A generalized model for the electrokinetic flow in microfluidic devices

BERLI , CLAUDIO L. A.

Pekín, República Popular China

Congreso; 12th International Conference on Surface and Colloid Science; 2006

International Association of Surface and Colloid Scientists

Integrated microfluidic devices, as those used in chemical, biological and medical applications, basically consist of a network of microchannels that connects chambers, valves, sensors and reservoirs. In most cases, bulk fluids are electrolyte solutions and the transport through microchannels is carried out by applying pressure (hydrodynamic flow), electric fields (electro-osmotic flow), or a combination of the two. This work presents a mathematical model to predict the electrokinetic flow developed in each branch of a microchannel network, as a function of applied electric potential and pressure gradients. The coefficients that relate driving forces and conjugated flows were derived for both axis- and plane-symmetric microchannels in a common fashion. For this purpose, steady state, fully developed flows were assumed, and the simultaneous presence of electro-osmosis and streaming phenomena was considered. The model comprises microfluidic networks containing multiple junctions, channels with arbitrary values of surface potential, and electrolyte solutions with different physicochemical characteristics. In order to illustrate practical applications, typical operations performed in analytical microsystems are discussed.