We investigate diffusion and mixing in a microchannel by using luminol chemiluminescence (CL) to estimate the local chemical reaction rate. The degree of mixing in micromixers is generally evaluated from the deviation of concentration profiles measured by fluorescence from a uniform concentration profile. The degree of mixing measured by this method is a macroscopic estimate, which is inappropriate for investigating diffusion and mixing in microchannels. In this study, the luminol CL reaction is used to visualize and quantitatively measure local diffusion and mixing at an interface between two liquids in a microchannel. Blue CL is observed where luminol reacts with hydrogen peroxide at the mixing layer. Diffusion and mixing in a microchannel are investigated by sequentially measuring the CL and fluorescence. The experimental results are compared with the results of a numerical simulation that involves solving transport equations including the chemical reaction term. By calibrating the CL intensity with the chemical reaction rate estimated by the numerical simulation, the local chemical reaction can be quantitatively estimated from the CL intensity profile.
This study focused on the diffusion and mixing phenomena investigated by using luminol chemiluminescence (CL) to estimate the local chemical reaction rate in the T-junction microchannel. Generally, the degree of mixing in microchannel is calculated by the deviation of the obtained concentration profiles from the uniform concentration profile by using fluorescence technique. Thus, the degree of mixing is a macroscopic estimate for the whole microchannel, which is inappropriate for understanding the diffusion and mixing phenomena in the mixing layer. In this study, the luminol CL reaction is applied to visualize the local chemical reaction and to estimate the local diffusion and mixing phenomena at an interface between two liquids in microchannel. Luminol emits blue chemiluminescence when it reacts with the hydrogen peroxide at the mixing layer. Experiments were carried out on the T-junction microchannel with 200 microns in width and 50 microns in depth casted in the PDMS chip. The chemiluminescence intensity profiles clearly show the mixing layer at an interface between two liquids. The experimental results are compared with the results of numerical simulation that involves solving the mass transport equations including the chemical reaction term. By calibrating CL intensity to the chemical reaction rate estimated by the numerical simulation, the local chemical reaction profile can be quantitatively estimated from the CL intensity profile.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.