A flexible sensor for eyelid pressure measurement and a method of manufacturing the same

Abstract

The application discloses a flexible sensor for eyelid pressure measurement and a preparation method thereof, and relates to the field of eyelid pressure measurement. The flexible sensor comprises a first organic silicon compound layer, a middle layer and a second organic silicon compound layer from top to bottom. The middle layer comprises a center electrode, a first wire, a first wire group, a piezoresistive unit group, an electric field receiving electrode group and a second wire group. One part of the first wire is connected with one end of the piezoresistive unit group and the center electrode, and the other part of the first wire is connected with the other end of the piezoresistive unit. The center electrode, the electric field receiving electrode group, the first wire, the first wire group and the second wire group are all conductive films with metal sputtered on the surface, and the piezoresistive unit group is a conductive film without sputtering metal. The second organic silicon compound layer is provided with a pit at the position in contact with the piezoresistive unit group. The above sensor can realize high sensitivity, high comfort and convenient and fast measurement of the eyelid pressure.

Description

Technical Field

[0001] This invention relates to the field of eyelid pressure measurement technology, and in particular to a flexible sensor for eyelid pressure measurement and its preparation method. Background Technology

[0002] Unlike intraocular pressure (IOP) measurement, eyelid pressure (APP) lacks standardized measurement methods. Extensive basic experimental research on sensor design and clinical testing related to APP measurement has been conducted both domestically and internationally. Yamaguchi et al. at Ehime University in Japan developed an APP pressure gauge with an overall thickness of 0.5 mm and a diameter of 10 mm based on the DigiTacts pressure sensor. A sterile, disposable soft contact lens was placed on the subject's cornea, and a 10 mm diameter DigiTacts pressure sensor covered with 0.5 mm of silicone rubber was inserted between the soft contact lens and the inner surface of the eyelid to measure APP pressure. At Tongren Hospital in China, after subjects wore contact lenses to protect their corneas, a thin-film pressure sensor with a thickness of <0.1 mm and a diameter of 7.5 mm was placed between the upper eyelid and the eyeball in the central region to detect the pressure exerted by the eyelid on the eyeball. Both methods use a contact lens + commercial pressure sensor measurement scheme and do not consider measurement errors caused by the contact area between the eyelid and the sensor.

[0003] Therefore, most existing eyelid pressure measurement devices involve inserting a commercial pressure sensor after wearing a contact lens for protection. These solutions do not consider the impact of the contact area between the eyelid and the sensor on measurement errors, and the wearing process is cumbersome, with the relative position of the pressure sensor and eyelid not being fixed, resulting in low wearing comfort. Therefore, this invention proposes a flexible sensor and its fabrication method for combined measurement of eyelid-eyeball interface pressure and contact area. By integrating a flexible pressure sensor, a flexible contact lens, and a contact area sensing module based on electric field sensing, high-sensitivity, high-comfort, and convenient eyelid pressure measurement is achieved. Summary of the Invention

[0004] The purpose of this invention is to provide a flexible sensor for measuring eyelid pressure and its preparation method, so as to achieve high sensitivity, high comfort and convenient and fast measurement of eyelid pressure.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] In a first aspect, the present invention provides a flexible sensor for measuring eyelid pressure, comprising:

[0007] From top to bottom: a first organosilicon compound layer, an intermediate layer, and a second organosilicon compound layer;

[0008] The intermediate layer includes:

[0009] Central electrode;

[0010] A first wire is connected to the central electrode;

[0011] First conductor group;

[0012] The piezoresistive unit group is connected to the center electrode via the first wire group;

[0013] A portion of the wires in the first wire resistor are connected to one end of the piezoresistive unit group and the center electrode, and another portion of the wires are connected to the other end of the piezoresistive unit.

[0014] An electric field receiving electrode group is located around the center electrode and the piezoresistive unit group;

[0015] The second set of conductors is connected to the electric field receiving electrode set.

[0016] The central electrode, the electric field receiving electrode group, the first wire, the first wire group, and the second wire group are all conductive thin films with metal sputtered on their surfaces, while the piezoresistive unit group is a conductive thin film without metal sputtering; the second organosilicon compound layer has pits arranged at the position where it contacts the piezoresistive unit group.

[0017] Optionally, both the first organosilicon compound layer and the second organosilicon compound layer are polydimethylsiloxane.

[0018] Optionally, the piezoresistive unit group includes four piezoresistive units, and the first wire group includes four wires.

[0019] Optionally, the electric field receiving electrode group includes four electric field receiving electrodes, and the second wire group includes four wires.

