多通道微流控电泳芯片CCD检测系统

针对微流控电泳芯片检测系统微型化、集成化的要求,分析了传统电泳芯片检测系统的优势和不足,提出一种以FPGA芯片为控制器的CCD多通道微流控电泳芯片检测系统。利用FPGA/NiosⅡ嵌入式系统解决方案,以EP2C8Q208芯片为核心,设计了CCD驱动及外围硬件电路。通过上位机软件进行数据处理,实现了荧光图谱的同步显示。实验结果表明:该系统能同时检测多通道微流控电泳芯片中各通道不同的荧光信号强度,具有较高的灵敏度和信噪比,对罗丹明B样品的最低检测浓度为1.0×10-6mol/L,能够满足多通道微流控电泳芯片检测的要求。     

用于微流控芯片的全波长实时荧光检测系统研制

为了连续检测出微流控芯片中不同荧光物质的发射光强度,设计了一套基于LabWindows编程的实时的、发射光波长在340-1200 nm的荧光检测系统。系统将控制光谱仪、采集荧光强度、数据降噪及存储、结果分析及显示等功能结合在一起,实现微流控芯片内荧光强度的实时动态检测及分析。系统采用卤钨灯和光谱仪相结合的方式,通过合理设计激发和探测光纤的位置,结合软件算法控制,来消除激发光和背景荧光的影响;系统无需针对不同的荧光物质选用特定的激发光和滤波片,增加系统的集成度、提高检测的多样性。基于本系统对微流控芯片中两种溶液的荧光强度进行检测,来验证系统的测试性能;同时对微流控芯片中不同浓度的荧光物质进行检测,来验证系统的准确性能。实验结果表明所设计的系统满足微流控芯片内不同荧光物质的荧光强度实时检测的要求,为后续基于微流控芯片的生化免疫分析、药物分析和多细胞生命体等研究提供研究基础和分析手段。     

嵌入式数字微流控荧光液滴分选平台EI北大核心CSCD

搭建了基于嵌入式系统的数字微流控芯片操纵平台,实现对片上液滴的自动化配发、检测和分选。将特定电极阵列结构的介电润湿(EWOD)芯片通过特制电路和基于STM32的控制电路结合,并利用荧光显微镜提供的光路,完成分选平台的硬件搭建。移植嵌入式实时操作系统μC/OS-Ⅲ到STM32芯片中,根据分选功能需求,划分功能任务,设计各任务程序及任务间通信方式,实现在芯片上按一定频率从包含荧光与非荧光微粒的混合液体中生成小液滴,并将小液滴运输至检测区,根据其荧光强度对其进行分选。本系统实现了对数字微流控芯片的自动化操控,为将数字微流控技术应用于细胞、蛋白质、微生物等领域的分选提供了便利。     

微流控芯片光学检测系统集成化新进展

微流控芯片是微全分析系统(μTAS)中当前最活跃的领域和发展前沿。目前人们在微流控芯片的研究中已经取得了很大的进展,研制出了多种微型化、集成化的芯片。相比之下,与微流控芯片配套的高灵敏度微型光学检测系统的研制却相对落后。介绍了分别基于CMOS、垂直腔面发射激光器(VCSEL)和微型雪崩光电二极管(μAPD)来实现光学检测系统与微流控芯片集成化的方法。     

微流控芯片发展与展望

介绍了微流控分析系统的一般特点、发展历史和近期的研究进展.分别讨论了微流控分析系统中有关流控系统、芯片材料、检测系统、集成化系统、分离系统、试样引入和前处理系统等研究领域的发展趋势,并对微流控分析系统的应用前景做出了展望.     

