Integrated optic waveguide immunosensor
First Claim
1. A kit for performing specific binding assays, which kit includes:
- a biosensor comprising;
a step gradient waveguide including a planar substrate formed of a first optical material of refractive index n1, said planar substrate having a surface disposed adjacent to and in direct contact with a waveguide film formed of a second optical material having a refractive index n2 which is greater than n1 ; and
at least one specific binding molecule immobilized to said waveguide film and configured to bind, with specificity, an analyte.
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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.
160 Citations
21 Claims
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1. A kit for performing specific binding assays, which kit includes:
a biosensor comprising; a step gradient waveguide including a planar substrate formed of a first optical material of refractive index n1, said planar substrate having a surface disposed adjacent to and in direct contact with a waveguide film formed of a second optical material having a refractive index n2 which is greater than n1 ; and at least one specific binding molecule immobilized to said waveguide film and configured to bind, with specificity, an analyte. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. Apparatus for performing evanescent immunofluorescence assays including:
a composite waveguide comprising; a substrate formed of a first optical material of refractive index n1 and having two parallel planar surfaces separated by a thickness and a surrounding edge, said thickness being between about 1 μ
m and about 10 mm, anda waveguide film deposited directly onto at least a portion of one of said two parallel planar surfaces and formed of a second optical material having a refractive index n2 which is greater than n1 and a thickness which is between about 0.1 μ
m and about 10 μ
m, said waveguide film having a plurality of specific binding molecules immobilized thereto;a light source operably disposed to aim a light beam into said composite waveguide for propagation by total internal reflection in said composite waveguide; light coupling means operably associated with said composite waveguide for facilitating coupling of light beam thereinto; light collection means positioned for collecting light that impinges on a plane spaced from said two parallel planar surfaces; and a detector operably disposed with respect to said light collection means to detect the collected light. - View Dependent Claims (13, 14, 15)
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16. An optical structure for performing specific binding assays with an optical unit comprising a light source positioned to direct light into a waveguide for propagation by total internal reflectance in said waveguide and a detector oriented to detect light from a region proximal to the optical structure, said optical structure comprising:
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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, the thickness being between about 0.3 μ
m and about 10 mm;a waveguide film of a second optical material of refractive index n2, wherein n2 is greater than n1, in direct contact with at least a portion of one of said two parallel planar surfaces of said substrate, said waveguide film having a thickness which is between about 0.3 μ
m and about 5 μ
m, and said waveguide film further having a plurality of specific binding molecules immobilized thereto; andcoupling means for coupling light into said waveguide film, said coupling means integrally contacting said waveguide film. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification