Collaborative Research: 3D Printing of Bioinspired Hierarchical Structures with Controllable Roughness for Stable and Long-term Air Retention

Stable and long-term air retention is essential for numerous applications, including energy-efficient low friction fluid transport and drag reduction for ships, three-dimensional cell culture, oil pollution removal, de-icing, and underwater robotics. The ‘Salvinia Molesta’ plant provides an innovative concept to develop biomimetic surfaces with stable and long-term air retention.

However, current fabrication approaches make it challenging build hierarchical structures consisting of microscale superhydrophobic hair with dual-scale roughness and wrinkled hydrophilic patches to replicate the ‘Salvinia effect.’ This grant will support fundamental research needed for the development of a multiscale additive manufacturing (AM) process that can selectively control the roughness and wettability of printed bioinspired hierarchical structures for stable and long-term air retention. This project builds knowledge in several areas, including advanced manufacturing, process planning, materials development, mechatronics, control, fluid theory, modeling, and simulation.

To enhance science and engineering education, high school students, underrepresented minorities, and females will be involved in the research and new curricula for students and mid-career professionals will be planned at both collaborative universities. Biomimetic design and manufacturing learning modules for K-12 outreach and workshops will be developed by incorporating the research outcomes.

To overcome the limitations of current AM techniques, an electrical-field-assisted multi-scale AM process will be established for fabricating bioinspired hierarchical structures with controllable roughness and wettability. The research will test the hypothesis that long-term stable air retention can be modulated by changing the morphology, roughness, and elasticity of bioinspired hierarchical structures.

The approach utilizes the electric field to control the distribution of carbon nanotube (CNT) bundles during the printing process for selective roughness. This project aims to fill the knowledge gap on controllable roughness during the 3D printing process. The project includes tasks involving electric field design, multiscale printing process planning, biomimetic morphology design, multi-physics modeling, air retention evaluation, and application development.

The research team will characterize the roughness, elasticity, fluid contact angle, and the volume and stability of trapped air of printed bioinspired hierarchical structures. The fundamental mechanisms for long-term stable air retention will be determined as a function of dual-scale roughness and the morphology of bioinspired structures. The research will provide scientific and engineering knowledge for fabricating bioinspired functional surface/interface structures.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.