Enhanced mixing is achieved using a zig-zag pattern of punched holes.

(A) Photomicrograph of six punch card controlled pumps driven by a zig-zag pattern (right inset). Left inset depicts the same device run through a traditional syringe pump (at the same flow rate) to highlight the striking difference in fluid mixing at the end of the channel (200 μm wide). (B) Mixing is quantified by mean-shift clustering approach (see methods for details) comparing four regions in the micro-channel marked a, b, c, d along the outflow. Six identified clusters merge into two. (C) Photomicrographs from video data reveal the mechanism for mixing. Pulsatile nature of flow induces increased folding of neighboring flow lines (and hence net interface length) thus enhancing diffusion and mixing.