Optimization of micro-mixing components is vital for efficient micro-electromechanical systems (MEMS) and lab-on-a-chips. In this area, it is ideal to have a universal micro-mixer design for general purpose multiple-phase fluidic mixing. Numerical methods to compute and analyze the mixing process in the spiral micro-mixer design are presented. This spiral design has also been found to be efficient for intra-droplet mixing as well as continuous particle separation by utilizing its attributing Dean flows. Analysis on the mixing performance of this design serves to present Archimedes’ spiral as a robust solution and exemplifies the effects of minute yet effective alterations to the design.