TABLE OF CONTENTS In Chapters 1 and 2, we have analyzed the motion of a liquid under the form of microflow as well as under the form of microdrop (digital microfluidics). In reality the fluid we have studied in these two chapters is a buffer fluid containing the micro- and nanoparticles or macromolecules in which we are interested.
In the rest of this book, we focus on the behavior of the microparticles themselves in the buffer fluid. Different forces may act on the particles. At a microscopic scale, diffusion is always present, assuming that the particles are sufficiently small. Often, other physical phenomena superpose with diffusion. In Chapter 4, we deal with advection/diffusion problems; in Chapter 5, with biochemical reactions; in Chapter 7, with magnetic forces on magnetic beads; and in Chapter 8, with electric forces on charged and neutral microparticles. In this chapter we present the basis of the diffusion theory and the different approaches to solve diffusion problems.
First we analyze the basis of diffusion that is the random walk of particles due to the Brownian agitation of the fluid molecules. Next we introduce the diffusion equation of concentration and present some examples of applications in the biotechnology domain, and then we introduce the discrete Monte Carlo approach and some applications to the diffusion of macromolecules in the human body.
Because Brownian motion is a movement on a microscopic scale, it is no wonder that the Brownian motion was first discovered by biologists J. Ingenhousj and...
