A light guiding system for photonic applications

Abstract

The invention includes a light guide system (1) designed for photonic or optical sensing applications. The system comprises a sensing layer (7) and one or more light pipes (10), where the sensing layer (7) is in direct contact with the one or more light pipes (10). The one or more light pipes (10) are arranged to receive light emitted from a light source (14), guide the light towards a sensing layer (7) at a predetermined incident angle, and guide reflected light away from the sensing layer (7). The invention further includes a method of using the light guide system (1).

Description

[0001] A Light Guiding System for Photonic Applications

[0002] Field of the Invention

[0003] The present invention relates to a system for guiding light, as well as a method of using the system, that may find particular utility in photonic applications. More particularly, the invention relates to a system incorporating a light pipe attached to a sensing layer.

[0004] Background of the Invention

[0005] This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present invention. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.

[0006] Photonic sensing technologies rely on the interaction between light and a sample to detect, analyse, and characterize various physical, chemical, or biological properties. One of the most fundamental properties that can be measured using light is the refractive index of a substance. The refractive index is an optical property that describes how light propagates through a material; it varies according to the material's composition, density, and molecular structure. By detecting changes in the refractive index near a sensor surface, valuable information can be obtained about the presence, concentration, and behaviour of specific substances, which is essential in applications like environmental monitoring, biomedical diagnostics, and chemical analysis.

[0007] When light encounters an interface between materials with different refractive indices, it refracts or reflects at specific angles. This bending or reflection is governed by the difference in refractive indices between the two materials. Refractive index-based sensing works because the refractive index change near the sensor surface alters how light is refracted, reflected, or absorbed at the material interface. In the context of photonic sensing, an analyte is the specific substance or molecule that the sensor aims to detect or measure. This could be a wide variety of entities, including ions, gases, biomolecules (such as proteins, DNA, or antibodies), pollutants, or chemicals. The sensor surface is the functional interface of the sensing device where interactions with the analyte occur and where changes in the environment can be detected by the sensor. When an analyte binds to the sensor surface, it shifts the refractive index locally. This shift provides a measurable signal indicating the presence orconcentration of the substance, enabling the monitoring of molecular interactions and binding events without requiring labels or additional markers.

[0008] One of the most widely adopted refractive index-based sensing techniques is surface plasmon resonance (SPR). In SPR, a metal-dielectric interface (a sensing layer) supports surface plasmons, coherent oscillations of electrons at the metal surface, that can be excited by light under specific conditions. The Kretschmann and Otto configurations are common SPR setups, both of which use a prism to achieve the conditions needed to excite surface plasmons. The Otto configuration is generally characterised by the inclusion of a dielectric gap between the metal film / sensing layer and the prism, and the Kretschmann configuration is generally characterised by the lack of a dielectric gap, such that the metal film / sensing layer is directly deposited on the prism. In a conventional Kretschmann arrangement, a thin metal layer is deposited on the base of a high-refractive-index prism, where light directed at the prism's critical angle creates an evanescent wave that excites surface plasmons at the metal-dielectric interface. Changes in the refractive index near the interface alter the conditions for surface plasmon resonance, leading to a shift in the resonance angle. This angle is determined by matching the wave vector of the incident light with that of the surface plasmons, which can be expressed mathematically as follows:

[0009]

[0010] where:

[0011] • kx, is the component of the wave vector of the incident light parallel to the interface;

[0012] • X, is the wavelength of the incident light;

[0013] • np, is the refractive index of the prism (or other medium through which light is directed); • ksp, is the wave vector of the surface plasmons;

[0014] • Em, is the permittivity of the metal layer; and

[0015] • Ed, is the permittivity (related to refractive index) of the dielectric medium near the metal surface.

[0016] The light ray, which will now have a lowered light intensity following the surface plasmon excitation, is then reflected off the metal layer, out of the prism, and towards a sensor. The drop in reflected lightintensity at the resonance angle is then measured by the sensor, and the results are analysed by a computer that processes the data and outputs useful information. SPR is therefore able to provide real-time results by continuously monitoring changes in the resonance angle, wavelength, or light intensity as an analyte interacts with a sensor surface.

[0017] However, despite their advantages, conventional photonic systems have limitations in current designs that impact their efficiency, size, and applicability. Particularly, the usage of prisms to direct an evanescent wave towards a metal sheet makes the setup bulky, limiting miniaturization. Additionally, because the light is not fully confined within the system, there is light loss, reducing efficiency and sensitivity. Prism-based systems also require additional optical components like collimating and collecting lenses, adding further bulk and alignment complexity to the apparatus. It is therefore an objective of the present invention to obviate or mitigate the aforementioned disadvantages with existing apparatus and systems.

[0018] Summary

[0019] It is an objective of the present invention to provide a light / radiation guiding system for photonics applications. This objective can be achieved by the features as defined by the independent claims. Further enhancements are characterized by the dependent claims.

[0020] According to an aspect of the present invention, there is provided a light guide system for photonic or optical sensing applications, the system comprising: one or more light pipes, wherein the one or more light pipes are arranged to receive light emitted from a light source, guide the light towards a sensing layer at a predetermined incident angle, and guide reflected light away from the sensing layer.

[0021] Optionally, the sensing layer may be in direct contact with the one or more light pipes. Advantageously, this provides a light guide system in which the one or more light pipes are directly in contact with the sensing layer. This removes any background interference or optical noise from other components of the system that may interfere with the light guided towards the sensing layer. This results in a more accurate angle of incident of the light, and therefore more accurate measurements taken from the light reflected away from the sensing layer. The one or more light pipes may be secured to the sensing layer.

[0022] Optionally, the sensing layer may comprise a metal, semiconductor or other materials with plasmonic properties. The sensing layer may comprise a coating of a metal or other plasmonic material.The system may further comprise a substrate. The one or more light pipes may be supported by the substrate. A point at which the light is incident on the sensing layer may be separated from the substrate. This allows the light within the one or more light pipes to avoid any interference from the substrate. Optionally, the substrate is comprised on an integrated circuit. Optionally, a length, width, and / or height of the substrate and one or more light pipes is no more than 50 millimetres.

[0023] The sensing layer may be separated from the one or more light pipes by a dielectric gap. The dielectric gap may comprise part of a substrate. The substrate may support the one or more light pipes.

[0024] Optionally, the system further comprises: a detector configured to receive light emitted from the one or more light pipes to measure at least one raw data property; and a computer configured to receive the at least one raw data property from the detector, process the at least one raw data property, and generate at least one processed data property; wherein the at least one raw data property is selected from a group comprising: a light intensity, an angle of minimum reflectance, wavelength, a temporal resolution, and a background noise.

[0025] Optionally, the at least one processed data property is selected from a group comprising: an analyte concentration, a kinetic parameter, a resonance curve.

[0026] Optionally, the light pipe may comprise at least one supporting element. Optionally, each supporting element may comprise: a base formed as a raised protrusion configured to be placed on a surface; a rod formed as an elongate structure extending between the base and the light pipe. In the case of the system including a substrate, the supporting element may be structured to affix the light pipe to the substrate. The base of each supporting element may be formed as a raised protrusion located on the substrate.

[0027] Optionally, the one or more light pipes may comprise: an input end arranged to receive light from a light source, an output end arranged to emit light that has travelled along the light pipe; and an intermediate portion located between the input end and the output end, the intermediate portion may be configured to direct light to transmit light received through the input end to the sensing layer.Optionally, light guided by the one or more light pipes exits the light pipe at the intermediate portion to interact with the sensing layer. Optionally, the sensing layer is directly adhered to the intermediate portion.

[0028] Optional ly, the one or more light pipes comprise: a first light pipe arranged to receive light from a light source and direct the light towards the sensing layer, wherein the first light pipe may be directly secured to the sensing layer; and a second light pipe arranged to receive light reflected by the sensing layer and direct the light away from the sensing layer, wherein the second light pipe may be directly secured to the sensing layer.

[0029] Optionally, the sensing layer is selected from a group of materials comprising: Gold, Silver, Aluminium, Palladium, metal alloy, transition metal nitrides, transparent conductive oxides, graphene, doped semiconductors, nanostructured plasmonic materials or combinations thereof. The sensing layer may also be a combination of multilayer metals, graphene, nanostructures, nanoparticles, or other plasmonic materials. The sensing layer may be any noble metal or two-dimensional material.

[0030] Optionally, the one or more light pipes comprise an input end configured to receive light from a light source, and wherein the input end is configured to divide a path of light into two or more subsidiary paths.

[0031] Optionally, the one or more light pipes may comprise an input end, wherein the input end may comprise a first section configured to receive light from a light source and a second section secured to the sensing layer, and wherein the first section of the input end may comprise a collimating lens configured to collimate the light from the light source.

[0032] Optionally, the one or more light pipes may comprise: an input end, wherein the input end comprises a first section configured to receive light from a light source and a second section secured to the sensing layer; and a reflective facet positioned between the first section and the second section of the input end, wherein the reflective facet is configured to direct the light received through the first section towards the sensing layer.

