Sensing device for the eye and corresponding manufacturing method and monitoring system

Abstract

A sensing device for an eye, a method of manufacturing the sensing device, and a corresponding monitoring system are provided, the sensing device comprising: a lens having an inner surface and an outer surface, the inner surface of the lens being adapted to be arranged on the eye; and at least two sensing elements, each of the at least two sensing elements comprising a respective substrate region, the substrate region of at least one sensing element having a different stiffness than the substrate region of at least another sensing element, the at least two sensing elements being arranged eccentrically and / or concentrically between the inner surface and the outer surface of the lens with respect to a center of the lens, and being configured for sensing a relevant parameter of the eye. Using the sensing device of the present invention, environmental noise and mechanical noise can be reduced, the signal-to-noise ratio of the measured eye-related parameter can be improved, thereby reducing errors of the eye-related parameter in a dynamic environment to obtain a higher measurement accuracy, and the accuracy and effectiveness of the eye monitoring can be improved.

Description

[0001] Related cross-applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 176,351, filed April 19, 2021, which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to the field of eye sensing, and more specifically, to an eye sensing device, a corresponding method for manufacturing the sensing device, and an eye monitoring system. Background Technology

[0004] Glaucoma is currently the leading cause of irreversible blindness worldwide. Glaucoma is often not noticed until it reaches an advanced stage. Peak intraocular pressure (IOP) during daytime clinical visits is usually lower than peak IOP at night, leading to missed diagnoses. Studies have shown that dynamic IOP time curves, including global IOP, daytime and nighttime peaks, and 24-hour fluctuations, provide crucial data that could improve glaucoma diagnosis accuracy by 50%.

[0005] Many methods have been developed for continuous 24-hour IOP curve measurement. Invasive implantable sensing elements and non-invasive wearable contact lens sensors (CLS) are known for IOP monitoring. Sensor implants have been successfully used for continuous IOP measurement, but this method is invasive.

[0006] One promising approach utilizes miniature sensors embedded in soft contact lenses. The contact lens sensor (CLS) is located on top of the cornea and wirelessly measures corneal deformation, then uses correlation to convert this deformation into intraocular pressure (IOP). Corneal deformation can be measured by embedding an array of sensing resistive elements (e.g., a Sensimed AG) into the CLS. Corneal deformation can also be measured by embedding reactive sensing elements into the CLS. This method avoids the use of silicon chips and provides a simplified solution approach, including improved safety for continuous IOP measurement. Therefore, continuous IOP-time curves from the contact lens sensor (CLS) reduce the probability of misdiagnosis and improve treatment monitoring. However, the signal of eye-related parameters such as IOP can be affected by the electrical and mechanical design of the sensing element and its interaction with the eye and ocular environment (including eyelid, tear film thickness changes, tear composition changes, etc.), leading to increased signal noise for in vivo measurements of eye-related parameters.

[0007] Chen et al. (G.-Z. Chen, I.-S. Chan, LK. Leung, and D.C. Lam, “Soft wearable contact lens sensor for continuous intraocular pressure monitoring”, Medical Engineering & Physics, vol. 36, pp. 1134-1139, 2014) tested a reactive sensing contact lens sensor concept. The sensing circuit, or LC resonator, embedded in the contact lens consists of a parallel-plate capacitor coupled to a spiral inductor coil that deforms with the curvature of the cornea. The resonator absorbs energy from an electromagnetic field generated by an external reader placed next to the eye. Experimental results showed that the resonant frequency of the LC circuit at the point of maximum energy loss varied linearly with IOP in silicone rubber model eyes, isolated pig eyes, and sedated rabbit eyes. Tests on live eyes revealed significant noise generated by tear film and eyelids.

[0008] Karunaratne et al. (I. Karunaratne, CHCLee, PWOr, Y. Wei, IT Chong, Y. Yang, et al., “Wearable Dual-Element Intraocular Pressure Contact LensSensor”, Sensors and Actuators A: Physical, p. 112580, 2021) added a reference sensor to their design in an attempt to reduce electrical and environmental noise. While adding a reference element to the sensor can reduce some noise, mechanical noise is still not negligible.

[0009] Therefore, an improved method for sensing eye-related parameters is needed. Summary of the Invention

[0010] The purpose of this invention is to provide a solution that can solve or at least improve the above-mentioned problems.

