Fabry-perot cavity optical fiber pressure sensor based on peg hydrogel pressure sensitive membrane

Abstract

The utility model discloses a high sensitivity and long -term stable based on PEG hydrogel pressure sensitive diaphragm's Fabry -Perot cavity optical fiber pressure sensor, including base, pressure sensitive diaphragm and optical fiber, pressure sensitive diaphragm is PEGDA / sodium alginate double network interpenetrating structure, including, first network layer is formed by polyethylene glycol diacrylate crosslinking;Second network layer is formed by sodium alginate and calcium ion crosslinking, and it is through first network layer. Adopt PEG hydrogel to replace traditional rigid material, through the light polymerization and crosslinking control technology preparation high elasticity, the pressure sensitive diaphragm 20 of fatigue resistance, this double network + surface modified structure makes hydrogel in blood swelling rate <5%, 37 under the elasticity modulus retention rate >95%, stability is high, is applicable to cardiovascular, intracranial pressure etc. and needs high -precision dynamic monitoring's implantation scene, and PEG raw material price is low, is favorable to the control cost.

Description

Technical Field

[0001] This utility model relates to the field of medical sensors, specifically to a Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane. Background Technology

[0002] With the rapid development of implantable medical devices, fiber optic pressure sensors, with their advantages of small size and good biocompatibility, can be implanted inside the human body to achieve real-time and accurate measurement of physiological parameters such as blood pressure, intracranial pressure, and lung pressure, providing important information for disease diagnosis and treatment. The Fabry-Perot cavity fiber optic pressure sensor is a high-precision pressure measurement device based on the Fabry-Perot interferometry principle. In existing technologies, the pressure-sensitive diaphragm is generally made of silicon or metal. However, the elastic modulus of silicon or metal diaphragms (>100 GPa) is much higher than that of human soft tissue (0.1-10 MPa), leading to pressure transmission distortion. Traditional flexible diaphragms (such as PDMS) are easily affected by temperature and deformation hysteresis, resulting in insufficient long-term stability. Utility Model Content

[0003] The purpose of this invention is to provide a highly sensitive and long-term stable fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane with a Fabry-Perot cavity.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive diaphragm, comprising a base, a pressure-sensitive diaphragm, and an optical fiber, wherein the pressure-sensitive diaphragm is a PEGDA / sodium alginate dual-network interpenetrating structure, comprising,

[0005] The first network layer is formed by crosslinking polyethylene glycol diacrylate;

[0006] The second network layer, formed by the cross-linking of sodium alginate and calcium ions, runs through the first network layer.

[0007] Furthermore, the thickness of the first network layer is 10–50 μm.

[0008] Furthermore, the aperture of the first network layer is 20–200 nm, and the second network layer fills the aperture to form a through-hole structure.

[0009] Furthermore, the elastic modulus of the pressure-sensitive diaphragm is 0.1–1 MPa.

[0010] Furthermore, a cavity is provided on the base, and a pressure-sensitive diaphragm is placed over the opening of the cavity to form an FP cavity. Reflective films are correspondingly provided on the two end faces of the FP cavity.

[0011] Furthermore, the thickness of the reflective film is 5–100 nm.

[0012] The outer surface of the sensor is coated with a HEMA / ε-polylysine composite coating.

[0013] Furthermore, the base includes a first substrate and a second substrate. A first through hole is provided on the first substrate. The first through hole, together with the surface of the second substrate and the surface of the pressure-sensitive film, forms an FP cavity. A reflective film is disposed in the FP cavity on the surface of the pressure-sensitive film and the surface of the second substrate.

[0014] Furthermore, an optical fiber sleeve is disposed on the second substrate, and the inner cavity of the optical fiber sleeve and the surface of the second substrate form an optical fiber mounting part. The FP cavity and the optical fiber mounting part are coaxially arranged and spaced apart along the axial direction of the optical fiber.

