Figure 2: A representative gradient-generating microfluidic network.
Solutions containing different chemicals were introduced from the top inlets and allowed to flow through the network. The fluid streams were repeatedly combined, mixed, and split to yield distinct mixtures with distinct compositions in each of the branch channel. When all the branches were recombined, a concentration gradient was established across the outlet channel. The width of this channel and the total number of the branches determined the width of the gradient and the resolution of the steps making up the gradient, respectively.