CN110013232B

CN110013232B - Eye sensor and preparation method

Info

Publication number: CN110013232B
Application number: CN201910349801.1A
Authority: CN
Inventors: 徐飞; 朱衡天; 熊毅丰; 陆延青; 胡伟
Original assignee: Nanjing University
Current assignee: Nanjing University
Priority date: 2019-04-28
Filing date: 2019-04-28
Publication date: 2021-08-10
Anticipated expiration: 2039-04-28
Also published as: CN110013232A

Abstract

The invention discloses an eye sensor and a preparation method thereof, wherein the eye sensor comprises a corneal contact lens, and a first interdigital capacitor, a second interdigital capacitor, a first inductance coil, a second inductance coil and a channel resistor which are packaged in the corneal contact lens. The preparation method of the eye sensor comprises the following steps: (a) photoetching a graphene channel on a metal substrate; (b) removing redundant graphene; (c) glucose oxidase is fixed on the graphene; (d) photoetching an electrode pattern; (e) preparing an electrode; (f) repeating the steps to obtain electrodes and channel resistors of the interdigital capacitor and the inductance coil; (g) spin-coating and curing a flexible material on the electrode; (h) a transfer electrode; (i) and (6) packaging. The invention can realize 24-hour real-time dynamic monitoring of a plurality of health parameters of intraocular pressure, eye temperature and tear sugar, and can correct the thermal expansion coefficient through the eye temperature to obtain more accurate intraocular pressure data; simple structure, mature and feasible process and low preparation cost.

Description

Eye sensor and preparation method

Technical Field

The invention relates to an eye sensor and a preparation method thereof, in particular to a wireless passive wearable eye sensor capable of monitoring intraocular pressure, eye temperature and tear sugar in real time for 24 hours and a preparation method thereof.

Background

Glaucoma is one of three major blinding diseases causing blindness in humans, with a total incidence of 1% and 2% after age 45. Pathological increased intraocular pressure and 24-hour ocular pressure fluctuations are the main ways to diagnose and judge the progression of glaucoma. The existing tonometers are point-type measurements, and during the course of 24-hour tonometry, doctors often require patients to measure the tonometers once at 5, 7, 10, 14, 18, and 22 points, respectively. When the method is used for diagnosing glaucoma, accurate intraocular pressure fluctuation data of a patient in sleep cannot be obtained, and the conditions of normal intraocular pressure in the daytime and increased intraocular pressure in the nighttime exist in most of patients, so that the conventional detection mode easily causes missed diagnosis and misdiagnosis. And this detection mode requires that the patient stays in the hospital throughout the day, has influenced daily activities such as normal work life, lacks the convenience.

In this context, a new class of tonometers has emerged, which can be classified into invasive and non-invasive. Although the invasive intraocular pressure sensor is developed from a silicon base to a flexible base in the development process and is developed from a hard base to a foldable base, the invasive intraocular pressure sensor inevitably causes trauma to a patient in the invasion process and is not easily accepted by the patient. The non-invasive intraocular pressure sensor is originally developed by a swiss company named as sensed, and the intraocular pressure is monitored by detecting the strain of the soft corneal contact lens in real time, so that the wound of a patient is avoided.

In addition, the sugar content of tear sugar in tears was found by the us chartgel in 2005 to reflect blood glucose levels in humans very accurately. Moreover, when the blood sugar content of the human body changes, the tear sugar also changes correspondingly. The conventional method for collecting the lachrymal glucose mainly comprises a cotton swab stimulation method, a capillary collection method and the like, which are high in risk, cannot be completed by a patient, results are difficult to quantify, and an expensive high-precision liquid chromatograph is required for detection, so that real-time monitoring cannot be realized.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a wireless and passive wearable eye sensor and a preparation method thereof, which can realize 24-hour real-time dynamic monitoring of a plurality of health parameters of intraocular pressure, eye temperature and tear sugar.

