Abstract
Across various length scales, nature excels in organizing materials and functions into coordinated geometries. At microscale, networks of blood vessel branches elegantly across various length scales (i.e., centimeter-scale (aorta) to the micron-scale (capillaries)), optimized to meet the needs of neighboring tissues. From the macroscale, living beings utilize highly optimized materials and geometries to perform functional locomotion. The complexity found in nature far exceeds our current fabrication capabilities, and mimicking all the functions of nature has remained a distant dream. 3D printing shows promise, but it has not yet advanced to a point where it can efficiently pack the relevant materials and functions into unconstrained geometries across various length scales. This thesis presents a set of 3D printing tools, processes, and design strategies to address the question: how can we combine 3D printing and design strategies to perform biomimicry across various length scales? The focus of the thesis is on 3D-printed microfluidics for systemic biomimicry at the microscale (i.e., vasculatures, organ-on-a-chip) and macroscale (i.e., soft robotics). The first section of the thesis (Chapter 1) introduces 3D printing and how they are currently employed in microfluidics fabrication. The second section (Chapter 2, Chapter 3) of the thesis explores the various 3D-printing technologies and how a modular and minimalist approach can enable better fabrication outcomes using commercially available 3D printers. We present a modular approach to fabricating complex fluidic networks using stereolithography 3D printer and a minimalist approach for the 3D printing of integrated microfluidic systems using direct ink writing (DIW). In the third section (Chapter 4, Chapter 5), we look at how our established 3D-printing approaches can be used to mimic in vitro vasculature models and organotypic systems. The modular approach was further expanded to fabricate biomimetic vascular (i.e., hierarchical, branching, freestanding) constructs incorporated with relevant vascular cells. This section also introduces a 3D-printing-enabled organotypic platform to effectively organize multiple cell types in the length scale comparable to microvasculature (i.e., 30 – 100 µm). In the final section (Chapter 6), we zoom out to explore how 3D-printed microfluidics can also be used to mimic living systems in the macroscale. Here, we employed 3D-printed microfluidics to create lightweight actuators that can be applied to mimic the locomotion of living systems (i.e., inchworms, bats, turtles). The concluding section summarizes the role of design strategies discussed in this thesis and highlights future works and possibilities.