Capturing System with Biotin-coated NPs and Avidin-coated Capture Beads: Commercial avidin-coated beads (Spherotech Inc., VP-30-5, diameter: 3 µm) and biotin-coated NPs (Spherotech Inc., TFP-00852-5, diameter: 0.15 µm) were used as models of capture beads and target NPs, respectively. To prevent nonspecific adsorption of beads and trapping of air bubbles when this mixture was applied, the surfaces of the PDMS substrate and cover glass were treated with blocking buffer (5 w/w% BSA in 1 × PBS), incubated for 15 min, and dried.