Various microfluidic systems have been developed to achieve the efficient and sensitive detection of NPs. In addition to merely reducing the sample volume, they have the advantage of facilitating mixing by reducing diffusion length. For example, He et al. developed a device to detect EVs, important biological NPs in disease diagnostics, by mixing the sample and affinity magnetic capture beads in a serpentine channel. To quantify the concentration of EVs on-chip, the fluorescence intensity of EVs adsorbed onto the magnetic beads is determined using CCD camera images. Although this method can detect EVs on-chip with high sensitivity (limit of detection (LOD) ~ 10 × 10 5 /mL), it requires fluorescence labeling and a high-sensitivity camera. Xu et al. used a flow channel with Y-shaped micropillars to promote the mixing of a flowing sample containing target EVs and affinity magnetic capture beads. They succeeded in detecting tumor-derived EVs in a sample with high sensitivity (LOD ~ 10 × 10 3 /mL) using an electrochemical method (differential pulse voltammetry) located downstream. This method detects the oxidation reaction using an electrochemical aptasensor that they designed; however, it requires a 45 min incubation to obtain optimum detection sensitivity. Shao et al. developed a system to capture and lyse EVs and detect the target mRNA contained within. This device enriched EVs using affinity magnetic capture beads, after which mRNA was extracted and captured on the surface of the glass beads packed within the channel. Finally, the amount of target mRNA was quantified by on-chip RT-qPCR. Although this system is highly effective in detecting specific species of EVs, it requires complex fluidic control with integrated valves to perform sequential processes. Similar microsystems have been developed for microbead-based immunocapturing of targets, followed by nucleic acid amplification to detect viruses and pathogens. As seen from the examples mentioned above, the target capturing/enrichment and detection processes are separated and must be conducted sequentially in pre-existing systems.