Abstract: A method of measuring a concentration of an analyte is provided, including: reacting a test solution including an analyte with a nanoparticle solution including a plurality of nanoparticles and an optical waveguide element to form a sandwich-like structure; and measuring evanescent wave energy of the optical waveguide element absorbed and/or scattered by the plurality of nanoparticles after the plurality of nanoparticles forming the sandwich-like structure by using a photodetector to obtain a first signal, and calculating the concentration of the analyte based on the first signal. Wherein, a detection recognition element is conjugated on a surface of each of the plurality of nanoparticles, and a capture recognition element is conjugated on a waveguide surface of the optical waveguide element.