Combinatorial Additive Manufacturing Approach for Fabricating Nano/Micro 3D Structures

The fabrication of three dimensional structures in free space is important for building certain miniaturized devices. Additive manufacturing popularly called as 3D printing is critical in advancing this field. Over the past three decades additive manufacturing methods have been explored to build complex parts using metals, ceramics and polymers. However, many of these methods can fabricate structures at a fixed dimension with minimal control on the local composition and microstructure. This limits their applicability to the manufacturing of novel devices which require variation in local topography. This research aims to develop a combinatorial additive process by combining microextrusion and droplet based fabrication methods. The hybrid manufacturing method will enable the fabrication of structures that have controlled density, material content, lattice structure, porosity and geometrical configuration based on the application intent. Typical applications include tissue engineering scaffolds, high performance energy devices, and embedded electronics for aerospace components. This research will positively impact the US economy by spurring jobs within the industrial sector and lead to fundamental process investigations within the academic and research communities. This research will impact underrepresented students in discovery based learning of advanced manufacturing methods at a historically black university.

This research investigates the additive manufacturing of hierarchical nano/microstructures using a combination of filament based micro extrusion and droplet based manufacturing. The objectives of this research include: (1) understanding micro/nano structure formations using the hybrid approach; (2) studying the filament extrusion, nano/micro droplet deposition, laser irradiation and solidification of materials; and (3) establishing relationships among interacting process parameters by experimental design of hybrid process. The micro extrusion process will be employed to deposit microscale filaments of material based on the nozzle size. These filament lattice structures will be deposited with droplets ranging from nano to micro size based on a scalable direct-write manufacturing method. The droplet content can range from molten metal, polymers to nanoparticle solutions which serve as an effective method to infiltrate selective regions of the filament to produce the desired microstructure and material property. High power CO2 laser system will be used to selectively sinter the deposited structures in multiple layers to generate a 3D part. Using finite element analysis and molecular dynamics models, computational models will be developed to study intriguing multiphysics phenomena during the interaction of micro filament structures with micro and nano droplets.