Micro flow system

The integration of sensing and other functions in a micro-flow system requires either monolithic, on-chip or hybrid, multi-scale approaches. Concerning the latter, Hessel and Lowe discuss the lack of compatibility of today s fluidic interfaces and report on a German project team developing a standard for micro-reactor interconnection [9, 10]. 

The performance of the Sonogashira reaction is claimed to be the first example of a homogeneously metal-catalyzed reaction conducted in a micro reactor [120], Since the reaction involves multi-phase postprocessing which is needed for the separation of products and catalysts, continuous recycling technology is of interest for an efficient production process. Micro flow systems with micro mixers are one way to realize such processing. 

Figure 4.69 Flow scheme of a Sonogashira reaction performed in a micro flow system [120].

From the time when it was shovm that micro flow reactors can provide valuable contributions to organic chemistry, it was obvious to develop them further and their workflow towards modern screening techniques [20]. It was especially the finding of high reaction rates, the capability to transport and transform minute sample volumes and the first integration of analytics that paved the way to a parallelization of micro flow processing. These benefits were combined with the ease of automation of a micro flow system. By this means, the potential of on-line analysis of the reactions can be fully exploited. 

Iwasaki T, Kawano N, Yoshida Y-I (2006) Radical polymerization using micro flow system. Numbering-up of microreactors and continuous operation. Org Proc Res Dev 10 1126-1131... 

Tashiro, K., Ikeda, S., Sekiguchi, T., Shoji, S., Makazu, H., Funatsu, T., Tsukita, S., A particle and biomolecules sorting micro flow system using thermal gelation of methyl cellulose solution. Micro Total Analysis Systems, Proceedings 5th i.TAS Symposium, Monterey, CA, Oct. 21-25, 2001, 471-473. 

Verpoorte, E., Manz, A., Widmer, H.M., van der Schoot, B., de Rooji, N.F., A three-dimensional micro flow system for a multi-step chemical analysis. Transducer 1993, 939-942. 

Numerical simulations of styrene free-radical polymerization in micro-flow systems have been reported. The simulations were carried out for three model devices, namely, an interdigital multilamination micromixer, a Superfocus interdigital micromixer, and a simple T-junction. The simulation method used allows the simultaneous solving of partial differential equations resulting from the hydrodynamics, and thermal and mass transfer (convection, diffusion and chemical reaction). 

J.C. Fettinger, A. Manz, H. Ludi, FLM. Widmer, Stacked modules for micro flow systems in chemical analysis concept and studies using an enlarged model, Sensor Actuator B 17 (1993) 19. 

The impurity by over-alkylation was 0.18%, while the batch impurity was 1.56% (Table 6.2) [33]. This was explained by the lower back-mixing in the micro-flow system. The optical purity of the microreactor product was 98.4% as compared with 97.9% at batch level. 

Suga S, Okajima M, Fujiwara K et al (2005) Electrochemical combinatorial organic syntheses using micro flow systems. QSAR Comb Sci 24 728-741... 

Figure 14.6 Schematic diagram of a micro-flow system for controlled anionic polymerization. M, T-shaped micro-mixer R, micro-tube reactor THF, tetrahydrofuran. (Reprinted with permission from Ref [9] 2011, American Chemical Society.)...

T. Kawaguchi, H. Miyata, K Ataka, K. Mae, J. Yoshida, Room temperature Swern oxidation using micro flow system, Angew. Chem. Int. Ed. 2005, 44, 2413-2416. 

W. Liu, Z. Zhang, Y. Zhang, Chemiluminescence micro-flow system for rapid determination of chemical oxygen demand in water, Microchim. Acta 160 (2008) 141-146. 

Masayoshi Esashi, "Integrated Micro Flow Systems", Sensors and Actuators, A21-A23, 1990, pp 161-167... 

The micro flow system used for this measurement is basically the same as given in figure 1. Next to the sample and wash pumps, two additional pumps are used to supply solutions of molybdate and ascorbic acid. Between the pumps and the detector, a mixing coil of approximately 30 microliters is located. Here the reaction mixture is held for 40 seconds to let the reaction proceed before it is flushed back through the detector. The detector is a capillary detector cell of 1 mm pathlength, inter ced to a UV-visible spectrometer by means of optical fibers. The setup of the system is given in Figure 6. 

DEVELOPMENT OF A MICRO FLOW-SYSTEM WITH INTEGRATED BIOSENSOR ARRAY... 

The demand for fast and reliable measurements in analytical chemistry, medicine, biotechnology and environmental sciences has evolved the need for small, easy to handle and inexpensive analytic devices For clinical purposes different parameters have to be measured at once [1,2] One possibility to develop such micro devices is the use of integrated chemo- and biosensors implemented in a micro flow system The urgency to use micro systems is caused by the fact that an analysing system has to handle analytes as serum or whole blood in a practical way for clinicians... 

Currently we are also investigating the effect of covalent immobilisation of different ion receptors for heavy metal ions, which can be used in a micro flow system and can be implemented in a total analysis system circuit. 

Figure10.12. Injection of sample volume increments into micro flow systems...

Stream. The volume element shifted can be determined by calibration. This principle is applied with all existing modern micro flow systems. 

Extremely high demands are made on detectors in micro flow systems. An oversized dead volume would frustrate all efforts at improving the efficiency of such systems. It is evident that with an overall total system volume in the microlitre range, the dead volume of the detector should not exceed the picolitre range. Otherwise, resolution would be worse than with macroscopic systems. 

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