Fast assembly of anti-voltage photonic crystals in microfluidic channels for ultrafast separation of amino acids and peptides.

Abstract

Photonic crystals (PCs) with periodically ordered particle beds are ideal media for high-performance separation but hard to be stably and crack-freely assembled in various microfluidic channels. Here we describe a facile method to fast assemble crack-free and high-voltage-sustainable PCs into the micro channels. The key is to speed up an evaporation-induced assembly by heating up (at 70 °C) and blowing away the solvent vapor from one end of a channel and supplying silica suspension at the other end. Crack-free PCs can be prepared at a speed of 0.2 cm/min. The heat also accelerates the silica particles to gel with solvent water and in turn to form a particle network by linking each other through their gelled surface. PCs with two pieces of particle network at their ends are capable of resistance to electrical fields up to 2,000 V/cm. Ultrafast separation of amino acids can be achieved along a 2.5-mm PC in 4 s and peptides along a 10-mm PC in 12 s.