*3.4. Enrichment Experiment*

In order to verify the enrichment effect of the microfluidic chip determined by the simulation, a quantitative number of nano-microspheres was sucked into the chip inlet, and then the enrichment efficiency of the particles in the chip was observed through a microscope. About 50 nano-microspheres of one particle size were mixed into the aerosol generator each time, all of them were entered from the chip inlet and out, and then the enriched particles were counted by a microscope and the enrichment rate was calculated. The particle size was tested five times, and the statistical boxplot of the enrichment experiment as shown in Figure 10 was obtained. The average enrichment efficiencies of 3 μm, 5 μm, 6 μm, and 8 μm were 87.5%, 82.625%, 82.5%, and 84.87%, respectively. It can be seen from Figure 10 that the enrichment rate obtained in the enrichment experiment is slightly lower than that obtained by simulation, but the enrichment efficiency is stable.

**Figure 10.** Enrichment Experiment Statistics Box Plot.
