Direct-Write Freeform Colloidal Assembly

Technology

This technology involves a novel integration of colloids with direct-write 3D printing, allowing for the precise creation of freeform structures using suspended colloidal solid particles that remain after the liquid has evaporated. The technology consists of a stage component, mechanism for dispensing, and controller system. As colloidal particles are suspended from the dispenser onto the stage, the controller determines and sets specific relative distances and orientations between the dispenser and the stage. The precision of the controller allows the system to create the desired configurations and maintain optimal building conditions. This is achieved via sensors, which communicate with the controller to ensure that the rate of colloidal particle suspension is equal to the rate of growth of the colloidal solid. The technology also includes an evaporation system which facilitates optimal evaporation of the liquid from the dispensed colloid with an improved temperature control system. Together, the stage, dispenser, controller, and sophisticated evaporation system allow for the fabrication of stable, crack-free freeform structures of specific configuration, geometry, composition, and arrangement. 

Problem Addressed

Current approaches to self-assembly of ordered solid particles are constrained by limitations in shape and geometry, while preexisting direct-write 3D printing methods similarly struggle to achieve sufficient particle ordering. Furthermore, current methods yield particles that are too large for effective ordering and can only produce conical and tower structures, lacking the ability to create freeform structures. Other challenges in the fabrication of freeform colloidal crystal structures include complications associated with particle evaporation processes, the inability to sustain stable crystal growth, and the occurrence of structural cracks. Moreover, pertaining to evaporation concerns, discrepancies between the rate of evaporation and the rate of dispensing prevent stable crystal growth and limit the height of the fabricated structure. This technology overcomes these limitations by combining aspects of direct-write 3D printing with evaporative colloidal assembly. When used together, this process allows for the previously impossible fabrication of structures with specific configurations, geometry, and compositions. 

Advantages

• Can produce novel materials and devices composed of colloidal solids with unique mechanical, optical, and chemical properties. 

• Makes possible the fabrication of freeform structures of specific configuration, geometry, composition, and arrangement. 

• Fabricated freeform structures are stable and crack-free.  

Publications

Beroz, J., Hart, A. J., Kolle, M., & Tan, A.T.L., “Direct-Write Freeform Colloidal Assembly.” Advanced Materials. 30(44): 1803620, 2018.