[0015] In the above scheme, PEG hydrogel is used to replace traditional rigid materials. A highly elastic and fatigue-resistant pressure-sensitive membrane 20 is prepared by photopolymerization and cross-linking control technology. This dual-network + surface modification structure makes the hydrogel have a swelling rate of <5% in blood and an elastic modulus retention rate of >95% at 37°C. It has high stability and is suitable for implantation scenarios that require high-precision dynamic monitoring, such as cardiovascular and intracranial pressure. Moreover, the price of PEG raw materials is low, which helps to control costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a Fabry-Perot cavity fiber optic pressure sensor;

[0017] Figure 2 for Figure 1 Schematic diagram of the middle section. Detailed Implementation

[0018] The working principle of a Fabry-Perot (FP) cavity fiber optic pressure sensor is as follows: A stable light source emits a light beam, which is transmitted through an optical fiber to the FP cavity of the sensor. The beam undergoes multiple reflections within the FP cavity, producing interference. The resulting interference pattern depends on the cavity length. External pressure is applied to an elastic diaphragm, causing the diaphragm to deform and thus changing the length of the FP cavity. As the cavity length changes, the characteristics of the interference pattern also change, such as the phase change of the interference fringes. A spectral analyzer or other suitable detection device is used to capture and analyze the phase change of the interference pattern, and after signal processing, the actual pressure value is obtained. Finally, the sensor outputs the detected pressure information in the form of a digital or analog signal for the user to read or further process.

[0019] Below, in conjunction with Figure 1 , Figure 2 The present invention will be described in detail.

[0020] A Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive diaphragm includes a base 10, a pressure-sensitive diaphragm 20, and an optical fiber 30. The pressure-sensitive diaphragm 20 is a PEGDA / sodium alginate dual-network interpenetrating structure.

[0021] The first network layer is formed by crosslinking polyethylene glycol diacrylate;

[0022] The second network layer, formed by the cross-linking of sodium alginate and calcium ions, runs through the first network layer.

[0023] PEGDA can form a network structure with a certain rigidity through photo-initiated or thermal-initiated crosslinking, providing basic mechanical support for the membrane; sodium alginate crosslinks in the presence of divalent cations such as calcium ions, forming a soft and elastic network; the two networks interpenetrate and work synergistically, giving the pressure-sensitive membrane 20 both high strength and good toughness.

[0024] In terms of sensitivity: The PEGDA network in the dual-network structure has good elastic recovery ability, which can deform rapidly under pressure and quickly return to its original shape after the pressure is released. The sodium alginate network can further enhance the membrane's response to pressure. Through the synergistic effect of the two networks, the pressure-sensitive membrane can produce significant optical signal changes even in the face of small pressure changes, thereby achieving highly sensitive pressure detection.

[0025] In terms of biocompatibility: The pressure-sensitive membrane formed by the dual network cross-linking of PEGDA and sodium alginate has no toxic side effects on biological tissues and will not cause immune or inflammatory reactions, making it suitable for use in biological bodies or in applications that come into direct contact with biological tissues.

[0026] In terms of stability: The pressure-sensitive membrane formed by the dual-network crosslinking of PEGDA and sodium alginate exhibits good stability under certain chemical environments. The PEGDA network can resist the erosion of some organic solvents and chemicals, while the sodium alginate network remains relatively stable under physiological conditions. This allows the pressure-sensitive membrane to maintain its performance stability in different application environments, extending its service life.

[0027] This invention uses PEG hydrogel to replace traditional rigid materials. A highly elastic and fatigue-resistant pressure-sensitive membrane 20 is prepared through photopolymerization and cross-linking control technology. This dual-network + surface-modified structure makes the hydrogel have a swelling rate of <5% in blood and an elastic modulus retention rate of >95% at 37°C. It has strong stability and is suitable for implantation scenarios that require high-precision dynamic monitoring, such as cardiovascular and intracranial pressure. Moreover, the price of PEG raw materials is low, which helps to control costs.

[0028] Taking into account factors such as the sensor's pressure range, sensitivity requirements, material properties, and manufacturing process, the thickness of the first network layer is 10–50 μm. In the Fabry-Perot cavity structure, the thickness of the pressure-sensitive diaphragm 20 has a significant impact on the sensor's sensitivity and dynamic response. A thickness of 10–50 μm ensures that the diaphragm has sufficient mechanical strength while maintaining high sensitivity. For example, a thickness less than 10 μm may be unable to withstand changes in physiological pressure, while a thickness exceeding 50 μm may lead to a sluggish response.

[0029] Furthermore, the pore size of the first network layer is 20-200 nm, and the second network layer fills the pore size to form a through-type structure, which not only helps the second network (sodium alginate) to penetrate and cross-link, but also regulates the swelling behavior and mechanical properties to a certain extent.

