共查询到20条相似文献，搜索用时 31 毫秒
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Amit Asthana Kwang Ho Lee Kyeong-Ohn Kim Dong-Myung Kim Dong-Pyo Kim 《Biomicrofluidics》2012,6(1):012821-012821-9
In this paper, we have presented a non-lithographic embedded template method for rapid and cost-effective fabrication of a selectively permeable calcium-alginate (Ca-alginate) based microfluidic device with long serpentine delay channel. To demonstrate the versatility of the presented method, we have demonstrated two different strategies to fabricate serpentine long delay channels without using any sophisticated microfabrication techniques, in formal lab atmosphere. The procedure presented here, also, enables the preparation of a multilayered microfluidic device with channels of varying dimensions, in a single device without using any sophisticated micromachining instrumentation. In addition, we have also qualitatively studied the diffusion of small and large molecules from a Ca-alginate based microfluidic device and proposed a method to effectively control the out-flow of macro biomolecules from the crosslinked Ca-alginate matrix to create a selectively permeable matrix required for various biological and biomimetic applications, as mentioned in the Introduction section of this work. 相似文献
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Ronald Pethig 《Biomicrofluidics》2010,4(2)
A review is presented of the present status of the theory, the developed technology and the current applications of dielectrophoresis (DEP). Over the past 10 years around 2000 publications have addressed these three aspects, and current trends suggest that the theory and technology have matured sufficiently for most effort to now be directed towards applying DEP to unmet needs in such areas as biosensors, cell therapeutics, drug discovery, medical diagnostics, microfluidics, nanoassembly, and particle filtration. The dipole approximation to describe the DEP force acting on a particle subjected to a nonuniform electric field has evolved to include multipole contributions, the perturbing effects arising from interactions with other cells and boundary surfaces, and the influence of electrical double-layer polarizations that must be considered for nanoparticles. Theoretical modelling of the electric field gradients generated by different electrode designs has also reached an advanced state. Advances in the technology include the development of sophisticated electrode designs, along with the introduction of new materials (e.g., silicone polymers, dry film resist) and methods for fabricating the electrodes and microfluidics of DEP devices (photo and electron beam lithography, laser ablation, thin film techniques, CMOS technology). Around three-quarters of the 300 or so scientific publications now being published each year on DEP are directed towards practical applications, and this is matched with an increasing number of patent applications. A summary of the US patents granted since January 2005 is given, along with an outline of the small number of perceived industrial applications (e.g., mineral separation, micropolishing, manipulation and dispensing of fluid droplets, manipulation and assembly of micro components). The technology has also advanced sufficiently for DEP to be used as a tool to manipulate nanoparticles (e.g., carbon nanotubes, nano wires, gold and metal oxide nanoparticles) for the fabrication of devices and sensors. Most efforts are now being directed towards biomedical applications, such as the spatial manipulation and selective separation∕enrichment of target cells or bacteria, high-throughput molecular screening, biosensors, immunoassays, and the artificial engineering of three-dimensional cell constructs. DEP is able to manipulate and sort cells without the need for biochemical labels or other bioengineered tags, and without contact to any surfaces. This opens up potentially important applications of DEP as a tool to address an unmet need in stem cell research and therapy. 相似文献
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Gang Li Yahui Luo Qiang Chen Lingying Liao Jianlong Zhao 《Biomicrofluidics》2012,6(1):014118-014118-16
This paper presents an easy-to-use, power-free, and modular pump for portable microfluidic applications. The pump module is a degassed particle desorption polydimethylsiloxane (PDMS) slab with an integrated mesh-shaped chamber, which can be attached on the outlet port of microfluidic device to absorb the air in the microfluidic system and then to create a negative pressure for driving fluid. Different from the existing monolithic degassed PDMS pumps that are generally restricted to limited pumping capacity and are only compatible with PDMS-based microfluidic devices, this pump can offer various possible configures of pumping power by varying the geometries of the pump or by combining different pump modules and can also be employed in any material microfluidic