Micro Total Analysis Systems. Recent Developments

Vilkner, Torsten; Janasek, Dirk; Manz, Andreas

doi:10.1021/ac040063q

Cited by 942 publications

(628 citation statements)

References 260 publications

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“…8,9 Currently available approaches to on-the-chip sample preparation are based on filtration4 , 8 ,33 or dielectrophoresis (DEP) 34 or require preliminary cell modification steps such as fluorescent labeling35 , 36 or tagging with magnetic beads.37 ,38 The current state of the art of these and other sample preparation methods is the focus of recent reviews. 3,6,7,10 The new leukocyte enrichment method described here has many important advantages over these technologies. It is simple, has no active (moving or otherwise) elements, requires only a small hydrostatic pressure gradient to function, and can be easily manufactured using conventional microfabrication.…”

Section: Resultsmentioning

confidence: 99%

Biomimetic Autoseparation of Leukocytes from Whole Blood in a Microfluidic Device

et al. 2004

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Leukocytes comprise less than 1% of all blood cells. Enrichment of their number, starting from a sample of whole blood, is the required first step of many clinical and basic research assays. We created a microfluidic device that takes advantage of the intrinsic features of blood flow in the microcirculation, such as plasma skimming and leukocyte margination, to separate leukocytes directly from whole blood. It consists of a simple network of rectangular microchannels designed to enhance lateral migration of leukocytes and their subsequent extraction from the erythrocytedepleted region near the sidewalls. A single pass through the device produces a 34-fold enrichment of the leukocyte-to-erythrocyte ratio. It operates on microliter samples of whole blood, provides positive, continuous flow selection of leukocytes, and requires neither preliminary labeling of cells nor input of energy (except for a small pressure gradient to support the flow of blood). This effortless, efficient, and inexpensive technology can be used as a lab-on-a-chip component for initial whole blood sample preparation. Its integration into microanalytical devices that require leukocyte enrichment will enable accelerated transition of these devices into the field for point-of-care clinical testing.The rapidly expanding field of lab-on-a-chip microanalytical devices promises inexpensive, portable, miniaturized tools that could potentially revolutionize clinical and basic research analyses by dramatically reducing sample size and handling.1 -3 An important application of this technology is the analysis of leukocytes (white blood cells) or their contents, for which these cells must first be isolated from the whole blood sample. [4][5][6][7] Blood is a 45% suspension of cells (erythrocytes, platelets, leukocytes) in plasma. Erythrocytes (red blood cells) constitute the vast majority of all blood cells and are normally ∼1000 times more abundant than leukocytes. Traditionally, several milliliters of whole blood are drawn and then centrifuged in order to separate blood cells of different density. Plasma, platelets, and white and red cells can be separated by this procedure, but it is a labor-, energy-, and time-intensive process that relies on special equipment and requires trained personnel. 8, 9 Many current microanalytical devices have no integrated sample

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Section: Resultsmentioning

confidence: 99%

Biomimetic Autoseparation of Leukocytes from Whole Blood in a Microfluidic Device

et al. 2004

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“…Reviews of various fluidic operations in microfluidic systems, such as sample preparation, sample injection, sample manipulation, reaction, separation, and detection, published in the period between 1998 and 2004 were presented by Auroux et al (2002) and Vilkner et al (2004). Three of the most important advantages of using microfluidic systems of reduced dimension for analytical applications are known to be: (1) the possibility of using minute quantities of sample and reagents (down to picoliters); (2) relatively fast reaction times when molecular diffusion lengths are of the order of the microchannel dimension; and (3) a large surface-to-volume ratio, offering an intrinsic compatibility between the use of a microfluidic system and surface-based assays.…”

Section: Introductionmentioning

confidence: 99%

Magnetic bead handling on-chip: new opportunities for analytical applications

Gijs

2004

Microfluid Nanofluid

496

555

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This review describes recent advances in the handling and manipulation of magnetic particles in microfluidic systems. Starting from the properties of magnetic nanoparticles and microparticles, their use in magnetic separation, immuno-assays, magnetic resonance imaging, drug delivery, and hyperthermia is discussed. We then focus on new developments in magnetic manipulation, separation, transport, and detection of magnetic microparticles and nanoparticles in microfluidic systems, pointing out the advantages and prospects of these concepts for future analysis applications.

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“…Not surprisingly, a considerable effort has been invested in the development of microvalves. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] While many of these microvalves are miniaturized versions of their macro, conventional counterparts, some of them are based on unconventional concepts ranging from elastomer, 9,10 hydrogel, 11,12 paraffin, 13,14 and ice valves [15][16][17][18] to colloid valves manipulated by magnetic 8 and electromagnetic 7 fields.…”

Section: Introductionmentioning

confidence: 99%

Thermally-actuated, phase change flow control for microfluidic systems

et al. 2005

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An easy to implement, thermally-actuated, noninvasive method for flow control in microfluidic devices is described. This technique takes advantage of the phase change of the working liquid itself-the freezing and melting of a portion of a liquid slug-to noninvasively close and open flow passages (referred to as a phase change valve). The valve was designed for use in a miniature diagnostic system for detecting pathogens in oral fluids at the point of care. The paper describes the modeling, construction, and characteristics of the valve. The experimental results favorably agree with theoretical predictions. In addition, the paper demonstrates the use of the phase change valves for flow control, sample metering and distribution into multiple analysis paths, sealing of a polymerase chain reaction (PCR) chamber, and sample introduction into and withdrawal from a closed loop. The phase change valve is electronically addressable, does not require any moving parts, introduces only minimal dead volume, is leakage and contamination free, and is biocompatible. CommentsFor personal or professional use only; May not be further made available or distributed.

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Micro Total Analysis Systems. Recent Developments

Cited by 942 publications

References 260 publications

Biomimetic Autoseparation of Leukocytes from Whole Blood in a Microfluidic Device

Biomimetic Autoseparation of Leukocytes from Whole Blood in a Microfluidic Device

Magnetic bead handling on-chip: new opportunities for analytical applications

Thermally-actuated, phase change flow control for microfluidic systems

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