Cross mixer with UV/visible absorbance detection. An ethanol solution of MY flowed through the sample channel at 3 μL min−1 and was hydrodynamically focused by ethanol side flows. Inset, absorption intensity of MY jet along dashed line (in main image), normalized to its maximum value, with respect to horizontal (left to right) pixel position of the camera for three separate side flow rates. As the side flow rate increases, the amount of advective diffusion increases and the sample is diluted more rapidly, hence the faster decrease in absorbance.