A three-dimensional microfluidic mixer of a homogeneous mixing efficiency fabricated by ultrafast laser internal processing of glass

We design a compact three-dimensional (3D) micromixer based on the Baker's transformation concept and fabricate it in fused silica by ultrafast laser direct writing. One of the issues in the micromixer is the unbalanced mixing efficiencies between the center and boundary areas of the microfluidic channel. We overcome this problem by periodically exchanging the microstreams in the center and near the boundary which gives rise to improved mixing efficiency and uniformity. The performance of the fabricated micromixer is examined by mixing a blue and a yellow ink solution, showing efficient mixing with a high throughput.