Facile Fabrication of Monolithic 3D Porous Silica Microstructures and a Microfluidic System Embedded with the Microstructure

Abstract

Monolithic 3D porous silica structures are fabricated into a multilayer framework with a bimodal pore size distribution in the micrometer and sub-micrometer range. The fabrication-which involves directed assembly of colloidal spheres, transfer, printing, and removal of a sacrifical template-yields robust and mechanically stable structures over a large area. The structure becomes monolithic upon pyrolyzing the stacked layer, which induces necking of the particles. The monolithic microstructues can easily be embedded in microchannels with the aid of photolithography, leading to the formation of a microfluidic system with a built-in microstructure in a site- and shape-controlled manner. Utilization of the system results in a fourfold increase in the mixing efficiency in the microchannel.