嵌入式数字微流控荧光液滴分选平台

搭建了基于嵌入式系统的数字微流控芯片操纵平台,实现对片上液滴的自动化配发、检测和分选。将特定电极阵列结构的介电润湿(EWOD)芯片通过特制电路和基于STM32的控制电路结合,并利用荧光显微镜提供的光路,完成分选平台的硬件搭建。移植嵌入式实时操作系统μC/OS-Ⅲ到STM32芯片中,根据分选功能需求,划分功能任务,设计各任务程序及任务间通信方式,实现在芯片上按一定频率从包含荧光与非荧光微粒的混合液体中生成小液滴,并将小液滴运输至检测区,根据其荧光强度对其进行分选。本系统实现了对数字微流控芯片的自动化操控,为将数字微流控技术应用于细胞、蛋白质、微生物等领域的分选提供了便利。     

细胞内钙离子浓度检测关键技术

研究并设计了用于活体单细胞内钙离子浓度定量检测的微流控荧光检测系统。首先用微流控芯片完成细胞的培养、染色、驱动和定位等操作,接着分别用波长为340 nm和380 nm的单色光去激发染色后的细胞使之发出荧光,并用光电倍增管(PMT)和电荷耦合器件(CCD)采集荧光强度和荧光图像,最后利用荧光比值法计算出细胞内钙离子的浓度。同时,使用该系统记录了高K~+刺激下细胞内钙离子浓度的变化。结果表明此系统稳定可靠,测量数据准确,满足生理学研究中检测活体细胞内钙离子浓度的需要。     

核酸检测一体化微流控芯片设计与液滴操纵分析

设计了一种基于磁珠法的两相流液滴微流控芯片,包含样品提纯、扩增和检测一系列连续的生化过程,可用于快速核酸检测.首先建立了磁珠和液滴在两相流体系内的动力学模型,并借助有限元仿真平台对磁珠微团所处环境进行了磁场仿真,得到不同体积磁珠微团所受的磁力.进一步还分析了磁珠微团、液滴体积、永磁体移动速度对液滴运动状态的影响,最终总结出液滴操纵图.     

微流控芯片光散射检测仿真研究

微纳米尺度下的光散射检测是微流控芯片技术的重要研究领域之一,由于尺寸微小,芯片结构、材料等因素对检测结果的影响,以及光子与物质碰撞导致的光的走向和散失等特性,无法在实验室中直接观测,因此,计算机仿真成为微流控芯片技术研究的重要手段。本实验利用Tracepro等软件进行微流控芯片的建模和检测仿真,验证其原理,并有效避免设计缺陷。     

基于透射式荧光型光纤生物传感器的结构设计

本文设计的基于透射式荧光型光纤生物传感器的样品反应池,采用光学技术和微流控技术、介电电泳及微/纳机械加工技术等,克服了现有同类仪器相对缺乏且多为断点测量的不足。该设计采用的微流控通道和温控系统保证生化样品在模拟生理条件下进行检测,真实地反映生物组分的特性;介电电泳将探针分子聚集到生物生物传感器的反应活性表面,保证靶标分子能探针分子的杂交,有利于微、痕量组分的富集;镜面的锥形腔体结构为聚光装置,然后将光信号耦合到光导纤维,导入光学型光纤生物传感器的检测器加工处理。该设计能缩短响应时间,提高生物传感器的检测灵敏度。     

激光透射法磁珠浓度测量系统

磁珠广泛应用于免疫检测、细胞分离等生物实验中,磁珠浓度的检测对于评价实验效果具有重要意义。本文提出了基于激光透射法的双光路磁珠浓度测量系统,通过测量入射激光强度与透射激光强度的比值来确定磁珠浓度。利用该系统对多个浓度的磁珠悬浊液进行了实验测量,每个浓度下测量多组实验数据,共采集了8 000组数据。通过拟合测量数据,建立了磁珠浓度与测量值的关系函数,二者呈现指数函数关系,拟合残差平方和为0.000 088 89,确定系数可达0.997 1,说明函数具有良好的拟合性能。实验结果表明,相对测量误差在2.5%以内,输出值相对波动范围在2.5%以内,测量系统具有较高的测量精度和良好的重复性。     

