| Description |
Biological materials that are composed of multiscale hierarchical microstructures embedded in a matrix material typically display different or even enhanced mechanical or material properties compared to an unstructured mixture of the same constituent materials. In this work, ultrasound directed self-assembly was integrated with 3D printing (direct-write (DW)) in a new manufacturing process called "ultrasound DW" to enable fabricating engineered materials with properties mimicking those of natural materials. A commercial fused deposition modeling (FDM) 3D printer was modified with a custom nozzle with ultrasound transducers embedded in it. This process allows 3D printing feedstock that consists of a liquid photopolymer resin with dispersed microfibers, and it enables fabricating materials with lines of aligned carbon microfibers. The effect of the primary operating parameters of the ultrasound DW process, including ultrasound operating frequency and print speed, on the alignment of the fibers, distance between adjacent lines of aligned fibers, as well as the resulting electrical conductivity and mechanical properties of the samples were evaluated. The results showed that the lines of aligned fibers in the material samples display statistically significant differences in terms of the distance between the adjacent lines of aligned fibers and the ultrasound operating frequency and the print speed. The lines of aligned fibers form local percolated networks resulting in electrically conductive areas. The ultrasound DW process allows fabricating materials with integrated substructures that tune specific electrical or material properties. |
