因测序、医学诊断等方面得到广泛的应用。基于MEMS技术研制了微结构的集成PCR -DNA分子扩增生物芯片 ,芯片集成了加热子、温度传感器、反应室、进样通道等 ;还介绍了芯片的设计、制作、温度循环特性。     

PCR生物芯片/微装置在微生物检测中应用研究

聚合酶链式反应(PCR)技术已经在分子生物学、生物化学、临床医学、遗传以及法医等领域得到广泛的应用.基于微电子机械系统技术开发而成的PCR生物芯片由于具有所需样品和反应混合物体积小、反应时间短、轻便等优点而日益受到人们的重视.介绍PCR生物芯片/微装置(包括反应池内固定扩增式和连续流动式)在微生物埃希氏大肠杆菌(E.coli)和微生物战剂检测中的应用.     

生物芯片技术的应用

生物芯片技术是国际上近年来发展起来的一门高新技术.本文综述了国内外生物芯片技术的研究现状及发展前景.主要内容有基本概念、生物芯片制作及其应用、国内外发展现状、生物芯片的研究开发方向等方面,以达到对生物芯片技术的发展有一个全面了解的目的.     

On-chip polymerase chain reaction microdevice employing a magnetic droplet-manipulation system

An on-chip polymerase chain reaction (PCR) device employing a magnetic beads-droplet-handling system was developed. Actuation with a magnet offers a simple system for droplet manipulation that allows separation and fusion of droplets containing magnetic beads by handling with a magnet. The device consists of a reaction chamber channel and two magnet-handling channels for the manipulation of micro-droplets containing magnetic beads. Micro-droplets were placed inside a reaction chamber filled with oil and manipulated with a magnet. When a droplet containing NaOH and magnetic beads was manipulated towards a droplet containing phenol red, a color change was observed after fusion. Sample preparation was performed by fusion of droplets containing a forward primer, reverse primer, template DNA and PCR mixture, using a droplet containing magnetic beads. PCR amplification or RT-PCR was also successfully performed, with efficiency comparable to manual methods that use this device by placing it on a thermal cycler for amplification. With a magnetic beads-manipulation step, purification of amplified DNA was also accomplished by using magnetic beads as the carrier. The amplified DNA was captured on streptavidin conjugated magnetic beads using a biotinylated primer, purified by washing and digested for separation of the target DNA.     

喷射器内液-液湍流反应过程的数值模拟

利用两环境矩直接积分模型(DQMOM)对喷射器内液液平行-竞争反应体系进行了研究,结果表明:在固定引射流速的情况下,随着喷嘴速度的增加,平行-竞争反应的选择性越来越高, 副反应的转化率越来越低;在固定喷嘴流速的情况下,随着引射流体速度的增加,平行-竞争反应的选择性越来越低,副反应的转化率越来越高;速度比一定时,喷嘴绝对速度值越大,副反应的转化率越低.     

生物芯片技术的应用与展望

生物芯片技术是20世纪90年代中期发展起来的一项尖端技术,已经成为科学界的研究热点之一。简述了生物芯片的概念与主要分类,主要介绍了生物芯片技术在基因测序与基因表达分析、基因突变和多态性检测、转基因食品的检测、食品中微生物的检测、临床医学、疫苗研制等方面的最新应用,并对其在中药研究以及农业、环保、司法鉴定、基因武器等领域的发展前景作了预测及展望。     

Enhancement of thermal uniformity for a microthermal cycler and its application for polymerase chain reaction

Thermal uniformity is essentially important for micro reactors which require precise control of critical reaction temperatures. Accordingly, we report a new approach to increase the temperature uniformity inside a microthermal cycler, especially for polymerase chain reaction (PCR). It enhances the thermal uniformity in the reaction region of a PCR chip by using new array-type microheaters with active compensation (AC) units. With this approach, the edges of the microthermal cyclers which commonly have significant temperature gradients can be compensated. Significantly, the array-type microheaters provide higher uniformity than conventional block-type microheaters. Besides, experimental data from infrared (IR) images show that the percentages of the uniformity area with a thermal variation of less than 1 °C are 63.6%, 96.6% and 79.6% for three PCR operating temperatures (94, 57 and 72 °C, respectively) for the new microheaters. These values are significantly better than the conventional block-type microheaters. Finally, the performance of this proposed microthermal cycler is successfully demonstrated by amplifying a detection gene associated with Streptococcus Pneumoniae (S. Pneumoniae). The PCR efficiency of the new microthermal cycler is statistically higher than the block-type microheaters. Therefore, the proposed microthermal cycler is suitable for DNA amplification which requires a high temperature uniformity and is crucial for micro reactors with critical thermal constraints.     

Numerical simulation of long-term precipitate evolution in austenitic heat-resistant steels

Numerical simulation of the long-term precipitate evolution in five different austenitic heat-resistant steels–NF709, Super304H, Sanicro25, CF8C-PLUS and HTUPS–has been carried out. MX and M₂₃C₆ are predicted to remain as major precipitates during long-term aging in these steels. While the average size of MX is maintained below several ten nanometers during the aging, that of M₂₃C₆ exceeds 100 nm after 100,000 h of aging at 700 ^°C. The addition of 3 wt% Cu produces very fine Cu-rich precipitates during aging in Super304H and Sanicro25. It is found that the amount of Z phase starts to increase remarkably between 1000 and 10,000 h of aging at the expense of MX precipitates in the steels containing a high nitrogen content. However, the growth rate of Z phase is relatively slow and its average size reaches at most a few ten nanometers after 100,000 h of aging at 700 ^°C, compared with 9%–12% Cr ferritic heat-resistant steels. The simulated precipitation sequence and precipitate size during aging are in general agreement with experimental observations.     

Continuous flow polymerase chain reaction using a hybrid PMMA-PC microchip with improved heat tolerance

Recently, polymeric materials have been explored as more versatile alternatives for the fabrication of polymerase chain reaction (PCR) microchips. Poly(methyl methacrylate) (PMMA) is a popular substrate material due to its high mechanical stability, good chemical properties and most importantly, its suitability for cheap and simple CO₂ laser ablation. However, it has a low glass transition temperature (T_g) of 105 °C, which is just above the denaturation temperature for PCR, thus the bond integrity is compromised. Polycarbonate (PC) is preferred as a substrate for PCR microchip as it has a higher T_g of 150 °C; but since its thermal properties are not suitable for CO₂ laser light, the more expensive excimer laser has to be employed. Here we report a novel hybrid PMMA-PC microchip by bonding a PC cover plate with a PMMA substrate containing microchannel which is fabricated by CO₂ laser ablation. This hybrid microchip has improved heat tolerance, such that the bonding integrity is sustained at the denaturation temperature. DNA amplification is found to be more efficiently performed in a PMMA-PC microchip than in a PMMA-PMMA microchip.     

弹性波数值模拟中计算空间导数的一种新算法

在弹性波的计算机模拟中,精度和效率取决于计算波动方程中空间导数与时间积分的方法,数值计算中的误差主要来自空间导数的近似。本文提出一种计算空间导数的新算法,能够将模拟扩展到更短的波长。一个合成数据体逆时偏移的结果表明,可显著减小基于有限差分方法的数值频散。