Visualization of Chemical Kinetics Processes and Miniaturization of Chemical Reactions via Dynamic Mixing in Microarray Chips

Abstract

Although chemical kinetics is an essential branch of physical chemistry, observing kinetic processes typically demands sophisticated and costly equipment. Digital green chemistry experiments are an important experimental-teaching direction for undergraduates. This study introduces a portable, interactive, and educational microarray chip platform that visualizes chemical kinetics through clock reactions via dynamic mixing. The microfluidic chip consists of a 3D-printed substrate, modeled in Cinema 4D, and an acrylic glass cover. By precisely controlling variables such as the reactant concentration and temperature with digital coding, we successfully demonstrate two iodine clock reactions, KIO₃-KI-H⁺ and Na₂S₂O₃-I₂-(NH₄)₂S₂O₈, as well as anthocyanin discoloration. This platform enables the clear visualization of phenomena including radial diffusion and microscale interfacial reactions, presenting the reaction progress in a color-card format referred to as “chemical amber,” which enhances the understanding of abstract chemical concepts. Notably, the chip allows users to calculate key kinetic parameters, including reaction rates, activation energy, and analyte concentration, by measuring diffusion rates, color-change times, and grayscale values from digitally scanned images obtained using a low-cost mini USB-electronic microscope and smartphone. This provides an enriched understanding of reaction dynamics. Furthermore, the platform was successfully implemented in comprehensive experimental teaching applications, demonstrating notable effectiveness in classroom settings.