Microsystems and Microfluidics

Abstract

Overview The main focus of micro-scale research and development is on device fabrication and expansion of microsystem applications. This implies innovative advances in the material sciences, manufacturing technology/methodology as well as creation of supportive design software. However, in this chapter we consider only the fluid flow, heat/mass transfer and particle transport aspects of microsystems, where phase changes such as boiling and condensation as well as thermal radiation are excluded (for boiling and radiation processes see Tong & Tang 1997 and Zhang 2007; among others).

Although microfluidics deals with fluid behavior in systems with “small” length scales, conventional (i.e., macro-scale) flow theory is typically applied, at least for liquid flows in microchannels with D_hydraulic ≥ 10 μm ?and standard gas flows when D_h ≥ 100 μm. However, for microchannel gas flows in the slip regime, i.e., 0.01 ≤ Kn ≤ 0.1, where the Knudsen number is the ratio of the molecular mean free path over a system length scale, modification to the velocity and temperature boundary conditions have to be made. tem equations and numerical solution techniques have to be considered.