Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Patent
1997-05-12
1998-04-14
Alexander, Lyle A.
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
422102, G01N 2101
Patent
active
057388253
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
This invention relates to the field of optical biosensors and the application of optical biosensors to biochemical analysis, particularly in combination with standard biochemical analysis techniques and equipment to permit automated analysis.
Optical biosensors are devices which make use of the refractive and coupling properties of light to detect the presence of substances on a surface. Usually integrated optical biosensors have a waveguiding film, of a certain refractive index, which forms the surface which the sample of the substance contacts. A base sheet, which has a lower refractive index than the waveguiding film, contacts the waveguiding film. A grating coupler or prism coupler is then positioned to cooperate with the base sheet to incouple light that is shone on the base sheet through the coupler. Monochromatic light is then shone on the base sheet through the coupler and the in- or out-coupled light monitored. Changes in the refractive index of the waveguiding film caused by molecules binding to it can be detected by observing changes in the angle of the emitted, out-coupled light. To detect the presence of specific substances in the sample, the waveguiding film can be coated with a complementary substance which specifically binds to the first substance.
An example of a biosensor that uses a grating coupler is disclosed in European Patent 0 226 604 B. This biosensor comprises a base sheet joined to a waveguiding film; the surfaces of the sheet and film that join together being formed into a grating coupler or Bragg coupler. This grating coupler can be a unidiffractive or multidiffractive structure. The refractive index of the waveguiding film is higher than that of the base sheet. A chemo-sensitive substance is coated on the waveguiding film in an area of the waveguiding film that contacts the sample. A laser is used to direct monochromatic light towards the grating coupler at a selected angle of incidence. The position of the laser or of the grating coupler is then altered to change the angle of incidence until light is incoupled in the waveguiding film. Any change in the effective refractive index caused by molecules binding to the waveguiding film, disturbs the incoupling condition and the angle of incidence must be changed to correct for this. Hence changes in the angle of incidence (and this correlates directly to the position of the laser with respect to the grating coupler) required to maintain the incoupled light are monitored. These changes in the angle of incidence are then correlated to changes in the amount of molecules binding to the surface of the chemo-sensitive substance.
It will be appreciated that this biosensor provides an extremely convenient means for detecting the presence and the amount of a substance in a sample. However a drawback of the system is that the laser or grating coupler must be continually moved.
A further optical biosensor is disclosed in WO 93/01487 and this optical biosensor permits the encoupled light to be monitored without the use of moving parts. This biosensor relies on the use of a fan-shaped, monochromatic light field which may be coupled in and out of the waveguiding structure. The outcoupled light field can be focussed to a point and the position of the point determined. Movement in the position of the point indicates changes in the effective refractive index of the waveguiding structure.
Optical biosensors provide a very convenient means of detecting the presence of substances without the use expensive reagents and labelling techniques. However at the present time, optical biosensors can only be used to test single samples which must be placed in special detection cells. Hence the laboratory technician must transport a sample to the optical biosenor, load it into the biosensor, and monitor it. Afterwards the biosensor must be cleaned. This severely limits the application of optical biosensors.
SUMMARY OF THE INVENTION
Accordingly in one aspect this invention provides a detection cell for use as a component
REFERENCES:
patent: 5082629 (1992-01-01), Burgess et al.
Advertising Brochure of Packard/TopCount, no date supplied.
Briquet Veronique
End Peter
Legay Francois
Marbach Peter
Pfefferkorn Roland
Alexander Lyle A.
Artificial Sensing Instruments ASI AG
Balzers Aktiengesellschaft
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