3D printing of bioinspired microstructures for unidirectional liquid transport

Abstract

Inspired by the unidirectional liquid transport on pitcher plant peristome and Araucaria leaf, scientists have fabricated various microstructures for applications such as microfluidic devices, fog collection, and oil-water separation. However, the structures in their work were very complex and the machines they employed were rather expensive. Additionally, the liquid transported only in a linear path. To address these problems, a novel bioinspired re-entrant microstructure was designed and fabricated by a commonly used 3D printer in this project.

The liquid transport on the bioinspired re-entrant microstructure is driven by capillary driving forces between two parallel surfaces between the roof of the re- entrant microstructure and the substrate surface. After each re-entrant microstructure, gaps known as capillary breaks were introduced to achieve unidirectional liquid transport. The capillary breaks in the novel design were short enough to allow liquid movement in one direction but long enough to inhibit liquid transport in the opposite direction, resulting in unidirectional liquid transport.

Results in this project revealed that feature sizes and spacing between adjacent re-entrant microstructures have a big effect on the performance of liquid transport on the bioinspired re-entrant microstructures. Applications of microfluidic chip and oil- water separation was realized in this project. This work can serve as a guide for future research work to explore other potential applications of unidirectional liquid transport on bioinspired re-entrant microstructures.