Soft sensing lens based on double-layer grating sensor

Abstract

The invention belongs to the related technical field of non-invasive human eye intraocular pressure measuring equipment, and discloses a soft sensing lens based on a double-layer grating sensor, the soft sensing lens comprises a lens and a double-layer grating sensor arranged in the lens, the lens comprises an inner concave surface used for fitting an eyeball and an outer surface facing air; the double-layer grating sensor is integrated on the outer surface; the double-layer grating sensor comprises a packaging layer, an air layer, a thin film layer, a grating layer and a substrate which are sequentially arranged from top to bottom. The grating layer is a layer of periodic nanostructure grating, and the stripe section of the grating layer is rectangular or isosceles trapezoid; the thin film layer is a high-refractive-index thin film covering the grating layer; while a more complex and precise optical sensing structure is integrated, the bandwidth of a diffraction spectrum can be effectively increased, the measurement stability, the actual durability and the wearing comfort of equipment in the experiment process are improved, and a guarantee is provided for obtaining reliable intraocular pressure dynamic data.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of non-invasive intraocular pressure measurement devices for human eyes, and more particularly relates to a soft sensing lens based on a double-layer grating sensor. BACKGROUND

[0002] Glaucoma is an eye disease caused by abnormally high intraocular pressure, which damages the optic nerve. If not treated in time, it can lead to vision loss and even permanent blindness. Glaucoma is mainly caused by the obstruction of the flow of intraocular fluid (aqueous humor), leading to increased intraocular pressure, which compresses the optic nerve and eventually causes vision loss. As the second leading cause of blindness worldwide, the focus of glaucoma treatment is to reduce the patient's intraocular pressure (IOP) to minimize damage to the optic nerve.

[0003] Currently, most intraocular pressure measurements need to be performed in hospitals or clinics, which means that patients can only be tested at fixed times. However, intraocular pressure is not static and it changes dynamically due to factors such as posture, emotion, time, etc. Therefore, traditional measurement methods cannot provide real-time, real intraocular pressure data in patients' daily lives, especially those that occur under dynamic conditions. For example, it is difficult to monitor the intraocular pressure fluctuations of patients under different activities or postures during the day, which limits the early detection and daily management of glaucoma.

[0004] Dynamic intraocular pressure detection technology is mainly divided into two categories: invasive dynamic intraocular pressure measurement method and non-invasive dynamic intraocular pressure measurement method. Invasive measurement by surgically implanting sensors can monitor intraocular pressure in real time, but increases the risk of infection and eye damage. Non-invasive measurement technology is based on the principle of corneal deformation. The existing wearable devices usually use rigid chips, which not only may cause discomfort when worn, but also increase costs, thereby limiting their widespread application.

[0005] The prior art patent application CN107908015A discloses a soft corneal contact lens based on optical grating and an intraocular pressure measuring method thereof. The soft corneal contact lens of the invention is composed of an optical grating and a soft corneal contact lens, and the optical grating is prepared on the soft corneal contact lens, so that the optical grating is integrated with the soft corneal contact lens. The design integrates the optical grating in the soft lens, which effectively improves the wearing comfort. However, the technical solution in this patent, including the idea of depositing a thin film on the grating, is mainly aimed at enhancing the signal reflectivity, and does not specifically design the optical spectrum bandwidth. Therefore, the diffraction spectrum bandwidth that can be achieved by such a simple thin film covering structure is still relatively limited, about 0.001-0.003um. This narrow bandwidth results in a relatively weak spectral response signal (i.e. color change), making it difficult to accurately capture the subtle color differences caused by intraocular pressure changes in experiments through the human eye or conventional spectral equipment. This not only increases the difficulty of experimental observation and data collection, but also increases the demand for equipment.

[0006] Therefore, in view of the above defects of the prior art in the test stage, it is urgent to design a soft sensing lens that can significantly enhance the spectral signal response and effectively widen the spectral bandwidth, so as to facilitate more clear and intuitive observation and analysis of the dynamic changes of intraocular pressure in the experimental environment. SUMMARY

[0007] In view of the above defects or improvement needs of the prior art, the present application provides a soft sensing lens based on a double-layer grating sensor, which aims to significantly widen the diffraction spectrum bandwidth through an innovative sensor structure, thereby enhancing the observability of the spectral signal caused by the change of intraocular pressure, and providing a more clear signal and more reliable result monitoring tool for dynamic intraocular pressure research in the experimental environment; thereby solving the technical problems of weak signal response and difficult change capture caused by the narrow spectral bandwidth of the prior art.

