DESC:TECHNICAL FIELD
[0001] The embodiments of the present disclosure generally relate to the field of surface plasmon resonance. More particularly, the present disclosure relates to a copper and bimetallic (Ag-Cu) based plasmonic sensing device on polycarbonate prism.

BACKGROUND
[0002] The following description of the related art is intended to provide background information pertaining to the field of the disclosure. This section may include certain aspects of the art that may be related to various features of the present disclosure. However, it should be appreciated that this section is used only to enhance the understanding of the reader with respect to the present disclosure, and not as admission of the prior art.
[0003] Surface plasmon resonance (SPR) is a powerful optical sensing technique that has revolutionized the field of biophysics and biochemistry. Over the years, SPR has found applications in various areas of research, including the development of new drugs, the characterization of protein-protein interactions, the study of antibody-antigen binding, and the detection of biomarkers in clinical diagnostics. Its sensitivity and real-time monitoring capabilities have made it an indispensable tool in biosensing. The behavior of surface plasmons depends on the changes in refractive index occurring at the metal-dielectric interface.
[0004] Despite the immense promise of SPR-based sensing, many lacunae in this emergent technology need addressing to make it more cost-effective, efficient, and scalable. One such issue pertains to the basic setup required for SPR sensing. A prism-based system with metal-dielectric architecture, also known as Kretschmann configuration, is one of the most straightforward systems for studying SPR behavior. However, for large-scale deployment of sensors based on this configuration, the bulky nature of this system, particularly because of the glass prisms is a significant hurdle. Although polymers have been used to enable low-cost, miniaturized, portable, mass-producible alternatives to glass in many applications, polymers have not yet been explored for their suitability in plasmonic sensors. Another crucial aspect is the choice of the metal layer for the SPR sensor. Gold and silver are the most preferred metals for plasmonic applications in the visible spectral region due to their excellent optical and electrical properties.
[0005] Gold, an expensive material, presents challenges to scaling, while the use of silver is constrained by its porosity and susceptibility to environmental degradation. Thus, the exploration of other effective metals or materials that can substitute gold and silver in the SPR sensor is a key area of research in this field.
[0006] On the other hand, copper possessing damping constant and plasma frequency values close to those of gold, along with electrical conductivity superior to gold, emerges as a promising alternative. Although copper has been explored as an alternative plasmonic material for the visible range of wavelengths, copper is also prone to corrosion in ambient environment.
[0007] Therefore, there is a need for a device that can mitigate the problems associated with conventional devices.

OBJECTS OF THE PRESENT DISCLOSURE
[0008] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are listed herein below.
[0009] It is an object of the present disclosure to provide a single-use sensing device including a highly sensitive sensor formed on a polycarbonate prism.
[0010] It is an object of the present disclosure to provide a sensing device that includes a sensing layer disposed on the prism, where light directed towards the sensing layer causes electron oscillations associated with the sensing layer and subsequently causes variation in the sensing layer upon binding with an analyte.
[0011] It is an object of the present disclosure to provide a sensing device where an interface layer is disposed between the prism and the sensing layer, where the interface layer is configured to promote adhesion of the sensing layer to the prism.
[0012] It is an object of the present disclosure to provide a sensing device where an encapsulation layer is disposed with the sensing layer, where the encapsulation layer is configured to inhibit oxidation of one or more elements configured with the sensing layer.
[0013] It is an object of the present disclosure to provide a sensing device where a 2D monolayer black phosphorus affinity layer promotes selective analyte binding and enhances signal quality in the sensing device.
[0014] It is an object of the present disclosure to provide a sensing device with high sensitivity factor, corresponding to high signal resolving power, which may be coupled with a processor to determine changes in the refractive index based on variations in reflectivity responses.

SUMMARY
[0015] This section is provided to introduce certain objects and aspects of the present disclosure in a simplified form that are further described below in the detailed description. This summary is not intended to identify the key features or the scope of the claimed subject matter.
[0016] An aspect of the present disclosure relates to a sensing device that includes a prism and a sensing layer disposed on the prism, where light directed towards the sensing layer causes electron oscillations with the sensing layer, and the sensing layer subsequently undergoes a variation upon binding with an analyte. An interface or adhesion layer disposed between the prism and the sensing layer, the interface layer configured to promote adhesion of the sensing layer to the prism. An encapsulation layer disposed with the sensing layer, the encapsulation layer configured to inhibit oxidation of one or more elements configured with the sensing layer. An affinity layer disposed with the encapsulation layer, the affinity layer configured to provide analyte binding.
[0017] In an aspect, the sensing layer may include one or more elements with any or a combination of a copper element or a silver-copper element, and where the sensing layer may include a dielectric surface that undergoes variation in refractive index upon binding with the analyte.
[0018] In an aspect, the sensing layer may include a bilayer configuration of the one or more elements, where the bilayer configuration may include a thin film of one or more metals deposited on a substrate followed by a thin film of a second metal deposited on top of the first metal layer.
[0019] In an aspect, the sensing layer may include a bimetallic layer comprising of one metal layer of one or more metals sandwiched between two layers of the second metal in a trilayer or sandwich configuration, with varying thicknesses of each layer.