devices. The key advantage of this pump is that its operation only requires the user to place the degassed PDMS slab on the outlet ports of microfluidic devices. To help design pumps with a suitable pumping performance, the effect of pump module geometry on its pumping capacity is also investigated. The results indicate that the performance of the degassed PDMS pump is strongly dependent on the surface area of the pump chamber, the exposure area and the volume of the PDMS pump slab. In addition, the initial volume of air in the closed microfluidic system and the cross-linking degree of PDMS also affect the performance of the degassed PDMS pump. Finally, we demonstrated the utility of this modular pumping method by applying it to a glass-based microfluidic device and a PDMS-based protein crystallization microfluidic device. 相似文献
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Xiaole Mao Ahmad Ahsan Nawaz Sz-Chin Steven Lin Michael Ian Lapsley Yanhui Zhao J. Philip McCoy Wafik S. El-Deiry Tony Jun Huang 《Biomicrofluidics》2012,6(2):024113-024113-9
In this work, we demonstrate an integrated, single-layer, miniature flow cytometry device that is capable of multi-parametric particle analysis. The device integrates both particle focusing and detection components on-chip, including a “microfluidic drifting” based three-dimensional (3D) hydrodynamic focusing component and a series of optical fibers integrated into the microfluidic architecture to facilitate on-chip detection. With this design, multiple optical signals (i.e., forward scatter, side scatter, and fluorescence) from individual particles can be simultaneously detected. Experimental results indicate that the performance of our flow cytometry chip is comparable to its bulky, expensive desktop counterpart. The integration of on-chip 3D particle focusing with on-chip multi-parametric optical detection in a single-layer, mass-producible microfluidic device presents a major step towards low-cost flow cytometry chips for point-of-care clinical diagnostics. 相似文献
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M. A. Fallah V. M. Myles T. Kr��ger K. Sritharan A. Wixforth F. Varnik S. W. Schneider M. F. Schneider 《Biomicrofluidics》2010,4(2)
Accurately mimicking the complexity of microvascular systems calls for a technology which can accommodate particularly small sample volumes while retaining a large degree of freedom in channel geometry and keeping the price considerably low to allow for high throughput experiments. Here, we demonstrate that the use of surface acoustic wave driven microfluidics systems successfully allows the study of the interrelation between melanoma cell adhesion, the matrix protein collagen type I, the blood clotting factor von Willebrand factor (vWF), and microfluidic channel geometry. The versatility of the tool presented enables us to examine cell adhesion under flow in straight and bifurcated microfluidic channels in the presence of different protein coatings. We show that the addition of vWF tremendously increases (up to tenfold) the adhesion of melanoma cells even under fairly low shear flow conditions. This effect is altered in the presence of bifurcated channels demonstrating the importance of an elaborate hydrodynamic analysis to differentiate between physical and biological effects. Therefore, computer simulations have been performed along with the experiments to reveal the entire flow profile in the channel. We conclude that a combination of theory and experiment will lead to a consistent explanation of cell adhesion, and will optimize the potential of microfluidic experiments to further unravel the relation between blood clotting factors, cell adhesion molecules, cancer cell spreading, and the hydrodynamic conditions in our microcirculatory system. 相似文献
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Massively parallel analysis of single immune cells or small immune cell colonies for disease detection, drug screening, and antibody production represents a “killer app” for the rapidly maturing microfabrication and microfluidic technologies. In our view, microfabricated solid-phase and flow cytometry platforms of the future will be complete with biosensors and electrical/mechanical/optical actuators and will enable multi-parametric analysis of cell function, real-time detection of secreted signals, and facile retrieval of cells deemed interesting. 相似文献
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Zuzana Svobodova Mohamad Reza Mohamadi Barbora Jankovicova Hermann Esselmann Romain Verpillot Markus Otto Myriam Taverna Jens Wiltfang Jean-Louis Viovy Zuzana Bilkova 《Biomicrofluidics》2012,6(2):024126-024126-12
