Project Description
Photopolymerization is a light-based additive manufacturing (AM) technique that facilitates the fabrication of complex three-dimensional (3D) structures quickly and cost-effectively. One-photon polymerization allows printing with high speed despite its limited resolution. In contrast, two-photon polymerization (2PP) offers sub-micrometer precision at the cost of slower throughput.
We propose a method combining 2PP and one-photon absorption (1PA) to get the advantages of the dual capabilities, allowing for faster printing while preserving high resolution and enhancing depth sectioning. In this study, we employ a CW laser beam at 405 nm to pre-excite a photocurable resin for rapidly reaching the polymerization threshold by 1PA and a tightly focused femtosecond (fs) laser beam at 780 nm to provide the missing energy for surpassing the threshold and solidifying the resin through two-photon absorption. The material is only polymerized at the intersection volume of two light sources. This sequential dual-excitation approach alters the voxel growth kinetics, reducing the polymerization threshold and accelerating the voxel growth.
Schematic illustration of the experimental setup. SEM image of the printed bridge by only 2PP and blue light-sheet assisted 2PP. The scale bars are 5 𝜇m [1].
Objectives
• Optimize the dual-beam printing systems, synchronization, and spatial overlap
• Design and fabricate 3D microstructures to benchmark speed, resolution, and fidelity improvements
• Study the influence of pre-sensitization on voxel growth and polymerization dynamics
• (Optional) Extend the system to functional materials or biocompatible resins for applications in photonics, microrobotics, or tissue engineering
🧩 Candidate Profile
We’re looking for someone who is curious, hands-on, and eager to learn!
• Background in optics, photonics, physics, or materials science
• Hands-on experience in laser systems or optical alignment (not mandatory – preferred)
• Programming skills (e.g., Python, MATLAB, Solidworks) for data analysis and experiment automation
• Interest in microfabrication, light-matter interaction, or additive manufacturing
📚 You’ll Learn
• Advanced light-based additive manufacturing techniques, both single- and two-photon polymerization
• Optical setup design, alignment and laser-matter interaction principles
• Microfabrication workflows and high-resolution imaging (SEM)
• Scientific communication and reporting
• Potential to contribute to a high-impact journal publication or conference presentation
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📬 To apply, send an email to [email protected]. Informal questions and lab visits are very welcome!
References
[1] B. Unlu, M.I. Álvarez-Castaño, A. Boniface, Y. Pu, C. Moser, Single-photon-assisted two-photon polymerization, Addit. Manuf. 94 (2024) 104455. https://doi.org/10.1016/j.addma.2024.104455.