Biosensors

• US 4,857,273 A
• Filed: 04/04/1986
• Issued: 08/15/1989
• Est. Priority Date: 04/12/1985
• Status: Expired due to Term

• Current Assignee: Marconi UK Intellectual Property Limited (Marconi Holdings Company Limited)
• Original Assignee: Plessey Overseas Limited (Marconi Holdings Company Limited)
• Inventors: Stewart, William J.
• Primary Examiner(s): Hill, Jr., Robert J.
• Application Number:
  US06/848,680
• Time in Patent Office: 1,229 Days
• Field of Search: 436/805, 422/57, 422/58, 422/69, 422/68, 422/55, 350/96.12, 350/96.15, 350/96.17, 350/96.19, 350/96.34, 435/287, 435/291, 435/808
• US Class Current: 422/82.11
• CPC Class Codes: G01N 21/7703 using reagent-clad optical fibres or optical waveguides using measurement of total internal reflection or attenuated total reflection G01N21/552; optical fibres or waveguides per se G02B
• CPC Class Codes: G01N 33/54373 involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings
• CPC Class Codes: Y10S 435/808 Optical sensing apparatus
• CPC Class Codes: Y10S 436/805 Optical property

Abstract

A biosensor includes an optically dense body provided with a coating sensitized to a specific assay species, and an input and output coupling structure. Light signal response is enhanced by incorporating a partially reflecting, partially transmitting medium between the coupling structure and the optically dense body having a lower refractive index. The thickness of such medium is chosen so that light may be coupled by frustrated total internal reflection and to enable the medium to serve as a resonant mirror.

Claims

1. A biosensor comprising:

an optically dense body having a coating sensitized for a given assay species, light coupling means positioned in operative adjacent relation to the optically dense body for directing light into and out of the same, and means operatively associated with the light coupling means for esablishing a mirrored resonant cavity within the optically dense body by frustrated total internal reflection, including a light reflecting and partially transmissive medium operatively interposed between the optically dense body and the light coupling means.

2. The biosensor as claimed in claim 1, wherein the light reflecting and partially transmissive medium comprises a single layer of material of a thickness establishing light coupling by frustrated total internal reflection, said material having a refractive index lower than that of the optically dense body.

3. The biosensor as claimed in claim 2, wherein the single of material layer is magnesium fluoride.

4. The biosensor as claimed in claim 2, wherein the single layer of material is alumina.

5. The biosensor as claimed in claim 1, wherein the light reflecting and partially transmissive medium comprises a dielectric multilayer structure.

6. A monitoring system comprising a light source, a photodetector, a biosensor comprising:

an optically dense body having a coating sensitized for a given assay species, light coupling means operatively positioned adjacent to the optically dense body for directing light into and out of the same and means operatively associated with the light coupling means for esablishing a mirrored resonant cavity within the optically dense body by frustrated total internal reflection, including a light reflecting and partially transmissive medium operatively interposed between the optically dense body and the light coupling means, said light source and the photodetector being positioned relative to the biosensor in optically coupled resonance relation to each other.