Fluidic unit

A microfluidic platform provides a set of fluidic unit operations, which are designed for easy combination within a well-defined fabrication technology. A microfluidic platform allows the implementation of different application-specific (bio-)chemical processes, automated by microfluidic process integration. 

Keywords Biosensor Detection format Environmental monitoring Fluidic unit ... 

In SPR biosensors, a fluidic unit is necessary to provide precise control of sample delivery to the sensor surface as the amount of analyte captured by the biorecognition elements (and thus the sensor response) depends on the flow conditions at the sensor surface [11,12]. 

Fig. 3 Scheme of a typical fluidic unit supporting an SPR biosensor... 

To date, several SPR biosensor systems with integrated automated fluidic system have been reported [2,19,20]. However, these devices rely on bulky components (e.g., external pumps and valves), which limits their further miniaturization. In future, we expect that development of more compact fluidic units will benefit from current advances in the micropumps and microvalves [21] and microfluidic technologies pursued for Micro Total Analysis Systems (/xTAS) and Lab-on-a-Chip devices [22-24]. 

Fig. 8 Portable SPR sensor system developed at the Institute of Radio Engineering and Electronics, Prague with SPR optical platform, fluidic unit, temperature stabilization, and supporting electronic hardware...

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... 

Viscosity is then a measure of the resistance of a material to flow. In fact, the inverse of viscosity is given the name fluidicity. A material s resistance to flow increases with its viscosity. Viscosity has been reported using a number of different names. The centimeter-gram-second (CGS) unit of viscosity is called the poise, which is a dyne seconds per square centimeter. Another widely used unit is the pascal (or Pa), which is Newton seconds per square centimeter. In fact, 1 Pa= 10 poise. 

Harry Diamond Labs. The Army has classified the Harry Diamond Laboratories at Adelphi, Maryland, as a permanent US Army installation. The facility is a corporate laboratory of the US Army Materiel Command, specializing in fuzes, fluidics, special purpose radars, nuclear weapons effects, and other research, development, and engineering for weapons systems Ref The Official Magazine of United States Army Logistics, Vol 5, No 2 (Mar-April 1973)... 

In a conventional design, each unit operation is modeled using terms and values which do not depend on the location inside the device. On the one hand, convection and diffusion in a micro structured device strongly influence the functioning of the device, and on the other hand the convection and diffusion conditions are affected by the shape of the device. To obtain an optimized fluidic micro device, some constraints on the shape of the device are necessary. These are constraints, e.g., on the average residence time, the residence time distribution and the temperature distribution [13]. 

Similar to computer technologies, so-called plug and play micro fluidic devices were developed. These devices are composed of a fluid driving unit and a polymer chip containing micro fluidic channels and reservoirs. The one and only connection is an electrical bus system which connects the chip with the external control unit. By filling the reservoirs with reagents, the chip can be used for performing chemical reactions or biochemical analysis [72],... 

R 18] A modular set of devices was developed within the pChemTec project introduced above. It consists of a base plate which is identical for all four devices. This base plate acts as the fluidic interface to the piping and is equipped with a micro structured mixer. The base plate can be combined with a heated tube to deliver a mixer-tube reactor. A combination with a porous tube delivers a degasser unit. A combination with a membrane unit (not shown) or a settler results in an extraction device (Figure 4.58). 

These examples underline the fact that macro-scale process simulation tools such as Aspen Plus will have to be supplemented by micro-type unit operations as introduced by the FAMOS initiative which consider the location of a fluidic cell in the device and does not assume a perfect mixing, piston flow or uniform heat transfer coefficient [13]. 

The field of chemical process miniaturization is growing at a rapid pace with promising improvements in process control, product quality, and safety, (1,2). Microreactors typically have fluidic conduits or channels on the order of tens to hundreds of micrometers. With large surface area-to-volume ratios, rapid heat and mass transfer can be accomplished with accompanying improvements in yield and selectivity in reactive systems. Microscale devices are also being examined as a platform for traditional unit operations such as membrane reactors in which a rapid removal of reaction-inhibiting products can significantly boost product yields (3-6). 

Precise control of concentration and residence time can increase the selectivity of the sulfonation of toluene, as this allows to optimally set the interplay between the readions 4.4.1-4.4.4 [315,316], The highly exothermic nature of the reaction demands for good temperature control. A single microreador is not suited to condud the various readion steps with all their different needs on temperature and residence time. Thus, a continuously operated plant with many microflow tools was developed. The plant design was based on a fluidic backbone providing unitized ports and plant unit sites to facilitate the connection of microstructured components from different suppliers (see Figure 4.49). 

Figure 4.49 Microplant for toluene sulfonation with falling-film microreactor as central apparatus and unitized backbone as fluidic bus system (by courtesy of Elsevier) [315],...

CONFUSIO — which is a pouring together, is a process for the commingling of liquids, which are naturally fluidic. Whether of the parts or of the whole, the consistency is aqueous, or fluidic. At the same time, there are many liquid substances which will unite readily without any methodical process. 

DIGESTION — That action by which a liquid body and a fluidic body are united, either wholly or in part, to extract their tincture, to modify them, to prepare them for dissolution or putrefaction, to cause them to circulate, and thus to volatilize the fixed and to fix the volatile by means of proportioned heat. Almost all the operations of the Great Work may be reduced to that of digestion, which the Philosophers call by various names, according to the phenomena which they have remarked in the vessel at the various stages of the operation. Thus when they make use of the terms Distillation, Sublimation, Imbibition, Ceration, Inspissation, Descension, Solution, Emission, Coagulation, etc., they understand one only operation, or digestion repeated in the medicines of the first, second and third order. 

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