3D micro-structure fabrication has attracted interest for both for fundamental issues as well as applications that include as micro-lenses for light collection and micro-droplet arrays for micro-bioassay. Previously reported methods require a fabricated 3D mold, a pulsed laser system, or photolithography protocols for individual substrates. We present a novel 3D structure fabrication technique using 2D hydrophilic / hydrophobic patterned wetting surfaces. The preparation of controlled wetting surfaces and subsequent liquid coating processes create reproducible sessile droplet arrays. These arrays can be covered with controlled thickness silicone prepolymers that are catalytically cured. The droplet array serves as a mold and the liquid is retained in the more hydrophilic regions due to a hydrophilic / hydrophobic confinement effect. The velocity of liquid application affects the volume of coated liquid yielding molds with varying feature height. Several types of liquid, including ionic liquids, water and solutions were studied to confirm the versatility of this molding process. Immiscibility between the silicone and certain ionic liquids permitted precise molding. On the other hand, the shape of resulting molded silicones when water was used depended on relative humidity, because of the significant water vapor permeability of silicones, In this talk, we will present our work on the preparation of wetting controlled surfaces, the creation and effect of the liquid droplet as a mold, and subsequent molding processes.

3D structure fabrication using 2D controlled wetting surfaces

2019 Spring National Meeting

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