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

稳定和长期的空气保持对于许多应用都是必不可少的，包括船舶的节能低摩擦流体传输和减阻、三维细胞培养、去除石油污染、除冰和水下机器人。‘Salvinia molesta’植物为开发具有稳定和长期空气滞留的仿生表面提供了一个创新的概念。然而，目前的制造方法使其具有挑战性地构建分层结构，包括具有双尺度粗糙度的微米级超疏水头发和带有皱纹的亲水性斑块，以复制“萨尔维尼亚效应”。这笔赠款将支持开发多尺度添加剂制造(AM)工艺所需的基础研究，该工艺可以选择性地控制印刷的生物启发分层结构的粗糙度和润湿性，以实现稳定和长期的空气保持。该项目建立了多个领域的知识，包括先进制造、工艺规划、材料开发、机电一体化、控制、流体理论、建模和仿真。为了加强科学和工程教育，高中生、代表性不足的少数民族和女性将参与研究，两所合作大学将为学生和职业生涯中期专业人员规划新的课程。将通过纳入研究成果，为K-12外联和讲习班开发仿生设计和制造学习模块。为了克服现有AM技术的局限性，将建立一种电场辅助多尺度AM工艺来制备具有可控粗糙度和润湿性的仿生分层结构。这项研究将检验这一假设，即长期稳定的空气滞留可以通过改变生物启发的分层结构的形态、粗糙度和弹性来调节。该方法利用电场来控制印刷过程中碳纳米管束的分布，以获得选择性的粗糙度。本项目旨在填补3D打印过程中关于可控粗糙度的知识空白。该项目包括电场设计、多尺度印刷工艺规划、仿生形态设计、多物理建模、空气保持性评估和应用开发。研究小组将对打印的生物灵感分层结构的粗糙度、弹性、流体接触角以及滞留空气的体积和稳定性进行表征。长期稳定的空气滞留的基本机制将被确定为双尺度粗糙度和生物启发结构的形态的函数。这项研究将为制造生物启发的功能表面/界面结构提供科学和工程知识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.