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Micro-and Nanofluidics describe fluidic regimes defined by the length scale
of the flow channels, the techniques for making the devices, and the dominant physics.
Microfluidics typically implies flow through channels between 100 nm-100 microns in microfabricated silicon,
glass, or polymer systems. The physics of microfluidic systems are well-described by continuum theory, but
the changes in length scale make surface tension and electrokinetic effects important and inertial forces
unimportant. Because microfabricated devices can be made with a variety of complex geometries, a number of novel
fluidic phenomena can be explored.
Nanofluidic systems span the overlap from regions best described by continuum theory (10-100 nm) to regions best described by
individual molecular dynamics (1-10 nm). In these systems, molecular confinement must be accounted for, the
the no-slip condition at times does not hold fully, and fluid constitutive relations are strongly affected by the
existence of the boundary.
Micro- and nanofluidic systems are invariably affected by surface phenomena, thus surface chemistry strongly
affects these systems. Research often involves detailed surface measurements using macroscopic electrokinetic
effects, contact angle measurements, ellipsometry, profilometry, atomic force microscopy, and electron microscopy.
Surface modifications including self-assembled monolayers, covalent attachement of sol-gels and polymers, and
chemical etches are also common.
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