Direct-Write Self-Assembly of 3D Colloidal Microstructures

Abstract

We present a direct-write technique for assembly of microscale 3D colloidal crystals on substrates. We use a custom-built high-resolution liquid manipulation system to dispense colloidal suspensions through a capillary tip. Using this system, we establish a liquid bridge between the capillary tip and a temperature-controlled substrate, initiating crystal growth upward from the substrate. We demonstrate construction of cone-shaped and tower structures by controlling the dynamic shape of the liquid meniscus during crystal precipitation. Interplay between lateral capillary forces and granular cohesion governs assembly. Finally, we show that confinement of the meniscus on microfabricated template features enables assembly of discrete particle clusters.