Micro/Nanofluidics

Microfluidics is the manipulation of fluids in channels, with at least two dimensions at the micrometer or submicrometer scale. This is a core technology in a number of miniaturized systems developed for chemical, biological, and medical applications. Both gases and liquids are used in micro-/nanofluidic applications, ° and generally, low-Reynolds-number hydrodynamics is relevant to bioMEMS applications. Typical Reynolds numbers for biofluids flowing in microchannels with linear velocity up to 10 cm/s are less than Therefore, viscous forces dominate the response and the flow remains laminar. 

In practice, specimen quality usually limits d ui to a value greater than this theoretical lower limit. The best horizontal resolution typically attained via confocal microscopy is approximately 0.2 pm, while the best vertical resolution is 0.5 pm [1]. This Encyclopedia focuses on fluorescence detection using confocal microscopy as adapted for micro-/nanofluidics research. 

Liquid handling Micro-/nanofluidics Surface acoustic waves... 

Fig. 1 Illustration of a fully integrated Lab-on-a-Chip (LOC) system. Historically, the analysis component was first to be miniaturized and is indispensable to detect the analyte it often includes the indieated upstream separation process. Sample preparation is often required to make real-world samples amenable to analysis the core micro-/ nanofluidic chip thus consists of these three components, often connected by microchaimels. For systems to be manufactured inexpensively in large volumes, the micro-/nanofluidic chip might be fabricated on a consumable plastic card or other supporting substrate. Reagents may be needed for sample preparation or...

Fluid flow in small devices acts differently from those in macroscopic scale. The Reynolds number (Re) is the most often mentioned dimensionless number in fluid mechanics. The Re number, defined by pf/L/p, represents the ratio of inertial forces to viscous ones. In most circumstances involved in micro- and nanofluidics, the Re number is at least one order of magnitude smaller than unity, ruling out any turbulence flows in micro-/nanochannels. Inertial force plays an insignificant role in microfluidics, and as systems continue to scale down, it will become even less important. For such small Re number flows, the convective term (pu Vu) of Navier-Stokes equations can be dropped. Without this nonlinear convection, simple micro-/ nanofluidic systems have laminar, deterministic flow patterns. They have parabolic velocity... 

The kinetic theory of liquid is less well developed compared to the gas kinetic theory. Continuous approaches in micro-/nanofluidics are often used in practice with modifications to the wall boundary conditions and the surface-flow interaction mechanisms. 

Planar Waveguide-Based Optofluidics As mentioned before, the planar waveguide can be easily combined with micro-/nanofluidic chip... 

Although there are numerous merits to optofluidic manipulation of biomolecules, it still is a long way from reaching the destination where the ideal optofluidic chip can trap and suspend the limited molecules in the micro-/nanofluidic solution for as longer as the researcher or clinical operator wants. Secondly, the ideal optofluidic chip can concentrate efficiently the small molecule of interest suspending in the sample. This is significantly important for the studies, such as binding mechanisms in the development of pharmaceuticals [1]. 

Surface chemistry is of great importance in micro /nanofluidic devices, especially in the case of miniaturized and integrated systems, owing to the high surface area-to-volume ratio. Surface properties play a vital role in a number of microfluidic devices through hydrophobic and electrostatic interactions. Protein and cell adhesion at surfaces can occur because of hydrophobic and electrostatic interactions, which is undesirable in bioanalytical applications. Control of surface properties is thus an indispensable prerequisite in microfluidic systems. The approach generally adopted is to modify the surface chemistry of the device to make it more useful for various applications. 

There are two forms of DEP being used in the micro-/ nanofluidic community. Most commonly, DEP is driven by electric field non-uniformities arising from multiple electrodes embedded throughout a fluidic system Recently considerable interest has been shown in insulator-based dielectrophoresis (IDEP), an alternative approach to conventional DEP. IDEP has also been called electrodeless... 

Taking advantage of the IME, the capture of bacterial cells in a micro-/nanofluidic device could he realized using dielectrophoresis (DEP). DEP is the electroki-netic motion of dielectrically polarized particles in non-uniform electric fields [9]. Combining the advantages of DEP concentration and antibody capture, target cells may be captured from a flow field achieved in a microfluidic biochip [8]. With the assistance of DEP to capture cells within the microfluidic device, IME impedi-... 

Y. Wang and B. Bhushan, Boundary slip and nanobubble study in micro/nanofluidics using atomic force microscopy. Soft Matter, 6, 29-... 

Future research will be focused in the development of small portable and automated systems that can be applied to a large number of species simultaneously in real samples. Downscaling of the analytical system toward a micro, nanofluidic format has become the trend for the development of future devices. Similarly to the larger-scale flow analysis, microfluidics systems are coupled with various methods to enhance the sensitivity of the... 

In parallel to the microelectromechanical systems (MEMS)-based approaches for miniaturizing of conventional power sources, micro/nanofluidics can provide new approaches for energy conversion systems [12] and take advantage of the specific phenomena that emerge by downsizing the fluidic systems. 

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