A little high-tech plumbing and colored water may change how engineers make miniaturized fluid-carrying structures.
A team at the University of Washington in Seattle has added a new twist to the light-blocking patterns, or photomasks, used like stencils in microchip manufacturing. They've invented photomasks containing tiny, transparent pipes into which the engineers have injected dyes that dim the ultraviolet (UV) radiation passing through.
Where less UV light penetrates the photomask, there's less breakdown of the photosensitive coatings, called photoresists, that cover chips during processing. The coating left behind forms a structure of varying heights that can serve as a mold.
With their additional control over UV exposure, the researchers have patterned polymeric materials with microscopic ramps, stairs, and other complex shapes. Such graded 3-D polymer structures may go into microfluidic devices–networks of microscopic pipes, pumps, and valves that ca