Investigating the influence of printing parameters in multiphoton lithography

Abstract

TPP (two-photon polymerization) is a versatile micro/nano additive manufacturing technique that enables the rapid and precise fabrication of intricate threedimensional (3D) micro/nano structures. Its effectiveness lies in a unique photopolymerization process triggered by the concurrent absorption of two photons, affording an unparalleled level of precision in controlling the formation of 3D nanostructures on a voxel-by-voxel basis. The size of the polymerized spot is strongly influenced by several parameters. Carefully optimizing these parameters (e.g., laser power, scanning speed, slicing, and hatching) in experiments allows for the fabrication of nanostructures with line widths below the diffraction limit. The dual-photon engagement in TPP enables finer resolution and control in 3D micro/nano structuring. The intricate interplay between printing parameters and photopolymerization dynamics necessitates a comprehensive understanding to effectively optimize the printing process. In this study, we investigate the influence of the Full Width at Half Maximum (FWHM) of the focal spot in the XY and Z directions on printing power thresholds and structure quality. By focusing on different printing parameters chosen based on FWHM calculations, we examine their effect on the printing threshold. Our goal is to determine if adjusting FWHM and examining its relationship to settings like hatching and slicing can help predict the optimal printing power needed for the best results. Using techniques such as scanning electron microscopy (SEM) and laser-induced microscopy (LSM) for imaging and measurements, we assessed the capabilities of our printing strategy. Specifically, we identified the feasible dimensions for printing with a given standard objective, using a simple lattice unit (LU) structure and cuboid structures as benchmarks to understand the structural thresholds. Additionally, the search process for the threshold led us to examine two methods for analysing the structures—one based on 2D and the other on 3D. Using both methods resulted in a new findings regarding printing at high slicing values. Our analysis aims to determine whether our internal calculations of the FWHM are crucial in setting the optimal printing parameters. This understanding highlights the importance of customizing optimization strategies to meet specific structural goals.

Date of Award	2024
Original language	English
Supervisor	Jaroslaw Jacak (Supervisor)