[0011] According to a first aspect of the present invention, a sensing device for the eye is provided, characterized in that the sensing device comprises:

[0012] A lens having an inner surface and an outer surface, the inner surface of the lens being adapted to be disposed on an eye; and

[0013] At least two sensing elements, each including a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element.

[0014] The at least two sensing elements are eccentrically and / or concentrically disposed between the inner and outer surfaces of the lens with respect to the center of the lens, and are configured to sense relevant parameters of the eye.

[0015] In one embodiment, the substrate region of the at least one sensing element and the substrate region of the at least another sensing element each comprise:

[0016] (1) At least one rigid region and at least one flexible region;

[0017] (2) At least a first rigid region and at least a second rigid region with different stiffness; or

[0018] (3) At least a first flexible region and at least a second flexible region with different stiffness.

[0019] In one embodiment, the rigid region has a tensile strength of 15.95 MPa-205 MPa, an elastic modulus of 1.9 GPa-46.9 GPa, and a Poisson's ratio of 0.25-0.41; and / or

[0020] The flexible region has a tensile strength of less than 8.2 MPa, an elastic modulus of less than 1.9 GPa, and a Poisson's ratio of 0.45-0.5.

[0021] In one embodiment, the lens has an optical zone at its center, and the at least two sensing elements are disposed between the optical zone and a position adjacent to the periphery of the lens.

[0022] According to a second aspect of the present invention, a method for manufacturing a sensing device for the eye is provided, characterized in that the method comprises:

[0023] A lens is provided having an inner surface and an outer surface, the inner surface of which is adapted to be disposed on an eye;

[0024] At least two sensing elements are formed, each of the at least two sensing elements including a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element; and

[0025] The at least two sensing elements are disposed off-center and / or concentrically between the inner and outer surfaces of the lens with respect to the center of the lens, and the at least two sensing elements are configured to sense relevant parameters of the eye.

[0026] In one embodiment, the substrate region of the at least one sensing element and the substrate region of the at least another sensing element respectively include:

[0027] (1) At least one rigid region and at least one flexible region;

[0028] (2) At least a first rigid region and at least a second rigid region with different stiffness; or

[0029] (3) At least a first flexible region and at least a second flexible region with different stiffness.

[0030] In one embodiment, the rigid region has a tensile strength of 15.95 MPa-205 MPa, an elastic modulus of 1.9 GPa-46.9 GPa, and a Poisson's ratio of 0.25-0.41; and / or

[0031] The flexible region has a tensile strength of less than 8.2 MPa, an elastic modulus of less than 1.9 GPa, and a Poisson's ratio of 0.45-0.5.

[0032] In one embodiment, the lens has an optical zone at its center, and the at least two sensing elements are disposed between the optical zone and a position adjacent to the periphery of the lens.

[0033] According to a third aspect of the present invention, a monitoring system for the eye is provided, characterized in that the monitoring system includes a sensing device according to any one of the preceding claims, and the monitoring system further includes:

[0034] An external antenna, configured to wirelessly communicate with the at least two sensing elements and receive corresponding frequency signals from the at least two sensing elements, and

[0035] An analysis device configured to store corresponding frequency signals received from the at least two sensing elements and to monitor relevant parameters of the eye by analyzing the corresponding frequency signals.

[0036] In one implementation, the monitoring system further includes:

[0037] An eye model, on which the sensing device is placed.

[0038] A titration apparatus configured to apply a force to the interior of the eye model, and

[0039] At least one polymer film is placed above the sensing device and configured to simulate the eye environment in which the eye model is located.

[0040] According to the above-described embodiments of the present invention, the sensing device for the eye, by embedding at least two sensing elements formed on substrates of different stiffnesses into a lens, enables the reduction of both electrical and environmental noise as well as mechanical noise when measuring eye-related parameters (such as IOP), thereby improving the signal-to-noise ratio of the measured eye-related parameters and reducing errors in eye-related parameters in dynamic environments to achieve higher measurement accuracy.

