In this book, the commercial computational fluid dynamics tool for micro-fluidics, known as Comsol multyphysics, is used to study the effect of different configuration on pressure drop as well as to study the mixing of two fluids in T and Y shape with different configurations. Micro-mixer with obstacles located on the channel wall as well as waveform configurations are used to enhance mixing in the channel, so as to reduce the mixing length. Micro channels with different geometric layout and with different shapes and sizes of obstacles such as rectangular, triangular and semicircular, are analyzed for their mixing length. The triangular obstacles within the T as well as Y channel gave minimum mixing length for the same distance between the obstacles. Also T and Y channel with 1w spacing between waveform gave minimum mixing length. A proof of experiment is carried out to show mixing of fluids from two inlets. It is observed that mixing length required for Y shape channel without obstacle is more than Y shape channel with triangular obstacles. In Y shape channel with triangular obstacles, turbulence created at tip of obstacles which increases mixing rate.