[0033] Optionally, the one or more light pipes may comprise an input end configured to receive light from a light source, and the input end may comprise an input surface that is textured, etched, concave, or convex.Optionally, the one or more light pipes are formed of a transparent material. The material may be transparent to any wavelength of light, such as visible light, infrared light or any other wavelengths of light.

[0034] Optionally, the transparent material of the one or more like pipes may be selected from a group comprising: polycarbonate, glass, polymethyl methacrylate (PMMA), a polymer-based material, a resin-based material, a semiconductor material, ceramic, or a nitride material.

[0035] Optionally, a cladding at least partially encompasses the one or more light pipes; wherein the one or more light pipes has a first refractive index; wherein the cladding has a second refractive index; and wherein the first refractive index is higher than the second refractive index.

[0036] Optionally, the substrate comprises a non-metal. Optionally, the non-metal is selected from a group comprising: Polycarbonate, Glass, Silicon, Polymethyl Methacrylate, or Polymer / resin materials.

[0037] According to a second aspect of the invention, there is provided a method comprising: providing a guiding system according to the first aspect of the invention, transmitting a radiation through an input end of the one or more light pipes to towards a sensing layer, and detecting radiation reflected by the sensing layer and transmitted through an output end of the light pipe away from the sensing layer.

[0038] Optionally, the method may further comprise: collimating the radiation received by the input end with a collimating lens positioned at a first section of the input end; and directing the collimated light through a second section of the input end towards the sensing layer with a reflective facet.

[0039] The arrangements described herein provide numerous advantages over known prior art. In particular, the guiding arrangement and system of the present invention is simple, and can be easily miniaturised, allowing it to be incorporated in a wide range of applications and environments, and in particular can be fabricated on a chip. Its small size also reduces manufacturing costs. Moreover, since the light pipe can be directly attached to the substrate or sensing layer, light loss is reduced and the light can be more precisely controlled to achieve the desired incident angle, thereby resulting in improved sensing sensitivity.

[0040] Brief Description of the DrawingsThe accompanying drawings illustrate presently exemplary embodiments of the disclosure and serve to explain, by way of example, the principles of the disclosure.

[0041] FIG. 1 is a schematic diagram of a light pipe guiding system according to an embodiment of the invention for use in photonic or optics applications;

[0042] FIGs. 2A and 2B are diagrams showing the light pipe of Figure 1 in 2 different known SPR arrangements;

[0043] FIGs. 3A and 3B are schematic diagrams of alternative light pipe configurations;

[0044] FIGs. 4A to 4D are schematic diagrams of alternative light pipe configurations;

[0045] FIG. 5 is a schematic diagram of an example light path through the light pipes of FIGs. 1 to 4D; FIGs. 6A and 6B are diagrams of the light pipes of FIGs. 3A to 5 in two different known SPR arrangements;

[0046] FIG. 7 is a diagram of various light pipe geometries;

[0047] FIG. 8 is a diagram of various light pipe input surfaces;

[0048] FIG. 9 is a diagram of a split end arrangement; and

[0049] FIG. 10 is a graph detailing how a SPR signal can be measured.

[0050] Detailed Description

[0051] FIG. 1 is a schematic diagram of a system for use in photonic applications, such as with Surface Plasmon Resonance-based sensing. In a basic configuration, guiding system 1 comprises a substrate 2 formed of a substantially planar surface having a first side 4, and a second side 6 located opposite to the first side 4. A sensing layer 7 (which may be a metallic sheet or coating or a nanoparticle layer, amongst others) is located on the second side 6 of the substrate. The system further comprises at least one light pipe 10, which is shown to include a first light pipe 10a and a second light pipe 10b in FIG. 1. A first end 8 (otherwise referred to as an input end) of the first light pipe 10a is configured to receive light from a light source 14 (e.g. a halogen lamp, laser or light emitting diode). A second end 12 (otherwise referred to as an output end) of the light pipe 10 is configured to emit light that has been transmitted through the light pipe 10. A detector 16 detects the light emitted (as will be discussed further below). Alternatively (although not shown in Fig 1), the at least one light pipe 10 may be a single light pipe 10, such that there is an intermediate portion located close between the input end 8 and the output end 12. In both cases, the one or more light pipes 10 are arranged to guide light to interact with the sensing layer 7 at a predetermined angle. The substrate and light pipe arrangement has an overall size that can be quantified in terms of its largest dimension. Specifically, the size of the system may be less than 50 millimeters. The design is further adaptable to achieve progressivelysmaller sizes, including dimensions smaller than 10 millimeters, 1 millimeter, 100 micrometers, and down to as small as around 50 micrometers. In FIG. 1, the one or more light pipes 10 are arranged generally to conform with the Kretschmann configuration. Attachment between the substrate and light pipe may take the form of an integral molding between the substrate 2 and light pipe. However, the attachment can be in the form of any suitable means, such as via glue or additive manufacturing techniques.