[0041] Specifically, the present invention provides a hybrid design strategy for noise reduction by forming at least two sensing elements, each comprising a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element. In one embodiment, this disclosure provides such a hybrid element sensing device and has prototyped and tested it. Test results show that noise is reduced to less than, for example, 3 mmHg under various environments. Analysis shows that the hybrid design combining at least two sensing elements with different stiffness reduces the overlap of deformable signals that vary with eye-related parameters (e.g., IOP) and increases signal separation. The design of the hybrid element sensing device effectively reduces sensing noise. For example, one of the sensing elements can be used as a reference element, such that the at least two sensing elements generate at least two different resonant frequencies with different sensitivity parameters. Analysis shows that the addition of the reference sensing element, combined with improved analysis of the signals generated by the at least two sensing elements (e.g., analysis via differential processing), effectively reduces electrical and environmental noise as well as mechanical noise. Attached Figure Description

[0042] Non-limiting and non-exhaustive embodiments of the invention are described by way of example with reference to the following figures, wherein:

[0043] Figure 1 An example of a sensing device for the eye according to one embodiment of the present invention is illustrated;

[0044] Figures 2A-2C Schematic diagrams illustrating a sensing device for the eye and variations thereof according to various embodiments of the present invention are shown.

[0045] Figure 3 A method for manufacturing a sensing device for the eye according to one embodiment of the present invention is illustrated;

[0046] Figure 4A schematic block diagram of an eye monitoring system according to one embodiment of the present invention is shown;

[0047] Figure 5 An example monitoring system for the eye according to another embodiment of the present invention is illustrated;

[0048] Figure 6A An illustration shows a comparison of the deformation and required force of a sensing element having a rigid substrate region and a sensing element having a flexible substrate region according to an embodiment of the present invention;

[0049] Figure 6B An example of an embodiment of the present invention is illustrated. Figure 6A A chart showing the comparison results; and

[0050] Figures 7A-7C The diagram illustrates test data showing high IOP accuracy obtained using an example monitoring system for the eye according to one or more embodiments of the present invention.

[0051] For ease of understanding, the same reference numerals are used where possible to denote the same elements common in the figures. Detailed Implementation

[0052] To make the above and other features and advantages of the present invention clearer, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments given herein are for the purpose of explanation to those skilled in the art and are exemplary only, not restrictive. Features shown in the drawings are not necessarily drawn to scale.

[0053] The features described herein may be embodied in different forms and should not be construed as limited to the examples described herein. Rather, the embodiments described herein are provided merely to illustrate some of the many possible ways in which the apparatus, device, and / or system described herein will become apparent upon understanding the disclosure of this application.

[0054] As used herein, the term “and / or” includes any one of the associated listed items and any combination of any two or more of the associated listed items.

[0055] Although terms such as “first,” “second,” and “third” may be used herein to describe various components, parts, sections, or elements, these components, parts, sections, or elements are not limited by these terms. Rather, these terms are used only to distinguish one component, part, section, or element from another. Therefore, without departing from the teachings of the invention, a first component, part, section, or element referred to herein may also be referred to as a second component, part, section, or element.

[0056] The terminology used herein is for the purpose of describing various embodiments only and is not intended to limit the scope of this disclosure. Unless the context clearly indicates otherwise, the negation of “a,” “an,” and “the” is intended to also include plural forms. The terms “comprising,” “including,” and “having” specify the presence of the stated features, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, operations, components, elements, and / or combinations thereof.

[0057] Figure 1 An eye-sensing device 10 according to one embodiment of the present invention is illustrated. The sensing device 10 includes a lens (also referred to as a contact lens, such as a silicone rubber lens) 102, a first sensing element 104 (such as a rigid element), and a second sensing element 106 (such as a flexible element). The lens 102 has an inner surface and an outer surface, the inner surface of which is adapted to be disposed on the eye.

[0058] The first sensing element 104 and the second sensing element 106 each include a corresponding substrate region, wherein the substrate region of the first sensing element 104 and the substrate region of the second sensing element 106 have different stiffnesses. Of course, as detailed below, the first sensing element and the second sensing element can also be two rigid elements with different stiffnesses, or two flexible elements with different stiffnesses.

[0059] The first sensing element 104 and the second sensing element 106 are offset relative to the center of the lens 102 (e.g., ...). Figure 1 (as shown) and / or concentric arrangements (e.g., the shape of concentric circles or concentric arcs) are located between the inner and outer surfaces of lens 102 and are configured to sense relevant parameters of the eye, such as intraocular pressure (IOP).

[0060] In one embodiment, the sensing device 10 may further include at least one other sensing element besides the first sensing element 104 and the second sensing element 106. In other words, the sensing device may include at least two sensing elements. Each of the at least two sensing elements includes a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element.

