Chip Micro-reactor devices

Liquid transport is achieved by hydrostatic action, pumping or electroosmotic flow (EOF). So far, chip reactors have been employed at low to very low flow rates, e.g. from 1 ml min to 1 pi min. Applications consequently were restricted to the laboratory-scale or even solely to analytics. However, this is not intrinsic. By choosing larger internal dimensions, similar throughputs as for the other classes of liquid or liquid/liquid micro reactors are in principle achievable. 

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This class of hybrid components comprises chip micro-reactor devices, as described in Section 4.1.3, connected to conventional tubing. This may be H PLC tubing which sometimes has as small internals as micro channels themselves. The main function of the tubing is to provide longer residence times. Sometimes, flow through the tube produces characteristic flow patterns such as in slug-flow tube reactors. Chip-tube micro reactors are typical examples of multi-scale architecture (assembly of components of hybrid origin). 

D devices have complex requirements on assembly and, in particular, sealing. Integration of sensing is not as facile as for chip micro reactors. In turn, 3-D devices are robust and comprise the classical materials for chemical engineering apparatus. 

Micro Total Analysis Systems (pTAS) are chip-based micro-channel systems that serve for complete analytics. The word Total refers to the monolithic system character of the devices, integrating a multitude of miniature functional elements with minimal dead volumes. The main fields of application are related to biology, pharmacology, and analytical chemistry. Detailed applications of pTAS systems are given in Section 1.9.8. Recently, pTAS developments have strongly influenced the performance of organic syntheses by micro flow (see, e.g., [29]). By this, an overlap with the micro-reactor world was made, which probably will increase more and more. 

A chip-type micro reactor array comprises parallel mixer units composed of inverse mixing tees, each followed by a micro channel that it is surrounded by heat exchange micro channels (so called channel-by-channel approach similar to the tube-in-tube concept). Such an integrated device was developed as a stack of microstructured plates made of a special glass, termed Foturan (Figure 4.26). The integrated device was attached to PTFE tubes of various lengths. 

For the low power supply in the range of few watts, chip-like reactors were developed by several groups. Frequently, production techniques usually applied for fabrication of Micro Electro Mechanical Systems (MEMS) were adapted to fabricate these small reactors. The devices are actually micro , not just as far as their channel dimensions are concerned, but also due to their outer dimensions. 

Microfluidic devices have become a marketable reality in the fields of chemistry and biology. Markets exist for micro total analysis systems (pTAS), polymerase chain reaction (PCR) chips, micro chemical reactors, etc. These micro devices are being produced using a variety of thermoplastics such as polycarbonate (PC), polymethylmethacrylate (PMMA), and cyclic olefin copolymer (COC), along with thermosets (PDMS and UV eurable polymers). 

Without being itself a screening device, the reactor of Jensen et al. [6, 42, 43] also has to be mentioned because they opened up a completely new field in catalysis by combining MEMS (micro-electro-mechanical systems) technology with a chip-based catalytic reactor (Fig. 4.10). A mixing-tee was equipped with heaters and temperature and flow sensors, thus giving on-stream information about the reaction conditions. 

In Sections 2.4-2.6 micro structured testing reactors for reforming, combustion and gas purification purposes and chip-like devices are presented Section 2.7 is dedicated to integrated reactors and micro structured fuel processor concepts and... 

So far, only a few reports have been dedicated solely to this topic. The available ones most often were developed for chip devices based on control concepts known from micro electronics. Although the concepts are probably not directly transferable to micro structured reactors of larger size, they may nonetheless serve as describing generic paths for how to approach the problem. 

A modular micro structured chemical reaction system (ICS) similar to [R 14] is claimed by Bard [84]. The system can use various replaceable and interchangeable cylindrical or rectangular reactors. Generally, the ICS system can include fluid flow handling and control components, mixers, reaction chip-type units, separator devices, process variable detectors and controllers and a computer interface for communicating with the master control center (see Figure 4.31) [84],... 

Microfluidic systems are based on Total Analysis System (TAS), which aims to diminish and accumulate all steps of analysis of a sample onto a single device (Guo et al., 2015). This system has to have driving equipment like pumps and reactors and necessary parts of the chemical processes like sample preparation, filtration, dilution, reaction, and detection (Guo et al., 2015 Connelly et al., 2012). Meanwhile, the miCToflnidic analytical platform. Micro Total Analysis System (pTAS), means a single miCTometer chip that contains the whole laboratory (Guo et al., 2015 Dittrich et al., 2006 Kovarik et al., 2013). 

Lab-on-a-chip devices of this kind, so-called micro-total analysis systems ((xTAS), are textbook examples of how an appropriate reactor design considerably facilitates analyses. These systems benefit from highly efficient heat transfer in different reaction zones, thus allowing for realizing a complete sequence of different reactions within a single reaction channel. It is for these reasons that jtTAS are particularly well suited for nucleic acid analyses by means of the polymerase chain reaction (PCR). Other fields of application comprise molecular diagnostics or forensics [53]. 

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