[0052] The substrate 2 may be formed of a non-metal base, and each side of the substrate 2 may have different properties and functions. The sensing layer 7 on second side 6, also known as the detection side, may be designed for facilitating surface plasmon resonance and / or molecular binding. Accordingly, the sensing layer 7 may comprise a layer of metal coating or nanostructures. The metal sensing may be deposited on the non-metal base such that the metal thickness is 40 - 60 nanometres, which is optimal to ensure accurate measurements in various sensing techniques whilst retaining structural rigidity. Alternatively, metal nanostructures may be arranged periodically on the substrate (and may be nano triangles, nano discs, nano cubes, etc). The metal is typically composed of gold, however other metals may be used, such as silver, aluminium, palladium (or alloy with other metals), and other materials with plasmonic properties (such as graphene). The metal layer may be polished to a nanometre scale smoothness (i.e. a root mean square roughness of less than 10 nanometre) to maintain a consistent resonance condition and minimise signal loss. The sensing layer 7 may also be provided with ligands (e.g. antibodies, proteins, or DNA), which are specific molecules that can selectively bind with a target analyte. To attach the ligands, the sensing layer 7 may be pre-treated with a functional coating (e.g. Self-Assembled Monolayers, Polyethylene Glycol (PEG) Coatings, Dextran-Based Coatings, proteins, aptamer, DNA, RNA and Zwitterionic) to facilitate the immobilisation of the ligands on the sensing layer 7. The second side 6 of the substrate 2 may be in fluid communication with a fluid containing the analytes of interest. The fluid may be provided by a fluid apparatus (shown in FIG. 4C as an example ) structured to provide a continuous contact the analyte molecules in the sample and the immobilized ligands on the metal-coated surface of the substrate 2. The first side 4, also known as the optical side, is designed with features to support the optical function of the sensor. Accordingly, the first side 4 comprises the non-metal base. The non-metal base may be selected from a group of optically transparent materials including Polycarbonate, Glass, Silicon, Polymethyl Methacrylate, and resin / polymer materials. Substrate 2 may be part of a chip or fabricated on a chip.The light pipe 10 is structured such that the light entering at the input end 8 is confined within total internal reflection, which may be achieved through the refractive index between the light pipe and the atmosphere. This mechanism minimizes loss and maintains light intensity throughout the length of the pipe. Accordingly, the light pipe may be formed from an optically transparent material having a first refractive index. The optically transparent material may be selected from a group of materials comprising: quartz, silica, borosilicate glass, crown or flint optical glass, crystalline optical materials such as sapphire or fluoride crystals, transparent semiconductor materials, high-index optical materials, polymethyl methacrylate (PM MA), polycarbonate, photopolymer or UV-curable resins, hybrid organic-inorganic materials, transparent ceramics, or other polymer- or glass-based optical materials.

[0053] Figures 2A and 2B show the light pipe of arranged in both the Otto (right) and Kretschmann (left) configurations. In a first arrangement shown in Figure 2A (associated with the Kretschmann configuration), the metal / sensing layer 7 (which may be fabricated on a second side 6 of the substrate 2) is separated from light pipe 10 only by substrate 2. When a light ray is transmitted through the input end 8 of the light pipe, this generates an evanescent wave that penetrates through the metal layer and excites surface plasmons at the second side 6 where the metal meets the fluid containing the analyte. In the second arrangement as shown in 2B (associated with the Otto configuration), the sensing layer 7 is not in direct contact with the substrate 2a. Instead, they are separated by a dielectric gap 17 (or a predetermined spacing), which may be a fluid medium arranged between the light pipe 10 and sensing layer 7. Accordingly, in the second arrangement, a first substrate 2a is provided for the light pipe, and a second substrate 2b is provided for the sensing layer 7. In use, an evanescent wave is capable of traveling across the gap and exciting surface plasmons at the metal-dielectric interface. Preferably, dielectric gap 17 is between 200 and 500 nanometers.

