Micromachining technology was used to prepare chemical analysis systems on glass chips (1 centimeter by 2 centimeters or larger) that utilize electroosmotic pumping to drive fluid flow and electrophoretic separation to distinguish sample components. Capillaries 1 to 10 centimeters long etched in the glass (cross section, 10 micrometers by 30 micrometers) allow for capillary electrophoresis-based separations of amino acids with up to 75,000 theoretical plates in about 15 seconds, and separations of about 600 plates can be effected within 4 seconds. Sample treatment steps within a manifold of intersecting capillaries were demonstrated for a simple sample dilution process. Manipulation of the applied voltages controlled the directions of fluid flow within the manifold. The principles demonstrated in this study can be used to develop a miniaturized system for sample handling and separation with no moving parts.

Micromachining a miniaturized capillary electrophoresis-based chemical analysis system on a chip

http://hg272.persiangig.com/che/Most%20Populare%20Papers/Micromixers%E2%80%94a%20review%20on%20passive%20and%20active%20mixing%20principles.pdf

Micromixers—a review on passive and active mixing principles

Polymers have assumed the leading role as substrate materials for microfluidic devices in recent years. They offer a broad range of material parameters as well as material and surface chemical properties which enable microscopic design features that cannot be realised by any other class of materials. A similar range of fabrication technologies exist to generate microfluidic devices from these materials. This review will introduce the currently relevant microfabrication technologies such as replication methods like hot embossing, injection molding, microthermoforming and casting as well as photodefining methods like lithography and laser ablation for microfluidic systems and discuss academic and industrial considerations for their use. A section on back-end processing completes the overview.

Polymer microfabrication technologies for microfluidic systems

A fully integrated biochip device that consists of microfluidic mixers, valves, pumps, channels, chambers, heaters, and DNA microarray sensors was developed to perform DNA analysis of complex biological sample solutions. Sample preparation (including magnetic bead-based cell capture, cell preconcentration and purification, and cell lysis), polymerase chain reaction, DNA hybridization, and electrochemical detection were performed in this fully automated and miniature device. Cavitation microstreaming was implemented to enhance target cell capture from whole blood samples using immunomagnetic beads and accelerate DNA hybridization reaction. Thermally actuated paraffin-based microvalves were developed to regulate flows. Electrochemical pumps and thermopneumatic pumps were integrated on the chip to provide pumping of liquid solutions. The device is completely self-contained:  no external pressure sources, fluid storage, mechanical pumps, or valves are necessary for fluid manipulation, thus eliminating possibl...

Self-contained, fully integrated biochip for sample preparation, polymerase chain reaction amplification, and DNA microarray detection.

PDMS is enjoying continued and ever increasing popularity as the material of choice for microfluidic devices due to its low cost, ease of fabrication, oxygen permeability and optical transparency. However, PDMS's hydrophobicity and fast hydrophobic recovery after surface hydrophilization, attributed to its low glass transition temperature of less than -120 degrees C, negatively impacts on the performance of PDMS-based microfluidic device components. This issue has spawned a flurry of research to devise longer lasting surface modifications of PDMS, with particular emphasis on microfluidic applications. This review will present recent research on surface modifications of PDMS using techniques ranging from metal layer coatings and layer-by-layer depositions to dynamic surfactant treatments and the adsorption of amphipathic proteins. We will also discuss significant advances that have been made with a broad palette of gas-phase processing methods including plasma processing, sol-gel coatings and chemical vapor deposition. Finally, we will present examples of applications and future prospects of modified PDMS surfaces in microfluidics, in areas such as molecular separations, cell culture in microchannels and biomolecular detection via immunoassays.

Recent developments in PDMS surface modification for microfluidic devices

The microchip capillary electrophoresis (CE) devices were fabricated in polycarbonate (PC) plastic material by compression molding. The molded devices were enclosed utilizing thermal bonding to another PC wafer. These thermal bonds do not yield up to an applied force equivalent to 150 psi. Aqueous fluid transport inside the plastic CE devices was enhanced by UV irradiation treatment of the hydrophobic polycarbonate plastic surfaces prior to thermal bonding. In comparison to glass microchannels, electroosmotic flow (EOF) in native PC channels is low and is independent of buffer pH at pH 7 and 9. UV irradiation of PC surfaces increases surface hydrophilicity and increases EOF. CE DNA separation was demonstrated in these PC CE devices with good resolution and run-to-run reproducibility. The on-chip PCR/CE analysis of a 500-bp region of bacteriophage λ DNA was also demonstrated.

Microfabricated polycarbonate CE devices for DNA analysis.

Plastic biochannel hybridization devices: a new concept for microfluidic DNA arrays.

Microfluidics technology shows excellent potential for applications in biotechnology, chemical sensing, and drug delivery The use of microfluidics results in cycle time reduction, reagent cost and labor intensity savings due to the benefits of miniaturization, and functional integration As a result, miniature DNA sample preparation and analytical devices may potentially become part of a point-of-care systems for rapid medical diagnoses Similar diagnostic devices will benefit veterinary and food safety applications In this paper, we discuss design, fabrication, and testing of plastic microfluidic devices for on-chip genetic sample preparation These fabrication methods are being used to produce components of a complete genetic sample preparation micro-system The detailed discussion on the development of micro-PCR (polymerase chain reaction) devices and bio-channel hybridization arrays is given We also describe a path to further individual component integration

Development of Plastic Microfluidic Devices for Sample Preparation

Microfluidic biochannel arrays that integrates massively parallel microfluidic channels with Motorola glass-based microarray biochips have been successfully developed. We demonstrated that such a device allows DNA hybridization assays to be performed in a miniaturized and highly parallel fashion. The biochannel arrays are a new DNA diagnostics platform that has several desirable features such as single-use and cost-effective, highly parallel (up to 52 protocols in parallel), and processed rapidly. Additionally, only nanoliter-volumes (/spl sim/100 nL) of DNA sample/reagents are consumed per array.

Highly parallel integrated microfluidic biochannel arrays

A plastic 3D “L-shaped” serpentine micromixer is developed to enhance mixing of biological samples. Both numerical simulation and experiments show such a device has high mixing efficiency and low shear strain field.

Dale Ganser

Papers

Microfabricated polycarbonate CE devices for DNA analysis.

Plastic biochannel hybridization devices: a new concept for microfluidic DNA arrays.

Development of Plastic Microfluidic Devices for Sample Preparation

Highly parallel integrated microfluidic biochannel arrays

Plastic In-Line Chaotic Micromixer for Biological Applications