[0020] Optionally, the conductive film is a conductive thermoplastic polyurethane rubber film.

[0021] Optionally, the metal is gold or platinum.

[0022] Optionally, the pit is an annular pit.

[0023] Secondly, the present invention provides a method for fabricating a flexible sensor for measuring eyelid pressure, the method comprising:

[0024] S1: Spin-coat polydimethylsiloxane onto a glass slide and cure it at high temperature to form a first polydimethylsiloxane film;

[0025] S2: Attach a layer of conductive thermoplastic polyurethane rubber film to the polydimethylsiloxane film, and then cure it at high temperature;

[0026] S3: The conductive thermoplastic polyurethane rubber film is laser-cut to process the required electrode and wire shapes;

[0027] S4: Apply masking tape to the piezoresistive unit for protection;

[0028] S5: Perform magnetron sputtering to sputter gold or platinum onto a conductive thermoplastic polyurethane rubber film;

[0029] S6: Peel off the protective paper tape and the remaining conductive thermoplastic polyurethane rubber film except for the required electrodes and wires to obtain the intermediate layer.

[0030] S7: Perform electrical breakdown;

[0031] S8: Spin-coat an ultrathin layer of polydimethylsiloxane onto the first polydimethylsiloxane film and the intermediate layer, and cure it at high temperature;

[0032] S9: Fabrication of the second polydimethylsiloxane film using a mold;

[0033] S10: Spin-coat an ultrathin layer of polydimethylsiloxane onto the second polydimethylsiloxane film, attach the second polydimethylsiloxane and the sensor component prepared in steps S1-S9, and cure at high temperature;

[0034] S11: The sensor edges are trimmed and made into curved surfaces. Polydimethylsiloxane is applied to the sensor edges and surfaces, cured at high temperature, and then encapsulated.

[0035] Optionally, the preparation method further includes the following step between S1 and S2:

[0036] Spin-coat an ultra-thin layer of polydimethylsiloxane.

[0037] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0038] To address the issues of cumbersome wearing process, inconsistent relative position of pressure sensor and eyelid, and low wearing comfort, this invention integrates a flexible pressure sensor and a flexible contact lens, achieving convenient and highly comfortable wearing.

[0039] To address the impact of contact area on measurement, a sensing module integrating the contact area between the eyelid and the sensing unit was integrated, thereby reducing measurement errors.

[0040] Electrical breakdown was employed to improve the sensitivity of conductive thermoplastic polyurethane rubber films for pressure measurement. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A schematic diagram of the flexible sensor structure for eyelid pressure measurement provided by the present invention;

[0043] Figure 2 A schematic diagram of the intermediate layer structure and external measurement circuit provided by the present invention;

[0044] Figure 3 This is a flowchart illustrating the fabrication method of the flexible sensor for eyelid pressure measurement provided by the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The purpose of this invention is to provide a flexible sensor for measuring eyelid pressure and its preparation method, so as to achieve high sensitivity, high comfort and convenient and fast measurement of eyelid pressure.

[0047] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1

[0049] Figure 1 This is a schematic diagram of the flexible sensor structure for eyelid pressure measurement provided by the present invention, as shown below. Figure 1 As shown, the flexible sensor in this invention includes:

[0050] Specifically, the present invention provides a flexible sensor for combined measurement of eyelid-eyeball interface pressure and contact area, which includes a first organosilicon compound layer, an intermediate layer and a second organosilicon compound layer from top to bottom. That is, the sensor in this embodiment has a three-layer structure, with the top and bottom layers being polydimethylsiloxane and the intermediate layer being a conductive thermoplastic polyurethane rubber film partially sputtered with gold. That is, the first organosilicon compound layer and the second organosilicon compound layer are both polydimethylsiloxane.

[0051] The intermediate layer includes:

[0052] Center electrode 1, first wire 4, first wire group 5, piezoresistive unit group, electric field receiving electrode group and second wire group 6;

[0053] The first wire 4 is connected to the center electrode; the piezoresistive unit group is connected to the center electrode 1 through the first wire group 5; wherein, a portion of the first wire group is connected to one end of the piezoresistive unit group and the center electrode, and another portion of the wire is connected to the other end of the piezoresistive unit.

[0054] An electric field receiving electrode group is located around the center electrode 1 and the piezoresistive unit group; the second wire group 6 is connected to the electric field receiving electrode group;

[0055] Among them, the electric field receiving electrode group includes four electric field receiving electrodes 2, and the piezoresistive unit group includes four piezoresistive units 3.

