Microfluidic parallel scaling

Although the direct oxidation of ethane to acetic acid is of increasing interest as an alternative route to acetic acid synthesis because of low-cost feedstock, this process has not been commercialized because state-of-the-art catalyst systems do not have sufficient activity and/or selectivity to acetic acid. A two-week high-throughput scoping effort (primary screening only) was run on this chemistry. The workflow for this effort consisted of a wafer-based automated evaporative synthesis station and parallel microfluidic reactor primary screen. If this were to be continued further, secondary scale hardware, an evaporative synthesis workflow as described above and a 48-channel fixed-bed reactor for screening, would be used. 

Microfabrication technology used to manufacture microreactors also introduces many advantages, most notably the ability to rapidly and cheaply mass-produce devices. The low cost of microfabricated devices makes it possible for these devices to be disposable, a characteristic desirable for many medical applications. Rapid scale-up of production by operating many microreactors in parallel can also be accomplished. Microfabrication also presents the opportunity for complete systems in a single monolithic device or systems on a chip as microreactors are incorporated with chemical sensors and analysis devices, microseparation systems, microfluidic components, and/or microelectronics. 

SPR is a representative physical phenomenon that is widely utilized for label-free characterization of molecules on thin metal films. The basic principle and operation of SPR has been described in more detail in several review articles [77, 78]. The reports on SPR-based immune sensors have steeply increased for detection of analytes with low molecular weights in recent years. SPR detection in microfluidic systems can provide various advantages. Immunoreactions are completed within a short time due to small sample volumes down to the nanolitre scale. Kim et al. developed a simple and versatile miniaturized SPR immunosensor enabling parallel analyses of multiple analytes [79]. Their SPR sensor was claimed to exhibit good stability and reusability for 40 cycles and more than 35 days. Feltis et al. demonstrated a low-cost handheld SPR-based immunosensor for the toxin Ricin [80]. Springer et al. reported a dispersion-free microfluidic system with a four-channel SPR sensor platform, which considerably improved the response time and sensitivity [81]. The sensor was able to detect short sequences of nucleic acids down to a femtomole level for 4 min. Waswa et al. demonstrated the immunological detection of E. coli 0157 H7 in milk, apple juice, and meat juice extracted from... 

From the point of view of multidimensional microfluidic systems, the off-line nature of MALDI-MS analysis represents a key advantage. First, MALDI-MS allows on-chip sample processing steps to be decoupled from back-end MS analysis. This is necessary when, for example, the time scales for biomolecular separations and online MS data acquisition are incompatible. More importantly for the present discussion, off-line MALDI-MS analysis provides a method for coupling simultaneous parallel on-chip analyses with MS detection, where ESI-MS from multiple microchannels is simply... 

The effects of flow rate(s), monodispersity, energy input, and ease of parallelization are evaluated to indicate the potential of microfluidic techniques for large-scale application. Cross-flow membrane emulsification will be used as benchmark technology as it is already available and relatively easy to scale up by using several membranes in series or in parallel. Table 1 shows a summary of various effects of which more detailed information is given in the remainder of this section. 

Emulsion Preparation with Microstructured Systems, Fig. 6 Outlines of mass-parallelized microfluidic systems. Left, Y-junctions, top circular layout in the insert a single Y-junction with continuous-phase flow indicated by the light gray arrow and the dispersed-phase flow by the dark gray double-headed arrow. Bottom, linear layout, C and D represent the continuous-phase and dispersed-phase supply, respectively, and E the emulsion collecting area. Dimensions are not according to scale. Right top. 

Microvortices created within the expansion zone of a microchannel are used for label-free isolation and enrichment of rare cells within an aqueous sample, where there is sufficient size difference between rare cells and the rest of the sample. This method allows for cell separation in a high-throughput, size, and density-based manner, where target cells are concentrated from tens of milliliters of volume into smaller microliter scale volumes [9]. In this manner, isolation of cancer cells from the human blood (circulating tumor cells, CTCs) has been demonstrated using a microfluidic device generating massively parallel laminar microscale vortices. 

The percentage yield or percentage atom economy is a widely reported quantitative metric for evaluating a microfluidic synthesis route and comparing it with conventional-scale synthesis. In the case of parallel reactions, the evaluation criterion with respect to obtaining the desired product is the percentage selectivity. The figures of merit are defined below ... 

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