GB2185308A - Optical waveguide material sensor - Google Patents
Optical waveguide material sensor Download PDFInfo
- Publication number
- GB2185308A GB2185308A GB08600522A GB8600522A GB2185308A GB 2185308 A GB2185308 A GB 2185308A GB 08600522 A GB08600522 A GB 08600522A GB 8600522 A GB8600522 A GB 8600522A GB 2185308 A GB2185308 A GB 2185308A
- Authority
- GB
- United Kingdom
- Prior art keywords
- waveguide
- metal film
- dielectric
- sensor device
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000463 material Substances 0.000 title claims abstract description 14
- 230000003287 optical effect Effects 0.000 title claims description 14
- 239000002184 metal Substances 0.000 claims abstract description 32
- 229910052751 metal Inorganic materials 0.000 claims abstract description 32
- 230000000644 propagated effect Effects 0.000 claims abstract description 7
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 239000004332 silver Substances 0.000 claims description 3
- 230000005684 electric field Effects 0.000 abstract description 3
- 230000003993 interaction Effects 0.000 abstract description 3
- 239000006096 absorbing agent Substances 0.000 abstract 1
- 239000010408 film Substances 0.000 description 24
- 238000010276 construction Methods 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 239000010409 thin film Substances 0.000 description 3
- 239000000427 antigen Substances 0.000 description 2
- 102000036639 antigens Human genes 0.000 description 2
- 108091007433 antigens Proteins 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000002198 surface plasmon resonance spectroscopy Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/55—Specular reflectivity
- G01N21/552—Attenuated total reflection
- G01N21/553—Attenuated total reflection and using surface plasmons
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/7703—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator using reagent-clad optical fibres or optical waveguides
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Plasma & Fusion (AREA)
- Engineering & Computer Science (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
A biochemical sensor device comprises a planar monomode waveguide 11 one surface of which is coated with a metal film 13 which in turn is coated with a dielectric film 14. The dielectric is as elective absorber of a material to be sensed. Light propagated through the waveguide interacts with surface plasmons in the metal film, the degree of interaction being a function of the electric field conditions adjacent the metal film. The attenuation is measured by a photodetector 16. A waveguide supporting two guided modes, only one of which exhibits resonance, may be employed, the non-resonant mode providing a reference signal. <IMAGE>
Description
SPECIFICATION
Optical sensor device
This invention relates to optical sensors, e.g. for chemical, biochemical or biological analysis.
Surface plasmon resonance is an optical surface phenomenon that has recently been employed in the construction of sensors. A surface plasmon is a surface charge density wave at a metal surface. A physical description of the phenomenon is given by H. Raether in Phys. Thin Films, 1977, 74 pp 237-244. The resonance can be observed when light interacts with a thin metal film applied to a smooth surface of a transparent, typically glass, body. Light reflected internally from the surface exhibits a minimum intensity for a particular (resonant) angle of incidence, this angle determined by the dielectric conditions adjacent the metal film and the properties of the metal film itself.
In a prior art sensor using this phenomenon, a metal film is applied to one surface of a glass prism. Such a device is described in Electronics Letters, 8th Nov. 1984, 20, No. 23, pp 968 to 970. In this device the resonant angle is determined by varying the angle of incidence and measuring the intensity of the reflected light. Such an arrangement is of course relatively bulky and requires a high degree of precision in the manufacture of its optical parts.
The object of the present invention is to minimise orto overcome these disadvantages.
According to one aspect of the invention there is provided a sensor device responsive to the presence of one or more materials, the device including an optical waveguide at least part of the surface of which is adapted to allow light propagated in discrete words along the waveguide to interact with surface plasmons thereby causing attenuation of the light, the degree of attenuation being characteristic of the presence or absence of the one or more materials, and means for detecting said attenuation.
