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根据介电泳操作原理,设计了微环形阵列电极结构,建立了细胞分离富集芯片模型,采用COMSOL软件分析微环形阵列电极的电场分布和介电泳力方向并确定了最大和最小电场强度的位置,利用ITO玻璃和PDMS制备了细胞分离富集芯片.通过酵母菌细胞的介电泳富集实验和酵母菌细胞与聚苯乙烯小球的分离富集实验,明确了酵母菌细胞的临界频率,实现了酵母菌细胞和聚苯乙烯小球的分离富集.结果显示,在溶液电导率为60μs/cm,交流信号电压为8Vp-p时,酵母菌细胞在1kHz~45kHz频率范围内做负介电泳运动并富集在环形内部,45kHz为酵母菌细胞的临界频率,在45kHz~10MHz频率范围内做正介电泳运动并富集在环形边缘;1.5MHz时聚苯乙烯小球做负介电泳运动并富集在环形内部,富集倍数达到11.66. 相似文献
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在浓度密集粒子下对血细胞进行检测与处理可以形成具有特异性的靶向血细胞,对生物和医疗系统的发展具有重要意义。已开发的多电极阵列微流控芯片的电极分布于5个菱形横截面,每个横截面嵌入12个均匀分布的电极。利用该微流控芯片的特殊结构,采用多电容传感法,在大量高浓度粒子中测量了标准聚苯乙烯颗粒的浓度。实验结果表明,在低密度0.3 vol%~1.5 vol%的情况下,粒子迁移率随浓度的增加而成比例地增加。而在中密度1.5 vol%~3.0 vol%的情况下,粒子迁移率增加较少,而在足够密集浓度大于3.0 vol%的情况下,由于颗粒间的相互作用,无论浓度如何变化,粒子迁移率几乎保持恒定。 相似文献
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设计了一种用于微尺度流动状态下电阻抗成像检测的多电极阵列微流控芯片,包括微流控芯片的结构设计、材料选择和加工工艺。设计的微流控芯片包含3个圆形电极横截面,每个横截面包含一组电极阵列。该阵列有3种数目的电极,分别为8电极,12电极和16电极。之后通过数值仿真方法实现了三种电极数目(8,12和16)微流控芯片的电阻抗成像,并与之前研究出来的菱形横截面8电极微流控芯片进行了对比,发现设计出来的16电极圆形微流控芯片具有较高的成像质量,验证了微流控芯片用于细胞电阻抗成像检测的可行性。 相似文献
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为了提高暗场检测的效率、获取高质量的传感信息,基于实验设备的物理尺寸以及实验环境,通过COMSOL Multiphysics仿真,并采取键合工艺,研制了一种适用于暗场生化传感系统的微流控芯片。该芯片可在同一暗场视野下观察到四个反应区域,实现对多种样品的并行检测。同时由于该设计的连通性,四个反应区域可以两两进行精确对照,对样本检测结果进行定性定量对比。实验中,在暗场显微成像系统下捕获到微流控芯片通入各反应区域的传感单元纳米粒子,测出散射光谱,验证其可行性。暗场显微成像系统和微流控芯片的结合,实现了自动化、集成化的实时原位并行检测,极大地提高了实验效率。 相似文献
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Sequential Field-Flow Cell Separation Method in a Dielectrophoretic Chip With 3-D Electrodes 总被引:2,自引:0,他引:2
Liming Yu Iliescu C. Guolin Xu Tay F.E.H. 《Journal of microelectromechanical systems》2007,16(5):1120-1129
This paper presents a sequential dielectrophoretic field-flow separation method for particle populations using a chip with a 3-D electrode structure. A unique characteristic of our chip is that the walls of the microfluidic channels also constitute the device's electrodes. This property confers the opportunity to use the electrodes' shape to generate not only the electric field gradient required for dielectrophoretic force but also a fluid velocity gradient. This interesting combination gives rise to a new solution for the dielectrophoretic separation of two particle populations. The proposed sequential field-flow separation method consists of four steps. First, the microchannel is filled with the mixture of the two populations of particle. Second, the particle populations are trapped in different locations of the microfluidic channels. The population, which exhibits positive dielectrophoresis (DEP), is trapped in the area where the distance between the electrodes is the minimum, while the other population that exhibits negative DEP is trapped in locations of maximum distance between electrodes. In the next step, increasing the flow in the microchannels will result in an increased hydrodynamic force that sweeps the cell population trapped by positive DEP out of the chip. In the last step, the electric field is removed, and the second population is swept out and collected at the outlet. For theoretical and experimental exemplification of the separation method, a population of viable and nonviable yeast cells was considered. 相似文献
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Characterization and modeling of a microfluidic dielectrophoresis filter for biological species 总被引:1,自引:0,他引:1
Microfabricated interdigitated electrode array is a convenient form of electrode geometry for dielectrophoretic trapping of particles and biological entities such as cells and bacteria within microfluidic biochips. We present experimental results and finite element modeling of the holding forces for both positive and negative dielectrophoretic traps on microfabricated interdigitated electrodes within a microfluidic biochip fabricated in silicon with a 12-/spl mu/m-deep chamber. Anodic bonding was used to close the channels with a glass cover. An Experimental protocol was then used to measure the voltages necessary to capture different particles (polystyrene beads, yeast cells, spores and bacteria) against destabilizing fluid flows at a given frequency. The experimental results and those from modeling are found to be in close agreement, validating our ability to model the dielectrophoretic filter for bacteria, spores, yeast cells, and polystyrene beads. This knowledge can be very useful in designing and operating a dielectrophoretic barrier or filter to sort and select particles entering the microfluidic devices for further analysis. 相似文献
