Microfluidic devices designes

Young-Laplace equation, 21 Y-shaped microfluidic device, design, 201, 201 f... 

The microfluidic device design and the relative flow rate of sheath and sample play important roles in hydrodynamic focusing. Lee et al. [6] proposed a theoretical model to predict the width of focused center flow inside a microfabricated flow cytometer [6]. Based on potential flow theory, they derived the equation for flow inside a planar microfabricated flow cytometer under the two-dimensional situation shown in Fig. 3a. The flow is considered laminar, and the diffusion and mixing between focused stream and sheath flows is assumed negligible. With these assumptions, conservation of mass yields... 

For saving samples, reducing cross-contamination and operating fluids with smaller volume in microfluidic devices, designers hope that the dimensions of channels or tubes are as small as possible. When the characteristic dimension of channels decreases to the nanoscale, picoliter-scale flow will occur. De Heij et al. [4] designed a nozzle array of 50 xm diameter, which can produce... 

Interestingly, these studies also illustrate that a systematic variation in topological pattern within the bounds of a TPL yields a driving force for liquid transport not reliant on capillary suction (Figure 3), which may have implications for microfluidic device design. 

Losey MW, Jackman RJ, Firebaugh SL, Schmidt MA, Jensen KF (2002) Design and fabrication of microfluidic devices for multiphase mixing and reaction. J Microelectromech Syst 11 709-717... 

Microchips fabrication with integrated tips can result in improved spray repeatability and efficiency since alignment and dead volume are not a critical issue anymore. However, production of fine and robust nanospray emitters as an integral part of a microdevice is not trivial, and highly specialized microfabrication procedures are required. Microfluidic devices with integrated ESI tips have been produced for infusion experiments, but to date, no microchips with such a design was fabricated for CE separation prior to MS detection. 

Zhu et al. [76] designed and fabricated microfluidic devices on polymethylmethacrylate (PMMA) substrates for electrochemical analysis applications using an improved UY-LIGA process. The microchannel structures were transferred from a nickel mold onto the plastic plates by the hot embossing... 

Kauppila et al. [28] developed a microfabricated heated nebulizer chip for atmospheric pressure photoionization-mass spectrometry. Various materials have been used to design and develop hyphenation of microfluidic devices and ESI-MS. These materials are photoresist SU-8 [29,30], polymers [31,32], and glassy carbon [33]. Thorslund et al. [34] developed a chip on which sample injection, separation, and ESI-emitter structures are integrated... 

Microfluidics and miniaturization hold great promise in terms of sample throughput advantages [100]. Miniaturization of analytical processes into microchip platforms designed for micro total analytical systems (/i-TASs) is a new and rapidly developing field. For SPE, Yu et al. [123] developed a microfabricated analytical microchip device that uses a porous monolith sorbent with two different surface chemistries. The monolithic porous polymer was prepared by in situ photoinitiated polymerization within the channels of the microfluidic device and used for on-chip SPE. The sorbent was prepared to have both hydrophobic and ionizable surface chemistries. Use of the device for sorption and desorption of various analytes was demonstrated [123]. 

FIGURE 3.24 Schematic diagram of a microfluidic device that creates a concentration gradient and a temperature gradient. The inset shows the channel layout design [447]. Reprinted with permission from Reprinted with permission from the American Chemical... 

Dodge, A., Fluri, K., Linder, V., Lettieri, G., Linchtenberg, J., Verpoorte, E., de Rooij, N.F., Valveless, sealed microfluidic device for automated heterogeneous immunoassay Design and operational considerations. Micro Total Analysis Systems, Proceedings of the 4th TTAS Symposium, Enschede, Netherlands, May... 

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