Flexible optical pressure sensitive film, intracranial pressure optical fiber sensor and preparation method of intracranial pressure optical fiber sensor

Abstract

The invention provides a flexible optical pressure sensitive film, an intracranial pressure optical fiber sensor and a preparation method thereof. The intracranial pressure optical fiber sensor comprises a flexible optical pressure sensitive film, a sleeve and an optical fiber, the flexible optical pressure sensitive film is fixedly carried at the tail end of the sleeve, and the sleeve sleeves the end part of the optical fiber. The flexible optical pressure sensitive film comprises an elastomer material and a fluorescent dye doped in the elastomer material. The method comprises the following steps: dissolving a fluorescent dye in a solvent, then uniformly mixing with an elastomer material, removing the solvent and bubbles, and carrying out spin coating and drying to obtain the flexible optical pressure sensing film, and fixedly loading the sleeve on the end face of the optical fiber, fixedly loading the flexible optical pressure sensing film at the tail end of the sleeve, and carrying out sealing treatment to obtain the intracranial pressure optical fiber sensor. The intracranial pressure sensor is novel in structure and stable in performance, the double-layer hydrogel optical fiber is good in biocompatibility and flexibility and not prone to brittleness, damage to organisms is avoided even if the double-layer hydrogel optical fiber is broken, process conditions are mild, and large-scale production is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biomedical engineering and optical sensing technology, in particular to a flexible optical pressure sensitive film, an intracranial pressure optical fiber sensor and a preparation method thereof. BACKGROUND

[0002] In the diagnosis and treatment of traumatic brain injury, stroke and other nervous system diseases, real-time monitoring of key physiological and biochemical parameters is of great significance. Among them, intracranial pressure is an important parameter, and if it continues to increase, it will lead to brain tissue displacement, loss of brain function and other serious consequences.

[0003] At present, commercially available and literature reported intracranial pressure sensors, especially optical fiber based sensors, mostly rely on micro-nano processing technology (such as etching, coating, grating preparation, etc.), which has the problems of complex manufacturing process, high equipment dependence, high production cost, fragile structure, difficult packaging and other problems, and it is difficult to realize batch production and long-term stable implantation application.

[0004] The optical fiber used in the current intracranial pressure sensor cannot be bent well. For example, quartz glass optical fiber has the advantages of anti-electromagnetic interference, small volume, etc., but the preparation technology still has obvious problems. The traditional commercial optical fiber uses quartz glass as the matrix, and the preparation technology can be roughly divided into two categories: 1) surface modification type: the surface of the quartz optical fiber is first treated by hydroxylation and silanization, and then functional materials such as fluorescent molecules, quantum dots, gold / silver nanoparticles are fixed on the surface of the cladding layer by physical adsorption or chemical grafting. This method has many process steps, the functional layer is easy to fall off, the probe is difficult to reuse, and the sensing signal must rely on external analysis equipment such as spectrometer and photodetector, which is complex and high in cost. 2) Microstructure type: femtosecond laser etching or photolithography is used to write one-dimensional periodic microstructures such as fiber Bragg gratings (FBG) inside the quartz optical fiber, and the wavelength selective reflection / transmission of the microstructure is used to realize sensing. This scheme avoids the problem of surface functional material falling off, but the microstructure processing precision requirement is very high, the yield is low, and the cost is relatively high. Most importantly, the quartz glass optical fiber has strong rigidity and cannot be bent at a large angle, which can easily cause secondary damage to the tissues and organs during intracranial monitoring.

[0005] Therefore, a new type of intracranial pressure sensor is needed to adapt to the special environment in the intracranial and improve the measurement accuracy. SUMMARY

[0006] The present application aims to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present application is to provide an intracranial pressure optical fiber sensor with simple preparation process and low cost, which utilizes ordinary multimode optical fiber combined with flexible fluorescent film to construct a pressure sensitive structure through simple spin coating, curing or assembly, and can achieve high sensitivity and signal stability without micro-nano processing, significantly reducing the manufacturing cost and having good biocompatibility and clinical generalizability.

[0007] To achieve the above-mentioned purposes, the first aspect of the present application provides an intracranial pressure optical fiber sensor.

