The LOD in the present system was of the order of 10 7 /mL in both cases. Although the dissociation constants for the avidin-biotin and Tim-4-serine systems are 10 -15 M and 10 -9 M, respectively, the dynamics of aggregate formation were similar under similar vibration conditions. The relationship between the strength of affinity and the dynamics of aggregate formation should be clarified in detail in the future; however, this study indicates that the flexibility of the VIF system in tuning the flow conditions is advantageous for various applications. Moreover, in this study, the LOD was 10 to 100 times more sensitive, and the processing was 2 to 3 times faster than the previous studies that determined macromolecular concentrations using aggregation-based detection systems. These results indicate that microscale stirring provides a more rapid and effective encounter of particles compared to diffusion or bulk agitation. It should be noted that the determination method of the slope of the aggregate formation, including the micropillar design and arrangement, remains to be further optimized. Here, the size of the vortices in the local flow determines the formation dynamics and size of aggregates. We envisage that large vortices form larger aggregates. It is advantageous for detection, but the resultant aggregate size will be stochastic and variable. On contrary, a large number of small vortices should provide statistically significant information, but may require larger magnification for imaging. Furthermore, we used the slope of the average area of aggregation as a facile and rapidly available index that correlates with the NP concentration. Proper determination of the slope also remains to be optimized depending on the dynamics of aggregate formation. The flexibility of VIF system is advantageous in optimizing the local flow patterns for these purposes.