The technical scheme is as follows: the eye sensor comprises a corneal contact lens, a first interdigital capacitor, a second interdigital capacitor, a first inductance coil, a second inductance coil and a channel resistor, wherein the first interdigital capacitor, the second interdigital capacitor, the first inductance coil, the second inductance coil and the channel resistor are packaged in the corneal contact lens; the electrodes of the first interdigital capacitor are radially arranged along the center of the corneal contact lens, and two ends of the electrodes are respectively connected to two ends of the first inductance coil; the electrodes of the second interdigital capacitor are tangentially arranged along the center of the corneal contact lens, and two ends of the electrodes are respectively connected to two ends of the second inductance coil; the first inductance coil and the second inductance coil are single-turn coils and are spirally arranged by taking the corneal contact lens as a center, and the first inductance coil is positioned at the outer edge of the second inductance coil; the channel resistor is positioned on the second inductance coil; the contact lens is used for fitting with the surface of the cornea when being worn by a patient.

Wherein, the corneal contact lens is a flexible material, including but not limited to PDMS or Ecoflex, and the thickness is 50-250 um. The electrode is prepared from a conductive metal material, including but not limited to gold, silver or copper and other metal materials, the thickness is 0.3-5 um, and the material of the channel resistor 6 comprises graphene and glucose oxidase.

The invention relates to a preparation method based on the eye sensor, which comprises the following steps: (a) transferring graphene on a metal substrate, and photoetching to obtain a graphene channel pattern; (b) removing redundant graphene; (c) glucose oxidase is fixed on the graphene; (d) photoetching an electrode pattern on the graphene channel pattern; (e) preparing an electrode with an electrode pattern by using a coating process; (f) repeating the steps to respectively obtain electrodes and channel resistances of the first interdigital capacitor, the second interdigital capacitor, the first inductance coil and the second inductance coil; (g) spin coating and curing a flexible material on the electrode; (h) removing the metal substrate and the transfer electrode; (i) and placing the prepared components in a corneal contact lens mold, and packaging by using a flexible material to prepare the eye sensor.

Wherein the metal substrate is an active metal substrate, preferably iron or aluminum. The coating process comprises magnetron sputtering coating, electron beam evaporation coating or electroplating. The flexible material includes but is not limited to PDMS or Ecoflex. The first interdigital capacitor and the second interdigital capacitor are only provided with one electrode layer, so that the preparation process is simple and the cost is low.

Has the advantages that: the wireless passive wearable eye sensor can dynamically monitor a plurality of health parameters of intraocular pressure, eye temperature and tear sugar in real time for 24 hours, and correct the thermal expansion coefficient through the eye temperature, so that more accurate intraocular pressure data can be obtained. The eye sensor has the advantages of simple structure, mature and feasible process and low preparation cost.

Drawings

FIG. 1 is a schematic diagram of an eye sensor according to the present invention;

FIG. 2 is a schematic view of a test of an ocular sensor of the present invention;

fig. 3 is a graph of the resonant frequency of an ocular sensor of the present invention.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

Referring to fig. 1, the wireless passive wearable eye sensor of the invention comprises a corneal contact lens 1, and a first interdigital capacitor 2, a second interdigital capacitor 3, a first inductance coil 4, a second inductance coil 5 and a channel resistor 6 packaged in the corneal contact lens 1; electrodes of the first interdigital capacitor 2 are radially arranged along the center of the corneal contact lens 1, and two ends of the electrodes are respectively connected to two ends of the first inductance coil 4; the electrodes of the second interdigital capacitor 3 are tangentially arranged along the center of the corneal contact lens 1, and two ends of the electrodes are respectively connected with two ends of the second inductance coil 5. The first inductance coil 4 and the second inductance coil 5 are single-coil coils, are spirally arranged by taking the corneal contact lens 1 as a center, and are used for radio frequency electromagnetic field energy coupling and information transmission; meanwhile, because the strain caused by the intraocular pressure is maximum at the corneoscleral junction, the first inductance coil 4 is positioned at the outer edge of the second inductance coil 5, and more accurate intraocular pressure data is obtained through the radial strain of the first interdigital capacitor 2 connected to the first inductance coil 4. The electrode resistance of the first inductance coil 4 and the second inductance coil 5 is low, which is beneficial to obtaining higher quality factor and improving the signal-to-noise ratio of the monitoring signal. The channel resistance 6 is located on the second inductor winding 5.

