  An increasing number of applications in biology, chemistry, and material
sciences require fluid manipulation beyond what is possible with current
automated pipette handlers, such as gradient generation, interface reactions,
reagent streaming, and reconfigurability. In this article, we introduce the
pixelated chemical display (PCD), a new scalable strategy to highly parallel,
reconfigurable liquid handling on open surfaces. Microfluidic pixels are
created when a fluid stream injected above a surface is confined by neighboring
identical fluid streams, forming a repeatable flow unit that can be used to
tesselate a surface. PCDs generating up to 144 pixels are fabricated and used
to project chemical moving pictures made of several reagents over both immersed
and dry surfaces, without any physical barrier or wall. Overall, this article
sets the foundation for massively parallel surface processing using continuous
flow streams and showcases new possibilities in both wet and dry surface
patterning and roll-to-roll processes.