[0020] In an aspect, the interface layer may include a dielectric material with any or a combination of oxides, fluorides, nitrides of a silicon dioxide (SiO2) element, a magnesium oxide (MgO) element, a magnesium fluoride (MgF2) element, a titanium dioxide (TiO2) element, a zinc oxide (ZnO) element, and an aluminum oxide (Al2O3) element.
[0021] In an aspect, the affinity layer may include any or a combination of a Graphene based two-dimensional material, one or more graphene oxide based two-dimensional material, one or more transition metal dichalcogenides (TMDC) based two-dimensional material, and one or more phosphorous based two-dimensional materials.
[0022] In an aspect, the sensing device includes a processor communicatively coupled to the sensing device and configured to determine optical response information associated with the prism and the sensing layer based on electric fields and magnetic fields generated between the prism and the sensing layer based on the directed light. In addition, the processor is configured to subsequently determine an optical response of the sensing device specific to solute concentration in the analyte, providing information on the analyte.
[0023] Another aspect of the present disclosure relates to a method of forming a sensing device on a prism. The method includes disposing, a sensing layer on the prism and directing light towards the sensing layer causing electron oscillations associated with the sensing layer, and subsequently causing, variation in the sensing layer upon binding with an analyte. The method also includes disposing, an interface layer between the prism and the sensing layer for promoting adhesion of the sensing layer to the prism. Additionally, the method includes disposing, an encapsulation layer with the sensing layer to inhibit oxidation of one or more elements configured with the sensing layer. The method further includes disposing, an affinity layer with the encapsulation layer for providing the analyte binding.
[0024] Another aspect of the present disclosure relates to a system for optical analyte detection. The system includes a sensing device and a processor communicatively coupled to the sensing device. The sensing device includes a prism and a sensing layer disposed on the prism. Light directed towards the sensing layer causes electron oscillations associated with the sensing layer, and subsequently leads to a variation in the refractive index of the sensing layer upon binding with an analyte. The sensing device further includes an interface layer disposed between the prism and the sensing layer. The interface layer is configured to promote adhesion of the sensing layer to the prism. An encapsulation layer is disposed with the sensing layer, and is configured to inhibit oxidation of one or more elements configured with the sensing layer. An affinity layer is disposed with the encapsulation layer and is configured to provide analyte binding. The system also includes a processor that is communicatively coupled to the sensing device, and a memory operatively coupled to the processor. The memory stores instructions that cause the processor to determine optical response information associated with the prism and the sensing layer, based on electric and magnetic fields generated between the prism and the sensing layer in response to directed light. The processor is further configured to determine an optical response specific to the solute concentration in the analyte, thereby providing information about the analyte.

BRIEF DESCRIPTION OF DRAWINGS
[0025] The accompanying drawings, which are incorporated herein, and constitute a part of this disclosure, illustrate exemplary embodiments of the disclosed methods and systems which like reference numerals refer to the same parts throughout the different drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Some drawings may indicate the components using block diagrams and may not represent the internal circuitry of each component. It will be appreciated by those skilled in the art that disclosure of such drawings includes the disclosure of electrical components, electronic components, or circuitry commonly used to implement such components.
[0026] FIG. 1 illustrates schematic diagram of a proposed sensing device, in accordance with an embodiment of the present disclosure.
[0027] FIG. 2 depicts illustration of the proposed high-volume processing for fabricating a single-use copper based sensor unit: (A) fabrication of polycarbonate prism sheet, (B) coating of sensor layers, and (C) assembly of single-use copper based sensor unit, in accordance with an embodiment of the present disclosure.
[0028] FIG. 3 illustrates a graphical representation of comprehensive quality factor (CQF), a mathematical quantity for assessing Surface Plasmon Resonance (SPR) curve surface plasmon resonance reflectivity curves, in accordance with an embodiment of the present disclosure.
[0029] FIG. 4 illustrates a graphical representation of a comparison of optimum reflectivity curves for pure copper, gold, silver, and silver-copper bimetallic configuration with surface plasmon resonance reflectivity curves, in accordance with an embodiment of the present disclosure.
[0030] FIG. 5 illustrates a graphical representation of CQF as a function of the change in refractive indices of different interface materials, in accordance with an embodiment of the present disclosure.
[0031] FIG. 6 illustrates a graphical representation of CQF as a function of the interface layer thickness shown for SiO2 and ZnO, in accordance with an embodiment of the present disclosure
[0032] FIG. 7 illustrates a graphical representation of CQF as a function of the change in refractive indices of different encapsulating layers, in accordance with an embodiment of the present disclosure.
[0033] FIG. 8 illustrates a graphical representation of CQF as a function of thickness of encapsulating layers shown for SiO2 and ZnO, in accordance with an embodiment of the present disclosure.
[0034] FIG. 9 depicts a sensing layer of a bimetallic copper system with silver insertions of different thicknesses at varied positions of the silver and copper layers are Ag and Cu, respectively, in accordance with an embodiment of the present disclosure.
[0035] FIG. 10 illustrates a graphical representation of CQF in PC-Ag/Cu -Analyte configuration where Ag occupies the ith level where i =1,2,3, the cumulative thickness of Cu is fixed at 55nm while the thickness of Ag = 5 nm, 7.5 nm, 10 nm, in accordance with an embodiment of the present disclosure.