[0054] FIGs 3A and 3B show various examples of the system. For the sake of brevity and to avoid unnecessary repetition, features common to examples described herein may not be redundantly restated in the description of each example. It should be understood that such common features are equally applicable to, and form an integral part of, each example unless explicitly stated otherwise or inherently inconsistent with the context of a particular example.

[0055] FIG. 3A illustrates an example light pipe 10. Two or more light pipes 10 may be arranged in parallel. Each light pipe 10 further comprises the intermediate portion 9 located between the input end 8 and the output end 12. The intermediate portion 9 is attached to or in a predetermined proximity with thesubstrate 2, such that the intermediate portion 9 is configured to direct light to and receive light from the first side 4 of the substrate 2. The light pipe 10 may further comprise at least one supporting element structured to affix the light pipe 10 to the substrate 2. In this example, each supporting element comprises a rod 15 and a base 13. The base 13 may take the form of a raised protrusion on the first side 4 of the substrate 2. The rod 15 is an elongate structure extending between the base 13 and the intermediate portion 9. The input end 8 and the output end 12 are aligned on a planar axis. Particularly, the input end 8 and output end 12 are orientated such that light entering and exiting the light pipe does so in a direction substantially perpendicular to the first side 4 of the substrate 2. The intermediate portion 9 is angled relative and towards the planar axis. The angles between the light pipes 10 input or output ends 8, 12 and the intermediate portion 9 may range from 100° to 170°, or may adopt a specific predefined value, such as 120°, 135°, or 150°.

[0056] FIG. 3B is similar to FIG. 3A, with the difference being that the input end 8 and output end 12 are orientated such that they are substantially parallel relative to the first side 4 of the substrate 2. The angles between the light pipes 10 input or output ends 8, 12 and the intermediate portion 9 may range from 10° to 80°, or may adopt a specific predefined value, such as 30°, 45°, or 60°.

[0057] FIG. 3A and 3B show a perpendicular and parallel orientation of input end 8 and output end 12 relative to the substrate 2 and 2a respectively. However, in other arrangements, the orientation of the input and output ends 8, 12 with respect to the substrate 2, 2a may include any oblique angle, such as 95° or 120° for example.

[0058] FIG. 4A shows another example of the light pipes 10. As shown in FIG. 4A, the system includes two light pipes 10. However, it is to be understood that the system may include any number of light pipes, including one light pipe. FIGs. 4B to 5 show one of the light pipes 10 of FIG.4A.

[0059] In the example of FIGs.4A to 5 , the light pipe 10 includes an intermediate portion 9. The intermediate portion 9 is directly secured to the sensing layer 7 (as shown in FIGs 4B and 4C). In operation, the light does not interact with a substrate at all. Instead, the light pipe 10 is directly attached to the sensing layer 7 so that light passes through the input end 8, interacts with the sensing layer 7 disposed on the intermediate portion 9, then exits through the output end 12.

[0060] The sensing layer 7 is provided as a thin-film metal layer, either directly or via one or more intermediate layers. The one or more intermediate layers include one or more of: an adhesion layer,an index-matching layer, a buffer layer, or a protective layer. The intermediate layers of the sensing layer 7 may be optically transparent at an operating wavelength of the plasmonic sensor.

[0061] The light pipe 10 is optically coupled to the sensing layer 7. The light pipe 10 is directly formed to the sensing layer 7. However, in other arrangements, the light pipe 10 may be bonded to, or aligned with, the sensing layer 7.

[0062] The light pipe 10 is formed to the sensing layer 7 using lithographic patterning. However, in other examples, the light pipe 10 may be optically coupled to the sensing layer 7 by one or a combination of: selective coating, electrodeposition, physical vapour deposition, atomic layer deposition, chemical vapour deposition, nano-imprint or replication techniques, additive manufacturing, wafer-level bonding, adhesive bonding, optical cement, index-matching materials, or any other suitable fabrication technique.

[0063] The light passes through the input end 10 and follows a first light path 20 towards the sensing layer 7 and exits the light pipe 10 on a second light path 21 after interacting with the sensing layer 7 through the output end 12.

[0064] As shown in FIG. 4B, the light is directed through the input end 8 of the light pipe and is directed towards the sensing layer 7. The light is incident on the sensing layer 7 at a sensing location 11 (shown in FIG. 4C). The sensing location 11 is within the intermediate portion 9 of the light pipe 10 secured to the sensing layer 7.

[0065] Alternatively to the angled light pipes 10 comprising the intermediate portions 9 shown in FIGs 4A to 4D, the system may include a first light pipe arranged to receive light from the light source 14 and direct the light towards the sensing layer 7, and a second light pipe arranged to receive light reflected by the sensing layer 7 and direct the light away from the sensing layer 7 (similar to the arrangement shown in FIGs 1 to 2B). In this case, the input and output light pipes are both directly secured to the sensing layer 7.