[0008] The intracranial pressure optical fiber sensor comprises a flexible optical pressure sensitive film, a sleeve and an optical fiber; wherein the flexible optical pressure sensitive film is fixed to one end of the sleeve, the other end of the sleeve is sleeved on the end of the optical fiber, and a closed cavity is formed between the three.

[0009] Optionally, the material of the flexible optical pressure sensitive film comprises fluorescent dye and elastomer material.

[0010] Further optionally, the fluorescent dye comprises N, N - di (octadecyl) - perylene - 3, 4, 9, 10 - tetracarboxylic acid bisimine.

[0011] Further optionally, the elastomer material comprises Ecoflex elastomer.

[0012] Optionally, the sleeve comprises a polyethylene sleeve.

[0013] Optionally, the optical fiber comprises an inner layer core and an outer layer cladding, wherein the inner layer core is cured by core monomer A, core monomer B, core monomer C and photoinitiator; the core monomer A comprises acrylamide, N-vinyl pyrrolidone or 2-hydroxyethyl methacrylamide, the core monomer B comprises polyethylene glycol diacrylate; the core monomer C comprises hydroxyethyl methacrylate, or comprises hydroxyethyl methacrylate and methyl methacrylate; the outer layer cladding is cured by low refractive index PEGDA hydrogel and photoinitiator, and the refractive index is lower than that of the inner layer core.

[0014] Further optionally, the diameter of the inner layer core is 50-600 μm, and the refractive index is 1.46-1.48; the thickness of the outer layer cladding is 20-100 μm, and the refractive index is 1.38-1.40.

[0015] The second aspect of the present application provides a preparation method of an intracranial pressure optical fiber sensor.

[0016] The method includes: dissolving a fluorescent dye in a solvent, then mixing it uniformly with an elastomer material, removing the solvent and air bubbles to obtain an intermediate product; spin-coating and drying the intermediate product to obtain a flexible optical pressure sensing film with uniform thickness; fixing a sleeve to the end face of an optical fiber, fixing the flexible optical pressure sensing film to the end of the sleeve, and sealing it to obtain an intracranial pressure fiber optic sensor.

[0017] A third aspect of the present invention provides a flexible optical pressure-sensitive membrane.

[0018] The flexible optical pressure-sensitive film includes an elastomer material and a fluorescent dye doped in the elastomer material.

[0019] The fourth aspect of this invention provides a method for preparing a flexible optical pressure-sensitive film.

[0020] The method includes: dissolving a fluorescent dye in a solvent, then mixing it evenly with an elastomer material, removing the solvent and air bubbles to obtain an intermediate product; and spin-coating and drying the intermediate product to obtain a flexible optical pressure sensing film with uniform thickness.

[0021] The fifth aspect of this invention provides a fluorescent dye.

[0022] The fluorescent dye is N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine, with the following structural formula: .

[0023] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: (1) The intracranial pressure sensor of the present invention is a novel structure with excellent stability. Compared with traditional fiber optic pressure sensors that rely on micro-nano fabrication, the present invention has a simple structure and a mild fabrication process. It does not require grating etching, vacuum coating, or precision microcavity fabrication. It can be fabricated simply by assembling ordinary multimode optical fiber and flexible fluorescent / reflective film, resulting in low manufacturing cost and high process repeatability. The probe diameter is less than 3 mm, and the flexible encapsulation material (such as PDMS, Ecoflex, or SEBS) has excellent biocompatibility and mechanical compliance, which can adapt to micro-deformation of brain tissue and reduce implantation trauma. The sensing signal is based on changes in light intensity or interference, and has high sensitivity, fast response, and anti-electromagnetic interference capability. The signal drift is small and the stability is excellent. The device adopts a modular fiber bundle design, which can realize reliable optical coupling and long-term monitoring. At the same time, it has the potential for mass production and single use, providing a low-cost, flexible, and clinically applicable practical solution for dynamic intracranial pressure monitoring.

[0024] (2) This invention, by designing a double-layer structure with a core refractive index greater than that of the cladding, ensures that total internal reflection is met when light propagates in the optical fiber, effectively reducing light transmission loss and improving light transmission efficiency. The preparation method is simple and easy to implement, with mild process conditions, facilitating large-scale production. Furthermore, the selected hydrogel material has good biocompatibility and flexibility, making the double-layer hydrogel optical fiber biocompatible, flexible, and not easily brittle. Even if it breaks, it will not cause harm to the organism, making it suitable for sensitive detection of parameters such as intracranial pressure and long-term monitoring of the brain tissue microenvironment. Attached Figure Description

[0025] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 A schematic diagram of the synthesis route of the intracranial pressure fluorescent dye of the present invention is shown.

[0026] Figure 2 A schematic diagram of the intracranial pressure fiber optic sensor of the present invention is shown.

[0027] Figure 3 The performance test diagram of the intracranial pressure fiber optic sensor of the present invention is shown.

[0028] Explanation of key figure labels: 1-Flexible optical pressure-sensitive membrane, 2-Sheath, 3-Fiber optic cable, 4-Cavity, F-Intracranial pressure. Detailed Implementation

[0029] In the following sections, the flexible optical pressure-sensitive membrane, intracranial pressure fiber optic sensor, and their fabrication method of the present invention will be described in detail with reference to exemplary embodiments.

[0030] Exemplary Example 1 This exemplary embodiment provides a flexible optical pressure-sensitive membrane that can be used to fabricate an intracranial pressure sensor.

[0031] The flexible optical pressure-sensitive film includes an elastomer material and a fluorescent dye doped in the elastomer material.

[0032] In this embodiment, the mass ratio of the elastomer material to the fluorescent dye is 400:1 to 100:1, for example, 380:1, 300:1, 200:1, 150:1, 110:1, etc.

[0033] In this embodiment, the thickness of the flexible optical pressure-sensitive film is 100~200 μm, such as 110, 150, 180 μm, etc.

[0034] In this embodiment, the fluorescent dye comprises N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine, with the following structural formula: .

[0035] In this embodiment, the elastomer material includes Ecoflex elastomer.

[0036] Exemplary Example 2 Based on Exemplary Example 1, the synthetic route for N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine is as follows: Figure 1 As shown, its specific preparation process includes: (1) Mix perylene-3,4,9,10-tetracarboxylic acid dianhydride, n-octadecylamine and imidazole, reflux, and cool to room temperature to obtain a reaction mixture.

[0037] (2) Disperse the reaction mixture in a polar solvent and add a solution that can form a salt with imidazole, stir, filter to obtain a solid, wash, dry, and obtain N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine (PDI).

[0038] In this embodiment, in step (1), the molar ratio of perylene-3,4,9,10-tetracarboxylic dianhydride and n-octadecylamine is at least 1:2 (n-octadecylamine can be in excess). It should be noted that at least 1:2 means that n-octadecylamine should be ≥2 in the ratio, such as 1:2.5, 1:3, etc. Imidazole is used as a solvent, and there is no specific requirement for the amount used; it is sufficient to dissolve perylene-3,4,9,10-tetracarboxylic dianhydride and n-octadecylamine.

[0039] The reflux temperature is the boiling point of imidazole (°C), and the reflux time is sufficient for complete reaction. Alternatively, the reflux time can be determined by thin-layer chromatography to confirm the completeness of the reaction.

[0040] In this embodiment, in step (2), the polar solvent may include polar solvents such as ethanol, methanol, acetonitrile, and isopropanol, for example, ethanol.

[0041] The solution that can form a salt with imidazole should be in excess to ensure that the imidazole is removed. Solutions that can form a salt with imidazole include: HCl solution, sodium bisulfate, trifluoroacetic acid, etc.

[0042] The drying process may include vacuum drying, for example, vacuum drying at room temperature to 110°C. Furthermore, in cases where the properties of the substance are uncertain, drying at temperatures below 60°C may be used to minimize the risk of deterioration.

[0043] As a specific example of the present invention, the preparation process may include: adding perylene-3,4,9,10-tetracarboxylic acid dianhydride (0.784 g, 2 mmol), n-octadecylamine (1.078 g, 4 mmol), and imidazole (4 g) to a 100 mL round-bottom flask, refluxing at 140°C for 3 hours, cooling to room temperature, dispersing the reaction mixture in 100 mL of ethanol, adding 300 mL of 2 M HCl, stirring overnight, filtering the resulting solid, thoroughly washing with distilled water, and drying the collected solid under vacuum at 100°C to finally obtain N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine (PDI).

