/pdf/micro-total-analysis-systems-1-introduction-theory-and-27f7corp18.pdf

Micro Total Analysis Systems. 1. Introduction, Theory, and Technology

■ Abstract Fluid flow at the microscale exhibits unique phenomena that can be leveraged to fabricate devices and components capable of performing functions useful for biological studies. The physics of importance to microfluidics are reviewed. Common methods of fabricating microfluidic devices and systems are described. Components, including valves, mixers, and pumps, capable of controlling fluid flow by utilizing the physics of the microscale are presented. Techniques for sensing flow characteristics are described and examples of devices and systems that perform bioanalysis are presented. The focus of this review is microscale phenomena and the use of the physics of the scale to create devices and systems that provide functionality useful to the life sciences.

https://www.researchgate.net/profile/Glennys_Mensing/publication/11260597_Physics_and_applications_of_microfluidics_in_biology/links/5437f5160cf2027cbb206767.pdf

Physics and applications of microfluidics in biology.

This critical review summarizes developments in microfluidic platforms that enable the miniaturization, integration, automation and parallelization of (bio-)chemical assays (see S. Haeberle and R. Zengerle, Lab Chip, 2007, 7, 1094–1110, for an earlier review). In contrast to isolated application-specific solutions, a microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. This allows the easy, fast, and cost-efficient implementation of different application-specific (bio-)chemical processes. In our review we focus on recent developments from the last decade (2000s). We start with a brief introduction into technical advances, major market segments and promising applications. We continue with a detailed characterization of different microfluidic platforms, comprising a short definition, the functional principle, microfluidic unit operations, application examples as well as strengths and limitations of every platform. The microfluidic platforms in focus are lateral flow tests, linear actuated devices, pressure driven laminar flow, microfluidic large scale integration, segmented flow microfluidics, centrifugal microfluidics, electrokinetics, electrowetting, surface acoustic waves, and dedicated systems for massively parallel analysis. This review concludes with the attempt to provide a selection scheme for microfluidic platforms which is based on their characteristics according to key requirements of different applications and market segments. Applied selection criteria comprise portability, costs of instrument and disposability, sample throughput, number of parameters per sample, reagent consumption, precision, diversity of microfluidic unit operations and the flexibility in programming different liquid handling protocols (295 references).

/pdf/microfluidic-lab-on-a-chip-platforms-requirements-3q5qdadspt.pdf

Microfluidic lab-on-a-chip platforms: requirements, characteristics and applications

Polymer microfluidic devices

Clinical diagnostics is one of the most promising applications for microfluidic lab-on-a-chip systems, especially in a point-of-care setting. Conventional microfluidic devices are usually based on continuous-flow in microchannels, and offer little flexibility in terms of reconfigurability and scalability. Handling of real physiological samples has also been a major challenge in these devices. We present an alternative paradigm—a fully integrated and reconfigurable droplet-based “digital” microfluidic lab-on-a-chip for clinical diagnostics on human physiological fluids. The microdroplets, which act as solution-phase reaction chambers, are manipulated using the electrowetting effect. Reliable and repeatable high-speed transport of microdroplets of human whole blood, serum, plasma, urine, saliva, sweat and tear, is demonstrated to establish the basic compatibility of these physiological fluids with the electrowetting platform. We further performed a colorimetric enzymatic glucose assay on serum, plasma, urine, and saliva, to show the feasibility of performing bioassays on real samples in our system. The concentrations obtained compare well with those obtained using a reference method, except for urine, where there is a significant difference due to interference by uric acid. A lab-on-a-chip architecture, integrating previously developed digital microfluidic components, is proposed for integrated and automated analysis of multiple analytes on a monolithic device. The lab-on-a-chip integrates sample injection, on-chip reservoirs, droplet formation structures, fluidic pathways, mixing areas and optical detection sites, on the same substrate. The pipelined operation of two glucose assays is shown on a prototype digital microfluidic lab-on-chip, as a proof-of-concept.

An integrated digital microfluidic lab-on-a-chip for clinical diagnostics on human physiological fluids

This paper describes a microfluidic system in which fluids are pumped by centrifugal force through microscopic channels defined in a plastic disk in order to perform complex analytical processes. The channels are created either by casting poly(dimethylsiloxane) against molds fabricated by photolithography or by conventional machining of poly(methyl methyacrylate). The channels have a wide range of diameters (5 μm−0.5 mm) and depths (16 μm−3 mm). Fluids are loaded into reservoirs near the center of the disk, the disk is rotated on the shaft of a simple motor at 60−3000 rpm, and the fluids are pumped outward by centrifugal force through microfluidic networks. The control of flow in the time domain, i.e., gating, is achieved by the use of passive valves based on capillary forces. Flow rates ranging from 5 nL/s to >0.1 mL/s have been achieved using channels of different dimensions and different rates of rotation. The method of pumping is insensitive to many physicochemical properties of the liquid, such as pH...

Microfabricated Centrifugal Microfluidic Systems: Characterization and Multiple Enzymatic Assays

This invention relates to methods and apparatus for performing microanalytic and microsynthetic analyses and procedures. The invention provides a microsystem platform and a micromanipulation device for manipulating the platform that utilizes the centripetal force resulting from rotation of the platform to motivate fluid movement through microchannels. The invention specifically provides devices and methods for performing miniaturized in vitro amplification assays such as the polymerase chain reaction. Methods specific for the apparatus of the invention for performing PCR are provided.

Devices and methods for the performance of miniaturized in vitro amplification assays

This invention relates to methods and apparatus for performing microanalytic and microsynthetic analyses and procedures. The invention particularly provides microsystem platforms for achieving efficient mixing of one or a plurality of fluids on the surface of the platform when fluid flow is motivated by centripetal force produce by rotation.

Bidirectional flow centrifugal microfluidic devices

This invention relates to methods and apparatus for performing microanalytic and microsynthetic analyses and procedures. The invention provides a microsystem platform and a micromanipulation device for manipulating the platform that utilizes the centripetal force resulting from rotation of the platform to motivate fluid movement through microchannels. These assays may be performed for a variety of purposes, including but not limited to screening of drug candidate compounds, life sciences research, and clinical and molecular diagnostics. Methods specific for the apparatus of the invention for performing any of a wide variety of microanalytical or microsynthetic processes are provided.

Devices and methods for the performance of miniaturized homogeneous assays

This invention relates to methods and apparatus for performing microanalytic and microsynthetic analyses and procedures. The invention provides a microsystem platform and a micromanipulation device for manipulating the platform that utilizes the centripetal force resulting from rotation of the platform to motivate fluid movement through microchannels. The microsystem platforms of the invention are provided having arrays of thermal control regions, wherein fluid applied to the platform can be placed at a temperature and maintained at that temperature for a time that is dependent on the path length of the channel in the region, the cross-section dimension of the channel, and the rotational speed of the platform. Methods specific for the apparatus of the invention for performing any of a wide variety of microanalytical or microsynthetic processes are provided.

Gregory J. Kellogg

Papers

Microfabricated Centrifugal Microfluidic Systems: Characterization and Multiple Enzymatic Assays

Devices and methods for the performance of miniaturized in vitro amplification assays

Bidirectional flow centrifugal microfluidic devices

Devices and methods for the performance of miniaturized homogeneous assays

Centripetally-motivated microfluidics system for performing in vitro hybridization and amplification of nucleic acids