[0036] FIG. 11 illustrates a graphical representation of CQF of four sensing metal layers (with their optimum thickness): Cu, Ag, Ag-Cu bilayer, and Cu-Ag-Cu tri-layer with the optimized polycarbonate prism and interface, encapsulation, and affinity layers for air as external analyte, in accordance with an embodiment of the present disclosure.
[0037] FIG. 12 illustrates a graphical representation of spatial distribution of the electric field of evanescent wave for four sensing metal layers (with their optimum thickness): Cu, Ag, Ag-Cu bilayer, and Cu-Ag-Cu tri-layer with the optimized polycarbonate prism and interface, encapsulation, and affinity layers for air as external analyte, in accordance with an embodiment of the present disclosure.
[0038] FIG. 13 illustrates a graphical representation of comparison of comprehensive sensing parameter (CSP) obtained for three different types of sensing layers (Cu, Ag-Cu and Ag-Cu-Ag) in the sensor design for the specific example of analytes of blood having different concentrations of hemoglobin (Hb), in accordance with an embodiment of the present disclosure.
[0039] FIG. 14 illustrates a commercial portable sensor connected to a smartphone, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0040] In the following description, for the purposes of explanation, various specific details are set forth in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent, however, that embodiments of the present disclosure may be practiced without these specific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An individual feature may not address all of the problems discussed above or might address only some of the problems discussed above. Some of the problems discussed above might not be fully addressed by any of the features described herein.
[0041] While the present disclosure has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.
[0042] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein. The present disclosure in its various embodiments discloses a highly sensitive polycarbonate prism-based sensing device. The present disclosure further discloses methods of production and use thereof.
[0043] An embodiment of the present disclosure relates to a sensing device that includes a prism and a sensing layer disposed on the prism, where light directed towards the sensing layer causes electron oscillations with the sensing layer, and the sensing layer subsequently undergoes a variation upon binding with an analyte. An interface/adhesion layer disposed between the prism and the sensing layer, the interface layer configured to promote adhesion of the sensing layer to the prism. An encapsulation layer disposed with the sensing layer, the encapsulation layer configured to inhibit oxidation of one or more elements configured with the sensing layer. An affinity layer disposed with the encapsulation layer, the affinity layer configured to provide analyte binding.
[0044] In an embodiment, the sensing layer may include one or more elements with any or a combination of a copper element or a silver-copper element, and where the sensing layer may include a dielectric surface that undergoes variation in refractive index upon binding with the analyte.
[0045] In an embodiment, the sensing layer may include a bilayer configuration of the one or more elements, where the bilayer configuration may include a thin film of one or more metals deposited on a substrate followed by a thin film of a second metal deposited on top of the first metal layer.
[0046] In an embodiment, the sensing layer may include a bimetallic layer comprising of one metal layer of one or more metals sandwiched between two layers of the second metal in a trilayer or sandwich configuration, with varying thicknesses of each layer.
[0047] In an embodiment, the interface layer may include a dielectric material with any or a combination of oxides, fluorides, nitrides of a silicon dioxide (SiO2) element, a magnesium oxide (MgO) element, a magnesium fluoride (MgF2) element, a titanium dioxide (TiO2) element, a zinc oxide (ZnO) element, and an aluminum oxide (Al2O3) element.
[0048] In an embodiment, the affinity layer may include any or a combination of a graphene based two-dimensional material, one or more graphene oxide based two-dimensional material, one or more transition metal dichalcogenides (TMDC) based two-dimensional material, and one or more phosphorous based two-dimensional materials.
[0049] In an embodiment, the sensing device includes a processor communicatively coupled to the sensing device and configured to determine optical response information associated with the prism and the sensing layer based on electric fields and magnetic fields generated between the prism and the sensing layer based on the directed light. In addition, the processor is configured to subsequently determine an optical response of the sensing device specific to solute concentration in the analyte, providing information on the analyte.
[0050] Another embodiment of the present disclosure relates to a method of forming a sensing device on a prism. The method includes disposing, a sensing layer on the prism and directing light towards the sensing layer causing electron oscillations associated with the sensing layer, and subsequently causing, variation in the sensing layer upon binding with an analyte. The method also includes disposing, an interface layer between the prism and the sensing layer for promoting adhesion of the sensing layer to the prism. Additionally, the method includes disposing, an encapsulation layer with the sensing layer to inhibit oxidation of one or more elements configured with the sensing layer. The method further includes disposing, an affinity layer with the encapsulation layer for providing the analyte binding.
[0051] Another embodiment of the present disclosure relates to a system for optical analyte detection. The system includes a sensing device and a processor communicatively coupled to the sensing device. The sensing device includes a prism and a sensing layer disposed on the prism. Light directed towards the sensing layer causes electron oscillations associated with the sensing layer, and subsequently leads to a variation in the refractive index of the sensing layer upon binding with an analyte. The sensing device further includes an interface layer disposed between the prism and the sensing layer. The interface layer is configured to promote adhesion of the sensing layer to the prism. An encapsulation layer is disposed with the sensing layer, and is configured to inhibit oxidation of one or more elements configured with the sensing layer. An affinity layer is disposed with the encapsulation layer, and is configured to provide analyte binding. The system also includes a processor that is communicatively coupled to the sensing device, and a memory operatively coupled to the processor. The memory stores instructions that cause the processor to determine optical response information associated with the prism and the sensing layer, based on electric and magnetic fields generated between the prism and the sensing layer in response to directed light. The processor is further configured to determine an optical response specific to the solute concentration in the analyte, thereby providing information about the analyte.
