Introduction to Microfluidics

Abstract The book includes six chapters: - Chap 1 is an introduction, including the history of microfluidics, the present situation, the market and an attempt to envision the future. - Chap 2 concerns the physics of miniaturization, in natural and microfluidic systems. A description of basic physical laws, starting with intermolecular forces, including Van der Waals and electrostatic forces is given. The three main domains of fluidics at small scales (sub nanofluidic, nanofluidics, microfluidics and millifluidics) are discussed. - Chap 3 concerns the hydrodynamics of small systems, without free interface. The foundations of the governing equations are discussed. Then the notion of slippage at walls are presented for the cases of liquids and gases. Sections are devoted to the notions of hydrodynamic resistances and capaticances. Finally, inertial microfluidics, i.e. microfluidics or millifluidics at moderate Reynolds numbers, is presented. - Chap 4 concerns the hydrodynamics of microfluidics, in the presence of free interfaces. Bbubbles an droplets in microchannels. Basics of interfaces are shown, surface tension Laplace law, wetting. Surfactants are presented and various laws are discussed - Chap 5 concerns electrokinetic phenomena. Electrokinetic equations are given, leading to Debye layer, elecroosmosis, sedimentation potential, electrophoresis, along with the various methods of separation used in the field. - Chap 6 offers an introduction to microfabrication techniques. Photolithography is presented. Techniques dedicated to hard materials. Direct writing and 3D printing are shown. Soft lithography, and in particular those using PDMS (PolyDimethylSiloxane) is presented, with applications to valving, pumping, along with recent technological approaches.