[0044] Exemplary Example 3 This exemplary embodiment provides a method for preparing a flexible optical pressure-sensitive film.

[0045] The method includes: A. Dissolve the fluorescent dye in a solvent, then mix it evenly with the elastomer material, remove the solvent and air bubbles, and obtain the intermediate product; B. Spin-coating and drying the intermediate product yields a flexible optical pressure sensing film with uniform thickness.

[0046] In this embodiment, the fluorescent dye and elastomer material in step A are the same as those in exemplary embodiment 1.

[0047] Solvents may include dichloromethane.

[0048] Methods for removing solvents and bubbles may include vacuuming.

[0049] In this embodiment, spin coating and drying in step B are conventional methods in the art, which are clear to those skilled in the art, and will not be described in detail here.

[0050] Exemplary Example 4 This exemplary embodiment provides an intracranial pressure fiber optic sensor.

[0051] like Figure 2 As shown, the sensor may include a flexible optical pressure-sensitive membrane 1, a sleeve 2, and an optical fiber 3. Figure 2 In this context, F represents intracranial pressure.

[0052] The membrane is encapsulated at the end of the sleeve 2 and coupled to the optical fiber 3. Specifically, the flexible optical pressure-sensitive membrane 1 is fixed to one end of the sleeve 2, and the other end of the sleeve 2 is fixed to the end of the optical fiber 3, forming a sealed cavity 4 between the three. Local pressure changes will cause the membrane to deform, thereby changing the fluorescence signal and realizing real-time monitoring of intracranial pressure.

[0053] In this embodiment, the flexible optical pressure-sensitive membrane 1 is the same as that in exemplary embodiment 1 or 2.

[0054] In this embodiment, the sleeve 2 includes polyethylene sleeve, polytetrafluoroethylene, polyimide, silicone rubber, PVC, polyurethane, etc. The inner diameter of the sleeve 2 is 1-3 mm.

[0055] In this embodiment, the fixation between the flexible optical pressure-sensitive membrane 1 and the sleeve 2 can be achieved through encapsulation. The fixation between the optical fiber 3 and the sleeve 2 can be achieved through biocompatible adhesive.

[0056] In this embodiment, the optical fiber can be a quartz optical fiber, a plastic optical fiber, a PDMS optical fiber, a hydrogel optical fiber, or a composite material thereof. Composite materials refer to optical fibers that are combined with other materials, such as quartz-nanomaterial composites, PDMS-inorganic material composites, etc.

[0057] Figure 3 The performance test results of the intracranial pressure fiber optic sensor are shown in the following figures: (a) The fluorescence spectrum of the intracranial pressure sensor changes under different pressure environments; (b) The fitting relationship between the fluorescence intensity of the intracranial pressure sensor at 575 nm and temperature; (c) The reversibility of the intracranial pressure sensor; (d) The selectivity of the intracranial pressure sensor to different interfering substances; (e) The pH stability of the intracranial pressure sensor; and (f) The temperature stability of the intracranial pressure sensor. The intracranial pressure fiber optic sensor of this invention has an excitation wavelength of 450 nm, and its emitted fluorescence is in the range of 500-850 nm, with a maximum emission wavelength of 635 nm. The fluorescence intensity of the sensor increases with increasing external pressure. The fluorescence intensity at 635 nm exhibits a non-linear relationship with temperature, with a coefficient of 0.99. This sensor demonstrates excellent continuous temperature monitoring capability, and its fluorescence is unaffected by other substances in the cerebrospinal fluid or temperature interference.

[0058] In this embodiment, the height of cavity 4 can be between 0.5 and 2 mm.

[0059] Exemplary Example 5 Based on Exemplary Example 4, the optical fiber is a double-layer hydrogel optical fiber, and the intracranial pressure sensor is an intracranial pressure double-layer hydrogel optical fiber sensor. The double-layer hydrogel optical fiber includes an inner core and an outer cladding.