[0052] Various embodiments of the present disclosure will be explained in detail with reference to FIGs. 1-14.
[0053] Referring to FIG. 1, a sensing device 100 (interchangeably referred to as sensor 100, herein) on a polycarbonate prism 108 is disclosed. The sensing device 100 is implemented as a single-use sensor unit, configured for one-time application to ensure measurement accuracy, prevent cross-contamination, and maintain the integrity of multiple layers. The sensing device 100 includes a sensing layer 102 disposed on the prism 108, and light (from any external source) directed towards the sensing layer 102 induces electron oscillations within the sensing layer 102. This interaction subsequently causes a variation in the sensing layer 102 upon binding with an analyte 104. The sensing layer 102 is configured to undergo a change in refractive index upon binding with the analyte 104. Additionally, the sensing layer 102 may include one or more elements, such as copper or a silver-copper multilayer, and is configured with a dielectric surface that undergoes a variation in refractive index upon analyte binding. The sensing layer may consist of a single metal layer or a combination of two metal layers. The sensing layer 102 further includes a bimetallic layer comprising one metal layer of the one or more metals sandwiched between two layers of a second metal in a trilayer or sandwich configuration, with varying thicknesses for each layer. The optical refractive index of the analyte correlates with its solute concentration. This process may be applied to analyze various analytes, such as hemoglobin in blood, glucose concentration in urine, adulterated liquids, or the identification of 2D materials.
[0054] In an embodiment, the sensing device 100 includes an interface or adhesion layer 106 disposed between the prism 108 and the sensing layer 102. The interface layer 106 is configured to promote adhesion of the sensing layer 102 to the prism 108. In addition, the interface layer 106 includes a dielectric material that may include any or a combination of oxides, fluorides, or nitrides. These may include materials such as a silicon dioxide (SiO2) element, a magnesium oxide (MgO) element, a magnesium fluoride (MgF2) element, a titanium dioxide (TiO2) element, a zinc oxide (ZnO) element, an aluminum oxide (Al2O3) element.
[0055] In an embodiment, the sensing device 100 includes an encapsulation layer 110 disposed over the sensing layer 102. This encapsulation layer 110 protects the sensing layer from oxidation. The sensing layer 102 may include metals such as copper, which can easily oxidize when exposed to air or moisture. Oxidation of these metal elements could degrade the performance of the sensor by interfering with the optical properties of the sensing layer and reducing its sensitivity. The encapsulation layer 110 made of a material like zinc oxide (ZnO), acts as a protective barrier that prevents the copper (or other metal components) in the sensing layer 102 from being exposed to environmental factors that may cause oxidation. By preventing oxidation, the encapsulation layer 110 helps maintain the effectiveness of the sensing layer 102, ensuring that the device provides accurate and reliable measurements over time.
[0056] In an embodiment, the sensing device 100 includes an affinity layer 112 that is disposed on top of the encapsulation layer 110. This affinity layer 112 provides a surface that facilitates binding of the analyte 104. The analyte refers to a substance being measured or detected by the sensor 100, such as a chemical compound or biomolecule. The affinity layer 112 is configured to have specific properties that allow it to interact with the analyte. It essentially acts as a receptor that binds with the analyte to enable its detection. The binding of the analyte to the affinity layer causes a measurable change in the sensor, which can then be used to analyze the analyte’s presence, concentration, or other properties.
[0057] In addition, the affinity layer 112 can be made from a variety of materials, particularly two-dimensional (2D) materials, which have unique properties that make them ideal for sensor applications. Some of these materials include graphene-based 2D materials, graphene oxide-based 2D materials, transition metal dichalcogenides (TMDC) based 2D materials, and phosphorous-based 2D materials. These materials are known for their exceptional electronic, optical, and mechanical properties, making them highly effective in sensing applications. By utilizing these advanced 2D materials, the affinity layer 112 enhances the sensitivity and selectivity of the sensing device. The choice of material for the affinity layer depends on the specific analyte to be detected, as different materials may provide stronger or more specific binding interactions with different types of analytes.
[0058] Further, the sensing layer 102 may be communicatively coupled to a processor (not shown), which is configured to determine optical response information associated with the prism 108 and the sensing layer 102 based on the electric and magnetic fields generated between the prism 108 and the sensing layer 102 as a result of the directed light. The communicative coupling may be implemented through an optical detection module, such as a photodetector or CCD (charge-coupled device), which detects changes in reflected light intensity corresponding to variations in the refractive index at the sensing layer 102. These detected signals are converted into electrical signals and transmitted to the processor for analysis. The processor is further configured to determine an optical response specific to the solute concentration in the analyte, thereby providing information regarding the analyte. For example, a shift in the surface plasmon resonance angle due to the binding of glucose molecules in a urine sample may be detected and translated by the processor into a concentration value, enabling non-invasive biomedical diagnostics.