[0008] To achieve the above-mentioned purpose, according to one aspect of the present application, a soft sensing lens based on a double-layer grating sensor is provided, which includes a lens and a double-layer grating sensor arranged in the lens, the lens comprising an inner concave surface for fitting the eyeball and an outer surface facing the air; the double-layer grating sensor is integrated on the outer surface; wherein the outer surface is a plane or a convex surface, so that the lens presents a flat-concave lens shape or a convex-concave lens shape, respectively; The double-layer grating sensor includes an encapsulation layer, an air layer, a thin film layer, a grating layer and a substrate arranged in sequence from top to bottom; the grating layer is a layer of periodic nanostructure grating, and the stripe cross section is rectangular or isosceles trapezoidal, and the structural parameters groove depth For , the period For duty cycle for ; the thin film layer is a high refractive index thin film layer covering the grating layer, with a thickness for ; Preferably, the material of the grating layer and the substrate is the same; to achieve effective widening of the spectral bandwidth, a high refractive index difference is formed between the material of the thin film layer and the refractive index of the grating layer material. Significant refractive index difference is the key to enhancing the grating reflection efficiency and widening the diffraction spectral bandwidth.

[0009] Preferably, the material of the grating layer and the substrate is polyethylene (PE), with a refractive index .

[0010] Preferably, the material of the thin film layer is one of the materials with a refractive index of 1.8-3.5.

[0011] Preferably, the height of the air layer is , and the thickness of the encapsulation layer is . .

[0012] Preferably, the double-layer grating sensor is prepared on the outer surface of the lens by micro-nano imprinting technology, ensuring high precision and consistency of the grating pattern.

[0013] Preferably, the lens is made of silicone hydrogel, with a diameter of , a base curve of , and a center thickness of .

[0014] Preferably, the silicone hydrogel includes a plurality of organosilicon polymers and hydrophilic polymers.

[0015] Preferably, the silicone hydrogel includes siloxane polymers, high oxygen permeable siloxane methacrylate, hydroxyethyl methacrylate (HEMA) to increase softness and wettability, and N-vinyl pyrrolidone (NVP).

[0016] Preferably, the silicone hydrogel also contains a crosslinking agent to improve the structural stability of the lens, and a surface hydrophilic treatment to improve the comfort and anti-deposition of wearing.

[0017] Overall, compared with the prior art, the soft sensing lens based on a double-layer grating sensor provided by the present application mainly has the following beneficial effects: ​1. Broaden the spectral bandwidth, reduce the system cost and measurement difficulty: The core advantage of the present invention is that through the composite design of "grating layer + high refractive index film layer", the bandwidth of the diffraction spectrum can be effectively increased. This makes the characteristic curve of the diffraction spectrum change more obviously, decisively reduces the technical requirements of the rear-end spectral analysis equipment, thereby significantly reduces the cost of the whole measurement system, makes the reading and analysis of the signal easier, and provides strong technical support for high-sensitivity dynamic intraocular pressure experimental research; 2. Structural design innovation, improve measurement stability and durability: The present invention creatively introduces the air layer and the packaging layer structure. The existence of the air layer optimizes the optical performance of the sensor, and the protective packaging layer at the outermost layer can effectively isolate the precise grating structure from the complex physiological environment in the eye (such as tears, secretions, etc.). This design not only prevents the optical performance from being disturbed, but also protects the sensor from physical wear and biological erosion, greatly improving the measurement stability and actual durability of the device during the experiment; 3. High integration and comfortable to wear: Compared with the prior art, the present invention integrates more complex and precise optical sensing structures (including multi-layer structures such as film layer, air layer, packaging layer, etc.) while still maintaining the excellent properties of soft contact lenses. This is due to the precise design of the thickness and material of each layer, ensuring the overall softness, high oxygen permeability and biocompatibility of the device, realizing the organic unity of high-performance sensing and comfortable wearing experience.

[0018] 4. Optimize the manufacturing process, improve device performance and consistency: For the 'flat-concave mirror form' of the present invention, its integrated flat outer surface provides an ideal working platform for micro-nano imprinting and other precise manufacturing processes. Compared to processing on the curved surface of traditional contact lenses, processing on the flat surface not only simplifies the process flow, but also greatly improves the pattern fidelity and performance consistency of the grating sensor. This ensures high comparability between different batches of experimental samples, laying a solid foundation for obtaining reliable and repeatable experimental data. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of the grating layer in the embodiment of the present invention; Figure 2 is a structural schematic diagram of a preferred embodiment of a soft sensing lens in the form of a flat-concave mirror provided by the present invention; Figure 3 is a structural schematic diagram of another preferred embodiment of a soft sensing lens in the form of a convex-concave mirror provided by the present invention; Figure 4 is a comparison diagram of the diffraction spectrum of a single-layer grating and a double-layer grating in embodiment one; Figure 5is a diffraction spectrum comparison chart of the single-layer grating and the double-layer grating in Example 2.