[0056] The central electrode 1, the electric field receiving electrode group, the first wire 4, the first wire group 5, and the second wire group 6 are all conductive thermoplastic polyurethane rubber films with gold or platinum sputtered on their surfaces. The piezoresistive unit group is a conductive thermoplastic polyurethane rubber film without gold sputtering. The second organosilicon compound layer, i.e., the lower polydimethylsiloxane layer, has an annular pit 7 at the position where it contacts the intermediate piezoresistive unit.

[0057] Gold has good conductivity, and gold-sputtered conductive thermoplastic polyurethane rubber films have low resistance, making them suitable as electrodes and wires. Unsputtered gold-sputtered conductive thermoplastic polyurethane rubber films have higher resistance; when a certain current is applied to their ends, they can undergo electrical breakdown, thereby improving the sensitivity of the piezoresistive unit's pressure measurement. When the sensor is subjected to eyelid pressure, the electrically broken-down conductive thermoplastic polyurethane rubber film undergoes tensile strain. This tensile strain causes some carbon conductive pathways to break, increasing resistance and converting the pressure signal into an electrical signal, thus achieving eyelid pressure measurement. The contact area measurement unit consists of a central electrode and four electric field receiving electrodes. The central electrode is the transmitting electrode; when a 30kHz square wave signal is input, it emits an electric field, which is received by the four receiving electrodes. If an object above the sensor interferes with the electric field signal, the received electric field signal will change; the change depends on the object's shape, size, position, and distance from the sensor. In the measurement of the contact area between the eyelid and the sensor, the eyelid is the object that interferes with the electric field signal. As its position changes, the electric field signal received by the four receiving electrodes will change, and thus the contact area between the eyelid and the sensing unit can be calculated.

[0058] Specifically, the contact area and the signal intensity of the four electrodes can be calibrated through experiments, and the contact area can then be deduced from the signal intensity.

[0059] like Figure 2 As shown, this invention can simultaneously measure pressure and contact area. The central electrode serves as both the transmitting electrode of the contact area sensing module and the electrode at one end of each of the four piezoresistive units in the pressure sensing module. During measurement, a voltage is input to the central electrode, and the four receiving electrodes receive the electric field, thus measuring the contact area. Simultaneously, a resistor is connected in series after each of the four piezoresistive units. By measuring the voltage between the piezoresistive unit and the series resistor, the resistance of the piezoresistive unit can be determined, thereby measuring the pressure.

[0060] Example 2

[0061] To prepare the flexible sensor for eyelid pressure measurement described in Example 1 above, a method for preparing the flexible sensor is provided below, comprising:

[0062] S1: Spin-coat polydimethylsiloxane onto a glass slide and cure it at high temperature to form a first polydimethylsiloxane film.

[0063] The high-temperature curing temperature and time are: 80℃, 2h.

[0064] S2: A layer of conductive thermoplastic polyurethane rubber film is attached to the polydimethylsiloxane film and then cured at high temperature.

[0065] S3: The conductive thermoplastic polyurethane rubber film is laser-cut to process the required electrode and wire shapes.

[0066] S4: Apply masking tape to the piezoresistive unit for protection.

[0067] S5: Perform magnetron sputtering to sputter gold or platinum onto a conductive thermoplastic polyurethane rubber film;

[0068] S6: Peel off the protective paper tape and the remaining conductive thermoplastic polyurethane rubber film except for the required electrodes and wires to obtain the intermediate layer.

[0069] S7: Perform electrical breakdown.

[0070] Specifically, when DC currents of 4mA, 5mA, 6mA, 7mA, and 8mA are sequentially input to both sides of the piezoresistive unit for 10 seconds, its resistance gradually decreases, forming carbonized wires. Because the resistance of the wires sputtered with gold is very small, the breakdown area is the black piezoresistive unit portion without gold sputtering.

[0071] S8: A layer of ultrathin polydimethylsiloxane is spin-coated onto the first polydimethylsiloxane film and intermediate layer, i.e., the sensor component that has been prepared above, and cured at high temperature for protection and fixation.

[0072] S9: Use a mold to produce a second polydimethylsiloxane film.

[0073] Specifically, a resin mold with circular protrusions is printed using photopolymerization 3D printing. Polydimethylsiloxane is poured into the mold and cured at 80°C for 2 hours in a hot oven. After cooling, the cured polydimethylsiloxane is gently removed. Polydimethylsiloxane has a surface structure opposite to that of the mold, namely, circular pits.

[0074] S10: Spin-coat an ultrathin layer of polydimethylsiloxane onto the second polydimethylsiloxane film, attach the second polydimethylsiloxane and the sensor component prepared in steps S1-S9, and cure at high temperature.