[0059] In an embodiment, a method (not shown) of forming a sensing device 100 on a prism 108 is disclosed. The method includes disposing a sensing layer 102 on the prism 108. The sensing layer 102 comprises one or more elements selected from copper or a silver-copper multilayer and includes a dielectric surface configured to undergo a variation in refractive index upon binding with an analyte 104. The method further includes configuring the sensing layer 102 as a bilayer, in which a thin film of one or more metals is deposited on the prism 108, followed by a thin film of a second metal. In another configuration, the sensing layer 102 is formed as a bimetallic trilayer, wherein a metal layer is sandwiched between two layers of another metal in a trilayer or sandwich structure with varying thicknesses, thereby enhancing the surface plasmon resonance (SPR) behavior of the sensing interface. The method further includes directing light towards the sensing layer 102. The incident light excites electron oscillations within the metallic structure of the sensing layer 102. Upon analyte binding, a change in the local refractive index occurs, which shifts the resonance condition and alters the resulting optical signal.
[0060] The method further includes disposing an interface layer 106 between the prism 108 and the sensing layer 102 to promote adhesion of the sensing layer 102 to the prism surface. The interface layer 106 includes a dielectric material selected from or comprising a combination of oxides, fluorides, or nitrides of elements such as silicon dioxide (SiO2), magnesium oxide (MgO), magnesium fluoride (MgF2), titanium dioxide (TiO2), zinc oxide (ZnO), and aluminum oxide (Al2O3). These materials ensure optical compatibility and mechanical integrity.
[0061] The method further includes disposing an encapsulation layer 110 over the sensing layer 102. The encapsulation layer 110 functions to inhibit oxidation of the one or more metallic elements used in the sensing layer, particularly copper. In one embodiment, materials such as ZnO are used to form a thin protective film that preserves plasmonic activity while maintaining transparency and chemical resistance.
[0062] The method further includes disposing an affinity layer 112 over the encapsulation layer 110 for specific analyte binding. The affinity layer 112 includes any one or a combination of graphene-based two-dimensional materials, graphene oxide-based materials, transition metal dichalcogenides (TMDCs), and phosphorous-based two-dimensional materials. These materials enhance specificity and sensitivity of the sensing device 100 by providing functional sites for binding target analytes.
[0063] The method further includes communicatively coupling the sensing layer 102 to a processor (not shown), either through integrated electronics or external interfacing. The processor is configured to determine optical response information associated with the prism 108 and the sensing layer 102, based on electric and magnetic fields generated from the interaction of light with the sensor. The processor further analyzes the optical response to determine the solute concentration of the analyte 104, thereby providing valuable diagnostic or analytical information. For example, a shift in resonance wavelength may indicate the presence of glucose in urine, hemoglobin in blood, or contaminants in a test sample.
[0064] In an embodiment, a system (not shown) for optical analyte detection includes a sensing device 100 with multiple layers. The sensing device 100 consists of a prism 108, typically made of glass or a similar transparent material, on which a sensing layer 102 is disposed. The sensing layer 102 may include one or more metals such as copper or silver-copper multilayer. The sensing layer 102 interacts with directed light, causing electron oscillations that change the refractive index upon analyte binding. An interface layer 106, typically made of dielectric materials such as silicon dioxide (SiO2) or titanium dioxide (TiO2), is placed between the prism 108 and the sensing layer 102 to promote adhesion. The encapsulation layer 110, made of materials like zinc oxide (ZnO) or other protective oxides, inhibits oxidation of elements of the sensing layer 102. The affinity layer 112 may be composed of materials like graphene-based two-dimensional materials, graphene oxide, or transition metal dichalcogenides (TMDC), which facilitate analyte binding. The system also includes a processor (not shown), communicatively coupled to the sensing device 100, that analyzes optical responses and determines the solute concentration in the analyte 104.
[0065] In an exemplary implementation of proposed sensing device 100, the comprehensive quality factor (CQF) may be described as:
CQF [deg -2] = – [ log(??min)×??×?R)/T ] (1)
?R is the amplitude of the SPR curve or the difference between the maximum reflectivity value (Rmax) and the lowest reflectivity value (Rmin). The sharpness of the signal can be assessed by the slope s of the linear region of the SPR curve, while the angular width, T of the SPR curve is the full width of the SPR curve at which the reflectance value drops to half of its maximum value. A sensor’s sensing quality is usually tested by the shift in the position of the reflectivity minima per unit change in the refractive index value, as shown below:
??? = ??1 - ??2 and ???SPR= ??SPR2 - ??SPR1 (2)
Sensitivity Factor, S, is defined as: S = ??SPR/??? (3)
Combining these terms, the comprehensive sensing parameter (CSP) can be obtained:
CSP [ RIU-1 deg-1] = CQF × S (4)
[0066] By responding to variations in the sensor’s optical environment and the characteristics of the curve, the CSP serves as an indicator of both the sensor’s sensitivity and the quality of the signal. Such an all-encompassing indicator can play a key role in the optimization of material layers for the fabrication of sensitive and specialized sensors.
[0067] In various embodiments, the design of the proposed sensor 100 uses polycarbonate as the prism material which offers a huge economic advantage over glass-based prisms. Polymer-based devices are compatible with mass manufacturing in both small batches and high volumes. Two such approaches, thermal embossing and molding using masters, are illustrated in FIG. 2A.
[0068] Especially when aimed for use in biomedical applications, the polymer-based prism can introduce a cost-effective way to mass-scale a replicable and disposable sensor. An example of a prism array made from a polymer sheet is depicted in (FIG. 2B), where the possibility of deposition of the constituent layers of the sensor using scalable techniques like physical vapor deposition is shown. Similar to the established method of copper electroplating in printed circuit board industry, the copper layer of the sensor can also be deposited on the prism array using electrodeposition, as shown in the image. Use of high-volume processes for the fabrication of the complete prism architecture can allow highly cost-efficient commercial production of such SPR biosensors. Such prism bases can also be integrated with polymer-based microfluidic devices, as shown in FIG. 2B.
