Figure 8: Density distribution of 2 μm sPsL particles for the platinum pump.

The reagent concentrations are 0.59 M H₂O₂ (orange) and 0.29 M H₂O₂ (blue). For ∼0.5 mm² areas along the centre of the pattern, the number of particles settled on the surface was determined by image analysis software as the per cent area covered by particles, which was then normalized. A fivefold increase in tracer particles at a distance of ∼8 mm from the reagent source was observed for 0.59 M H₂O₂. In contrast, for 0.29 M H₂O₂, the location of the maximum changed to ∼4 mm. The observed shift in maximum for the tracer density distribution agrees qualitatively with simulated shifts presented in Fig. 5.