Dynamic Microfluidic Photomasking

This paper presents a novel microfluidic photomasking strategy. Laminar microfluidic streaming is exploited to achieve photomasking with dynamic spatial control. Two light-absorbing streams hydrodynamically focus a transparent stream to define a line of light transmission. A device incorporating two such microfluidic layers, which are aligned orthogonally, enables light transmission only where the transparent streams overlap. Control of fluid flow in the microfluidic layers enables dynamic spatial control of the exposed region. The dynamic microfluidic photomasking strategy is tested through transmitted light microscopy and applied to microfabrication via photoresist patterning. When applied to microfabrication in a frontal photopolymerization mode, this method affords both planar and depthwise control of feature geometry.