Method and apparatus for measuring concentration of biogenic substance

A method for measuring a concentration of a biogenic substance, comprising steps of:

• (a) preparing an apparatus for biogenic substance concentration measurement,
• said apparatus comprising a light source, a polarization controller which controls a polarization of the light from said light source, a substrate which has periodic metal structures and generates surface enhanced Raman scattering light by being irradiated with light emitted from said light source, and spectroscopic means which disperses and detects said surface enhanced Raman scattering light, wherein
• said periodic metal structure is arranged with a first distance in a first direction and with a second distance in a second direction,
• said first distance is set to generate surface plasmon by matching a phase of the light emitted by said light source, and
• said second distance is smaller than said first distance and the second distance is set between 300 nm and 350 nm;
• (b) irradiating the substrate with the light emitted from the light source so as to generate the surface enhanced Raman scattering, wherein the polarization of said light is controlled along with said first direction by said polarization controller;
• (c) detecting said generated surface enhanced Raman scattering with said spectroscopic means;
• (d) recording an intensity of said surface enhanced Raman scattering detected in step (c);
• (e) irradiating the substrate with the light emitted from the light source so as to generate the surface enhanced Raman scattering, wherein the polarization of said light is changed by said polarization controller;
• (f) detecting said generated surface enhanced Raman scattering at said step (e) with said spectroscopic means;
• (g) recording an intensity of said surface enhanced Raman scattering detected in step (f);
• (h) determining a larger intensity of surface enhanced Raman scattering and recording said larger intensity by comparing the recorded intensity of the surface enhanced Raman scattering at said step (g) with the recorded intensity of the surface enhanced Raman scattering at step (d);
• (i) calculating the maximum intensity of surface enhanced Raman scattering by repeating the steps of (e) to (h);
• (j) calculating the concentration of the biogenic substance on the basis of said maximum intensity of surface enhanced Raman scattering calculated in said step (i).