超磁致伸缩超声振动系统的机电转换效率研究

为提高超声振动系统的能量转换效率和功率容量,提出超磁致伸缩超声振动系统的设计方法,研究导磁体材料特性对超声系统振动性能的影响规律。采用硅钢、铁氧体和磁粉心三种磁性材料设计导磁体,并建立超声振动系统的等效电路模型;通过阻抗分析建立3种超声振动系统的阻抗圆曲线,得到谐振频率和机电转换系数等参数,提出导磁材料特性对系统机电能量转换效率的影响规律。为验证阻抗分析结果的正确性,试验测定3种超声系统在不同电压幅值激励下的振幅-电流灵敏度与频率的关系曲线,验证导磁材料参数与系统机电能量转换效率之间的关系。结果表明：高磁导率铁氧体材料可提高超声振动系统在小功率工作条件下的机电能量转换效率,而对于大功率超声振动系统而言,需要兼顾磁导率和饱和磁通密度,使导磁体工作于非磁饱和状态,以提高系统换能效率,这有助于指导不同功率大小超声振动系统的导磁体材料选择。     

Single HeLa and MCF-7 cell measurement using minimized impedance spectroscopy and microfluidic device

This study presents an impedance measurement system for single-cell capture and measurement. The microwell structure which utilizes nDEP force is used to single-cell capture and a minimized impedance spectroscopy which includes a power supply chip, an impedance measurement chip and a USB microcontroller chip is used to single-cell impedance measurement. To improve the measurement accuracy of the proposed system, Biquadratic fitting is used in this study. The measurement accuracy and reliability of the proposed system are compared to those of a conventional precision impedance analyzer. Moreover, a stable material, latex beads, is used to study the impedance measurement using the minimized impedance spectroscopy with cell-trapping device. Finally, the proposed system is used to measure the impedance of HeLa cells and MCF-7 cells. The impedance of single HeLa cells decreased from 9.55 × 10(3) to 3.36 × 10(3) Ω and the impedance of single MCF-7 cells decreased from 3.48 × 10(3) to 1.45 × 10(3) Ω at an operate voltage of 0.5 V when the excitation frequency was increased from 11 to 101 kHz. The results demonstrate that the proposed impedance measurement system successfully distinguishes HeLa cells and MCF-7 cells.     

磁珠分离式样品提取微流控芯片的磁珠运动速度建模及特性研究

为提高磁珠分离式生物医学样品的提取效率,采用永磁和软磁体相结合的磁场设计结构,提出一种新型磁珠分离式样品提取微流控芯片。利用静磁学和流体力学基本原理推导出流场中磁珠运动的速度模型,通过多物理场耦合仿真软件对流场中磁珠运动规律进行瞬态仿真,分析软磁体的结构和分布对微流道内磁珠的水平分速度以及竖直分速度的影响关系,计算不同设计结构所允许的磁珠完全吸附时微流道中最大允许流量。结果表明,增大软磁体的厚度可以快速减小磁珠水平运动的速度,并减小其在垂直方向上的波动,且在双软磁体作用时,软磁体的间距越大,水平方向和垂直方向的速度波动越大;间距越小,磁珠粒子速度稳定的时间越短。     

基于微螺线管电感式传感器的金属颗粒形态对输出特性影响的研究

基于电感测量技术与微流体技术的油液检测芯片, 不仅可以区分出铁磁性和非铁磁性金属颗粒, 还可以对油液中的颗粒进行计数统计和颗粒大小测量,从而判断金属颗粒污染物的来源及设备的磨损状态。通过理论分析、数值模拟及实验验证, 分析不同形态铁磁颗粒退磁场, 研究铁磁颗粒形态对电感式传感器的输出影响。建立理论模型描述不同形状颗粒的退磁因子、磁化场, 以及磁化的金属颗粒产生磁场从而导致线圈电感发生变化。基于模型计算并验证同体积下球形、不同轴长比的圆柱、椭球颗粒的磁场和电感输出, 分析结果显示颗粒越细长、退磁因子越小则越容易磁化, 因此细长颗粒引起传感器的电感变化更大, 另外圆柱形颗粒的电感变化大于旋转椭球型颗粒。     

