Extrusion of High-Resolution Polymer Structures with Direct Ink Writing Techniques

This chapter explores 3D printing, often called additive manufacturing, with a focus on printing structures with high-detail resolution. There are mainly two techniques that allow for 3D printing in the μm to sub-μm range: two-photon printing and direct ink writing (DIW). The two-photon technique is briefly explained, while the focus here is on DIW since this technique gives an opportunity to print a wide variety of materials. To exemplify high-detail resolution polymer 3D printing, biocompatible cellulose acetate (CA) is selected. Printability and the possibility of printing μm feature-size structures with inks containing different amounts and molecular weights of cellulose acetate are presented. Results indicate that by optimizing inks and printing parameters such as the internal and external diameter of the nozzle, strands down to sub-μm can be printed with high placement control. Various challenges as clogging and low printing speed are also discussed.