Optical biosensor using magnet beads inserted in Si waveguide gap

We propose an optical biosensor using Si waveguides to detect a bio target with magnet beads as a transducer. A gap is placed between input and output waveguides. The antibody of the target antigen is coated on the floor of the gap. When the antigen arrived at the gap, it binds with the antibody. The magnet beads are coated with 2nd antibody of the target. By dropping fluid containing the magnet beads to the gap, it binds with the captured antigen and shuts down the light transmission. The lowered light transmission indicates that the antibody is detected.