(294f) Micro to Nanometer Scale 3D Printing for Geometrical Design of Functionally Graded Polymeric Materials

Micro- and nano-meter geometrical structures dictate critical polymeric material properties ranging from mechanical robustness to transport selectivity. While additive manufacturing (AM) has enabled free-form patterning of polymeric materials, the trade-off in resolution and scalability has limited its capability to control material properties through simple geometrical designs. In this talk, we will discuss our development of single-digit resolution AM technology based on Continuous Liquid Interface Production (CLIP). Building upon photopolymerization kinetics, complex fluid dynamics, projection optics design, and software system integration, the single-digit micrometer CLIP 3D printer has enabled direct fabrication of micrometer scale, functionally graded, latticed capacitive pressure sensors with varying sensitivities for pressure and shear sensing. We found that by introducing different unit cell types and geometrical thicknesses, we can vary the sensitivities and thus the capacitive responses of the pressure sensors. An analytical model was established to capture the capacitive responses of pressure sensors that consist of different unit cell types, and a close match was obtained between the analytical results and experimental measurements. In-situ micro-CT scans were further conducted to capture the microstructure deformation under shear and normal force, and a qualitative finite element method was developed to capture the deformation of the micro-struts. Taken together, the single-digit micrometer resolution AM enables direct tuning of material mechanical properties through varying simple geometrical designs.