UC San Diego

Additive Manufacturing (AM) is a process most commonly defined by the addition of material to an object, specified by digital instructions, typically in a layer-by-layer fashion. It offers numerous advantages over conventional manufacturing processes since it can be used to form objects that would otherwise be difficult or impossible to fashion. It also allows for the on-demand production of parts which would otherwise require large, bulky mass production tooling. However, AM is subject to many of the same limitations as other “Top-Down” manufacturing processes: the objects produced by an AM system (or conventional manufacturing system) must be smaller than the system's build volume.

A method to circumvent this limitation is described which utilizes a photopolymer resin incorporating a soluble blowing agent. This resin can be patterned into a desired structure using a commercially available Masked Stereolithography (MSLA) printer. The printed structures may then be thermally expanded to produce objects up to 40x larger than the original printed parts, and which retain their expanded shape and size after cooling. Using this method, production of objects larger than the printer itself is demonstrated. These isotropically expanded structures can subsequently be sprayed with a low-viscosity isocyanyl acrylate-based photocurable resin to enhance their mechanical properties for structural applications. Mechanical tensile and compression analysis of the novel resin and composite foam/resin structures is presented.

The construction, testing and characterization of a small format bench-scale polymer melt processing system is documented as well as the design, fabrication and testing of a bench-scale injection molding system. Such devices enable the lab-scale production of customizable solvent-free polymeric implants and microneedle patches. Characterization of the fabricated polymer devices via Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX), and fluorescence micrography is documented.

Fundamental scaling relationships of AM, and bottom-up biosynthetic approaches to AM are also explored.