[0069] As shown in FIG. 2C, miniaturization and structuring at the small-scale for portable applications can be achieved in polymer-based devices for a fraction of the cost incurred for machining glass-based devices at the same scale.
[0070] Referring to FIG. 3, a graphical representation of Comprehensive quality factor (CQF, a mathematical quantity for assessing Surface Plasmon Resonance (SPR) curve parameters) plotted against refractive indices of prism materialsis disclosed. This work demonstrates that polycarbonate based prism is not only a commercially viable material for fabrication of prism, but also capable of offering performance at par with or superior to that of conventional prism materials. The comprehensive quality factor (a mathematical quantity for assessing the SPR curve parameters as described in the Eq. (1), CQF values of different glass materials such as conventional BK7 and high-indexed SF5, SF10, and SF11 with values 14.63 deg-2, 16.95 deg-2, 16.85 deg-2, and 17.12 deg-2, respectively. The CQF of sapphire is 17.05 deg-2. In the polymer-based prism (108), the CQF value of PMMA is 13.67 deg-2, whereas it is 17.26 deg-2 for polycarbonate (PC), the highest among all these prism materials. In various embodiments, the high sensitivity of the proposed sensor 100 is disclosed. This work demonstrates that copper is not only a commercially viable metal for SPR sensing but also capable of offering performance at par with or superior to that of benchmark gold sensors. The approaches in this invention have been guided by a focus on the commercial and industrial viability of the device design. A comparative analysis is performed shown in FIG. 4 and results indicate that using polycarbonate as the prism material and copper as the sensing layer are viable approaches to reduce both the cost of production and the barrier to scalability.
[0071] Referring to FIG. 3, a graphical representation of comparison of optimum reflectivity curves for pure copper, gold, silver, and silver-copper bimetallic configuration with surface plasmon resonance reflectivity curves is illustrated.
[0072] Referring to FIG. 3, a graphical representation of CQF, a mathematical quantity for assessing the SPR curve parameters is illustrated as a function of the change in refractive indices of different interface materials.
[0073] Referring to FIG. 6, a graphical representation of CQF is illustrated as a function of the interface layer thickness shown for SiO2 and ZnO.
[0074] Referring to FIG. 7, a graphical representation of CQF is illustrated as a function of change in refractive indices of different encapsulating layers.
[0075] Referring to FIG. 8, a graphical representation of CQF is illustrated as a function of thickness of encapsulating layers shown for SiO2 and ZnO.
[0076] In various embodiments, the proposed sensor 100 design shown in FIG. 1 offers simple mitigation strategies to address common issues related to sensor performance, such as adhesion, oxidation, and functionalization. To sum up, among the various options explored for an interfacial layer placed between the prism and metal layer, SiO2 showed an optimum comprehensive quality factor, CQF for the thickness of 20 nm as shown in FIG. 5. and FIG. 6. The prevention of degradation of the Cu film surface can be successfully controlled using a 5 nm thick encapsulant layer of ZnO as shown in FIG.7 and FIG.8. In the incorporation of an affinity layer, 2D black phosphorus showed better CQF values among several commonly considered 2D materials.
[0077] Referring to FIG. 9, the sensing layer 102 of a bimetallic copper system with silver insertions of different thicknesses at varied positions of silver and copper layers are Ag and Cu, respectively is disclosed. The bimetallic system was optimized where a silver layer of a particular thickness (various thickness values explored) is inserted at different levels in the copper layer of a specific thickness (various thickness values explored as in FIG. 10). The optimum configuration is obtained for a bimetallic system with a silver layer thickness (< 1/10th of the optimum copper thickness) inserted underneath the copper layer. As shown in FIG. 10, the CQF variation in PC-Ag/Cu -analyte configuration where Ag occupies the ith level where i =1, 2, 3. The cumulative thickness of Cu is fixed at 55 nm while the thickness of Ag = 5 nm, 7.5 nm, 10 nm.
[0078] In an embodiment, the calculated CQF values of the SPR signals obtained for the optimum thickness of Au, Cu, Ag, and Ag-Cu bilayer are shown in FIG. 11 for the sensor design 100. The CQF values are 5.41 deg-2, 8.62 deg-2, 37.51 deg-2, 68.20 deg-2 for pure gold, copper, silver, and silver-copper bimetallic configuration, respectively. It is evident from FIG. 11 that the CQF value of pure copper is higher than gold, suggesting copper is not only a cost-effective alternative to traditional gold as a plasmonic material but also possesses better sensing capabilities. In addition, the bimetallic configuration of Ag-Cu bilayer sensing layer provides the highest CQF value.