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This paper presents the modeling and optimization of a magnetophoretic bioseparation chip for isolating cells, such as circulating tumor cells from the peripheral blood. The chip consists of a continuous-flow microfluidic platform that contains locally engineered magnetic field gradients. The high-gradient magnetic field produced by the magnets is spatially non-uniform and gives rise to an attractive force on magnetic particles flowing through a fluidic channel. Simulations of the particle–fluid transport and the magnetic force are performed to predict the trajectories and capture lengths of the particles within the fluidic channel. The computational model takes into account key forces, such as the magnetic and fluidic forces and their effect on design parameters for an effective separation. The results show that the microfluidic device has the capability of separating various cells from their native environment. An experimental study is also conducted to verify and validate the simulation results. Finally, to improve the performance of the separation device, a parametric study is performed to investigate the effects of the magnetic bead size, cell size, number of beads per cell, and flow rate on the cell separation performance. 相似文献
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Ming Li Shunbo Li Wenbin Cao Weihua Li Weijia Wen Gursel Alici 《Microfluidics and nanofluidics》2013,14(3-4):527-539
This article presents a dielectrophoresis (DEP)-based microfluidic device with the three-dimensional (3D) microelectrode configuration for concentrating and separating particles in a continuous throughflow. The 3D electrode structure, where microelectrode array are patterned on both the top and bottom surfaces of the microchannel, is composed of three units: focusing, aligning and trapping. As particles flowing through the microfluidic channel, they are firstly focused and aligned by the funnel-shaped and parallel electrode array, respectively, before being captured at the trapping unit due to negative DEP force. For a mixture of two particle populations of different sizes or dielectric properties, with a careful selection of suspending medium and applied field, the population exhibits stronger negative DEP manipulated by the microelectrode array and, therefore, separated from the other population which is easily carried away toward the outlet due to hydrodynamic force. The functionality of the proposed microdevice was verified by concentrating different-sized polystyrene (PS) microparticles and yeast cells dynamically flowing in the microchannel. Moreover, separation based on size and dielectric properties was achieved by sorting PS microparticles, and isolating 5 μm PS particles from yeast cells, respectively. The performance of the proposed micro-concentrator and separator was also studied, including the threshold voltage at which particles begin to be trapped, variation of cell-trapping efficiency with respect to the applied voltage and flow rate, and the efficiency of separation experiments. The proposed microdevice has various advantages, including multi-functionality, improved manipulation efficiency and throughput, easy fabrication and operation, etc., which shows a great potential for biological, chemical and medical applications. 相似文献
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The modification of polymer surface wettability is receiving increasing interest in recent years. As surface wettability affects
the flowing resistance, and thus the separation ratio and/or mixing ratio of samples in different microchannels, the controlled
modification of surface wettability is highly desirable. In this study, microfluidic channels with controlled surface wettability
were achieved and fabricated using femtosecond (fs) laser direct ablation of polymethyl methacrylate at various fluences.