[0020] In all the drawings, the same reference signs are used to denote the same elements or structures, wherein: 1 - substrate; 2 - grating layer; 3 - thin film layer; 4 - air layer; 5 - encapsulation layer. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are merely intended to explain the present application and are not intended to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0022] In order to facilitate understanding of the present application, the relevant concepts and terms are described below: As Figure 1 shown, the present application adopts a spatial rectangular coordinate system, the grating surface is an XY plane, the right direction is the positive direction of the X axis, the Y axis is along the grating axis, and the forward direction is the positive direction of the Y axis; the Z axis is perpendicular to the XY plane, and the downward direction is the positive direction; the incident point of the incident light on the grating surface is the origin. The plane formed by the incident light and the reflected light is the incident plane, the incident angle θ is the included angle between the incident light and the normal line (Z axis) of the optical grating surface, and the azimuth angle ϕ is the included angle between the incident plane and the positive direction of the X axis.

[0023] When performing rigorous coupled-wave analysis (RCWA) modeling on a grating structure of any shape, the cross section of the grating needs to be first layered and a rectangle is used to approximate the grating shape of each layer. Then, the RCWA modeling theory of the rectangular grating is used to model and calculate each layer. By applying the boundary conditions of the electromagnetic field, the calculation results of each layer are associated, and finally the spectral characteristics of the entire grating can be obtained by using the corresponding iterative solution algorithm. As Figure 1 shown, the grating structure is divided into three sub-regions from top to bottom, which are incident / reflection region 1, grating region 2, and transmission region 3, respectively. The longitudinal coordinate of the incident / reflection region 1 is , the longitudinal coordinate of the grating region 2 is , and the longitudinal coordinate of the transmission region 3 is The period of the rectangular grating is , the groove depth is , the thin film layer thickness is , and the duty cycle is

[0024] Example 1 This embodiment provides a soft sensing lens which is integrated and in the form of a flat concave mirror. As Figure 2As shown, the lens includes a concave surface for conforming to the eyeball and a flat outer surface. The dual-layer grating sensor is fabricated on this flat outer surface using micro-nano imprinting technology (such as close-mold imprinting). The flat surface provides ideal conditions for high-precision processing. The dual-layer sensor includes, from top to bottom, an encapsulation layer 1, an air layer 2, a thin film layer 3, a grating layer 4, and a substrate 5. The concept of "dual-layer grating" here refers to the composite optical structure composed of the grating layer 4 and the thin film layer 3 covering it.

[0025] Encapsulation layer 1 and air layer 2: Encapsulation layer 1 is designed with a thickness of 100nm to protect the delicate internal sensor structure. It effectively isolates the sensor from the complex physiological environment such as tear film inside the eye, preventing liquid interference with optical performance, thereby ensuring long-term measurement stability and durability. Air layer 2 is located between encapsulation layer 1 and thin film layer 3, with a height of 100nm. The presence of this air layer is precisely designed to optimize overall optical performance while ensuring the fit and wearing comfort of the contact lens.

[0026] Grating layer 4 and substrate 5: Grating layer 4 is a periodic nanostructure with rectangular fringe cross-section. In this embodiment, its structural parameters are: groove depth. for ,cycle for Duty cycle for Both the grating layer 4 and the substrate 5 are made of polyethylene (PE), and their refractive index is [missing information]. Polyethylene was chosen not only because of its excellent optical transparency, but also because of its good flexibility and structural stability, making it suitable as a substrate for flexible sensors.

[0027] Thin Film Layer 3: The design of thin film layer 3 is one of the core aspects of this invention. Its purpose is to significantly broaden the diffraction spectrum bandwidth by selecting a material with a high refractive index difference from the grating layer material. In this embodiment, two different thin film materials are compared. When the material of thin film layer 3 is zinc sulfide (ZnS), with a thickness h = 100 nm, its refractive index... The refractive index difference between the grating layer material and the grating layer material is as high as This greatly improves the bandwidth of the diffraction spectrum. For example... Figure 4 As shown, compared to a bandwidth of only The single-layer grating increases the bandwidth of the double-layer grating of the ZnS thin film to [amount missing]. If other parameters remain unchanged, the material of thin film layer 3 is changed to cadmium selenide (CdSelenide). Its refractive index is The refractive index difference between the PE material and the grating layer 4 further increases to .like Figure 5As shown, a larger refractive index difference results in a more significant bandwidth broadening effect. Compared to a bandwidth of... Compared to single-layer gratings, the bandwidth of double-layer gratings using CdSe thin films increases to [missing information]. This significant increase in bandwidth makes spectral features (i.e., visible color changes) easier to capture and identify, thus facilitating highly sensitive experimental observations and data analysis.

