Microfluidics theory in practice

© The Royal Society of Chemistry 2015. At the outset, the readers are briefly introduced to the different physical laws that govern and affect fluid flow, heat and mass transfer at the micrometre scale. Since microfluidics deals with a different physical scale from conventional analytical systems, a scaling law that depicts the importance of physical quantities in this scale is presented. To design a robust lab-on-achip (LoC) detection system, consideration must be given to the presence of a dominant laminar-flow regime and an inherent diffusion-based transport mechanism. Describing laminar flow, the readers are directed towards the Navier-Stokes equation, further developing into the Poiseuille flow, the Couette flow and the Stokes flow. As regards the transport phenomena, various physical quantities and dimensionless numbers have been mentioned to better understand the behaviour of the analyte in a system. In an effort to help the readers develop a better understanding of LoC detection systems through this chapter, the authors assert that even though numerous systems have been fully developed and characterised in the past, there still lies a lot of potential that is yet to be tapped in this field.