Varied flow velocities and separation ratio of water in microfluidic channels have been successfully obtained through fs laser-induced
modification in wetting characteristics of the microchannel surfaces. A concave flow front was observed in a microchannel
with hydrophilic surface. Correspondingly, a convex flow front was observed with hydrophobic surface. For an untreated channel,
a straight flow front was observed. These results would be attractive for various microfluidic chip applications, such as
control of the reagent reaction through controlling liquid medium separation or control of mixing ratio in different channels. 相似文献
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The development of techniques for manipulating particles and integrating them into the digital microfluidic (DMF) devices has been the subject of several studies in recent years. This paper presents a dielectrophoretic-based method that uses triangular traps to manipulate particles and purify a droplet in DMF platforms. Numerical and experimental studies are conducted to show the effectiveness of the proposed trap geometry which is also compatible with the other operators in the DMF platform. The triangular trap geometry is used to move the polystyrene particles to one side of the trap using negative dielectrophoresis (nDEP). The droplet is then split into two smaller droplets with very low and high concentrations of particles using the electrowetting on dielectric technique. The average velocity of the particles (as they move along the trap) as a function of the vertex angle of the triangular trap and the gap between the top and bottom plate is examined. It is observed that the vertex angle of the trap plays more important role on the motion of the particles than the gap. Thus, to enhance the motion of the particles and minimize the effect of splitting on the purification process, the vertex angle and the slope of the side arms of the triangular trap are modified based on the results of the numerical model simulating the dielectrophoretic force on the particle. The enhanced geometry is fabricated and tested experimentally to show the effectiveness and ease-of-use of the proposed technique in purifying (or concentrating) a droplet in DMF. The results show that using the proposed nDEP electrode geometry purification (or concentration) can be performed with the efficiency of 90 %. 相似文献
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Hun Lee Linfeng Xu Byungwook Ahn Kangsun Lee Kwang W. Oh 《Microfluidics and nanofluidics》2012,13(4):613-623
This paper presents a continuous-flow in-droplet magnetic particle separation in a droplet-based microfluidic device for magnetic bead-based bioassays. Two functions, electrocoalescence and magnetic particle manipulation, are performed in this device. A pair of charging metallic needles is inserted into two aqueous channels of the device. By electrostatic force, two different solutions can be merged to be mixed at a junction of droplet generation. The manipulation of magnetic particles is achieved using an externally applied magnetic field. The magnetic particles are separated by the magnetic field to one side of the droplet and extracted by splitting the droplet into two daughter droplets: one contains the majority of the magnetic particles and the other is almost devoid of magnetic particles. The applicability of the continuous-flow in-droplet magnetic particle separation is demonstrated by performing a proof-of-concept immunoassay between streptavidin-coated magnetic beads and biotin labelled with fluorescence. This approach will be useful for various biological and chemical analyses and compartmentalization of small samples. 相似文献
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研究一种单动力源、聚焦流形态可控的用于细胞排队的微流控芯片。建立了样品沟道与鞘流沟道不同长度比例、不同夹角的模型并进行了不同负压条件下聚焦流形态仿真,运用SPSS软件进行了回归分析并进行了模型优化。在芯片的微加工过程中,利用印刷电路板(PCB)制作了母板,以聚二甲基硅氧烷(PDMS)为芯片主要材料,制作了PDMS—PDMS,PDMS—玻璃及PCB—PDMS三种芯片。制作的芯片能够在单个动力源条件下控制聚焦流宽度,使不同大小的微粒及细胞呈单个排列流动。研究结果为分析不同尺寸的细胞而选择合适的样品流沟道与鞘流沟道长度、夹角等条件提供了依据,所制作的芯片也达到了廉价且实用的目的。 相似文献
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This paper demonstrates simple and cost-effective microfluidic devices for enhanced separation of magnetic particles by using soft magnetic microstructures. By injecting a mixture of iron powder and polydimethylsiloxane (PDMS) into a prefabricated channel, an iron–PDMS microstructure was fabricated next to a microfluidic channel. Placed between two external permanent magnets, the magnetized iron–PDMS microstructure induces localized and strong forces on the magnetic particles in the direction perpendicular to the fluid flow. Due to the small distance between the microstructure and the fluid channel, the localized large magnetic field gradients result a vertical force on the magnetic particles, leading to enhanced separation of the particles. Numerical simulations were developed to compute the particle trajectories and agreed well with experimental data. Systematic experiments and numerical simulation were conducted to study the effect of relevant factors on the transport of superparamagnetic particles, including the shape of iron–PDMS microstructure, mass ratio of iron–PDMS composite, width of the microfluidic channel, and average flow velocity. 相似文献
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Recently, the ability to create engineered heart tissues with a preferential cell orientation has gained much interest. Here, we present a novel method to construct a cardiac myocyte tissue-like structure using a combination of dielectrophoresis and electro-orientation via a microfluidic chip. The device includes a top home-made silicone chamber containing microfluidic channels and bottom integrated microelectrodes which are patterned on a glass slide to generate dielectrophoresis force and orientation torque. Using the interdigitated-castellated microelectrodes, the induction of a mutually attractive dielectrophoretic force between cardiac myocytes can lead to cells moving close to each other and forming a tissue-like structure with orientation along the alternating current (ac) electric field between the microelectrode gaps. Both experiments and analysis indicate that a large orientation torque and force can be achieved by choosing an optimal frequency around 2 MHz and decreasing the conductivity of medium to a relatively low level. Finally, electromechanical experiments and biopolar impedance measurements were performed to demonstrate the structural and functional anisotropy of electro-oriented structure 相似文献