Two-photon polymerization for three-dimensional micro/nanofabrication

As an advanced three-dimensional micro-/nanofabrication technique, two-photon polymerization (TPP) has attracted tremendous interest from both the academic and industrial communities. Two key reasons make TPP an attractive solution. First, TPP is intrinsically a true three-dimensional (3D) writing technique that naturally writes arbitrary structures and does not require a layer-by-layer approach to create complex objects. Second, TPP can create microstructures with submicron feature size in a relatively straightforward manner. Furthermore, applications in the real world require the as-fabricated structures to have good mechanical properties, small shrinkage, high throughput, and small feature size. To meet these requirements, the research efforts described in this dissertation focused on the following points. 1) A variety of millimeter (mm) to submillimeter (sub-mm) target structures were fabricated with nanoscale accuracy and precision for high-energy-density (HED) plasma physics research. To the best of the author’s knowledge, it is the first time the target/target components were directly fabricated using TPP to realize mm/sub-mm-scale structures with a feature size of a few hundred nanometers (nm). 2) The cross-linking of the ultimate polymers was measured under different TPP parameters and correlated to the mechanical properties of the as-fabricated microstructures using the degree of conversion (DC). Since the DC can significantly impact the final stability and mechanical properties of the fabricated structures, the correlation was established to achieve precise 3D micro/nanofabrication using TPP. 3) Performance improvement of thiol-acrylate resin in TPP was investigated, including the extended writing dynamic range, finer feature size, enhanced writing speed, and mechanical strength. In addition, it was confirmed, by means of microspectrometry, that thiol-acrylate two-photon copolymerization promotes monomer conversion, thereby inducing a higher degree of cross-linked network formation