[0061] The at least two sensing elements are eccentrically and / or concentrically arranged between the inner and outer surfaces of the lens with respect to the center of the lens, and are configured to sense relevant parameters of the eye.

[0062] Optionally, the at least two sensing elements in the substrate regions with different stiffnesses can be made separately or integrated together, for example, integrated into concentric circles or concentric arcs.

[0063] At least two sensing elements with different stiffness substrate regions have different IOP sensitivities and different degrees of deformation at the same IOP, thereby each obtaining a corresponding different deformation-related frequency signal. For example, a sensing element with a relatively large stiffness substrate region can be used as a reference element relative to a sensing element with a smaller stiffness substrate region. Of course, in other embodiments, a sensing element with a relatively small stiffness substrate region can also be used as a reference element.

[0064] The following will be combined with the appendix Figure 2A-2C The deformation behavior of the sensing element is described. Figure 2A - Figure 2C Schematic diagrams of example sensing devices 10a-10c and their variations under the same IOP are shown respectively.

[0065] The sensing element includes an inductor L and a capacitor C, and the resonant frequency of the sensing element is f, where

[0066]

[0067] From the above formula (1), it can be seen that the resonant frequency f is a function of the inductance L and capacitance C of the circuit. The resonant frequency is affected by the bending of the spiral coil of the inductor L. The bending of the coil embedded in the sensing element depends on the stiffness of the coil and the substrate below it. Figure 2A -Figure 2C). For the same IOP variation, when the substrate of the sensing element is rigid (see Figure 2C). Figure 2B The change in inductance L is reduced by sensing elements 203 and 207.

[0068] In a preferred embodiment, the substrate region of the at least one sensing element and the substrate region of at least another sensing element each include at least one rigid region and at least one flexible region, as in the following combination. Figure 2A As shown in the embodiments.

[0069] like Figure 2AAs shown, the example sensing device 10a includes at least a third sensing element 203 and a fifth sensing element 205, wherein the substrate region of the third sensing element 203 is a rigid region and the substrate region of the fifth sensing element 205 is a flexible region, resulting in low IOP noise. The third sensing element 203 can serve as a reference element. Therefore, in this embodiment, a dual-element design with mixed stiffness is formed by combining the flexible substrate of one sensing element and the rigid substrate of the other. The third sensing element 203 has lower sensitivity to curvature changes due to IOP; that is, for the same curvature change ΔIOP, the sensitivity of the third sensing element 203 is less than that of the fifth sensing element 205. Alternatively, the deformation of the third sensing element 203 has a smaller response to changes in IOP, i.e., d... r <d f d r This indicates the degree of deformation of the third sensing element 203 and d f This indicates the degree of deformation of the fifth sensing element 205.

[0070] In another embodiment, the substrate region of the at least one sensing element and the substrate region of the at least another sensing element each include at least a first rigid region and at least a second rigid region with different stiffnesses, as combined below. Figure 2B The embodiments shown in the example are as follows.

[0071] like Figure 2B As shown, the example sensing device 10b includes at least a fourth sensing element 207 and a third sensing element 203, wherein the substrate region of the fourth sensing element 207 is a first rigid region, and the substrate region of the third sensing element 203 is a second rigid region having a stiffness greater than that of the first rigid region. The third sensing element 203 has lower sensitivity to curvature changes caused by IOP; that is, for the same curvature change ΔIOP, the sensitivity of the third sensing element 203 is less than that of the fourth sensing element 207.

[0072] In another embodiment, the substrate region of the at least one sensing element and the substrate region of the at least another sensing element each include at least a first flexible region and at least a second flexible region with different stiffnesses, as combined below. Figure 2C The embodiments shown in the example are as follows.

[0073] like Figure 2CAs shown, the example sensing device 10c includes at least a fifth sensing element 205 and a sixth sensing element 209, wherein the substrate region of the fifth sensing element 205 is a first flexible region and the substrate region of the sixth sensing element 209 is a second flexible region with a stiffness greater than that of the first flexible region. The sixth sensing element 209 has a lower sensitivity to curvature changes caused by IOP, that is, for the same curvature change ΔIOP, the sensitivity of the sixth sensing element 209 is less than that of the fifth sensing element 205.

[0074] For the sensitivity design parameters of the sensing device, please refer to Table 1.