According to another aspect of the invention there is provided a sensor device responsive to the presence of one or more materials, the device including an optical waveguide for the propagation of light in one or more discrete guided modes, a metal film disposed on at least a portion of the waveguide surface, and a dielectric film supported on the metal film, wherein the relative dielectric constraints of the waveguide, the metal and the dielectric and the thicknesses of the metal and dielectric films are such that at least one said guided mode interacts with surface plasmons in the metal film thereby causing attenuation of that mode, the degree of attenuation being characteristic of the presence or absence of the one or more materials adjacent the dielectric film.
Whilst plasmon resonance has been conventionally observed under unguided propagation conditions which can be described using ray optics, we have found that resonance can- also be observed for discrete guided mode propagation. Under the latter conditions ray optics are inappropriate for describing the physical process involved.
In an optical waveguide light propagates in one or more discrete modes. Aguided mode has a characteristic wave vector which is a function of the waveguide construction.
Plasmon resonance is observed when the component of the guided mode wave vector parallel to the metal/dielectric interface (Kx) is equal to the surface plasmon wave vector (Ksp) as given by the following equation:
where W is the optical frequency, C the free space velocity of light and Em is the real part of the dielectric constant of the metal. E1 is the dielectric constant of the waveguide and e2 is the dielectric constant of a dielectric applied to the metal e is the characteristic angle of the guided mode at the metal/dielectric interface. Thus the value of the wave vector at resonance is a function of both dielectric constants, the optical wavelength and of the metal.
We have found that, if the cladding of a multimode or monomode waveguide is sufficiently reduced in thickness that the evanescent field of the guided mode or modes extends from the core, surface plasmons can be excited in a thin metal film deposited on to the waveguide surface.
Embodiments of the invention will now be described with reference to the accompanying drawings in which Figures 1 and 2 are respectively sectional and plan views of a waveguide sensor arrangement;
and Figures 3 and 4 show respectively alternative sensor constructions.
Referring to Figures 1 and 2, the sensor arrangement includes a planar monomode optical waveguide 11 supported on a substrate 12. The waveguide 11 is coated with a very thin metal film 13, typically 500 to 1000 A (0.05 to 0.1 microns), which film is in turn coated with a thin dielectric film 14. We prefer to employ vacuum evaporated
(or sputtered) gold or silver as the coating metal 13.
Light is launched into the waveguide from a monochromatic light source 15, e.g. a light emitting diode or a laser, and is propagated along the waveguide 11. Light emitted from the waveguide 11 is received by a photodetector 16.
Light propagating along the waveguide 11 interacts with surface plasmons, the degree of interaction having a function of inter alia, the electric field condition adjacent the metal film 13.
When the waveguide is contacted with a material that is selectively absorbed by the dielectric 14 the electric field conditions adjacent the metal film 13 are altered causing a corresponding change in the plasmon resonance condition. This change in the resonance condition is detected and measured as a change in the output light intensity via the photodetector 16.
In a modification of the arrangement of Figure 1, only half of the surface of the device is coated with the dielectric so as to define two paths one of which has no dielectric film. This path forms a reference or control path to provide a differential sensor. In a further construction the sensor may comprise a plurality of light paths each sensitive to a different material.
Figure 3 shows a further sensor arrangement in which differential detection may be employed. A thin film optical waveguide 21 is formed on a substrate 22, the waveguide including a Y coupler whereby light launched into the guide via a light source 23 is split into first and second paths 24, 25 respectively. The waveguide defining one path (25) is coated with a thin film 26 comprising a silver or gold film and a dielectric film. Thus, light travelling along the path 25 displays surface plasmon resonance whilst light travelling along the other path 24 is unaffected. Light propagated via the paths 24 and 25 is received by a respective photodetector 27, 28. The outputs of the detectors 27 and 28 are coupled to a differential amplifier 29.Variation of the plasmon resonance condition in response to the presence of a selectively absorbed material in contact with the film 26 produces a corresponding change in the amplifier output.