[0075] S11: The sensor edges are trimmed and made into curved surfaces. Polydimethylsiloxane is applied to the sensor edges and surfaces, cured at high temperature, and then encapsulated.

[0076] Applying polydimethylsiloxane to the cut edges and surface of the sensor can fill the gaps created by the cutting and maintain the overall curved surface.

[0077] The high-temperature curing temperature and time are: 80℃, 2h.

[0078] To improve the bonding strength, the present invention further includes, between steps S1 and S2: spin-coating an ultra-thin layer of polydimethylsiloxane before attachment, and then curing it at high temperature after attachment, thereby improving the bonding strength between the conductive thermoplastic polyurethane rubber film and the polydimethylsiloxane, wherein the thickness of the ultra-thin polydimethylsiloxane is less than 100 μm.

[0079] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0080] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A flexible sensor for measuring eyelid pressure, characterized in that, include: From top to bottom: a first organosilicon compound layer, an intermediate layer, and a second organosilicon compound layer; The intermediate layer includes: Central electrode; A first wire is connected to the central electrode; First conductor group; The piezoresistive unit group is connected to the center electrode via the first wire group; A portion of the wires in the first wire resistor are connected to one end of the piezoresistive unit group and the center electrode, and another portion of the wires are connected to the other end of the piezoresistive unit. An electric field receiving electrode group is located around the center electrode and the piezoresistive unit group; The second set of conductors is connected to the electric field receiving electrode set. The central electrode, the electric field receiving electrode group, the first wire, the first wire group, and the second wire group are all conductive thin films with metal sputtered on their surfaces, while the piezoresistive unit group is a conductive thin film without metal sputtering; the second organosilicon compound layer has pits arranged at the position where it contacts the piezoresistive unit group; The electric field receiving electrode group includes four electric field receiving electrodes, and the second wire group includes four wires; The central electrode serves as both the transmitting electrode of the contact area sensing module and the electrode at one end of the four piezoresistive units in the pressure sensing module. During the measurement process, a voltage is input to the central electrode, and the four electric field receiving electrodes receive the electric field to measure the contact area.

2. The flexible sensor for eyelid pressure measurement according to claim 1, characterized in that, Both the first organosilicon compound layer and the second organosilicon compound layer are polydimethylsiloxane.

3. The flexible sensor for eyelid pressure measurement according to claim 1, characterized in that, The piezoresistive unit group includes four piezoresistive units, and the first wire group includes four wires.

4. The flexible sensor for eyelid pressure measurement according to claim 1, characterized in that, The conductive film is a conductive thermoplastic polyurethane rubber film.

5. The flexible sensor for eyelid pressure measurement according to claim 1, characterized in that, The metal is either gold or platinum.

6. The flexible sensor for eyelid pressure measurement according to claim 1, characterized in that, The pit is a circular pit.

7. A method for fabricating a flexible sensor for measuring eyelid pressure, characterized in that, The preparation method is applied to the flexible sensor for eyelid pressure measurement as described in any one of claims 1-6, and the preparation method includes: S1: Spin-coat polydimethylsiloxane onto a glass slide and cure it at high temperature to form a first polydimethylsiloxane film; S2: Attach a layer of conductive thermoplastic polyurethane rubber film to the polydimethylsiloxane film, and then cure it at high temperature; S3: The conductive thermoplastic polyurethane rubber film is laser-cut to process the required electrode and wire shapes; S4: Apply masking tape to the piezoresistive unit for protection; S5: Perform magnetron sputtering to sputter gold or platinum onto a conductive thermoplastic polyurethane rubber film; S6: Peel off the protective paper tape and the remaining conductive thermoplastic polyurethane rubber film except for the required electrodes and wires to obtain the intermediate layer. S7: Perform electrical breakdown; S8: Spin-coat an ultrathin layer of polydimethylsiloxane onto the first polydimethylsiloxane film and the intermediate layer, and cure it at high temperature; S9: Fabrication of the second polydimethylsiloxane film using a mold; S10: Spin-coat an ultrathin layer of polydimethylsiloxane onto the second polydimethylsiloxane film, attach the second polydimethylsiloxane and the sensor component prepared in steps S1-S9, and cure at high temperature; S11: The sensor edges are trimmed and made into curved surfaces. Polydimethylsiloxane is applied to the sensor edges and surfaces, cured at high temperature, and then encapsulated.

8. The method for fabricating a flexible sensor for eyelid pressure measurement according to claim 7, characterized in that, The preparation method further includes the following step between steps S1 and S2: Spin-coat an ultra-thin layer of polydimethylsiloxane.

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