[0075] Table 1

[0076] Sensing element IOP Sensitivity Environmental sensitivity Substrate region with low stiffness high high substrate region with high stiffness Low high

[0077] The stiffness dependence of the sensing device will be described below. Inductance built on a rigid substrate is not very sensitive to changes in corneal curvature with IOP. The effect of stiffness can be understood from the relationship between pressure and inductance. The inductance of the coil in the sensing element is designed to vary linearly with pressure, as shown in the following formula (2):

[0078] ΔL∝Δp (2)

[0079] This makes the total inductance L of the sensing element a linear function of the pressure p (see Equation (3)), where k p1 and k p2 It is a constant:

[0080] L = k p1 ·p+k p2 (3)

[0081] The total capacitance C of the sensing element is composed of a fixed part C const Part C related to the environment pvar Composition, as shown in formula (4):

[0082]

[0083] in The dielectric environment ε of the eye varies, as shown in formula (5), where k ε1 It is a constant:

[0084]

[0085] Substituting formulas (3)-(5) into formula (1), we obtain formula (6) for the resonant frequency f:

[0086]

[0087] And it is extended using Taylor series, as shown in formula (7):

[0088] f(p, ε) = f p (p0, ε0).p+f ε (p0, ε0).ε+f(p0, ε0)

[0089] -f p (p0, ε0).p0-f ε (p0, ε0).ε0 (7)

[0090] Dependency relationships can be collected and represented in a concise form, as shown in formula (8):

[0091] F=α.p+β.ε+c (8)

[0092] Where α is the pressure parameter and β is the dielectric constant parameter.

[0093] For a sensing device scheme that includes two sensing elements, the resonant frequencies of the two sensing elements can be expressed as F1 and F2, respectively, resulting in formulas (9) and (10):

[0094] F1=α1·p+β1·ε+c1 (9)

[0095] F2=α2·p+β2.ε+c2 (10)

[0096] When the signal from one sensing element is subtracted from the signal from another sensing element, the environment-dependent ε is eliminated, resulting in formula (11):

[0097]

[0098] Define the differential frequency F d , where F d It can be called a parameter related to the frequency difference between the two sensing elements; in fact, F d It is a pressure-related function that is slightly affected by environmental factors, as shown in formula (12):

[0099]

[0100] Formula (13) is derived:

[0101] F d =α d ·p+c d (13)

[0102] Where parameter c d and α d As shown in formulas (14) and (15) respectively, where C d This can be described as a parameter related to the capacitance difference between the two sensing elements:

[0103]

[0104]

[0105] Where α d It is F d The pressure parameter. When the pressure parameter α1, which is used as the reference sensing element, is at its minimum, F d maximum.

[0106] In one embodiment, the rigid region has a tensile strength of 15.95 MPa-205 MPa, an elastic modulus of 1.9 GPa-46.9 GPa, and a Poisson's ratio of 0.25-0.41, wherein the rigid region includes the first rigid region and the second rigid region mentioned above.

[0107] In one embodiment, the flexible region has a tensile strength of less than 8.2 MPa, an elastic modulus of less than 1.9 GPa, and a Poisson's ratio of 0.45-0.5, wherein the flexible region includes the first flexible region and the second flexible region mentioned above.

[0108] In one embodiment, the lens has an optical zone at its center, such as 4 mm in diameter, and the at least two sensing elements are disposed between the optical zone and a position, such as 1 mm away from the periphery of the lens.

[0109] Another aspect of the present invention provides a method for manufacturing a sensing device for the eye, the method comprising:

[0110] A lens is provided having an inner surface and an outer surface, the inner surface of which is adapted to be disposed on an eye;

[0111] At least two sensing elements are formed, each of the at least two sensing elements including a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element, and

[0112] The at least two sensing elements are eccentrically and / or concentrically arranged between the inner and outer surfaces of the lens with respect to the center of the lens, and the at least two sensing elements are configured to sense relevant parameters of the eye.

[0113] In one or more embodiments of the above method, the relevant features of the lens and the at least two sensing elements are as mentioned in the embodiments described above regarding the sensing device, and will not be repeated here.

[0114] Figure 3A method for manufacturing a sensing device for the eye according to one embodiment of the present invention is illustrated. In one embodiment, a hybrid dual-element sensing device having a flexible substrate region and a rigid substrate region is manufactured.

[0115] For example, silicone rubber is used in the flexible substrate region, while polyimide (PI), which can serve as a rigid material, is used in the rigid substrate region. Alternatively, polyethylene terephthalate (PET) can be used as a rigid material to form the rigid substrate region.

