Commercial fluorescent tracer particles used for particle image velocimetry are available in a very limited range of sizes and densities, and are prohibitively expensive for large-scale experiments. Therefore, a method for producing tracer particles with a wide range of densities and sizes, in a robust and inexpensive way is highly desirable.
In this work, we extend an earlier microfluidic system for tracer particle production to a more stable, pressure-driven operation, and optimize the fluorescence and polydispersity of the resulting particles as a function of chemistry and flow properties. We show that the density of the resultant particles is limited by chemistry, whereas the size is limited by both chemistry and flow. We examine the robustness and operating limits of the new system, and validate the sufficiency of the fluorescent response of the fabricated particles in a realistic experimental environment.