[0066] FIG. 4C shows the guiding system 1 of FIG. 1 using the example light pipe 10 of FIGs. 4A, 4B and 4D integrated with fluids apparatus. The fluid apparatus includes an inlet 22, a channel 23 and an outlet 24. The inlet receives the fluid (liquid or gas) containing the analytes of interest. The fluid flows along the channel 23, where it interacts with the material of the sensing layer 7. The light reflects under thesensing layer 7 at the sensing location 11 and excites surface plasmons at the second side 6 of the sensing layer 7 where the metal meets the fluid containing the analyte. The measured sample is output from the channel via the outlet 24.

[0067] Optional ly, the input end 8 and output end 12 of the light pipe 10 are attached to substrate 2. The function of the substrate 2 in this example is to hold the light pipe 10 in place, thus the substrate may be made of any suitable material. The intermediate portion 9 of the light pipe 10 in this case is angled relative and away from the plane of the substrate. The intermediate portion 9 may further comprise a metal coating fabricated directly thereon.

[0068] In the case of the light pipe 10 being attached to the substrate 2, the sensing location 11 is separated from the substrate 2. Figure 4D shows a schematic diagram of a position of the sensing location 11 compared to the substrate 2. Figure 4D shows a plane of incident 18 of the light from the source 14. The light travels along the plane (along the light pipe 10 not shown in the FIG. 4D) and is incident on the sensing layer 7 at the sensing location 11. The arrows labelled 20 and 21 show the light path taken by the light through the light path 10. As shown, the sensing location 11 is separated from the substrate 4, and is positioned at a different location on the plane of incident 18 compared to the substrate 4.

[0069] The sensing location 11 in which the light is incident on the sensing layer 7 is positioned away from the substrate 2, such that the substrate 2 does not interfere with the light passing through the light pipe 10 and onto the sensing layer 7.

[0070] FIG. 5 show the light path 20 of the light through the light pipe 10 towards the sensing layer 7. The light pipe 10 includes a collimating lens 25. The collimating lens 25 is integral to the light pipe 10. However, in other arrangements the collimating lens 25 may be a separate part attached to the input end 8 of the light pipe 10.

[0071] The collimating lens 25 is positioned at a first section 28 of the input end 8 of the light pipe 10. The first section 28 is the section of the input end 8 that initially receives the light from the light source 14 (as shown in FIG. 5). The input end 8 also includes a second section 29 which is the section of the input end 8 that contacts the sensing layer 7.The light pipe 10 includes a reflective facet 26. The reflective facet 26 is an angled portion of the light pipe 10 that guides the light from the first section 28 of the input end 8 towards the second section 29 and the sensing layer 7. The reflective face 26 may be an angled, curved, or segmented portion of the light pipe 10.

[0072] The light from the source 14 (which is shown in Figures 1 and 2) is collimated by the collimating lens 25 as it enters the light pipe 10. This ensures that all light enters the sensing region at a controlled and uniform incident angle. The collimated light is then reflected by the reflective facet 26 towards the sensing layer 7.

[0073] The reflective facet 26 guides the collimated light at a constant angle. The reflective facet 26 of the light pipe 10 is oriented along the light path 20 to maintain a uniform incident angle at which the light reaches the sensing layer 7. This ensures that the angle of incidence of the light on the sensing layer 7 is uniform and controlled, as shown by arrow 27 on FIG. 5. Having the light collimated and then reflected at a constant angle reduces loss of light and eliminates inefficiencies associated with uncontrolled or substrate-dependent excitation.

[0074] The collimating lens 25 and reflective facet 26 are monolithically fabricated using additive manufacturing.

[0075] FIGs 6A and 6B demonstrate how the embodiments of FIGs. 3A to 5can be used in the first and second known SPR arrangements respectively (Figure 6A shows the Kretschmann arrangement and Figure 6B shows the Otto arrangement). The light pipes 10 of FIGs, 3A to 5 can, in the Kretschmann configuration, be in direct contact with sensing layer 7 (as per FIG. 6A), because the light pipe is secured to the sensing layer 7. In this case, the substrate 2 is not adjacent to the sensing layer 7 (which is the case in FIG. 6B).

