Cross channel microfluidic

Figure 2.5 Schematic diagram of cross channel microfluidic (dimension in mm) [65].

Microfluidic Circuits, Fig. 1 Schematic view of a four-channel microfluidic logic gate [3]. The lengths and cross-sectional areas of the input channels A and B are the same. The flow resistance of the output channel Y is higher than that of X owing to its smaller cross-sectional area... 

Chang, C.L. Hou, H.H. Fu, L.M. Tsai, C.H. A low-leakage sample plug injection scheme for crossform microfluidic capillary electrophoresis devices incorporating a restricted cross-channel intersection. Electrophoresis 2008, 29(15), 3135-3144. 

A study of doxombicin-induced apoptosis (programmed cell death) in individual cardiomyoctes was performed using a microfluidic device created by Horky and coworkers [25]. Apoptotic DNA fragments from individual cells were electrophoreticaUy separated and detected by LIE. The device consisted of a simple cross channel design cells were injected into the device and transported by pressure-driven flow by application of a vacuum. Cell lysis was achieved by activating an electric field across the T-junction, which was filled with a 2% solution of linear polyacrylamide. 

F.F. Ouali, G. McHale, H. Javed, C. Trabi, N.J. Shirtcliffe and M. I. Newton, Wetting considerations in capillary rise and imbibition in closed square tubes and open rectangular cross-section channels. Microfluid. Nanofluid. 15,309-326 (2013). 

Microfluidic pumps, switches and valves are used to manipulate fluid flow in microchannels (flow regulation, switching, sealing) [124, 125]. The fluid displacement inside chips can also be actuated with stimuli-responsive hydrogels [126, 127]. Mechanical means of flow control are also possible. For example, a pneumatically actuated elastomeric switch works by applying external pressure across the contact area of two crossing channels situated in two different layers [13]. Thermally formed microbubbles [128] and magnetic valves [129] can also be used for flow control. 

While the previous studies refer to straight channels exceptionally, microfluidic devices often comprise channels with a curvature. It is therefore helpful to know how hydrodynamic dispersion is modified in a curved channel geometry. This aspect was investigated by Daskopoulos and Lenhoff [155] for ducts of circular cross-... 

FIGURE 11.32 Flow profiles in microchannels, (a) A pressure gradient, - AP, along a channel generates a parabolic or Poiseuille flow profile in the channel. The velocity of the flow varies across the entire cross-sectional area of the channel. On the right is an experimental measurement of the distortion of a volume of fluid in a Poiseuille flow. The frames show the state of the volume of fluid 0, 66, and 165 ms after the creation of a fluorescent molecule, (b) In electroosmotic flow in a channel, motion is induced by an applied electric field E. The flow speed only varies within the so-called Debye screening layer, of thickness D. On the right is an experimental measurement of the distortion of a volume of fluid in an electroosmotic flow. The frames show the state of the fluorescent volume of fluid 0, 66, and 165 ms after the creation of a fluorescent molecule [165], Source http //www.niherst.gov.tt/scipop/sci-bits/microfluidics.htm (see Plate 12 for color version). 

While the ring length can be increased simply by increasing the ring radius, this again leads to large structures that have a poor cross-section with the microfluidic channels. As in the case of the MZI-based devices, incorporating a folded... 

An infrared C02 laser (1060 nm) was used to cut through a polycarbonate PC (black) (carbon-coated) wafer of 250-pm thickness to create microfluidic channels. The laser-machined black PC wafer was then thermally bonded between two transparent PC wafers at 139°C under two tons of pressure for 45 min [937], A C02 laser was also used to ablate Mylar sheets (with adhesive). Then the machined Mylar sheets were laminated together [1051]. Moreover, a PMMA substrate was machined by a C02 laser [201,202]. However, the microchannel ( 200 pm deep) has a Gaussian-like cross section and a certain degree of surface roughness [201], The C02 laser has also been used to machine PET substrates [203],... 

FIGURE 5.14 (a) Schematic of a three-dimensional gated-injection separation device consisting of two crossed microfluidic channels with a PCTE membrane interconnect, (b) Electrical bias configurations for active electrokinetic injection control. (Right) Nanocapillary array gated injections. (Left) Main channel separations [591]. Reprinted with permission from the American Chemical Society. 

DEP can be used to create regular patterns of particles on a surface or in a microfluidic channel. For example, two-dimensional (2D) patterns of polystyrene latex microbeads were fabricated on glass substrates using n-DEP, and the line- and grid-patterned microparticles, which formed due to the repulsive force of this n-DEP, were covalently bound on the substrate via cross-linking agents (Suzuki et al., 2004). In this work, interdigitated microelectrodes were incorporated into a fluidic channel in order to direct the particles into very specific patterns. 

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