[0030] Furthermore, the elastic modulus of the pressure-sensitive diaphragm 20 is 0.1 to 1 MPa, which increases the pressure sensitivity of the pressure-sensitive diaphragm 20 by 2 to 3 times.

[0031] A cavity is provided on the base 10, and a pressure-sensitive diaphragm 20 is placed over the opening of the cavity to form an FP cavity. Reflective films 40 are provided on the two end faces of the FP cavity to reduce light loss and improve the stability of the interference signal.

[0032] Furthermore, the thickness of the reflective film 40 is 5–100 nm. The thickness of the reflective film 40 typically affects the reflectivity and interference effect. In the visible light band, a reflective film thickness of 5–100 nm made of metal (such as gold or silver) or a high refractive index medium can achieve a high reflectivity. For example, a gold film with a thickness of 40–80 nm is often used in FP interference structures, exhibiting good reflectivity and mechanical stability.

[0033] The outer surface of the sensor is coated with a HEMA / ε-polylysine composite coating to form a surface resistant to biofouling.

[0034] The base 10 includes a first substrate 11 and a second substrate 12. A first through-hole 111 is provided on the first substrate 11. The first through-hole 111, together with the surface of the second substrate 12 and the surface of the pressure-sensitive diaphragm 20, forms an FP cavity. A reflective film 40 is disposed on the surface of the pressure-sensitive diaphragm 20 and the surface of the second substrate 12 within the FP cavity. The base 10 is encapsulated as a whole from multiple substrates using bonding technology. The first substrate 11, where the first through-hole 111 is to be provided, is treated as a separate substrate, on which the through-hole 111 is processed. Since the first through-holes 111 are all through-holes, surface unevenness caused by wet etching or ion etching methods is avoided, thereby ensuring high flatness of the reflective film on the end face of the FP cavity and high sensor accuracy. Simultaneously, the sensors exhibit high consistency, ensuring stable performance of sensors from the same batch.

[0035] To fix the optical fiber 30, an optical fiber sleeve 50 is provided on the second substrate 12. The inner cavity of the optical fiber sleeve 50 and the surface of the second substrate 12 form an optical fiber mounting part. The FP cavity and the optical fiber mounting part are coaxially arranged and spaced apart along the axis of the optical fiber 30. The end of the optical fiber 30 abuts against the base 50. The base 50 has a high surface flatness, which reduces the deviation generated during optical signal reception and reduces the impact of signal loss.

Claims

1. A Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive diaphragm, comprising a base (10), a pressure-sensitive diaphragm (20), and an optical fiber (30), characterized in that: The pressure-sensitive membrane (20) is a PEGDA / sodium alginate double-network interpenetrating structure, comprising, The first network layer is formed by crosslinking polyethylene glycol diacrylate; The second network layer, formed by the cross-linking of sodium alginate and calcium ions, runs through the first network layer.

2. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 1, characterized in that: The thickness of the first network layer is 10–50 μm.

3. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 1, characterized in that: The aperture of the first network layer is 20–200 nm, and the second network layer fills the aperture to form a through-hole structure.

4. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 1, characterized in that: The elastic modulus of the pressure-sensitive diaphragm (20) is 0.1 to 1 MPa.

5. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 1, characterized in that: A recessed cavity is provided on the base (10), and a pressure-sensitive diaphragm (20) is placed on the opening of the recessed cavity to form an FP cavity. A reflective membrane (40) is provided on the two end faces of the FP cavity.

6. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 1, characterized in that: The thickness of the reflective film (40) is 5–100 nm.

7. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 1, characterized in that: The outer surface of the sensor is coated with a HEMA / ε-polylysine composite coating.

8. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 5, characterized in that: The base (10) includes a first substrate (11) and a second substrate (12). A first through hole (111) is provided on the first substrate (11). The first through hole (111), the surface of the second substrate (12), and the surface of the pressure-sensitive film (20) together form an FP cavity. A reflective film (40) is disposed on the surface of the pressure-sensitive film (20) and the surface of the second substrate (12) in the FP cavity.

9. The Fabry-Perot cavity fiber optic pressure sensor based on a PEG hydrogel pressure-sensitive membrane according to claim 8, characterized in that: A fiber optic sleeve (50) is provided on the second substrate (12). The inner cavity of the fiber optic sleeve (50) and the surface of the second substrate (12) form a fiber optic mounting part. The FP cavity and the fiber optic mounting part are coaxially arranged and spaced apart along the axial direction of the fiber (30).

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