This textbook introduces students to the basic physical principles to analyse fluid flow in micro- and nano-size devices. This is the first book that unifies the thermal sciences with electrostatics and electrokinetics and colloid science; electrochemistry; and molecular biology. Key concepts and principles are discussed, such as the essentials of viscous flows, introductory electrochemistry, heat and mass transfer phenomena, elements of molecular and cell biology and much more. State-of-the-art analytical and computational approaches to problems in all of these areas are presented, especially electrokinetic flows, and examples are given of the use of these approaches to design devices used for rapid molecular analysis, biochemical sensing, drug delivery, DNA analysis, the design of an artificial kidney and other transport phenomena. There are exercise problems and modern examples of applications, as well as a solutions manual available for qualified instructors.