[0060] In this embodiment, the inner core is formed by curing core monomer A, core monomer B, core monomer C, and a photoinitiator. Based on a total mass fraction of 100 parts, core monomer A comprises 20-50 parts, core monomer B comprises 10-40 parts, and core monomer C comprises 10-60 parts. The photoinitiator accounts for 0.2%-1% of the total mass of core monomers A, B, and C. When the photoinitiator content is <0.2%, the double bond conversion rate is <85%, and the mechanical strength decreases; when the photoinitiator content is >1%, residual photoinitiator will reduce cell viability.

[0061] The core monomer A includes acrylamide (AAm), N-vinylpyrrolidone (NVP), or 2-hydroxyethylmethacrylamide (HEMAAm). When core monomer A is AAM, its mass fraction is 20-50 parts. When AAM < 20 parts, the polymerization rate decreases, and the core strength is < 80 kPa. When AAM > 50 parts, brittleness increases, and the elongation at break is < 150%. When core monomer A is NVP, its mass fraction is 30-50 parts. When core monomer A is HEMAAm, its mass fraction is 20-50 parts. NVP and HEMAAm maintain high hydrophilicity and biocompatibility.

[0062] The fiber core monomer B includes polyethylene glycol diacrylate (PEGDA). When Mn < 400, the crosslinking density is too high, leading to an increase in the fiber core refractive index but a modulus > 300 kPa and decreased flexibility; when Mn > 1000, the refractive index < 1.45, resulting in insufficient Δn. Mn is the number-average molecular weight, and raw materials within the range of 400-1000 can be used.

[0063] The core monomer C includes hydroxyethyl methacrylate (HEMA), or a mixture of hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA). When the core monomer C is HEMA, its mass fraction is 10-60 parts; when it is a mixture of HEMA and MMA, the mass fraction of MMA is 5-15 parts, with the remainder being HEMA. 5-15 parts of MMA can increase the refractive index, but it needs to be controlled to ≤15 parts to maintain hydrophilicity. If it exceeds 15 parts, hydrophobicity increases, and the water content becomes less than 40%, affecting subsequent performance.

[0064] Photoinitiators may include: 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone IRGACURE 2959 or water-soluble phenyl-2,4,6-trimethylbenzoyl lithium phosphinate LAP, etc.

[0065] In this embodiment, the water content of the inner fiber core is 40-55% to meet the total internal reflection requirements. The inner fiber core achieves a water content of 40%-55% through a combination of acrylamide and other hydrophilic monomers, satisfying both flexibility and hydrophilicity requirements.

[0066] In this embodiment, the outer cladding is formed by curing a low-refractive-index PEGDA hydrogel and a photoinitiator, with a refractive index lower than that of the inner fiber core. The mass ratio of PEGDA hydrogel to photoinitiator is 400~100:1. Unless otherwise specified, all solvents used in the hydrogel optical fiber are ultrapure water. The photoinitiator can be the same as those described above.

[0067] In this embodiment, the PEGDA in the outer cladding layer can form a network structure with high cross-linking density, which restricts water molecule penetration, maintains low refractive index and good mechanical protection.

[0068] In this embodiment, the inner fiber core (high refractive index layer) has a refractive index of 1.46~1.48, a water content of 40~55%, a tensile modulus of 80~300 kPa, and an optical loss ≤0.2 dB cm⁻¹. -1 The core diameter can be 50~600μm. If it is <50 µm, the probe loading is insufficient, resulting in a signal-to-background ratio <3. When it is >600 μm, the central oxygen inhibition is severe, resulting in an uncured soft core.

[0069] The outer cladding (low refractive index layer) has a refractive index of 1.38–1.40 and a swelling rate in water of <15%. The cladding thickness can be 20–100 µm. When it is <20 µm, mechanical protection is insufficient, the lateral tearing force is <0.1 N, and the protection of the core layer is lost. When it is >100 µm, the overall stiffness of the optical fiber increases, which can easily induce an increase in inflammatory response.

[0070] The core refractive index of the bilayer hydrogel fiber is greater than that of the cladding, satisfying the total internal reflection condition and making it suitable for high-sensitivity fluorescence sensing. The refractive index Δn is 0.06~0.10. If Δn < 0.06, the numerical aperture NA < 0.3 and the bending loss > 1 dB (bending radius 5 mm). If Δn > 0.10, the cladding water content < 25%, which will reduce the probe diffusion coefficient.

