Metamaterial Architectures with Micro 3D Printing

Tendon and ligament injuries are common and often require effective restoration materials to regain full functionality. However, engineering tissues with biocompatible materials that mimic native tissue mechanics presents numerous challenges. In a groundbreaking study, Nikos Karathanasopoulos and Oraib Al-Ketan from New York University, Abu Dhabi campus, explored the use of metamaterial architectures to address these challenges. By employing micro 3D printing technology, they were able to fabricate and test innovative metamaterial designs with promising mechanical properties. 

Additive Manufacturing for Metamaterial Architectures

Karathanasopoulos and Al-Ketan sought additive manufacturing solutions to test six different unit-cell metamaterial architectures. These architectures needed to exhibit strength under normal loading, softness under shear loading, and higher contractility compared to conventional engineering materials. To meet these requirements, they turned to Boston Micro Fabrication’s microArch S240, a 3D printer capable of fabricating structures with high accuracy at the scale of tenths of µm, with overall specimen lengths in the order of mm. The printed parts included diagonal strut elements with diameters as small as 50µm, enabling the creation of intricate metamaterial designs.

Identifying Ideal Metamaterial Designs

The researchers successfully identified metamaterial architectures that demonstrated substantial normal stiffness along the primal tissue loading direction, low shear resistance, and Poisson’s ratio values well above unity. These characteristics make them highly desirable in the context of tissue and ligament restoration. Notably, the metamaterials exhibited a remarkable property – they were up to 18 times stiffer under normal loading conditions compared to shear loading, surpassing the limits of isotropic common engineering materials. Typically, common engineering materials cannot exceed normal-to-shear loading ratios of 3. This discovery opens up new possibilities for advanced architected materials that can better mimic the mechanical behavior of native tissues.

The fabricated metamaterials underwent rigorous testing, including shear and uniaxial compression tests. The results showed exceptional promise, paving the way for potential applications in tendon and ligament repairs. These metamaterial architectures hold the potential to revolutionize restoration praxis by providing biocompatible materials that closely mimic the native tissue mechanics, thus enhancing post-repair functionality significantly.  

Conclusion

Nikos Karathanasopoulos and Oraib Al-Ketan’s work at New York University’s Abu Dhabi campus represents a remarkable step forward in the field of tissue and ligament restoration. By utilizing micro 3D printing technology, they successfully designed and tested metamaterial architectures that closely mimic native tissue mechanics. These advanced architected materials offer significantly improved stiffness under normal loading compared to shear loading, a crucial characteristic for successful tissue repair. As this research continues to evolve, it holds the promise of transforming the landscape of tissue engineering and regenerative medicine, benefiting countless individuals with tendon and ligament injuries. The potential applications of such metamaterials extend beyond the medical field, with possibilities in other engineering applications that require enhanced mechanical performance. Boston Micro Fabrication’s microArch S240 has proven instrumental in bringing these ideas to life, showcasing the importance of cutting-edge additive manufacturing technologies in advancing biomedical research and materials science. 


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3D Printing Technology for Medical Device