Optical assay: method and apparatus

An optical assay apparatus comprising:

• a light source;
• a light detector;
• a propagating medium arranged relative to the source and detector for directing light from the source onto the detector;
• a buffer means of optically less dense material than that of the propagating medium adjacent to a surface of the propagating medium;
• a metallic medium, having the form of a metal film, on the surface of the buffer medium remote from the propagating medium;
• and
• a coating, adjacent to the metallic medium, sensitized for a specific assay species.

An optical assay apparatus comprising:

• a light source;
• a light detector;
• a propagating medium arranged relative to the source and detector for directing light from the source onto the detector;
• an optical grating at a surface of the propagating medium;
• a metallic medium, having the form of a metal film, on a surface of the optical grating;
• and
• a coating, adjacent to the metallic medium, sensitized for a specific assay species.

An optical assay apparatus comprising:

• a light source;
• a light detector;
• a propagating medium, arranged relative to the source and the detector, for directing light from the source onto the detector;
• a dispersion of fine metal particles, each coated with a material sensitized for a specific assay species;
• and
• said propagating medium and dispersion of fine metal particles being positioned relative to one another to provide optical coupling therebetween.

An optical assay apparatus comprising:

• a light source;
• a light detector;
• a light propagating medium having a reflecting surface, said reflecting surface being arranged relative to the source and the detector for directing light from the source onto the detector;
• a coated metallic medium arranged in close proximity to said reflecting surface, said metallic medium having a coating sensitized for a specific assay species;
• and
• said propagating medium and metallic medium being positioned relative to one another to provide optical coupling therebetween.

An optical assay apparatus comprising:

• a light source;
• a light detector;
• a light propagating medium having a reflecting surface, said reflecting surface being arranged relative to the source and the detector for directing light from the source onto the detector;
• a coating metallic medium arranged in close proximity to said reflecting surface, said metallic medium having a coating sensitized for a specific assay species;
• and
• said coated metallic medium having the form of a continuous thin metal film spaced from the reflecting surface of the light propagating medium by a buffer layer of material optically less dense than that of the light propagating medium.

An optical assay apparatus comprising:

• a light source;
• a light detector;
• a light propagating medium having a reflecting surface, said reflecting surface being arranged relative to the source and the detector for directing light from the source onto the detector;
• and
• a coating metallic medium arranged in close proximity to said reflecting surface, said metallic medium having a coating sensitized for a specific assay species;
• and
• said metallic medium having the form of a dispersion of metal particles, with a multiplicity of the metal particles lying upon the reflecting surface.

An optical assay method comprising the following steps:

• providing a light propagating medium having a reflecting surface, said reflecting surface arranged to direct light from a source onto a detector;
• providing a coated metallic medium arranged in close proximity to said reflecting surface, said coated metallic medium having a coating sensitized for a specific assay species;
• providing optical coupling between the coated metallic medium and the directed light to generate in the coated metallic medium a resonant signal at optical frequency with the power of said signal extending into the coating;
• exposing the coated metallic medium to a fluid assay sample;
• and
• measuring any changes in the directed light to detect a response to the presence of the specific assay species in the fluid assay sample.