Figure 2.

Fabrication of the two-layer device. (a) Three masks used for making the masters. (b) Two photolithographic masters that are used for replicating PDMS molds. The master (i) has two layers: The base of the master is white, the first layer is blue and the second layer is dark blue. The master (ii) has only the dark blue layer. (c) Two PDMS molds, the top one with three convex triangles replicated from the master (i) in (b) and the bottom one with three concave triangles replicated from the master (ii) in (b) are bonded face to face, with three pairs of concave-convex triangles on both sides matching to align the molds and make the final device. (d) The fabricated device of model XH.