Determination of amyloid β (Aβ) isoforms and in particular the proportion of the Aβ 1-42 isoform in cerebrospinal fluid (CSF) of patients suspected of Alzheimer’s disease might help in early diagnosis and treatment of that illness. Due to the low concentration of Aβ peptides in biological fluids, a preconcentration step prior to the detection step is often necessary. This study utilized on-chip immunoprecipitation, known as micro-immunoprecipitation (μIP). The technique uses an immunosorbent (IS) consisting of magnetic beads coated with specific anti-Aβ antibodies organized into an affinity microcolumn by a magnetic field. Our goal was to thoroughly describe the critical steps in developing the IS, such as selecting the proper beads and anti-Aβ antibodies, as well as optimizing the immobilization technique and μIP protocol. The latter includes selecting optimal elution conditions. Furthermore, we demonstrate the efficiency of anti-Aβ IS for μIP and specific capture of 5 Aβ peptides under optimized conditions using various subsequent analytical methods, including matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), capillary electrophoresis, microchip electrophoresis, and immunoblotting. Synthetic Aβ peptides samples prepared in buffer and spiked in human CSF were analyzed. Finally, on-chip immunoprecipitation of Aβ peptides in human CSF sample was performed. 相似文献
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《中国科学院研究生院学报》2001,(1)
Ｔｈｅｓｅｐａｒａｔｉｏｎｏｆｅｎａｎｔｉｏｍｅｒｓ ,ｗｈｉｃｈｄｅｍａｎｄｓｈｉｇｈｓｅｎｓｉｔｉｖｉｔｙ ,ｈｉｇｈｓｅｌｅｃｔｉｖｉｔｙａｎｄｈｉｇｈｓｅｐａｒａｔｉｏｎｅｆｆｉｃｉｅｎｃｙ ,ｉｓｍａｉｎｃｈａｌｌｅｎｇｅｔｏｃｈｅｍｉｓｔｒｙ ,ｅｓｐｅｃｉａｌｌｙａｎａｌｙｔｉｃａｌｃｈｅｍｉｓｔｒｙ .Ｃｈｒｏｍａｔｏｇｒａｐｈｙｔｅｃｈｎｉｑｕｅｓ,ｉｎｃｌｕｄｉｎｇＨＰＬＣ ,ｔｈｉｎｌａｙｅｒｃｈｒｏｍａｔｏｇｒａｐｈｙ(ＴＬＣ) ,ｇａｓｃｈｒｏｍａｔｏｇｒａｐｈｙ(ＧＣ)ａｎｄｈｉｇｈｐ… 相似文献
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动词不定式与动名词都属非谓语动词,用法复杂且灵活,不受人称和数的限制.都可充当主语、表语、宾语、定语等,但也有不同,动词不定式还可作补语、状语,而动名词可作介词宾语、短语动词等.本文就它们在语法、词法、句子结构中的异同作了详尽的比较,提出此看法. 相似文献
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动词不定式与动名词都属非谓语动词,用法复杂且灵活,不受人称和数的限制。都可充当主语、表语、宾语、定语等,但也有不同,动词不定式还可作补语、状语,而动名词可作介词宾语、短语动词等。本文就它们在语法、词法、句子结构中的异同作了详尽的比较,提出此看法。 相似文献
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《国家科学评论(英文版)》2014,(4)
<正>he year 2014 may prove to be a major turning point in China’s development of world-class science and innovation system.At the mid-term juncture of China’s Medium-and Long-Term Program(MLP)for Science and Technology(ST)development,the Ministry of Science and Technology conducted a comprehensive review and assessment 相似文献
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YAN Jun 《中国科学院院刊(英文版)》2011,25(3)
This article elucidates the background and significance of astronomy, overviews the important progress over the past decade, and points out the main scientific problems for world astronomy. Based on a comparison between China＇s astronmical facilities, existing and in planing, and the major international facilities, the author proposes some strategies for promoting China＇s astronomy. 相似文献
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r Klaus Hahlbrock 《中国科学院院刊(英文版)》2004,(2)
The common goals and the almost perfect complement of the initiatives taken in parallel at Kunming and at several Max Planck sites could serve as valuable starting points for further promoting the CAS/MPS partnership in all matching areas of ecological research. 相似文献
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Contemporary ICTs such as speaking machines and computer games tend to create illusions. Is this ethically problematic? Is it deception? And what kind of “reality” do we presuppose when we talk about illusion in this context? Inspired by work on similarities between ICT design and the art of magic and illusion, responding to literature on deception in robot ethics and related fields, and briefly considering the issue in the context of the history of machines, this paper discusses these questions through the lens of stage magic and illusionism, with the aim of reframing the very question of deception. It investigates if we can take a more positive or at least morally neutral view of magic, illusion, and performance, while still being able to understand and criticize the relevant phenomena, and if we can describe and evaluate these phenomena without recourse to the term “deception” at all. This leads the paper into a discussion about metaphysics and into taking a relational and narrative turn. Replying to Tognazzini, the paper identifies and analyses two metaphysical positions: a narrative and performative non-dualist position is articulated in response to what is taken to be a dualist, in particular Platonic, approach to “deception” phenomena. The latter is critically discussed and replaced by a performative and relational approach which avoids a distant “view from nowhere” metaphysics and brings us back to the phenomena and experience in the performance relation. The paper also reflects on the ethical and political implications of the two positions: for the responsibility of ICT designers and users, which are seen as co-responsible magicians or co-performers, and for the responsibility of those who influence the social structures that shape who has (more) power to deceive or to let others perform. 相似文献