[0076] As shown in FIG. 7, the cross section of the light pipe 10 may be circular, rectangular, or another cross section depending on the application requirements. The light pipe may further include an angled, curved, or segmented portion to guide light along a desired path. Optionally, the light pipe is at least partially covered by a cladding material having a second refractive index lower than the first refractive index. The cladding may cover all areas of the light pipe aside from the input and output ends. As shown in FIG. 8, the input end 8 may have an input surface that may be flat, convex, or concave,depending on the light source(s) to be used. Moreover, that the input surface may be textured, etched, and / or coated with an anti-reflective material to enhance light acceptance and reduce input losses.

[0077] FIG. 9 illustrates a split end arrangement 19 that may be located at the input end 8 of the light pipe 10. As illustrated, the split end arrangement 19 may include a branching section configured to divide the flow path of light into two or more subsidiary paths. The branching section may adopt a fork-like configuration, such that a primary pipe segment 19a transitions into multiple secondary pipe segments 19b. The split end arrangement 19 is structured to create an array of detection regions on the metal layer, as some analytical devices require measurements of separate samples simultaneously.

[0078] The system may further comprise a detector 16 configured to capture the light emitted from the output end 12 of the light pipe 10, and provide at least one raw data property. The detector may be in electronic communication with a computer configured to receive at least one raw data property from the detector, process the at least one raw data property, and generate at least one processed data property.

[0079] FIG. 10 shows a graph detailing how a SPR signal can be measured with the light guide system 1 of FIGs. 1 to 9. Particularly, the detector may be engineered to identify and monitor precise shifts in light intensity at specific angles, thereby detecting shifts in the surface plasmon resonance angle that correspond to binding events on the sensor surface. Accordingly, the detector may comprise a camera (such as charge-coupled device (CCD) or complementary-metal oxide semiconductor (CMOS)), photodiode array, or other high-sensitivity light-detecting apparatus that is capable of recording light intensity at multiple angles or wavelengths simultaneously. The at least one raw data property may include any of a light intensity value, a wavelength Information, and a temporal value. The at least one post processed data property may include any of a sensorgram generation, kinetic and affinity analysis and a concentration estimation. Preferably, the computer is further configured to correct background noise received by the detector by known processing methods.

[0080] An example operation of the system when used in SPR applications will now be described. A polarised light ray, typically a laser, is received by the input end 8 of the light pipe 10, where it then undergoes total internal reflection due to the properties of the light pipe 10. As the light ray passes through the light pipe 10 and through the non-metal base, If the light ray hits the metal at a specific resonance angle, the resulting evanescent waves excite surface plasmons in the metal layer (i.e., the sensing layer7). The surface plasmons lower the light intensity of the radiation, and the light ray is reflected off the metal surface, through the output end 12 of the light pipe 10, and towards a detector. The detector captures the reflected light and measures the angle at which the intensity dip has shifted. This shift correlates to the amount of analyte bound to the surface. Whilst this is occurring, the second side 6 of the sensing layer 7, which will have been provided with ligands, is in fluid communication with a fluid containing an analyte. The fluid is flown across the second side 6 such that the analyte binds with the ligands, thereby changes the local refractive index at the metal layer. This change in refractive index alters the conditions for SPR, causing a shift in the resonance angle where the dip in reflected light intensity occurs. A computer processes raw data parameters received from the detector including light intensity, resonance angles, and a time stamp, and generates processed data for a user.

[0081] Unless otherwise specified, the term 'angle' is inclusive of all such variations and encompasses acute, obtuse, or any intermediate angular orientations.

[0082] Components ancillary to photonic systems such as, but not limited to a fluid delivery apparatus, computer, or lens have not been depicted for clarity purposes, though the inclusion and use of such equipment in the current disclosure would be known and appreciated by those skilled in the art.

[0083] The scope of the disclosure is not intended to be limited to the precise details of the embodiment or exact adherence with all method steps. Variations will be apparent to a skilled person and are deemed also to be covered by the description.

[0084] Descriptive terms should also be given the broadest possible interpretation; e.g. the term "comprising" as used in this specification means "consisting at least in part of" such that interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. Directional terms such as "vertical", "horizontal", "up", "down", "top", "bottom" "upper" and "lower" are relative terms that may be used for convenience of explanation usually with reference to the illustrations and are not intended to be ultimately limiting if an equivalent function can be achieved with an alternative dimension and / or direction.

Claims

Claims1. A light guide system for photonic or optical sensing applications, the system comprising: a sensing layer;one or more light pipes, wherein the sensing layer is in direct contact with the one or more light pipes, wherein the one or more light pipes are arranged toreceive light emitted from a light source,guide the light towards the sensing layer at a predetermined incident angle, and guide reflected light away from the sensing layer.

