Micro-fluidics

Microfabrication techniques used for the production of MEMS (micro electro-mechanical systems) have been successfully used to produce highly efficient micro fluidic systems. 

A method of detecting herbicides is proposed the photosynthetic herbicides act by binding to Photosystem II (PS II), a multiunit chlorophyll-protein complex which plays a vital role in photosynthesis. The inhibition of PS II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase (HRP). The sensing device proposed combines the production and detection of hydrogen peroxide in a single flow assay by combining all the individual steps in a compact, portable device that utilises micro-fluidic components. 

Bayraktar T, Pidugu SB (2006) Characterization of liquid flows in micro-fluidic systems. Int J Heat Mass Transfer 49 815-824... 

Wen, S. M., Theories of Micro-fluidic Boundary Layers and Its Application, Beijing, Metallurgical Industry Press, 2002. 

Wegeng et al. mentioned fouling as a major problem, decreasing micro-fluidic system reliability [1]. Active control over fouling was demanded in their review, but no strategies to overcome it were given. 

Mass transfer of a solute dissolved in a fluid is not only the fundamental mechanism of mixing processes, it also determines the residence-time distribution in micro fluidic systems. As mentioned in Section 1.4, in many applications it is desir-... 

Agilent Technologies Micro Fluidic Systems Naval Medical Research Center SRI... 

Tyrrell E., Gibson C., MacCraith B.D., Gray D., Byrne P., Kent N., Burke C., Pauli B., Development of a micro-fluidic manifold for copper monitoring utilising chemiluminescence detection, Lab on a Chip 2004 4 384-390. 

Tamanaha C.R., Whitman L.J., Colton R.J., Hybrid macro-micro fluidics system for a chip-based biosensor,./. Micromech. Microeng. 2002 12 N7. 

A.E. Kamholz, B.H. Weigl, B.A. Finlayson, and P. Yager, Quantitative analysis of molecular interaction in a micro fluidic channel the T-sensor. Anal. Chem. 71, 5340—5347 (1999). 

K. Macounova, C.R. Cabrera, M.R. Holl, and P. Yager, Generation of natural PH gradients in micro fluidic channels for use in isoelectric focusing. Anal. Chem. 72, 3745—3751 (2000). 

In this method, NWs can be aligned by passing a suspension of NWs through microfluidic channel structures, for example, formed between a poly(dimethylsiloxane) (PDMS) mold 49 and a flat substrate (Fig. 11.3a). Images of NWs assembled on substrate surfaces (Fig. 11.3b) within micro-fluidic flows demonstrate that virtually all NWs are aligned along the flow direction. This alignment readily extends over hundreds of micrometers, and... 

The main feature of a micro-fluidic-based system is the presence of a micron-scale channel network in which chemical reactions and/or bio-... 

Fig. 1. Micro-fluidic chips made of different material for chemical synthesis and biochemical and chemical processing and analysis...

The relatively large surface area within micro-fluidic structures can be exploited in a proactive way to add chemical and or biological functionalisation to a process. A range of surface modification techniques have been developed and some of the more widely used techniques are outlined below. 

Fig. 4. Microwave heating system showing a micro-fluidic chip with a golden film (10 nm thick) patterned on the channel and to act as an efficient heating patch, which will have high thermal energy but low thermal mass...

The concept of an integrated micro-fluidic-based system has now been developed (Zhang et al. 2006), with an example shown in Fig. 7. This particular system is based on conventional chromatographic instrumentation and employs a multi-valving system, located between two syringe pumps, shown in the foreground, to enable the introduction of multiple reagents from an auto-sampler to be loaded onto the micro-reactor. Because of the low diffussional distances obtained in this sys-... 

Fig. 7. Illustration of an automated reagent introduction, reaction and analysis set-up based on the incorporation of a micro-fluidic device into a conventional HPLC system...

Link DR, Anna SL, Weitz DA, Stone, HA (2004) Geometrically mediated breakup of drops in micro fluidic devices. Phys Rev Lett 92 054503-1-4... 

Sumetsky, M. Dulashko, Y. Windeler, R. S., Temperature and pressure compensated micro fluidic optical Sensor, In Conference on lasers and electro optics quantum electronics and laser science conference and photonic applications systems technologies, OS A Technical Digest (CD), Optical Society of America, 2008, paper CMJ6... 

Wang C., Oleschuk R., Ouchen F., Li J., Thibault R, and Harrison D.J. (2000), Integration of immobilized trypsin bead beds for protein digestion within a micro-fluidic chip incorporating capillary electrophoresis separations and an electrospray mass spectrometry interface, Rapid Commun. Mass Spectrom. 14(15), 1377-1383. 

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