Micro 3D Printing Elastomeric IP-PDMS Using Two-Photon Polymerisation: A Comparative Analysis of Mechanical and Feature Resolution Properties

The mechanical properties of two-photon-polymerised (2PP) polymers are highly dependent on the employed printing parameters. In particular, the mechanical features of elastomeric polymers, such as IP-PDMS, are important for cell culture studies as they can influence cell mechanobiological responses. Herein, we employed optical-interferometer-based nanoindentation to characterise two-photon-polymerised structures manufactured with varying laser powers, scan speeds, slicing distances, and hatching distances. The minimum reported effective Young's modulus (YM) was 350 kPa, while the maximum one was 17.8 MPa. In addition, we showed that, on average, immersion in water lowered the YM by 5.4%, a very important point as in the context of cell biology applications, the material must be employed within an aqueous environment. We also developed a printing strategy and performed a scanning electron microscopy morphological characterisation to find the smallest achievable feature size and the maximum length of a double-clamped freestanding beam. The maximum reported length of a printed beam was 70 mu m with a minimum width of 1.46 +/- 0.11 mu m and a thickness of 4.49 +/- 0.05 mu m. The minimum beam width of 1.03 +/- 0.02 mu m was achieved for a beam length of 50 mu m with a height of 3.00 +/- 0.06 mu m. In conclusion, the reported investigation of micron-scale two-photon-polymerized 3D IP-PDMS structures featuring tuneable mechanical properties paves the way for the use of this material in several cell biology applications, ranging from fundamental mechanobiology to in vitro disease modelling to tissue engineering.

Automated summary

The mechanical properties of 2PP polymers depend on printing parameters. The study characterized these structures fabricated with different parameters and found the minimum and maximum reported Young's modulus. The study also investigated the smallest achievable feature size and maximum beam length, and showed the potential of this material in various cell biology applications.