[0028] Example 2 This embodiment provides another form of the invention, namely, an integrated, overall convex-concave mirror (or spherical crown) soft sensing lens. For example... Figure 3 As shown, its main structure is similar to that of Embodiment 1. The core difference is that its outer surface is a convex curved surface, and the double-layer grating sensor is directly fabricated on this convex curved surface by micro-nano imprinting technology.

[0029] The dual-layer grating sensor integrated on this lens has the same multi-layer structure (including an encapsulation layer, an air layer, a thin film layer, a grating layer, and a substrate) as described in Example 1. This type of lens can also incorporate high-refractive-index thin films such as zinc sulfide (ZnS) or cadmium selenide (CdSe) as described in Example 1. Compared to traditional single-layer grating structures, it can also achieve the beneficial effects of significantly broadening the diffraction spectral bandwidth and enhancing signal observability.

[0030] The two embodiments described above verify that this invention, by designing an integrated flexible sensing lens (whether plano-concave or convex-concave), and employing a dual-layer grating sensor comprising a high refractive index difference thin film layer, an air layer, and a protective encapsulation layer, successfully solves the problem of excessively narrow bandwidth in single-layer gratings in existing technologies, which leads to difficulty in signal observation during experiments. This invention effectively broadens the spectral bandwidth, significantly enhances the readability of spectral signals and their color changes, and makes signal extraction clearer and more accurate, thus providing a reliable technical solution for achieving more reliable and sensitive dynamic intraocular pressure measurement.

[0031] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flexible sensing lens based on a dual-layer grating sensor, characterized in that, The device includes a lens and a double-layer grating sensor disposed within the lens. The lens comprises a concave surface for conforming to the eyeball and an outer surface facing the air. The double-layer grating sensor is integrated on the outer surface. The outer surface can be planar or convex, causing the lens to be shaped like a plano-concave mirror or a convex-concave mirror, respectively. The double-layer grating sensor comprises, from top to bottom, an encapsulation layer, an air layer, a thin film layer, a grating layer, and a substrate. The grating layer is a periodic nanostructure grating with rectangular or isosceles trapezoidal fringe cross-sections and a groove depth as a structural parameter. for ,cycle for Duty cycle for The thin film layer is a high-refractive-index thin film covering the grating layer, with a thickness of... for .

2. The flexible sensing lens based on a dual-layer grating sensor as described in claim 1, characterized in that: The grating layer and the substrate are made of the same material; a high refractive index difference is formed between the refractive index of the thin film layer and the refractive index of the grating layer.

3. A flexible sensing lens based on a dual-layer grating sensor as described in claim 2, characterized in that: The grating layer and the substrate are made of polyethylene.

4. A flexible sensing lens based on a dual-layer grating sensor as described in claim 1, characterized in that: The thin film layer material is set to one of the materials with a refractive index between 1.8 and 3.

5.

5. A flexible sensing lens based on a dual-layer grating sensor as described in claim 1, characterized in that: The height of the air layer for The thickness of the encapsulation layer for .

6. A flexible sensing lens based on a dual-layer grating sensor as described in claim 1, characterized in that: The dual-layer grating sensor is fabricated on the outer surface of the lens using micro-nano imprinting technology, ensuring high precision and consistency of the grating pattern.

7. A flexible sensing lens based on a dual-layer grating sensor as described in claim 1, characterized in that: The lens is made of silicone hydrogel and has a diameter of [missing information]. The base arc is The center thickness is .

8. A flexible sensing lens based on a dual-layer grating sensor as described in claim 7, characterized in that: The silicone hydrogel includes a variety of organosilicon polymers and hydrophilic polymers.

9. A flexible sensing lens based on a dual-layer grating sensor as described in claim 8, characterized in that: The silicone hydrogel comprises a siloxane polymer, a highly oxygen-permeable siloxane methacrylate, hydroxyethyl methacrylate, and N-vinylpyrrolidone.

10. A flexible sensing lens based on a dual-layer grating sensor as described in claim 7, characterized in that: The silicone hydrogel also contains a crosslinking agent to improve the structural stability of the lens, and enhances wearing comfort and anti-deposition properties through surface hydrophilic treatment.

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