[0071] In this embodiment, the method for preparing the bilayer hydrogel optical fiber includes: S1. Prepare a core prepolymer solution by mixing core monomers A, B, and C with a photoinitiator. Inject the core prepolymer solution into a capillary mold and cure it by irradiation with ultraviolet light (200~400 nm). After photocrosslinking and curing, remove the prepolymer from the mold to form the core. The curing time can be 1~8 min. For core diameters of 50~600 µm, simply change the capillary mold. When the diameter is >400 µm, add 0.05 wt% hydroquinone (HQ) to the prepolymer solution to inhibit oxygen inhibition and ensure sufficient central curing.

[0072] Alternatively, a certain amount of water (such as high-purity water) can be added during the preparation of the fiber core prepolymer solution, so that the fiber core prepolymer solution contains a certain amount of water, and ultimately the water content of the inner core of the hydrogel fiber is 40~55%, which satisfies the total internal reflection adjustment.

[0073] Alternatively, water may not be added during the preparation of the fiber core prepolymer solution. In the subsequent step S2, the hydrogel fiber core will absorb water, ultimately resulting in a water content of 40-55% in the inner core of the hydrogel optical fiber.

[0074] S2. The obtained hydrogel fiber core is placed in the hydrogel precursor solution (i.e., the outer prepolymer solution), and its surface is treated using an immersion pulling process. After the pulling process, the hydrogel fiber core is straightened and hung vertically, and then irradiated under a UV lamp again to solidify the hydrogel precursor solution on the surface of the hydrogel fiber core, forming a cladding layer with a thickness of 20~100 µm, thus obtaining a hydrogel optical fiber. The hydrogel optical fiber consists of a core and a cladding layer, has a double-layer structure, and is cylindrical. The pulling speed is 10~50 mm / min. -1 The viscosity is controlled in conjunction with the viscosity, which ranges from 80 to 300 mPa·s. The PEGDA content in the outer prepolymer solution is 40% wt% to 60 wt%, which helps to form a network structure with high cross-linking density, restricts water molecule penetration, keeps the water content below 15%, maintains a low refractive index, and provides good mechanical protection. The mass ratio of PEGDA hydrogel to photoinitiator is 400 to 100:1. The solvent in the solution is water, such as ultrapure water. Unless otherwise specified, ultrapure water can be used as the solvent in hydrogel optical fibers.

[0075] Alternatively, the hydrogel core can be left to stand in the solution before the lifting operation, for example, for 10 seconds, to aid wetting and degassing.

[0076] To better understand the above preparation method, a specific preparation example is provided below.

[0077] (1) Core preparation: The core prepolymer solution was prepared according to the following mass percentages: Aam: 40%, PEGDA (Mn = 700): 30%, HEMA: 30%, photoinitiator (Irgacure 2959): 0.5%. Among them, the 0.5% photoinitiator refers to 0.5 wt% of the total mass of the three monomers.

[0078] The above solution was injected into a capillary mold with an inner diameter of 0.2 mm, irradiated with 365 nm ultraviolet light for 3 min to cure, and then removed to form a fiber core.

[0079] (2) Cladding preparation: The fiber core is immersed in the outer prepolymer solution (PEGDA 1000, 50 wt%, containing 0.5% photoinitiator), and its surface is treated by dip-coating process. Then it is hung and irradiated with 365 nm ultraviolet light for 1 min 30 s to form a cladding layer with a thickness of about 0.03 mm.

[0080] Exemplary Example 6 This exemplary embodiment provides a method for fabricating an intracranial pressure fiber optic sensor.

[0081] The method includes: dissolving a fluorescent dye in a solvent, then mixing it uniformly with an elastomer material, removing the solvent and air bubbles to obtain an intermediate product; spin-coating and drying the intermediate product to obtain a flexible optical pressure sensing film with uniform thickness; fixing a sleeve to the end face of an optical fiber, fixing the pressure sensing film to the end of the sleeve, and sealing it to finally obtain a fiber optic pressure sensor.

