Composite waveguide for solid phase binding assays
First Claim
1. A kit for performing specific binding assays with an optical unit including a light source positioned to direct light into an optical substrate and detector oriented to detect light from a region proximal to the optical substrate, which includes:
- a biosensor comprising;
a step-gradient waveguide including a substrate formed of a first optical material of refractive index n1 and having a surface disposed adjacent and in contact with a waveguide film formed of a second optical material having a refractive index n2 which is greater than n1, said substrate surface having a grating formed thereon, said grating constructed to facilitate coupling of light from an incident excitation beam into said waveguide film, said step-gradient waveguide being manufactured by a process of manufacture including the steps of;
providing a piece of the first optical material having a surface;
vapor depositing the second optical material on said first optical material surface to a depth of between about 0.1 μ
m and about 10 μ
m to produce said waveguide film;
coating at least one region of said waveguide layer film with a resist compound which resists an etchant to produce a coated region and an uncoated region; and
etching said waveguide film with said etchant to remove said second optical material from said uncoated region; and
at least one specific binding molecule immobilized to said waveguide film and constructed to bind with specificity an analyte.
2 Assignments
0 Petitions
Accused Products
Abstract
A step-gradient composite waveguide for evanescent sensing in fluorescent binding assays comprises a thick substrate layer having one or more thin film waveguide channels deposited thereon. In one embodiment, the substrate is silicon dioxide and the thin film is silicon oxynitride. Specific binding molecules having the property of binding with specificity to an analyte are immobilized on the surface of the thin film channels. In preferred embodiments, the composite waveguide further includes light input coupling means integrally adapted to the thin film channels. Such light coupling means can be a grating etched into the substrate prior to deposition of the thin film, or a waveguide coupler affixed to the upper surface of the thin film. The waveguide coupler has a thick input waveguide of high refractive index which receives the laser light through one end and propagates it by total internal reflection. The propagated light is then coupled evanescently into the thin film waveguide across a spacer layer of precise thickness and having an index of refraction lower than either the input waveguide or the thin-film waveguide. The composite waveguide can be constructed by plasma vapor deposition of silicon oxynitride onto the silicon dioxide substrate, masking the channel waveguides with a photoresist, and using reactive ion etching to expose the substrate in the unmasked regions.
189 Citations
12 Claims
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1. A kit for performing specific binding assays with an optical unit including a light source positioned to direct light into an optical substrate and detector oriented to detect light from a region proximal to the optical substrate, which includes:
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a biosensor comprising; a step-gradient waveguide including a substrate formed of a first optical material of refractive index n1 and having a surface disposed adjacent and in contact with a waveguide film formed of a second optical material having a refractive index n2 which is greater than n1, said substrate surface having a grating formed thereon, said grating constructed to facilitate coupling of light from an incident excitation beam into said waveguide film, said step-gradient waveguide being manufactured by a process of manufacture including the steps of; providing a piece of the first optical material having a surface; vapor depositing the second optical material on said first optical material surface to a depth of between about 0.1 μ
m and about 10 μ
m to produce said waveguide film;coating at least one region of said waveguide layer film with a resist compound which resists an etchant to produce a coated region and an uncoated region; and etching said waveguide film with said etchant to remove said second optical material from said uncoated region; and at least one specific binding molecule immobilized to said waveguide film and constructed to bind with specificity an analyte. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of making a waveguide biosensor for performing specific binding assays with an optical unit including a light source positioned to direct light into an optical structure for propagation by total internal reflectance therein and detection means oriented to detect light from a region proximal to the optical structure, said optical structure constructed by the steps of:
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providing a substrate comprising a first optical material of refractive index n1 and having two parallel planar surfaces separated by a thickness and a surrounding edge; depositing a waveguide layer of a second optical material having a refractive index n2 on one of said surfaces, said waveguide layer having a thickness which is between about 0.1 μ
m and about 10 μ
m and n2 being greater than n1 ;coating at least one region of said waveguide layer with a resist compound which resists an etchant to produce a coated region and an uncoated region; etching said waveguide layer with said etchant to remove said second optical material from the uncoated region; removing the resist compound from the etched waveguide later to expose the coated region; and immobilizing a plurality of capture molecules to said exposed coated region, said capture molecules being constructed to bind with specificity a selected analyte molecule. - View Dependent Claims (10, 11)
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12. A kit for performing specific binding assays with an optical unit including a light source positioned to direct light into an optical substrate and detection means oriented to detect light from a region proximal to the waveguide, which includes:
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a biosensor comprising; a step gradient waveguide including; a substrate formed of a first optical material of refractive index n1 and having a surface disposed adjacent and in contact with a waveguide film formed of a second optical material having a refractive index n2 which is greater than n1 ; and a waveguide coupler contactingly disposed on said waveguide film, said waveguide coupler comprising; an input waveguide formed of an optical material having a refractive index n3, and having a thickness which is between about 0.5 mm and about 5 mm; and a spacing layer formed of an optical material having a refractive index n4, wherein n4 <
n3 and n4 <
n2, and having a thickness selected to optimize evanescent coupling of light from said input waveguide into said waveguide film andat least one specific binding molecule immobilized to said waveguide film and constructed to bind with specificity an analyte.
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Specification