Three-Dimensional Superhydrophobic Structures Printed using Solid Freeform Fabrication Tools

Superhydrophobic surfaces exhibit a range of properties such as large contact angle, low contact angle hysteresis and icephobicity. These properties make superhydrophobic surfaces of fundamental and commercial interest as they can enable a wide variety of applications including microfluidic components, biomedical devices, and micro-batteries. Superhydrophobic behavior is achieved through a combination of the hydrophobicity of the polymer and the roughness of the surface. Two printing techniques are described in this paper to fabricate superhydrophobic surfaces with unique properties. In one approach, a commercially available multi-jet modeling rapid prototyping machine was used to fabricate 3D objects where the superhydrophobic surface is monolithic with the part. Complex, non-planar components with novel structures including helical conduits and porous meshes were fabricated. In addition, a robotic dispensing tool was developed that enables greater freedom of material selection. Both approaches have been used to fabricate arrays of surface features with diameters below 175 µm and with aspect ratios greater than 8:1. The fabrication and wetting properties of surfaces made using these two techniques will be discussed.