[0116] As in Figure 3 As shown in step (a), a flexible silicone rubber substrate is fabricated internally by laminating a screen-printed silicone rubber interlayer (NuSil MED-6033, liquid silicone elastomer, NuSil Technology LLC, Carpinteria, CA, UST) between two 12μm copper films. The laminate is cured in an oven at 60°C for 1 hour. A commercially available 25μm polyimide laminate with 12μm copper cladding on both sides (R-F775, Panasonic, Japan) is used for rigid components. The mechanical properties of the materials are detailed in Table 2.

[0117] Table 2 Material properties selected for rigid-flexible sensing devices

[0118] characteristic silicone rubber polyimide elastic modulus 0.00000500-1.90GPa 0.107-46.9 GPa Poisson's ratio 0.500 0.250-0.410

[0119] The sensing elements with flexible substrate regions and sensing elements with rigid substrate regions described above are manufactured using processes such as photolithography, development, and etching.

[0120] As in Figure 3 As shown in step (b), such as dry photoresist (DuPont) Photoresist was laminated on both sides of a double-sided copper-clad laminate. A photomask was used to define the circuitry, and 0.04M NaOH solution was used for development. The patterned substrate was etched using 1.85M FeCl2 solution, and any remaining photoresist was removed using NaOH solution, thereby exposing the LC circuitry on the substrate, as shown in [the image / image / etc.]. Figure 3 As shown in step (c).

[0121] Next, Figure 3 Sensing elements with flexible substrate regions and sensing elements with rigid substrate regions, manufactured in this process, are embedded in contact lenses to form sensing devices for the eye, for example... Figure 1The sensing device 10 shown is illustrated. The sensing device 10 has a center thickness of 225 ± 25 μm, a diameter of 14 ± 0.5 mm, and a base curve of 8.8 ± 0.1 mm (specific parameters are shown in Table 3). Based on the hybrid sensing device concept, a clinical prototype with a transparent center can be fabricated.

[0122] Table 3 Parameters of Rigid-Flexible Materials

[0123]

[0124] Figure 4 A schematic block diagram of an eye monitoring system 4 according to one embodiment of the present invention is shown. The monitoring system 4 includes a sensing device 10, an external antenna 42, and an analysis device 44. The sensing device 10 can be any of the eye sensing devices described above.

[0125] The external antenna 42 is configured to wirelessly communicate with at least two sensing elements in the sensing device 10 and to receive corresponding frequency signals from the at least two sensing elements. The external antenna 42 is, for example, circular, elliptical, rectangular, or any other suitable shape, preferably adapted to the shape of the device to which it is attached—e.g., glasses, eye mask, clothing, etc.—and / or the external antenna 42 is configured or included in an electronic device such as a reader to wirelessly communicate with at least two sensing elements of the sensing device 10, for example, via Wi-Fi, Bluetooth, etc.

[0126] The analysis device 44 is configured to store corresponding frequency signals received from at least two sensing elements and to monitor relevant eye parameters, such as IOP, by analyzing the corresponding frequency signals.

[0127] Figure 5 An example monitoring system 5 for the eye is illustrated according to one embodiment of the present invention.

[0128] Similar to Figure 4 The monitoring system 4 shown includes, in addition to sensing devices (such as CLS) 10, external antenna 42, and analysis devices (such as vector network analyzer) 44, Figure 5 The monitoring system 5 may also include an eye model (such as a silicone rubber eye) 51, a titration device (such as a burette) 53, and at least one polymer membrane 55.

[0129] like Figure 5 As shown, the sensing device 10 is placed on the eye model 51, and the titration device 53 is configured to apply force to the inside of the eye model 51, for example, by inserting a needle into the eye of the model and adjusting the IOP inside the eye model by changing the water level in the burette.

[0130] Preferably, at least one polymer film 55 is placed above the sensing device 10 and configured to simulate the eye environment of the eye model 51. In one embodiment, the polymer film is made of polyvinylidene chloride and has a thickness of 90 μm. For example, a thin 90 μm polyvinylidene chloride sheet can be placed on top of the lens to change the dielectric environment on the sensing device.

[0131] The sensing device 10 can be any of the sensing devices described above, which can be used not only for actual sensing of the user's eyes, but also for sensing of the eye model 51. For example, a 25mm rigid PCB coil antenna 42 connected to a network analyzer (R60, Copper Mountain Technologies, Indianapolis, IN, USA) can be positioned above the sensing device to measure the resonant frequency as a function of IOP in five phases between 23-58 mmHg.

