Microfluidic reactors

Mixed Flow Reactor-Microfluid. When a microfluid containing reactant A is treated as in Fig. 16.1, the reactant concentration everywhere drops to the low value prevailing in the reactor. No clump of molecules retains its high initial concentration of A. We may characterize this by saying that each molecule loses its identity and has no determinable past history. In other words, by examining its neighbors we cannot tell whether a molecule is a newcomer or an old-timer in the reactor. 

To fulfill such requirements, attempts have been made in the past decade by researchers working on peptide mapping and proteomics through development of immobilized microfluidic enzymatic reactors. Microfluidic enzymatic microreactors are an alternative to in-solution method employing immobilization of proteases on microchaimels of chip-based reactors or surfaces of capillaries. The microreactors that enable proteolytic digestion by enzymes immobilized on solid supports are also referred to as immobilized enzyme reactors, IMERs. The great potential of IMERS for proteomic applications comprise rapid and enhance... 

For catalyst testing, conventional small tubular reactors are commonly employed today [2]. However, although the reactors are small, this is not the case for their environment. Large panels of complex fluidic handling manifolds, containment vessels, and extended analytical equipment encompass the tube reactors. Detection is often the bottleneck, since it is still performed in a serial fashion. To overcome this situation, there is the vision, ultimately, to develop PC-card-sized chip systems with integrated microfluidic, sensor, control, and reaction components [2]. The advantages are less space, reduced waste, and fewer utilities. 

The realization of complete bench-scale micro reactor set-ups is certainly still in its infancy. Nevertheless, the first investigations and proposals point at different generic concepts. First, this stems from the choice of the constructing elements for such set-ups. Either microfluidic components can be exclusively employed (the so-caUed monolithic concept) or mixed with conventional components (the so-called hybrid or multi-scale concept). Secondly, differences concerning the task of a micro-reactor plant exist. The design can be tailor-made for a specific reaction or process (specialty plant) or be designated for various processing tasks (multi-purpose plant). 

Mills, P. L., Mitchell, R. E., Wetzel, M. D., Schmidt, M. A., Jensen, K. F., Device level integration to form a parallel microfluidic reactor system, in Ramsey,... 

The focus of the examples given in this chapter is clearly on micro reactors for chemical processing in contrast to p-TAS or Lab-Chip systems for bioanalytical applications. In the latter microfluidic systems, the fluidic requirements are somehow different from those in micro reactors. Typically, throughput plays only a minor role in p-TAS systems, in contrast to micro reactors, where often the goal is to achieve a maximum molar flux per unit volume of a specific product. Moreover, flow control plays a much greater role in p-TAS systems than in micro reactors. In... 

In chemical micro process technology there is a clear dominance of pressure-driven flows over alternative mechanisms for fluid transport However, any kind of supplementary mechanism allowing promotion of mixing is a useful addition to the toolbox of chemical engineering. Also in conventional process technology, actuation of the fluids by external sources has proven successful for process intensification. An example is mass transfer enhancement by ultrasonic fields which is utilized in sonochemical reactors [143], There exist a number of microfluidic principles to promote mixing which rely on input of various forms of energy into the fluid. 

A final example of MDFI exploiting polarization resolution is given in Fig. 4.12. This shows the application of optically sectioned TR-FAIM to image ligand binding in a microfluidic reactor [67], Solutions of a small dye molecule (Hoechst 33258) and a (nonfluorescing) 5.8 kbp DNA plasmid were mixed in a 50-/mi wide... 

Scheme 4. Synthesis of the radiolabeled imaging probe [18F]FDG 28 in a PDMS-based microfluidic reactor...

Recently, we described the application of a silicon microfluidic reactor to the assembly of oligo-0-peptides (Llogel et al. 2006). The microreactor not only allowed for quick scanning of reaction conditions, but also the procurement of synthetically useful amounts of peptides (Curran 2001 Curran and Luo 1999 Zhang 2004). 

Multiphase copolymers, Ziegler-Natta catalysts for, 26 535, 537-540 Multiphase laminar flow patterning, in microfluidics, 26 961 Multiphase reactions, in microbial transformations, 16 412-414 Multi-phase reactors, 21 333-335 Multiphoton effects, in photochemical technology, 19 109... 

Passive heat-transfer enhancement techniques, retrofitted, 13 267 Passive mixers, in microfluidics, 26 966, 967 Passive noise detectors, 11 673 Passive nondestructive tests, 17 416, 425 Passive reactors, 17 555 Passive sensing materials, 22 706-707 Passive smart textiles, 24 625 Passive solar collection, silica aerogel application, 1 761-762 Pasta products, 26 278 Paste-extrusion process, 18 301-302 Paste forming, ceramics, 5 651 Paste inks, 14 315-316... 

Flow in Microfluidic Reactors 7.4. Solid-State Electrical Characterization of 4487... 

Membraneiess Opportunities with Laminar Flow in Microfluidic Reactors... 

One way to ease any difficulties that may arise in fabricating a membrane, especially in design configurations that are not planar, is to go membraneless. Recent reports take advantage of the laminar flow innate to microfluidic reactors ° to develop membraneless fuel cells. The potential of the fuel cell is established at the boundary between parallel (channel) flows of the two fluids customarily compartmentalized in the fuel cell as fuel (anolyte) and oxidant (catholyte). Adapting prior redox fuel cell chemistry using a catholyte of V /V and an anolyte of Ferrigno et al. obtained 35 mA cmr at... 

S.-A. Leung, R.F. Winkle, R.C.R. Wootton and A.J. deMello, A method for rapid reaction optimisation in continuous-flow microfluidic reactors using online Raman spectroscopic detection, Analyst, 130, 46-51... 

In order to obtain the advantage of other high-throughput and combinatorial techniques in microfluidic reactors, it is critical that other processing and measurement... 

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