Additionally, either amplification machinery or an expensive detection system is required to achieve high sensitivity. As an amplification-free or labeling-free method for detecting target molecules, some researchers have exploited the aggregation of micrometer-sized affinity beads induced by the adsorption of target molecules. Wu et al. demonstrated the detection of target proteins by examining the aggregation of antibody-coated microparticles (MPs). They showed that the volume of the aggregates correlated well with antigen concentrations. Conversely, Pawan et al. quantified the concentration of target proteins secreted by cells, based on the disaggregation of MPs. In their study, the presence of secreted proteins inhibited the antibody-antigen reaction that caused MP aggregation. This approach enables us to detect invisible molecules under ordinal optical microscopy; therefore, the system can be simple and low-cost. However, in previous studies, the processes to induce aggregation/disaggregation have merely relied on Brownian motion or bulky agitation; therefore, the mixing method and time for aggregate formation have not been optimized. The application of local and micro-scale mixing is expected to enhance the affinity-based aggregation of microbeads as an output. The introduction of simple and well-controlled active mixing should facilitate fast and reproducible detection.