[0082] As a specific example of the present invention, the fabrication process of the intracranial pressure fiber optic sensor intracranial pressure sensing module may include: dissolving the synthesized fluorescent dye PDI in dichloromethane, then mixing it uniformly with Ecoflex 10, and removing the dichloromethane and air bubbles by vacuuming. A flexible optical pressure sensing film of uniform thickness is obtained by spin coating and drying. A polypropylene sleeve with a diameter of 1-3 mm is fixed to the end face of the optical fiber, and then the pressure sensing film is fixed to the end of the sleeve, followed by sealing, ultimately obtaining the fiber optic optical pressure sensor.

[0083] The sealing process includes: after covering the fiber end face or the top of the cavity with a cured fluorescent silicone film and inserting its edge into the inner wall of the sleeve, uniformly coating a small amount of uncured silicone (such as PDMS, Ecoflex or medical silicone colloid) at the contact interface, applying slight pressure to remove air bubbles, and then curing at room temperature or 40–60 ℃ for 1–2 h to form a continuous sealing connection layer.

[0084] Exemplary Example 7 This exemplary embodiment provides a fluorescent dye, which may be the same as that in Exemplary Embodiment 1. For example, the fluorescent dye is N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine, with the following structural formula: .

[0085] In this embodiment, the preparation process of the fluorescent dye can be the same as that in Exemplary Embodiment 2.

[0086] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. An intracranial pressure fiber optic sensor, characterized in that, include: The flexible optical pressure-sensitive membrane, the sleeve, and the optical fiber are arranged together. The flexible optical pressure-sensitive membrane is fixed to one end of the sleeve, and the other end of the sleeve is fitted onto the end of the optical fiber, forming a closed cavity between the three components.

2. The intracranial pressure fiber optic sensor according to claim 1, characterized in that, The flexible optical pressure-sensitive membrane is made of fluorescent dyes and elastomer materials.

3. The intracranial pressure fiber optic sensor according to claim 2, characterized in that, The fluorescent dye comprises N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine.

4. The intracranial pressure fiber optic sensor according to claim 2, characterized in that, The elastomer material includes Ecoflex elastomer.

5. The intracranial pressure fiber optic sensor according to claim 1, characterized in that, The optical fiber comprises an inner core and an outer cladding, wherein, The inner core is formed by curing core monomer A, core monomer B, core monomer C and a photoinitiator; core monomer A includes acrylamide, N-vinylpyrrolidone or 2-hydroxyethylmethacrylamide, core monomer B includes polyethylene glycol diacrylate; core monomer C includes hydroxyethyl methacrylate, or includes hydroxyethyl methacrylate and methyl methacrylate. The outer cladding is formed by curing low-refractive-index PEGDA hydrogel and photoinitiator, and its refractive index is lower than that of the inner fiber core.

6. The intracranial pressure fiber optic sensor according to claim 5, characterized in that, The inner core has a diameter of 50-600 μm and a refractive index of 1.46-1.48; the outer cladding has a thickness of 20-100 µm and a refractive index of 1.38-1.

40.

7. A method for fabricating an intracranial pressure fiber optic sensor, characterized in that, The method includes: Fluorescent dyes are dissolved in a solvent and then mixed evenly with an elastomer material. The solvent and air bubbles are removed to obtain an intermediate product. The intermediate product is then spin-coated and dried to obtain a flexible optical pressure sensing film with uniform thickness. A sleeve is fixed to the end face of the optical fiber, and a flexible optical pressure sensing membrane is fixed to the end of the sleeve. After sealing, an intracranial pressure fiber optic sensor is obtained.

8. A flexible optical pressure-sensitive membrane, characterized in that, This includes elastomer materials and fluorescent dyes doped in elastomer materials.

9. A method for preparing a flexible optical pressure-sensitive film, characterized in that, The method includes: Fluorescent dyes are dissolved in a solvent and then mixed evenly with an elastomer material. The solvent and air bubbles are removed to obtain an intermediate product. The intermediate product is then spin-coated and dried to obtain a flexible optical pressure sensing film with uniform thickness.

10. A fluorescent dye, characterized in that, The fluorescent dye is N,N-bis(octadecyl)-perylene-3,4,9,10-tetracarboxylic acid diimine, with the following structural formula: 。

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