[0132] By using a monitoring system that includes sensing devices for the eye as described above to subtract the corresponding frequency signals of the responses of at least two sensing elements, when monitoring a user's eye or an eye model to measure relevant parameters (such as IOP), environmental noise is reduced while mechanical noise is reduced based on one or more rigid substrate regions, thereby improving the signal-to-noise ratio of the measured eye-related parameters and achieving higher measurement accuracy to facilitate eye monitoring.

[0133] Figure 6A Examples of stiffness testing for sensing elements with rigid and flexible substrate regions are illustrated. A Universal Tensile Machine (UTM) (MTSInsight, MN, USA) hardness tester indenter was used to test the same lens embedded with silicone rubber and reinforced polyimide. The example sensing device under test was placed on an acrylic clamp, and the UTM was used to characterize the stiffness behavior of the individual element sensing device. The UTM has a 3mm diameter flat head aligned with the center of the contact lens (e.g., Figure 6A (As shown in the diagram). The inductor (e.g., induction coil) in the sensing device deforms along with the sensing device under a certain degree of force.

[0134] Figure 6B An example of an embodiment of the present invention is illustrated. Figure 6AThe results are shown in a graph. The downward force was recorded after a downward deformation of 0.3 mm, and the test was repeated 5 times on two single-element sensing elements. The results show that the sensing element made of polyimide requires more than 10 times the load (e.g., compared to an element using a substrate containing silicone rubber). Figure 6B The 0.20N shown is compared to 0.015N, and it has a stiffness greater than 10 times. Specifically, see... Figure 6B The results showed that, compared to lenses made of silicone rubber, reinforced rigid lenses require more than 13 times the force to deform by 0.3 mm, meaning that the stiffness of reinforced rigid lenses is more than 10 times that of lenses made of silicone rubber.

[0135] Figures 7A-7C The diagram illustrates test data showing high IOP accuracy obtained using an example monitoring system for the eye according to one or more embodiments of the present invention.

[0136] The IOP sensitivity of rigid and flexible elements can be determined based on the change of their frequency with IOP. Figure 7A The normalized frequency variations of the rigid and flexible elements as a function of IOP are plotted. The frequency variation of the rigid element is almost zero, exhibiting a horizontal characteristic and a small slope of -6.5E⁻⁴. In the test range up to 50 mmHg, the flexible silicone rubber element exhibits a strong IOP dependence with a slope of -1.2E⁻², which is 15 times that of the rigid element. Increasing the stiffness by a 13-fold reduces the IOP sensitivity of the rigid polyimide element to approximately 5% of that of the flexible silicone rubber element. Figure 7A The changes in IOP of rigid and flexible elements in a static environment are compared, and the changes of a reference assumed coil with substrate stiffness close to that of a flexible element are shown.

[0137] In one implementation, the IOP sensitivity of the induction coil of the flexible element is 18 times that of the induction coil of the rigid element. The rigid element is more than ten times more rigid than the flexible element, which results in a reference element (such as...) that is insensitive to IOP. Figure 7A The signal shown has no IOP interference. Conversely, a rigid element with stiffness similar to that of a flexible element has non-zero sensitivity to IOP measurements, making the differential frequency F obtained by the smaller stiffness element... d The value has a large error. Some embodiments of this disclosure show the design of a hybrid sensing element with large stiffness differences, increasing the differential frequency F. d .

[0138] Some embodiments of this disclosure can be improved by designing the stiffness of the substrate regions of at least two sensing elements, wherein, as shown in formula (16),

[0139]

[0140] Through α d Optimized to maximize F d Experiments have shown that at the differential frequency F d The measurement results are better when the stiffness difference between the substrate regions of at least two sensing elements is at its maximum.

[0141] Figure 7B The effects of changes in the sensing device environment on the frequency response of rigid and flexible elements in a hybrid sensing device are illustrated. These changes include no interference (such as no polymer film simulating the eye environment), a single interference (one polymer film simulating the eye environment), and two interferences (two polymer films simulating the eye environment).

[0142] In one embodiment, the initial frequencies of the induction coils of the flexible element and the rigid element in the uncovered polymer film state are 626.35 MHz and 498.63 MHz, respectively, by placing up to two films on top of the sensing device to alter the dielectric environment. The polymer film, as described above, can be made of polyvinylidene chloride with a thickness of 90 μm.

