  Microfluidic mixing is a fundamental functionality in most lab on a chip
(LOC) systems,whereas realization of efficient mixing is challenging in
microfluidic channels due to the small Reynolds numbers. Here, we design and
fabricate a compact three-dimensional (3D) micromixer to enable efficient
mixing at various flow rates. The performance of the fabricated micromixer was
examined using blue and red inks. The extreme flexibility in fabricating
microfluidic structures of arbitrary 3D geometries using femtosecond laser
micromachining allows us to tackle the major disadvantageous effects for
optimizing the mixing efficiency.
