In the case of VIF, vibration parameters such as frequency and amplitude influence the localized flow field. In this study, the vibration frequency f was varied to 200 Hz, 500 Hz, 800 Hz, and 1000 Hz, and the amplitude A was varied to 1.5 µm, 3.3 µm, and 5.2 µm. Furthermore, Figure shows the representative velocity magnitude of the mean flow field (magnitude of the azimuthal velocity at r = 60 µm from the center or 10 µm away from the pillar wall) for each vibration condition (2D vector plots for each vibration condition are shown in Figure , Supporting Information). The induced velocities increased with the increase in vibration frequency and amplitude, suggesting that the induced velocity can be readily tuned using these parameters. Subsequently, we analyzed the extent of aggregation induced by these flow fields. For simplicity, we considered the area of the bead aggregates as an index, which could be readily obtained via image binarization and standard particle analysis (see Figure , Supporting Information). The dependence of the average area of capture-bead aggregates after 15 min on the velocity magnitude of the mean flow field is plotted in Figure . The concentrations of NPs and capture beads were 5.7 × 10 9 /ml and 3.0 × 10 7 /ml, respectively. The average area of aggregates increased with velocity magnitude in the range below 300 μm/s. In this region, the higher the induced velocity, the more likely it is that the collision of beads proceeds such that aggregates grow in size. However, at velocities above 300 μm/s, the aggregate size decreased. This result indicates that shear stress acted on the bead aggregates and caused them to break, resulting in smaller aggregates (the average area of aggregates for each vibration parameter is shown in Figure , Supporting Information). Although the largest aggregate formation was obtained at condition f = 500 Hz and A = 5.2 μm, the variability among triplicated experiments was relatively large. Thus, we employed the condition f = 500 Hz and A = 3.3 μm, which exhibited the smallest variability, in the following experiments. (c) Relationship between the magnitude of the velocity and the average area of capture-bead aggregates after 15 min.