Process Sensitivity Analysis and Resolution Prediction for the Two Photon Polymerization of Micro/Nano Structures

Two photon polymerization (2PP) is a rapid prototyping technique for the fabrication of micro/nano structures from photosensitive polymers. The polymerization process and its resolution depend on the combination of various chemical and physical process parameters. In this research, statistical techniques are employed to evaluate the sensitivity of the 2PP process on the applied laser power, scanning speed, and concentration of photoinitiator. The experiments were performed using the ethoxylated (6) trimethylolpropane triacrylate (SR499-Sartomer) monomer and acyl phosphine oxide (Lucirin TPO-L-BASF) photoinitiator. A design of experiments approach is utilized to evaluate the effect of these process parameters at various set levels on the polymerized width and height. The proposed model is checked for interaction among the process parameters and multiple comparisons are performed to evaluate the statistically significant differences. Also, a detailed discussion of the model verification based on error analysis is performed and presented. A regression model is also developed for the prediction of polymerization resolution and the developed statistical model is experimentally verified. Finally, the developed model and the understanding acquired through the statistical analysis were used for the prototyping of various micro/nano structures.