Image Analysis of the Capture-Bead Aggregates: The extent of aggregation of capture beads was evaluated by considering the average areas of the capture-bead aggregates. To simplify the detection system, only the bright-field images were obtained with the simple optical microscope. Subsequently, the images were analyzed using an ImageJ software package (see Figure , Supporting Information). After binarizing the images containing capture beads, the number, and area of each aggregate were obtained using the built-in particle-analysis function.