Abstract: Disclosed are methods for building colloidal solids by precipitation from a liquid bridge using a needle through which a colloidal particle suspension is dispensed onto a substrate in a temperature-controlled environment. The substrate can rest on a motion-controlled stage, and freeform shapes can be built by coordinating the motion of the stage with the rate of dispense of colloidal particle suspension. Aspects include a scaling law that governs the rate of assembly and a direct-write colloidal assembly process that combines self-assembly with direct-write 3D printing, and can be used to build exemplary freestanding structures using a diverse materials, such as polystyrene, silica and gold particles. Additionally, disclosed are methods for predicting and eliminating cracking by a geometric relationship between particle size and structure dimensions, enabling the production of macroscale, crack-free colloidal crystals.

Abstract: Disclosed are methods for building colloidal solids by precipitation from a liquid bridge using a needle through which a colloidal particle suspension is dispensed onto a substrate in a temperature-controlled environment. The substrate can rest on a motion-controlled stage, and freeform shapes can be built by coordinating the motion of the stage with the rate of dispense of colloidal particle suspension. Aspects include a scaling law that governs the rate of assembly and a direct-write colloidal assembly process that combines self-assembly with direct-write 3D printing, and can be used to build exemplary freestanding structures using a diverse materials, such as polystyrene, silica and gold particles. Additionally, disclosed are methods for predicting and eliminating cracking by a geometric relationship between particle size and structure dimensions, enabling the production of macroscale, crack-free colloidal crystals.