abstract
The present paper reports local mixing and chemical reaction in a T-junction microchannel investigated
using luminol chemiluminescence (CL). Generally, the degree of mixing in a microchannel is calculated
based on the deviation of the obtained concentration profiles from the uniform concentration using a
fluorescence technique. In the present study, the luminol CL reaction is applied to estimate the local
chemical reaction rate at the interface between two liquids in the microchannel. Luminol emits blue
chemiluminescence when it reacts with hydrogen peroxide at the mixing layer. Experiments were carried
out using a T-junction microchannel 200 lm in width and 50 lm in depth that was cast in a PDMS chip.
The chemiluminescence intensity profiles clearly show the mixing layer at the interface between the two
liquids. The experimental results are compared with the results of a numerical simulation that involves
solving mass transport equations that include a chemical reaction term. By calibrating the 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. The effects of the chemical species concentrations
on the local mixing and the chemical reaction were investigated.