Preparation of Orthogonal Physicochemical Gradients on PDMS Surface Using Microfluidic Concentration Gradient Generator

Abstract Recently, surface with desirable gradients has been proved to be a powerful tool for diverse applications from biological systems and chemical analysis to material science. In this work, we demonstrate a versatile and universal approach to realize controllable physicochemical properties in orthogonal gradients on polydimethylsiloxane (PDMS) surface. Based on a novel microfluidics network, we can easily establish the concentration gradients within the microfluidic channel for surface polymerization or chemical deposition to realize the stable characteristic gradient on the PDMS substrate. The method was introduced to prepare surface with two-dimensional physical (roughness) gradients, or combinational physicochemical gradients to study the synergistic effect on interested phenomenon. As a proof of concept, the experimental results show that the as-prepared substrate can effectively influence in various fields, such as protein adsorption and nano-particle immobilization, which can potentially be used for future systematical study in biological systems or practical applications in bio/chemical analysis/sensing.