Rapid Prototyping of Microfluidic Reactors for the Synthesis of Morphologically Controlled Inorganic Crystals and Programmed Magnetic Droplets

Additive manufacturing techniques like 3D printing have enabled rapid and iterative fabrication of solid objects defined by 3D CAD models in a wide variety of materials. The recent developments in additive manufacturing techniques have lowered the cost associated with prototyping devices when compared to more traditional fabrication techniques like photolithography. Strategies that take advantage of 3D printing for the fabrication of microfluidic masters have seen rapid development in recent years. In the present work, a standard set of 3D printed thermoplastic building blocks are printed, thermally treated, and used for soft lithography to fabricate a wide variety of microfluidic devices in PDMS. The methods described here enable scientists with varying levels of expertise to prototype functional microfluidic devices easily and rapidly. A microfluidic platform is presented that uses 3D printed masters to define channel geometry. The microfluidic devices are sealed to various surfaces of arbitrary geometry using compression or tension. These reconfigurable devices enable easy reuse of microfluidic reactors and substrates and sequential synthesis or deposition of material on substrates. A microfluidic platform that transports and stores microdroplets is also presented. In crystal growth, crystal habit is determined by energetically favorable pathways for crystal systems. Bottom-up strategies use surfactants, templates, interface-confined growth etc. to circumvent crystal habit and produce desired morphologies. High velocity shear flow was used to modify the morphology of ZnO nanorods by etching/dissolution; the methods presented here offer additional routes to augment current bottom-up approaches. Symmetric etching of the nanorods is attributed to Jeffery orbits. Magnetite is a naturally occurring ferrimagnetic mineral. Magnetotactic bacteria synthesizes magnetite nanoparticles by localizing precursors in its environment. Inspiration from magnetotactic bacteria led to a system where iron ions are compartmentalized to microdroplets and reacted by passive diffusion of precursors through a lipid bilayer. Nucleation and growth of magnetite is localized to the edge of droplets. The localized growth enables the production of droplets with programmed magnetic domains. The system that enables production of droplets with programmed magnetic domains is expanded to include additional materials with various functionalities. A concept that enables the fluid-flow modification of pre-synthesized nanomaterials is presented