Reaction-diffusion dynamics: Confrontation between theory and experiment in a microfluidic reactor

We confront, quantitatively, the theoretical description of the reaction-diffusion process of a second-order reaction to experiment. The reaction at work is ${\mathrm{Ca}}^{2+}/\mathrm{CaGreen},$ a fluorescent tracer for calcium. The reactor is a T-shaped microchannel, $10\mu \mathrm{m}$ deep, $200\mu \mathrm{m}$ wide, and 2 cm long. The experimental measurements are compared with the two-dimensional numerical simulation of the reaction-diffusion equations. We find good agreement between theory and experiment. From this study, one may propose a method of measurement of various quantities, such as the kinetic rate of the reaction, in conditions yet inaccessible to conventional methods.