Microscale Photopatterning of Through-Thickness Modulus in a Monolithic and Functionally Graded 3D-Printed Part

3D printing is transforming traditional processing methods for applications ranging from tissue engineering to optics. To fulfill its maximum potential, 3D printing requires a robust technique for producing structures with precise 3D (x, y, and z) control of mechanical properties. Previous efforts to realize such spatial control of modulus within 3D-printed parts have largely focused on low-resolution (from mm to cm scale) multimaterial processes and grayscale approaches that spatially vary the modulus in the x-y plane and energy dose-based (E=I(0)t(exp)) models that do not account for the resin's sublinear response to irradiation intensity. Here, a novel approach for through-thickness (z) voxelated control of mechanical properties within a single-material, monolithic part is demonstrated. Control over the local modulus is enabled by a predictive model that incorporates the material's nonreciprocal dose response. The model is validated by application of atomic force microscopy to map the through-thickness modulus on multilayered 3D parts. Overall, both smooth gradations (30MPa change over approximate to 75 mu m) and sharp step changes (30MPa change over approximate to 5 mu m) in the modulus are realized in poly(ethylene glycol) diacrylate-based 3D constructs, paving the way for advancements in tissue engineering, stimuli-responsive 4D printing, and graded metamaterials.

Automated summary

3D printing is revolutionizing traditional processing methods by enabling precise control of mechanical properties in structures. A novel technique has been developed to achieve through-thickness control of mechanical properties within a single-material, monolithic part. This advancement opens up possibilities for tissue engineering, stimuli-responsive 4D printing, and graded metamaterials.