Light may be launched into the waveguide by a number of techniques. Thus converging lenses may be used, or light may be led to and from the waveguide via optical fibre couplings. In a further construction the waveguide itself can provide the necessary coupling.
Figure 4 shows a waveguide structure that facilitates launching of the input light. The structure comprises a waveguide section 31 having input and output diffraction gratings 32 and 33 at the ends thereof. The waveguide 31 is provided with a surface metal film 34 which in turn is coated with a dielectric film 35. Light from a light source (not shown) is focussed by a lens 36 on to the input grating 32 whereby the light is propagated along the waveguide whereby plasmon interaction with the metal film 34 takes place. The propagated light is emitted from the waveguide via the output grating 33 and the light intensity pattern is monitored by a photodetector array 37.
In a further application a waveguide which supports two guided modes, only one of which exhibits resonance, may be employed. In such a device the non-resonant mode is angularly resolved to provide a reference signal from the attenuated resonant mode.
The sensor arrangements described herein may be employed in chemical, biochemical and biological applications. They are particularly adapted to forensic use as their small size renders them responsive to trace quantities of materials. in particular the dielectric film may contain antibodies for detecting binding of antigens to the antibodies. The availability of one or more reference light paths will allow the effect of the solution in which the antigens are contained to be compensated for.
Claims (8)
1. A sensor device responsive to the presence of one or more materials, the device including an optical waveguide at least part of the surface of which is adapted to allow light propagated in discrete modes along the waveguide to interact with surface plasmons thereby causing attenuation of the light, the degree of attenuation being characteristic of the presence or absence of the one or more materials, and means for detecting said attenuation.
2. A sensor device responsive to the presence of one or more materials, the device including an optical waveguide for the propagation of light in one or more discrete guided modes, a metal film disposed on at least a portion of the waveguide surface, and a dielectric film supported on the metal film, wherein the relative dielectric constraints of the waveguide, the metal and the dielectric and the thicknesses of the metal and dielectric films are such that at least one said guided mode interacts with surface plasmons in the metal film thereby causing attenuation of that mode, the degree of attenuation being characteristic of the presence or absence of the one or more materials adjacent the dielectric film.
3. A sensor device as claimed in claim 2, wherein said metal film is 0.05 to 0.1 microns thick.
4. A sensor device as claimed in claim 2 or 3, wherein said metal film comprises silver or gold.
5. A sensor device as claimed in any one of claims 1 to 4, wherein said waveguide is a planar waveguide.
6. Asensor device as claimed in any one of claims 1 to 5, wherein said waveguide is a monomode waveguide.
7. A sensor device as claimed in any one of claims 1 to 6 wherein said waveguide incorporates diffraction gratings whereby light is conveyed to and from the waveguide.
8. A sensor device substantially as described herein with reference to and as shown in Figures 1 and 2, or
Figure 3, or Figure 4 of the accompanying drawings.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8600522A GB2185308B (en) | 1986-01-10 | 1986-01-10 | Optical sensor device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8600522A GB2185308B (en) | 1986-01-10 | 1986-01-10 | Optical sensor device |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8600522D0 GB8600522D0 (en) | 1986-02-19 |
GB2185308A true GB2185308A (en) | 1987-07-15 |