Corneal contact lens 1 is flexible material, preferred PDMS for the patient laminates with the cornea surface when wearing to seal electrical component, keep apart external environment's interference, thickness can select arbitrary scope in 50 ~ 250 um.

Because the intraocular pressure causes the strain of the corneal contact lens 1 to be radial strain, the material thermal expansion causes the strain of the corneal contact lens 1 to be radial strain and tangential strain, and the change amounts of the radial strain and the tangential strain to the capacitance are different for interdigital capacitors with different geometric configurations, the respective capacitance change amounts are detected by the radial design of the first interdigital capacitor 2 and the tangential design of the second interdigital capacitor 3, the resonance frequency drift values are obtained, and the intraocular pressure and temperature data can be recovered through the fitting coefficients. Meanwhile, the channel resistor 6 is made of graphene, glucose oxidase and other materials, and due to the fact that glucose with different concentrations in tears can generate different numbers of electron hole pairs on the graphene, the resistance value of the graphene channel is further influenced, and the resistance-type tear glucose sensor is achieved.

The first interdigital capacitor and the second interdigital capacitor of the sensor only have one electrode layer, and meanwhile, the area of a single interdigital is small, so that the sensor is easy to couple and integrate with a corneal contact lens flexible material, and the comfort level of a user is improved. The electrode is made of conductive metal copper, the thickness of the electrode can be in any range of 0.3-5 um, and the sensor is packaged by flexible materials outside the electrode layer. The electrode layer is divided into two independent R-L-C resonant circuits, wherein the capacitors are respectively formed by the first interdigital capacitor 2 and the first interdigital electrode 3, so that the monitoring of two parameters of intraocular pressure and eye temperature is realized, and the influence of thermal expansion on the detection of the intraocular pressure is compensated in later signal processing through the detection of the eye temperature, so that more accurate intraocular pressure data is obtained; the resistance is formed by the resistance of the first inductance coil 4 and the second inductance coil 5 and the channel resistance 6, the channel resistance 6 is far larger than the resistance of the first inductance coil 4 and the second inductance coil 5, and the glucose oxidase is connected to realize the monitoring of the tear glucose.

The invention relates to a preparation method based on the eye sensor, which comprises the following steps: (a) transferring multilayer graphene on an active wave metal substrate, photoetching a graphene channel pattern, and preferably selecting an iron substrate for the active wave metal substrate; (b) removing redundant graphene by using oxygen plasma; (c) glucose oxidase is fixed on the graphene; (d) photoetching an electrode pattern on the graphene channel pattern; (e) evaporating a conductive metal material onto the pattern in the step (d) by using a coating process to prepare an electrode, wherein the coating process is preferably a magnetron sputtering coating process, and the conductive metal material is preferably copper; (f) repeating the steps to respectively manufacture the electrodes of the first interdigital capacitor 2, the second interdigital capacitor 3, the first inductance coil 4 and the first inductance coil 5 and the channel resistor 6; (g) spin coating and curing a flexible material, preferably PDMS, on the electrodes; (h) removing the metal substrate by a corrosion method, and transferring the electrode; (i) the prepared components are placed in a mold of the corneal contact lens 1 and encapsulated by using a flexible material, preferably PDMS, so as to prepare the eye sensor.

Referring to fig. 2, the wireless passive wearable eye sensor of the present invention performs energy coupling by means of electromagnetic field through an external vector network analyzer VNA7 and a third inductor 8, performs measurement of the resonant frequency of the sensor by using return loss S11 parameter, and obtains the resonant frequency of two R-L-C series circuits simultaneously through the same vector network analyzer VNA7 and the third inductor 8 by using HFSS simulation design.