[0143] Figure 7C A graph showing the correlation between intraocular pressure measured using a hybrid contact lens sensing element and a set intraocular pressure was plotted, with the error of the test results within ±3 mmHg.

[0144] like Figure 7C As shown, in a changing environment (simulated by changing the state of the polymer film), the frequency response of the sensing element is measured as a function of IOP. Figure 7C The test results show that the correlation is parallel, confirming that this behavior can be represented by a linear function with a single dielectric constant parameter β. Subsequently, F... d The relationship between IOP (i.e., p in formula (13)) can be easily determined from test data. For Figure 7C All test environments and 3mmHg error bands, according to F d The predicted IOP is plotted as a function of the set IOP (set by the water level difference in the burette). Figure 7C The figure shows that the predicted IOP corresponds one-to-one with the set IOP and the measurement error is within ±3 mmHg.

[0145] Therefore, under different eye environments, by using the sensing device for the eye of the present invention to obtain corresponding and different deformation frequency signals, and by subtracting the corresponding different deformation frequency signals to reduce signal noise in dynamic environments, high-precision parameters of the user's eye can be obtained.

[0146] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0147] Although the invention has been described in conjunction with embodiments, those skilled in the art will understand that various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the scope of protection of the invention should be determined by the appended claims.

Claims

1. A sensing device for the eye, characterized in that, The sensing device includes: A lens having an inner surface and an outer surface, the inner surface of the lens being adapted to be disposed on an eye; and At least two sensing elements, each including a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element. Wherein, the substrate region of the at least one sensing element and the substrate region of the at least another sensing element respectively include: (1) At least one rigid region and at least one flexible region; (2) At least a first rigid region and at least a second rigid region with different stiffness; or (3) At least a first flexible region and at least a second flexible region with different stiffness; The rigid region has a tensile strength of 15.95 MPa-205 MPa, an elastic modulus of 1.9 GPa-46.9 GPa, and a Poisson's ratio of 0.25-0.41; and / or The flexible region has a tensile strength of less than 8.2 MPa, an elastic modulus of less than 1.9 GPa, and a Poisson's ratio of 0.45-0.

5. The at least two sensing elements are eccentrically and / or concentrically disposed between the inner and outer surfaces of the lens with respect to the center of the lens, and are configured to sense relevant parameters of the eye.

2. The sensing device according to claim 1, characterized in that, The lens has an optical zone at its center, and the at least two sensing elements are disposed between the optical zone and a position adjacent to the periphery of the lens.

3. A method for manufacturing a sensing device for the eye, characterized in that, The method includes: A lens is provided having an inner surface and an outer surface, the inner surface of which is adapted to be disposed on an eye; At least two sensing elements are formed, each of the at least two sensing elements including a corresponding substrate region, wherein the substrate region of at least one sensing element has a different stiffness than the substrate region of at least another sensing element, and the substrate regions of the at least one sensing element and the at least another sensing element respectively include: (1) At least one rigid region and at least one flexible region; (2) At least a first rigid region and at least a second rigid region with different stiffness; or (3) At least a first flexible region and at least a second flexible region with different stiffness; The rigid region has a tensile strength of 15.95 MPa-205 MPa, an elastic modulus of 1.9 GPa-46.9 GPa, and a Poisson's ratio of 0.25-0.41; and / or the flexible region has a tensile strength of less than 8.2 MPa, an elastic modulus of less than 1.9 GPa, and a Poisson's ratio of 0.45-0.

5. as well as The at least two sensing elements are eccentrically and / or concentrically arranged between the inner and outer surfaces of the lens with respect to the center of the lens, and the at least two sensing elements are configured to sense relevant parameters of the eye.

4. The method according to claim 3, characterized in that, The lens has an optical zone at its center, and the at least two sensing elements are disposed between the optical zone and a position adjacent to the periphery of the lens.

5. A monitoring system for the eye, characterized in that, The monitoring system includes a sensing device according to any one of claims 1 to 2, and the monitoring system further includes: An external antenna, configured to wirelessly communicate with the at least two sensing elements and receive corresponding frequency signals from the at least two sensing elements, and An analysis device configured to store corresponding frequency signals received from the at least two sensing elements and to monitor relevant parameters of the eye by analyzing the corresponding frequency signals.

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