[0079] As shown in FIG. 11, the SPR comprehensive quality factors four sensing metal layers (with their optimum thickness) is illustrated: Cu, Ag, Ag-Cu bilayer, and Cu-Ag-Cu tri-layer with the optimized polycarbonate prism and interface, encapsulation, and affinity layers for air as external analyte medium. The field distribution in the metal-analyte interface region is critical to the sensitivity of the SPR sensor. This region, known as the near-field region or the evanescent field region (shown in FIG. 1) extends only a few hundred nanometres from the metal surface. The sensitivity of the SPR signal to changes in the analyte, or the vicinity of the metal surface is determined by the strength of the electric field generated. This electric field has the highest amplitude at the interface and decays exponentially as a function of distance from the interface. A comparison of position-dependent electric field distribution profiles of the evanescent wave from the prism interface for the SPR sensor 100 for different sensing layers (Cu, Ag, Ag/Cu bilayer and Cu/Ag/Cu trilayer), with the optimized polycarbonate prism and interface, encapsulation, and affinity layers for air as external analyte is shown in FIG. 12. The maximum evanescent field distribution value ~ 1.17×106 V/m was obtained for Ag-Cu bilayer system, higher than that of pure Ag and Cu and the trilayer Ag-Cu-Ag system at the metal/analyte interface.
[0080] In an embodiment, the CSP calculated as the product of the sensor's sensitivity (S) and the signal quality (CQF), as mentioned in Eq. (4), considers both the sensitivity and the signal quality simultaneously, enabling a combinatorial sensing measurement. In FIG. 13, the CSP values of the sensor designs were calculated for specific example of different analytes of hemoglobin (Hb) concentration in blood (g/dL) with respect to the concentration values. The refractive index values corresponding to the concentrations are shown on the top x-axis.
[0081] In various embodiments, the proposed sensor is attached with other optical components and electronic system. In various embodiments, the proposed sensor 100 is connected with a smartphone as shown in FIG. 14. The proposed sensor 100 may be used in various applications including pharmaceutical research, environmental analysis, and clinical diagnostics. The following commercial aspects of the disclosure are enumerated: 1. Drug Discovery and Development: SPR sensors enable the real-time monitoring and binding interactions between target proteins and drug compounds for screening and characterizing potential drug candidates. 2. Food and Environment Monitoring: SPR sensors are widely used in the food industry for detecting adulterants and pathogens. 3. Point-of-care Diagnostics: Portable and miniaturized SPR devices have a potential for point-of-care diagnostics. These carry-on devices could be used for rapid and on-site detection of various biomolecules. 4. Material Science: SPR biosensors find applications in material science for studying and identifying the refractive indices of coatings, 2D materials, and material interactions. While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be implemented merely as illustrative of the disclosure and not as a limitation.
[0082] Thus, the sensing device 100, with its innovative use of a polycarbonate prism (108) and copper sensing layer, represents a significant advancement in the field of optical analyte detection. The sensing device 100 combines cost-effective materials with robust sensor architecture, enabling low-cost, mass production, and portability without compromising on performance. The integration of multiple layers ensures high sensitivity and reliability in detecting a wide range of analytes. Further, the proposed sensing device 100 offers a practical and scalable solution for real-time, high-performance optical sensing in various applications, including biomedical diagnostics and environmental monitoring.
[0083] While considerable emphasis has been placed herein on the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter to be implemented merely as illustrative of the invention and not as limitation.

ADVANTAGES OF THE INVENTION
[0084] The present disclosure provides a polycarbonate prism-based optical Surface Plasmon Resonance (SPR) sensor that uses copper as a low-cost alternative to expensive noble metals.
[0085] The present disclosure provides an optimized, high-performance sensor architecture, our study systematically explores the optimal specifications of sensor components, such as a polycarbonate prism, an adhesion-promoting interface layer between the prism and the sensing layer, a copper-based sensing layer, a protective encapsulation layer over the sensing layer, and a final analyte-binding two-dimensional (2D) affinity layer.
[0086] The present disclosure evaluates and compares the quality of the SPR signal using a comprehensive quality factor (CQF). Furthermore, by combining sensitivity and CQF, we describe the comprehensive sensing parameter, or CSP, that enables a more practicable and quantitative assessment of sensor architectures.
[0087] The present disclosure combines sensitivity and CQF, to generate the comprehensive sensing parameter (CSP) that enables a more practicable and quantitative assessment of sensor architectures.
[0088] The present disclosure combines the CQF and the CSP to parameterize the performance and suitability of an SPR sensor for any desired application in a more standardized manner. Characterizing the performance of the SPR sensor using these parameters promotes comparability and reliability.
[0089] The present disclosure shows that SPR sensors based on polycarbonate prisms and copper offer a viable and attractive alternative to existing gold based SPR sensing technology.
,CLAIMS:1. A sensing device (100), comprising:
a prism (108);
a sensing layer (102) disposed on the prism (108), wherein light directed towards the sensing layer (102) causes electron oscillations associated with the sensing layer (102) and subsequently causes variation in the sensing layer (102) upon binding with an analyte (104);
an interface layer (106) disposed between the prism (108) and the sensing layer (102), the interface layer (106) configured to promote adhesion of the sensing layer (102) to the prism (108);
an encapsulation layer (110) disposed over the sensing layer (102), the encapsulation layer (110) configured to inhibit oxidation of one or more elements configured with the sensing layer (102); and
an affinity layer (112) disposed with the encapsulation layer (110), the affinity layer (112) configured to provide analyte (104) binding.
2. The sensing device (100) as claimed in claim 1, wherein the sensing layer (102) comprises the one or more elements with any or a combination of: a copper element or a silver-copper element, and wherein the sensing layer comprises a dielectric surface that undergoes variation in refractive index upon binding with the analyte.
