A new review article published in Engineering delves into the world of multi-photon 3D nanoprinting, a technology that has been making waves in the micro/nano-additive manufacturing field.

Multi-photon 3D nanoprinting is renowned for its 3D processing capability and nanoscale resolution beyond the diffraction limit. It has found extensive applications in various fields such as optics, biology, and mechanical engineering. For example, in optics, it can create optical lenses with sub-nanometer features, offering more design flexibility. In the biomedical field, it is used for cell-related research and fabricating drug delivery devices.

However, the technology still faces several hurdles. One of the key issues is the relatively slow processing speed, which has limited its large-scale industrial production. To address this, researchers have been exploring different methods. Projection-based processing technologies, like mask-based and holographic-based projections, have shown high processing speeds. Mask-based projection technology can modulate the optical field through digital masks to expose entire model slice patterns at once. Holographic-based projection technology can generate holograms to project modulated light fields. But these projection-based methods face difficulties in achieving a uniformly distributed light field along the vertical z-axis, resulting in relatively low vertical resolution. Point-scanning-based processing technologies, including random-access and raster scanning, have higher resolution but slower processing speed. For random-access scanning, researchers have tried to increase the number of foci to enhance parallel processing efficiency. In raster scanning, efforts have been made to improve the performance of scanning devices such as galvanoscanners, resonant scanners, polygon scanners, and acousto-optical scanners.

Another challenge lies in the materials limitation. Organic polymers, inorganic compounds, and composites all have their own limitations. Organic polymers, although widely used, may face issues like shrinkage. Inorganic compound materials often need to adopt the structure of organic materials as a frame. After annealing, as the organic components are removed, the structure may shrink or the feature size may decrease. Composites, while promising, have problems in achieving a highly concentrated and uniform dispersion of dopant materials.

Looking ahead, the researchers believe that increasing the throughput by orders of magnitude, optimizing cross-scale processing, and refining material systems are crucial for the future development of multi-photon 3D nanoprinting. With continuous research and innovation, this technology is expected to overcome its current challenges and play an even more significant role in future industries.

The paper “Recent Advances and Challenges in Multi-photon 3D Nanoprinting,” authored by Fayu Chen, Shaoxi Shi, Songyan Xue, Huace Hu, Zexu Zhang, Xuhao Fan, Mingduo Zhang, Xinger Wang, Zhe Zhao, Hui Gao, Wei Xiong. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.09.028. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).