电容耦合非接触电极及心电信号获取

电极与皮肤间接触所导致的不适感,是穿戴式心电信号测量系统实际应用中的常见问题。设计了一种非接触心电信号测量系统。采用印刷电路板制作的测量电极,借助电容耦合测量位移电流的方式获取心电信号。采用反接二极管提供测量所需的高阻值偏置电阻,结合高输入阻抗仪表放大器,制作了测量电极信号提取电路。测量系统由两个测量电极与一个直接与测量电路地相连的参考电极组成。选择金属铝板、导电纤维和导电橡胶作为参考电极,实验研究了共模干扰抑制性能与参考电极接触阻抗之间的量化关系。将主元分析与奇异谱分析相结合,提出了一种心电信号处理算法。实验结果表明,该系统可在棉质线衣外侧有效获得满意的心电信号。     

Optical detection of red blood cell aggregation in a disposable microfluidic channel

The aggregability of red blood cells (RBCs) was determined by laser backscattering light analysis in a microfluidic channel Available techniques for RBC aggregation often adopt a rotational Couette-flow using a bob-and-cup system for disaggregating RBCs, which causes the system to be complex and expensive A disposable microfluidic channel and vibration generating mechanism were used in the proposed new detection system for RBC aggregation Prior to measurement, RBC aggregates in a blood sample were completely disaggregated by the application of vibration-induced shear With the present apparatus, the aggregation indexes of RBCs can be measured easily with small quantities of a blood sample The measurements with the present aggregometer were compared with those of LORCA and the results showed a strong correlation between them The aggregability of the defibrinogenated blood RBCs is markedly lower than that of the normal RBCs The noble feature of this design is the vibration-induced disaggregation mechanism, which can incorporate the disposable element that holds the blood sample     

Superporous agarose beads as a solid support for microfluidic immunoassay

We demonstrate here with the feasibility of superporous agarose (SA) beads as a solid support in microfluidic immunoassay by detecting goat IgG. In our procedure, SA beads containing superpores were covalently conjugated to protein A. The conjugated beads were introduced into a polydimethyl siloxane microfluidic device. The sandwich immunoassay was performed in the microfluidic device by subsequently introducing anti-goat IgG as the primary antibodies, goat IgG as analytes, alkaline phosphatase-conjugated F(ab')2 anti-goat IgG as detection antibodies, and 5-bromo-4-chloro-3-indolylphosphate/nitroblue tetrazolium as substrate in a flow. Depending on the goat IgG concentration, dark and pinky precipitates appeared inside the microchannel immediately after the introduction of all the reagents. The minimum detection limit, 100pg goat IgG/mL in PBS, was achieved with the naked eye. This enhanced sensitivity is mainly because analytical reagents were allowed to access the outer surface as well as the inner matrices of the beads. This is supported by the facts that the binding of fluorescein isothiocyanate IgG happened throughout the inside matrices of protein A-conjugated SA beads but was limited to the outer surface of protein A-conjugated homogeneous agarose beads. These results suggest that SA beads are highly suitable as a solid support for microfluidic immunoassays.     

一种新型的基于四电极结构的生物电阻测量方法

提出了一种成本低而且精度高的人体阻抗测量系统。测量电路采用四电极结构,使每个电极模拟人体皮肤电阻,分别与人体的赤足接触,利用单片机产生50kHz的正弦波信号,经过四电极以及与其接触的人体后形成电压降,再经过信号放大电路处理,最终实现人体阻抗的测量。系统有效降低了产品的成本,克服了接触阻抗以及空间电磁波的干扰,试验结果与理论值证明了测量方法具有高精度、高稳定性和准确性。     

ac Modeling and impedance spectrum tests of the superconducting magnetic field coils for the Wendelstein 7-X fusion experiment

The impedance spectrum test was employed for detection of short circuits within Wendelstein 7-X (W7-X) superconducting magnetic field coils. This test is based on measuring the complex impedance over several decades of frequency. The results are compared to predictions of appropriate electrical equivalent circuits of coils in different production states or during cold test. When the equivalent circuit is not too complicated the impedance can be represented by an analytic function. A more detailed analysis is performed with a network simulation code. The overall agreement of measured and calculated or simulated spectra is good. Two types of short circuits which appeared are presented and analyzed. The detection limit of the method is discussed. It is concluded that combined high-voltage ac and low-voltage impedance spectrum tests are ideal means to rule out short circuits in the W7-X coils.