3. The sensing device (100) as claimed in claim 2, wherein the sensing layer (102) comprises a bilayer configuration of one or more elements, wherein the bilayer configuration comprises a thin film of one or more metals deposited on a substrate followed by a thin film of a second metal deposited on top of the first metal layer.
4. The sensing device (100) as claimed in claim 3, wherein the sensing layer (102) comprises a bimetallic layer comprising of one metal layer of the one or more metals sandwiched between two layers of the second metal in a trilayer or sandwich configuration, with varying thicknesses of each layer.
5. The sensing device (106) as claimed in claim 1, wherein the interface layer (106) comprises a dielectric material with any or a combination of oxides, fluorides, nitrides of: a silicon dioxide (SiO2) element, a magnesium oxide (MgO) element, a magnesium fluoride (MgF2) element, a titanium dioxide (TiO2) element, a zinc oxide (ZnO) element, and an aluminum oxide (Al2O3) element.
6. The sensing device (100) as claimed in claim 1, wherein the affinity layer (112) comprises any or a combination of: a graphene based two-dimensional material, one or more graphene oxide based two-dimensional material, one or more transition metal dichalcogenides (TMDC) based two-dimensional material, and one or more phosphorous based two-dimensional materials.
7. The sensing device (100) as claimed in claim 1, further comprises a processor communicatively coupled to the sensing device (100) and configured to:
determine optical response information associated with the prism (108) and the sensing layer (102) based on electric fields and magnetic fields generated between the prism (108) and the sensing layer (108) based on the directed light; and
subsequently determine optical response specific to solute concentration in the analyte, to provide information on the analyte.
8. A method of forming a sensing device (100) on a prism, the method comprising:
disposing, a sensing layer (102) on a surface of the prism , wherein light directed towards the sensing layer causes electron oscillations associated with the sensing layer (102), and subsequently causing, variation in the sensing layer (102) upon binding with an analyte (104);
disposing, an interface layer (106) between the prism (108) and the sensing layer (102) for promoting adhesion of the sensing layer (102) to the prism (108);
disposing, an encapsulation layer (110) over the sensing layer (102) to inhibit oxidation of one or more elements configured with the sensing layer (102); and
disposing, an affinity layer (112) over the encapsulation layer (110) to enable binding with the analyte (104).
9. The method as claimed in claim 8, wherein the sensing layer (102) comprises the one or more elements with any or a combination of: a copper element or a silver-copper element, and wherein the sensing layer comprises a dielectric surface that undergoes variation in refractive index upon binding with the analyte.
10. The method as claimed in claim 8, wherein the interface layer (106) comprises a dielectric material with any or a combination of: oxides, fluorides, nitrides of a silicon dioxide (SiO2) element, a magnesium oxide (MgO) element, a magnesium fluoride (MgF2) element, a titanium dioxide (TiO2) element, a zinc oxide (ZnO) element , and an aluminum oxide (Al2O3) element.
11. The method as claimed in claim 8, wherein the affinity layer (112) comprises any or a combination of: a graphene based two-dimensional material, one or more graphene oxide based two-dimensional material, one or more transition metal dichalcogenides (TMDC) based two-dimensional material, and one or more phosphorous based two-dimensional materials.
12. The method as claimed in claim 8, wherein the sensing layer (102) comprises a bilayer configuration of one or more elements, wherein the bilayer configuration comprises a thin film of one or more metals deposited on a substrate followed by a thin film of a second metal deposited on top of the first metal layer.
13. The method as claimed in claim 12, wherein the sensing layer (102) comprises a bimetallic layer comprising of one metal layer of the one or more metals sandwiched between two layers of the second metal in a trilayer or sandwich configuration, with
varying thicknesses of each layer.
14. The method as claimed in claim 8, comprising:
determining, by a processor associated with the sensing device (100), optical response information associated with the prism (108) and the sensing layer (102) based on electric fields and magnetic fields generated between the prism (108) and the sensing layer (102) based on the directed light; and
subsequently determining, by the processor, optical response specific to solute concentration in the analyte, to provide information regarding the analyte.
15. A system for optical analyte detection, comprising:
a sensing device (100), comprising:
a prism (108)
a sensing layer (102) disposed on the prism (108), wherein light directed towards the sensing layer (102) causes electron oscillations associated with the sensing layer (102) and subsequently causes variation in refractive index of the sensing layer (102) upon binding with an analyte (104);
an interface layer (106) disposed between the prism (108) and the sensing layer, (102) the interface layer (106) configured to promote adhesion of the sensing layer (102) to the prism (102);
an encapsulation layer (110) disposed with the sensing layer (102), the encapsulation layer (110) configured to inhibit oxidation of one or more elements configured with the sensing layer (102); and
an affinity layer (112) disposed with the encapsulation layer (110), the affinity layer (112) configured to provide analyte (104) binding;
a processor communicatively coupled to the sensing device (100); and
a memory operatively coupled to the processor, wherein the memory stored instructions causing the processor to:
determine optical response information associated with the prism (108) and the sensing layer (102) based on electric fields and magnetic fields generated between the prism (108) and the sensing layer (102) based on the directed light; and
subsequently determine optical response specific to solute concentration in the analyte, to provide information on the analyte.