Referring to fig. 3, the abscissa of the peak of the S11 curve reflects the resonant frequency of the R-L-C series circuit, which is determined by the inductance L and the capacitance C, and in the sensor of the present invention, the resonant frequency is mainly affected by the interdigital capacitor C; the amplitude of the ordinate reflects the Q value of the R-L-C series circuit, which is determined by the inductance L, the capacitance C, and the resistance R, and in the sensor of the present invention the amplitude is mainly influenced by the channel resistance 6. The left peak 9 is the S11 curve for the R-L-C series circuit comprising the first interdigital capacitor 2 and the right peak 10 is the S11 curve for the R-L-C series circuit comprising the second interdigital capacitor 3. Strain of the corneal contact lens 1 in the radial direction and the tangential direction is obtained by obtaining respective resonance frequency of the corneal contact lens and the intraocular pressure and real-time dynamic change data of the intraocular pressure and the eye temperature are obtained, and the influence of thermal expansion on intraocular pressure detection is compensated in later signal processing by detecting the eye temperature so as to obtain more accurate intraocular pressure data; the resistance value of the channel resistor 6 is obtained by obtaining the resonance amplitude of the right peak 10, and then the real-time dynamic change data of the tear glucose is obtained.

Claims

1. An ocular sensor, characterized by: the contact lens comprises a contact lens (1), a first interdigital capacitor (2), a second interdigital capacitor (3), a first inductance coil (4), a second inductance coil (5) and a channel resistor (6), wherein the first interdigital capacitor (2), the second interdigital capacitor (3), the first inductance coil (4), the second inductance coil (5) and the channel resistor (6) are packaged in the contact lens (1); the electrodes of the first interdigital capacitor (2) are radially arranged along the center of the corneal contact lens (1), and two ends of the electrodes are respectively connected to two ends of the first inductance coil (4); the electrodes of the second interdigital capacitor (3) are tangentially arranged along the center of the corneal contact lens (1), and two ends of the electrodes are respectively connected to two ends of the second inductance coil (5); the first inductance coil (4) and the second inductance coil (5) are single-turn coils and are spirally arranged by taking the corneal contact lens (1) as a center, and the first inductance coil (4) is positioned at the outer edge of the second inductance coil (5); the channel resistor (6) is positioned on the second inductance coil (5); the corneal contact lens (1) is used for being attached to the surface of a cornea when being worn by a patient.

2. An ocular sensor as claimed in claim 1, characterized in that the corneal contact lens (1) is of a flexible material and has a thickness of 50 to 250 um.

3. The ocular sensor of claim 2, wherein the flexible material comprises PDMS or Ecoflex.

4. The ocular sensor of claim 1, wherein the electrodes are made of a conductive metal material and have a thickness of 0.3-5 um.

5. The ocular sensor of claim 4, wherein the conductive metal material comprises gold, silver, or copper.

6. An eye sensor according to claim 1, characterized in that the material of the channel resistance (6) comprises graphene and glucose oxidase.

7. A method of making the ocular sensor of claim 1, comprising the steps of:

(a) transferring graphene on a metal substrate, and photoetching to obtain a graphene channel pattern;

(b) removing redundant graphene;

(c) glucose oxidase is fixed on the graphene;

(d) photoetching an electrode pattern on the graphene channel pattern;

(e) preparing an electrode with an electrode pattern by using a coating process;

(f) repeating the steps to respectively manufacture the first interdigital capacitor (2), the second interdigital capacitor (3), the first inductance coil (4), the second inductance coil (5) and the channel resistor (6);

(g) spin coating and curing a flexible material on the electrode;

(h) removing the metal substrate and the transfer electrode;

(i) and placing each prepared assembly in a mould of a corneal contact lens (1), and packaging by using a flexible material to prepare the eye sensor.

8. The method of claim 7, wherein the metal substrate is an active metal substrate.

9. The method of claim 7, wherein the coating process comprises magnetron sputtering, electron beam evaporation, or electroplating.

10. The method of claim 7, wherein the flexible material comprises PDMS or Ecoflex.