UC Irvine

Architected materials are a novel class of materials consisting of a (generally) periodic repetition of a geometrically defined unit cell in three dimensions. As their properties are determined not only by the constituent solid, but also (and predominantly) by the architecture (i.e., the unit cell topology), architected materials can achieve combinations of properties not reachable with conventional monolithic materials.The complex topologies of architected materials almost inevitably require fabrication by novel additive manufacturing (AM) processes, and nearly any class of AM technologies has been used to demonstrate architected materials with superior combinations of properties. Among all AM technologies, Direct Ink Writing (DIW), a unique class of Material Extrusion (ME), is particularly interesting for its simple implementation and almost unlimited materials palette. In this process, a rheologically optimized complex liquid is extruded along a defined path, building the architected material layer by layer. In this thesis, we designed and assembled a custom DIW system and employed it to address three important scientific questions: (i) Can we design and fabricate ceramic architected materials that exploit the architecture to control crack propagation and achieve higher strength than the monolithic solid at a fraction of its density? (ii) Can we develop a high-throughput approach to quickly characterize the distribution in mechanical properties of multiple ceramic materials, thus dramatically accelerating new material design? (iii) Can we demonstrate a framework for the fabrication of architected materials that serve as scaffold for the growth of biological tissue, with special application to the development of cartilage from stem cells? Collectively, these studies expand the development of Direct Ink Writing as a versatile approach for the fabrication of a wide range of materials for structural and biological applications.