Synthesis and characterization of particle loaded sol–gel composite material for microfluidic chip system

Abstract

Sol–gel immobilization provides a simple method for introducing different functions into microfluidic devices. In this study, sol–gel was employed for the immobilization of C4 modified silica particles in microfluidic channels, which were etched in quartz using photolithography and wet etching. The effect of variation in sol–gel synthesis conditions was evaluated by preparing a variety of composite materials. Sol–gel syntheses were carried out under both acidic and basic conditions. The effect of additives was also evaluated by introducing formamide and urea into the sol–gel precursor solutions. Composite materials prepared under different conditions were characterized using SEM visualization, nitrogen adsorption experiments, conductivity ratio of packed to empty channels, and separation experiments. SEM visualization provided qualitative information about the overall morphology of the composite material. In addition, more quantitative characterization was obtained by calculating pore size distributions and by measurements of conductivity ratios. Separation experiments were employed in order to evaluate the accessibility of the C4 functional group in the materials prepared under different sol–gel synthesis conditions. While acidic conditions promoted accessibility of the C4 functional group and improved separations, other conditions lead to reduced accessibility and separation efficacy.