2. The system according to claim 1, wherein the sensing layer comprises a metal, semiconductor or other plasmonic material.

3. The system according to any preceding claim, wherein the one or more light pipes are supported by a substrate.

4. The system according to claim 3, wherein a point at which the light is incident on the sensing layer is separated from the substrate.

5. The system according to claim 3 or claim 4, wherein the substrate is comprised on an integrated circuit.

6. The system according to any of claims 3 to 5, wherein a length, width, and / or height of the substrate and one or more light pipes is no more than 50 millimetres.

7. The system according to any preceding claim, further comprising:a detector configured to receive light emitted from the one or more light pipes to measure at least one raw data property; anda computer configured to receive the at least one raw data property from the detector, process the at least one raw data property, and generate at least one processed data property;wherein the at least one raw data property is selected from a group comprising: a light intensity, an angle of minimum reflectance, wavelength, a temporal resolution, and a background noise.

8. The system according to claim 7 , wherein the at least one processed data property is selected from a group comprising: an analyte concentration, a kinetic parameter, a resonance curve.

9. The system according to any preceding claim, wherein the light pipe comprises at least one supporting element.

10. The system according to claim 9, wherein each supporting element comprises:a base formed as a raised protrusion configured to be placed on a surface; anda rod formed as an elongate structure extending between the base and the light pipe.

11. The system according to any preceding claim, wherein the one or more light pipes comprises:an input end arranged to receive light from a light source,an output end arranged to emit light that has travelled along the light pipe; andan intermediate portion located between the input and the output end, wherein the intermediate portion is configured to transmit light received through the input end to the sensing layer.

12. The system of claim 11, wherein light guided by the one or more light pipes exits the light pipe at the intermediate portion to interact with the sensing layer.

13. The system according to claim 11 or claim 12, wherein the sensing layer is directly adhered to the intermediate portion.

14. The system according to any of claims 1 - 10 wherein the one or more light pipes comprise:a first light pipe arranged to receive light from a light source and direct the light towards the sensing layer, wherein the first light pipe is directly secured to the sensing layer; anda second light pipe arranged to receive light reflected by the sensing layer and direct the light away from the sensing layer, wherein the second light pipe is directly secured to the sensing layer.

15. The system according to any preceding claim, wherein the sensing layer is selected from a group of materials comprising: gold, silver, aluminium, palladium, metal alloys, transition metal nitrides, transparent conductive oxides, graphene, doped semiconductors, nanostructured plasmonic materials, or combinations thereof.

16. The system according to any preceding claim, wherein the one or more light pipes comprise an input end configured to receive light from a light source, and wherein the input end is configured to divide a path of light into two or more subsidiary paths.

17. The system according to any preceding claim, wherein the one or more light pipes comprise an input end, wherein the input end comprises a first section configured to receive light from a light source and a second section secured to the sensing layer, and wherein the first section of the input end comprises a collimating lens configured to collimate the light from the light source.

18. The system according to any preceding claim, wherein the one or more light pipes comprise:an input end, wherein the input end comprises a first section configured to receive light from a light source and a second section secured to the sensing layer; anda reflective facet positioned between the first section and the second section of the input end, wherein the reflective facet is configured to direct the light received through the first section towards the sensing layer.

19. The system according to any preceding claim, wherein the one or more light pipes comprise an input end configured to receive light from a light source, and wherein the input end comprises an input surface that is textured, etched, concave, or convex.

20. The system according to any preceding claim, wherein the one or more light pipes are formed of a transparent material.

21. The system according to claim 20, wherein the transparent material of the one or more light pipes is selected from a group comprising: polycarbonate, glass, polymethyl methacrylate (PMMA), a polymer-based material, a resin-based material, a semiconductor material, ceramic, or a nitride material.

22. The system according to any preceding claim,wherein a cladding at least partially encompasses the one or more light pipes;wherein the one or more light pipes has a first refractive index;wherein the cladding has a second refractive index; andwherein the first refractive index is higher than the second refractive index.

23. The system according to any preceding claim, wherein the substrate comprises a non-metal.

24. A method comprising:providing a guiding system according to any preceding claim;transmitting a radiation through an input end of the one or more light pipes to towards a sensing layer, anddetecting radiation reflected by the sensing layer and transmitted through an output end of the light pipe away from the sensing layer.

25. The method according to claim 24, the method further comprising:collimating the radiation received by the input end with a collimating lens positioned at a first section of the input end; anddirecting the collimated light through a second section of the input end towards the sensing layer with a reflective facet.

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