Microfluidics is recognized as a powerful tool to perform series of experiments with high efficiency and low reagent consumption. Micromixers are known to be a very important part of the integrated microfluidic systems. The present work investigates the mixing enhancement of microfluids using a micromixer through a passive method. New type of baffles based on topology optimization are presented to augment the advection part of the mixing. Numerical simulation is carried out using Comsol Multiphysics software. The results are verified using experimental findings collected from a manufactured sample of the designed micromixer. The demonstrated geometry causes the entire mixing to take place at a short time and the length of a microchannel. The mixing quality was declined by increasing Reynolds number from Re = 0.2-5. In addition, the mixing mechanism in this range is a pure diffusion. Consequently, an increase of the Reynolds number results in lower residence time and mixing index. By increasing the Reynolds number (exceeding Re = 5), the mixing index can be improved (reaching MI = 0.98 at Re = 100). The formation of vortexes behind the designed baffles (exceeding Re = 5) is the main proof for the enhanced mixing. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.