GB2185308B GB2185308B (en) | 1989-10-25 |
Family
ID=10591157
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8600522A Expired GB2185308B (en) | 1986-01-10 | 1986-01-10 | Optical sensor device |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2185308B (en) |
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0326291A1 (en) * | 1988-01-27 | 1989-08-02 | AMERSHAM INTERNATIONAL plc | Biological sensors |
EP0353937A1 (en) * | 1988-07-25 | 1990-02-07 | Applied Research Systems Ars Holding N.V. | Method of assay |
GB2228082A (en) * | 1989-01-13 | 1990-08-15 | Marconi Gec Ltd | Gas or liquid chemical sensor |
WO1992005426A1 (en) * | 1990-09-13 | 1992-04-02 | Amersham International Plc | Biological sensors |
DE4033912A1 (en) * | 1990-10-25 | 1992-04-30 | Fraunhofer Ges Forschung | OPTICAL SENSOR |
GB2256270A (en) * | 1991-05-31 | 1992-12-02 | De Beers Ind Diamond | Determination of the condition of or change in state of an environment |
EP0568652A4 (en) * | 1991-01-24 | 1994-05-18 | Fiberchem Inc | Waveguide sensor |
US5478755A (en) * | 1988-07-25 | 1995-12-26 | Ares Serono Research & Development Ltd. | Long range surface plasma resonance immunoassay |
WO1997035180A1 (en) * | 1996-03-20 | 1997-09-25 | Institut für Chemo- und Biosensorik Münster E.V. | Optical lightwave sensor based on resonant optical excitation of surface plasma waves |
US6139797A (en) * | 1997-08-20 | 2000-10-31 | Suzuki Motor Corporation | Immunoassay apparatus |
EP1704429A4 (en) * | 2003-12-31 | 2012-02-01 | Life Technologies Corp | Waveguide comprising scattered light detectable particles |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB8509492D0 (en) * | 1985-04-12 | 1985-05-15 | Plessey Co Plc | Optical assay |
-
1986
- 1986-01-10 GB GB8600522A patent/GB2185308B/en not_active Expired
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1989007252A1 (en) * | 1988-01-27 | 1989-08-10 | Amersham International Plc | Biological sensors |
US5047213A (en) * | 1988-01-27 | 1991-09-10 | Amersham International Plc | Biological sensors |
EP0326291A1 (en) * | 1988-01-27 | 1989-08-02 | AMERSHAM INTERNATIONAL plc | Biological sensors |
AU638938B2 (en) * | 1988-07-25 | 1993-07-15 | Applied Research Systems Ars Holding N.V. | Method of assay |
EP0353937A1 (en) * | 1988-07-25 | 1990-02-07 | Applied Research Systems Ars Holding N.V. | Method of assay |
WO1990001166A1 (en) * | 1988-07-25 | 1990-02-08 | Ares-Serono Research & Development Limited Partnership | Method of assay |
US5478755A (en) * | 1988-07-25 | 1995-12-26 | Ares Serono Research & Development Ltd. | Long range surface plasma resonance immunoassay |
GB2228082A (en) * | 1989-01-13 | 1990-08-15 | Marconi Gec Ltd | Gas or liquid chemical sensor |
WO1992005426A1 (en) * | 1990-09-13 | 1992-04-02 | Amersham International Plc | Biological sensors |
EP0482377A3 (en) * | 1990-10-25 | 1992-11-19 | Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. | Optical sensor |
DE4033912A1 (en) * | 1990-10-25 | 1992-04-30 | Fraunhofer Ges Forschung | OPTICAL SENSOR |
EP0568652A4 (en) * | 1991-01-24 | 1994-05-18 | Fiberchem Inc | Waveguide sensor |
GB2256270A (en) * | 1991-05-31 | 1992-12-02 | De Beers Ind Diamond | Determination of the condition of or change in state of an environment |
GB2256270B (en) * | 1991-05-31 | 1995-04-19 | De Beers Ind Diamond | Determination of the condition of or change in state of an environment |
WO1997035180A1 (en) * | 1996-03-20 | 1997-09-25 | Institut für Chemo- und Biosensorik Münster E.V. | Optical lightwave sensor based on resonant optical excitation of surface plasma waves |
US6139797A (en) * | 1997-08-20 | 2000-10-31 | Suzuki Motor Corporation | Immunoassay apparatus |
EP1704429A4 (en) * | 2003-12-31 | 2012-02-01 | Life Technologies Corp | Waveguide comprising scattered light detectable particles |
Also Published As
Publication number | Publication date |
---|---|
GB8600522D0 (en) | 1986-02-19 |
GB2185308B (en) | 1989-10-25 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |