Medical composite film material and endoscope-assisted water bag

Abstract

This invention belongs to the field of medical device technology and discloses a medical composite film material and its application in endoscopic water balloons. The material comprises a stacked acoustic matching layer and an optical polarization composite layer: the acoustic matching layer consists of a transparent elastomer matrix and hollow spherical fillers, with an equivalent acoustic impedance of 1.50-1.60 MNayl; the optical polarization composite layer includes laminated linear polarization elements and quarter-wave plate elements, possessing a deployable wrinkled structure, maintaining a phase retardation deviation of less than ±15% and an extinction ratio greater than 8:1 under biaxial tensile strain not exceeding 8%. This material achieves efficient ultrasonic coupling and optical polarization extinction simultaneously through layered functional separation and microscopic wrinkle deformation compensation mechanisms, solving the technical problems of acoustic-optical functional conflict and optical performance degradation under flexible deformation in traditional materials. It is suitable for preparing ultrasonic endoscopic auxiliary water balloons, improving diagnostic accuracy and clinical operational convenience.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to ultrasound endoscopic probe technology. Background Technology

[0002] Endoscopic ultrasound (EUS) is an advanced medical diagnostic tool that combines endoscopic and ultrasound imaging technologies. It allows physicians to generate detailed images of the digestive tract wall and surrounding structures using high-frequency ultrasound waves while performing an endoscopic examination. EUS plays a vital role in gastroenterology and oncology, particularly in assessing digestive system diseases, guiding biopsies, and planning treatment.

[0003] In recent years, with the rapid development of digestive endoscopy technology, various lesions, including raised, flat, and depressed lesions in the digestive and respiratory tracts, have been discovered. To determine the nature and depth of these lesions, endoscopic ultrasound (EUS) technology has been widely used, providing a more scientific basis for treatment planning. However, an air gap exists between the EUS instrument and the mucosa, causing ultrasound waves to be poorly transmitted and absorbed in the air, resulting in ineffective reflected images. Therefore, clean water is required as a medium to obtain clear images. However, during diagnosis and treatment, difficulties in storing water, interference from secretions, and intolerance to conventional EUS examinations often prevent doctors from effectively completing the examination, and there is even a risk of suffocation. With the development of EUS technology, water balloons have been introduced, solving some of the operational and diagnostic challenges of EUS.

[0004] However, existing water bladder structures still have the following problems:

[0005] 1. The stability of the water sac structure itself: In actual operation, the water sac structure is placed on the surface of human organs. Due to the fluidity of water and the spherical shape of the sac, its stability is not good. During ultrasound observation, even slight vibrations may cause the entire image to be unclear.

[0006] 2. The water bladder structure itself is not transparent enough. When observing a typical water bladder structure, the material of the water bladder structure causes a fog-like effect, which may make it difficult to observe the details of some structural mechanisms.

[0007] 3. During in vivo observations, such as gastroscopy and colonoscopy, the presence of human mucosa causes reflective phenomena, and the presence of mucosal bubbles makes the overall observation of human mucosa unclear.

[0008] 4. Existing water-filled balloons are mostly made of latex or silicone, whose acoustic impedance differs significantly from that of soft tissue, resulting in a large amount of ultrasound energy being lost due to reflection at the interface, leading to insufficient image resolution and penetration depth.

[0009] 5. Existing water bladders either prioritize optical transparency or fail to adequately address acoustic functionality. Furthermore, the existing water bladder structures lead to a significant increase in ultrasound attenuation at the interlayer interfaces. Therefore, there is an urgent clinical need for an integrated composite thin-film material that can simultaneously achieve efficient ultrasound coupling and stable optical polarization within a single structure. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art, and to disclose a medical composite film material, its corresponding endoscopic water bag, and related preparation methods, as detailed below:

[0011] A medical composite film material includes an acoustic matching layer and an optical polarization composite layer stacked together, with each layer bonded together by a medical-grade ultraviolet-curable optical adhesive. The optical adhesive has a visible light transmittance ≥90% and a refractive index difference ≤0.05 with the adjacent layer material.

[0012] The acoustic matching layer consists of a light-transmitting elastomer matrix and acoustic impedance adjusting filler dispersed therein. The acoustic impedance adjusting filler is an isotropic hollow spherical particle with a particle size of 0.5-5μm and a volume fraction of 5%-20%. The acoustic matching layer is optically isotropic, with an equivalent acoustic impedance of 1.50-1.60MRayl and a thickness of 30-100μm.

[0013] The optical polarization composite layer includes a linear polarizing element and a quarter-wave plate element laminated together by optical adhesive. The transmission axis of the linear polarizing element forms an angle of 45°±5° with the fast axis of the quarter-wave plate element. The optical polarization composite layer has a deployable wrinkle structure with an amplitude of 2-8 μm and a period of 80-150 μm. The wrinkle structure is configured to absorb strain by flattening the wrinkles when the composite film material is subjected to a biaxial tensile strain of no more than 8%, so as to maintain the deviation of its phase retardation relative to λ / 4 within ±15% and the extinction ratio above 8:1.

[0014] Furthermore, the light-transmitting elastomer matrix is ​​an addition-type polydimethylsiloxane or an aliphatic medical polyurethane;

[0015] The acoustic impedance regulating filler is a hollow glass microsphere or a hollow polymer microsphere. The particle size distribution of the filler is D50 = 1-3 μm, the maximum particle size does not exceed 5 μm, and the wall thickness is 5%-15% of the particle size.

[0016] Furthermore, the linear polarizing element is a moisture-resistant dye-based polarizing film or a hydrophobically treated polyvinyl alcohol polarizing film, with an initial extinction ratio ≥100:1 and a thickness of 20-40 μm;

[0017] The quarter-wave plate element is a birefringent polymer film or a liquid crystal polymer film, with a phase retardation of λ / 4±10% and a thickness of 10-30μm.

[0018] Furthermore, the deployable wrinkled structure is formed by pre-stretching the linear polarizing element or the quarter-wave plate element by 15%-25% and then attaching it to the elastic buffer layer. After releasing the prestress, wrinkles are formed. The storage modulus of the elastic buffer layer is 10-100MPa, and the thickness is 5-15μm. The elastic buffer layer is a component of the optical polarization composite layer and is attached to the side of the linear polarizing element or the quarter-wave plate element away from the other element.

[0019] Furthermore, the total thickness of the optical polarization composite layer is 40-80 μm, and the thickness ratio of the acoustic matching layer to the optical polarization composite layer is 1.5-2.5:1.

[0020] Furthermore, it also includes a protective layer covering the outer surface of the optical polarization composite layer. The protective layer is made of transparent thermoplastic polyurethane or polyether block amide, with a thickness of 15-25 μm and a visible light transmittance of ≥85%.

[0021] Furthermore, the material has an acoustic insertion loss of less than 1.5 dB at ultrasonic frequencies of 5 MHz to 20 MHz and an ultrasonic attenuation of less than 2.5 dB at a frequency of 10 MHz; the material has a transmittance of ≥75% in the visible light band of 400-760 nm.

[0022] The innovation of this invention lies in the integrated acoustic-optical functional design. The specific principles are as follows:  A medical-grade UV-curable optical adhesive rigidly couples the acoustic matching layer and the optical polarization composite layer into a single optical medium, eliminating the solid-gas interface between layers, avoiding multiple ultrasonic reflections and optical scattering, and achieving single-pass, low-loss transmission of ultrasound and optics.  The expandable wrinkle structure built into the optical polarization composite layer deforms synchronously with the acoustic matching layer. By flattening the wrinkles rather than stretching the material itself to absorb strain, optical polarization performance is maintained while keeping the acoustic impedance matching low, overcoming the technical bottleneck of optical element failure under flexible deformation.  The volume fraction (5%-20%) and particle size (0.5-5μm) of the hollow microspheres in the acoustic matching layer are optimized to be within the Rayleigh scattering controllable region. Furthermore, the high transparency of the optical polarization composite layer and the protective layer compensates for the slight scattering of the acoustic layer, resulting in a total transmittance ≥75%, meeting the needs of clinical observation.

[0023] This invention further discloses a method for preparing medical composite film materials, comprising the following steps:

[0024] (1) Preparation of acoustic matching layer: The transparent elastomer prepolymer is mixed with hollow spherical fillers with a particle size of 0.5-5μm. After vacuum degassing, a uniform film layer with a thickness of 30-100μm is formed by precision scraping or casting process. After heating and curing, the acoustic matching layer is obtained.

[0025] (2) Fabrication of optical polarization composite layer:

[0026] (2a) Align the linear polarizing film and the phase retardation film at an angle of 45°±5° between the transmission axis and the fast axis;

[0027] (2b) A UV-curable optical adhesive is coated between the linear polarization film and the phase retardation film, and a double-layer composite structure is formed by roll pressing. The structure is then cured by UV irradiation, and the curing energy density is 400-800 mJ / cm².

[0028] (2c) The double-layer composite structure obtained in step (2b) is bonded to the surface of the elastic buffer layer. During bonding, a pre-tension strain of 15%-25% is applied. After bonding, the pre-stress is released to form an optical polarization composite layer with a deployable wrinkle structure.

[0029] (3) Interlayer bonding: The optical polarization composite layer prepared in step (2) is bonded to the surface of the acoustic matching layer prepared in step (1) using UV-curable optical adhesive. The bonding pressure is controlled at 0.1-0.5 MPa and the temperature is 25-40℃. After bonding, it is cured by UV irradiation with a curing energy density of 500-1000 mJ / cm².

[0030] 13. The preparation method according to claim 12, characterized in that it further includes step (4) protective layer forming: a transparent thermoplastic polyurethane or polyether block amide solution is cast and coated on the outer surface of the optical polarization composite layer, and then dried and cured to form a protective layer with a thickness of 15-25 μm.

[0031] The present invention also protects an endoscope-assisted water bag, characterized by being made of the aforementioned medical composite film material.

[0032] Furthermore, the total thickness of the water bladder wall is 100-250 μm, and the sound path delay generated at a 10 MHz ultrasonic working frequency is less than 0.3 μs.

[0033] The beneficial effects of this invention are:

[0034] 1. Achieving integrated ultrasound and optical functions: Through layered functional separation design, the acoustic matching layer achieves low acoustic impedance matching (1.50-1.60MRayl), and the optical polarization composite layer eliminates mucosal specular reflection. A single material simultaneously meets the requirements of efficient ultrasound coupling and clear optical observation, avoiding the cumbersome operation of replacing accessories required by traditional solutions.

[0035] 2. Solving the problem of optical performance degradation under flexible deformation: Adopting a deployable wrinkle structure (amplitude 2-8μm, period 80-150μm), the deformation is absorbed by the wrinkle flattening under 8% biaxial tensile strain, maintaining a phase delay deviation of less than ±15% and an extinction ratio of greater than 8:1, breaking through the limitation of traditional polarizing films failing upon stretching.

[0036] Improved clinical diagnostic accuracy: Ultrasound insertion loss is reduced by more than 50%, optical glare elimination rate is greater than 80%, and the identification of mucosal microstructure and ultrasound image resolution are improved simultaneously, reducing the risk of missing early lesions.

[0037] 3. Improved patient comfort and ease of operation: The material is flexible and fits the mucosa, reducing the required filling pressure by about 30%; the total thickness is less than 250μm and can be folded through the biopsy channel, allowing for dual-modal examinations to be completed in a single insertion, shortening the operation time by 20%-30%.

[0038] 4. Expanding the application scope of materials: In addition to endoscope water bags, this composite film material can also be used in a variety of medical devices such as extracorporeal ultrasound coupling pads, capsule endoscope shells, and OCT probe windows, forming a platform-based technical solution. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a certain embodiment of the medical composite film material of the present invention.

[0040] Figure reference numerals: 1. Water inlet end; 2. Human tissue end; 10. Optical adhesive layer; 11. Acoustic matching layer; 12. Optical adhesive layer; 13. Linear polarization unit layer; 14. Optical adhesive layer; 15. Quarter-wave plate layer; 16. Elastic buffer layer; 17. Protective layer. Detailed Implementation

[0041] To better understand the present invention, the present invention will be further described below with reference to specific embodiments.

[0042] Example 1

[0043] Raw material selection:

[0044] Acoustic matrix: addition-type polydimethylsiloxane (PDMS), model: Dow Corning SYLGARD184, base adhesive to curing agent weight ratio is 10:1.

[0045] Acoustic impedance regulating filler: hollow glass microspheres, supplier: 3M or equivalent, model: K20 or S22. Specifications: true density 0.20-0.22 g / cm³, particle size D50=2.2μm, maximum particle size <5μm, wall thickness 8%-12% of particle size, compressive strength >3000psi.

[0046] Linear polarizing element: Moisture-resistant dye-based polarizing film, model: Nitto Denko NPF-G1220. Specifications: Initial extinction ratio ≥150:1, thickness 30μm.

[0047] Quarter-wave plate element: Liquid crystal polymer (LCP) film, model: Fujifilm Fujitac WF series custom model. Specifications: Phase retardation Rth = 137.5nm ± 5nm (@550nm), thickness 18μm.

[0048] Elastic buffer layer: Low-modulus modified silicone elastomer film. Formulation: PDMS base adhesive: curing agent = 20:1, storage modulus after curing is about 25MPa, thickness is 12μm.

[0049] Optical adhesive: Medical-grade UV-curable acrylic optical adhesive, model: Debon DB6103. Specifications: Visible light transmittance 93%, refractive index 1.49.

[0050] Protective layer material: transparent thermoplastic polyurethane aqueous dispersion; substrate: BASF Elastollan 1185A modified aqueous emulsion. Specifications: solid content 30%, solvent is deionized water, no organic solvents.

[0051] This embodiment describes the preparation steps of a medical composite film material:

[0052] Step 1: Preparation of Acoustic Matching Layer

[0053] Ingredients: Weigh 100g of PDMS base adhesive, add 10g of curing agent, and mechanically stir for 5 minutes until uniform.

[0054] Filler mixing: Add 18% by volume of hollow glass microspheres (D50=2.2μm) to the above mixture. Disperse the mixture at 2000rpm for 15min using a high-speed shear disperser to ensure that the microspheres do not agglomerate.

[0055] Degassing: Place the mixed slurry in a vacuum degassing machine and degas for 30 minutes at -0.095 MPa and room temperature until no bubbles are visible to the naked eye.

[0056] Molding: Using a precision scraper, the slurry is scraped onto the release film with a scraper gap of 55μm and a speed of 0.5m / min.

[0057] Curing: Heat and cure in an 80℃ oven for 1 hour, then peel off the release film after cooling to room temperature.

[0058] Results: An optically isotropic acoustic matching layer with a thickness of 52±2μm, a surface roughness Ra<0.15μm, and an equivalent acoustic impedance of approximately 1.58MRayl was obtained.

[0059] Step 2: Fabrication of the optical polarization composite layer

[0060] (2a) Optical axis alignment: Adjust the linear polarizing film and the quarter-wave plate using an optical axis alignment instrument so that the angle between the transmission axis of the linear polarizing element and the fast axis of the quarter-wave plate element is 45°±2°;

[0061] (2b) Roller lamination: UV-curable optical adhesive is coated between the two film layers and placed in a roller laminator. The film is then rolled and laminated at a pressure of 0.3 MPa and a speed of 0.3 m / min. After curing by 365 nm UV light, the curing energy density is 600 mJ / cm², resulting in a three-layer composite structure.

[0062] (2c) Pleating: The above three-layer composite structure is bonded to the surface of the elastic buffer layer. A 20% pre-stretch strain is applied by a stretching machine, and the bonding pressure is 0.2MPa. After bonding, the prestress is slowly released, and a developable pleated structure with an amplitude of 5μm and a period of 120μm is naturally formed, resulting in an optical polarization composite layer with a total thickness of 60μm.

[0063] Step 3:

[0064] Interlayer lamination involves coating the aforementioned UV-curable optical adhesive (wet thickness 10μm) on both sides of the acoustic matching layer, then laminating the optical polarization composite layer onto it. The layers are then rolled and laminated under a lamination pressure of 0.3MPa and a temperature of 30℃, followed by curing under 365nm UV light with a curing energy density of 800mJ / cm², achieving seamless lamination between the two layers.

[0065] Step 4

[0066] For the protective layer forming, TPU is dissolved in DMF solvent to prepare a 30% solid content solution, which is then coated onto the outer surface of the optical polarization composite layer using a casting coating machine at a speed of 0.4 m / min and a wet thickness of 60 μm. The solution is then dried and cured in a 60°C oven for 2 hours to form a 20 μm thick protective layer, thus obtaining the final medical composite film material.

[0067] The composite thin film material prepared in this embodiment has been tested and all performance indicators meet the requirements, as detailed below:

[0068] After biaxial stretching of 8%, the phase retardation relative to 550nmλ / 4 deviates by ±8%, and the extinction ratio is 15:1.

[0069] The acoustic insertion loss is 1.2 dB at ultrasonic frequencies of 5 MHz to 20 MHz, and the ultrasonic attenuation is 2.0 dB at 10 MHz.

[0070] The transmittance in the visible light band (400-760nm) is 82%, the interlayer peel strength is 1.8N / 15mm, and there is no delamination or debonding.

[0071] Referring to the accompanying drawings in the specification will provide a better understanding of the structural layers of this invention. From the water inlet 1 to the human tissue end 2, the layers are sequentially designed as follows: optical adhesive layer 10, acoustic matching layer 11, optical adhesive layer 12, linear polarization unit layer 13, optical adhesive layer 14, quarter-wave plate layer 15, elastic buffer layer 16, and protective layer 17. In this embodiment, the optical polarization composite layer described in step 2 includes these four layers: linear polarization unit layer 13, optical adhesive layer 14, quarter-wave plate layer 15, and elastic buffer layer 16.

[0072] Example 2

[0073] This embodiment is an acoustic performance optimization embodiment. The raw materials and processes in this embodiment are basically the same as in embodiment 1, except that the parameters of the acoustic matching layer and the optical polarization composite layer are adjusted in a gradient. The specific adjustments and performance are as follows:

[0074] Parameter adjustments: the volume fraction of the acoustic matching layer hollow glass microspheres is 20%, the thickness is 100μm, and the equivalent acoustic impedance is 1.60MRayl; the total thickness of the optical polarization composite layer is 40μm, and the thickness ratio of the acoustic matching layer to the optical polarization composite layer is 2.5:1; the amplitude of the deployable wrinkled structure is 8μm and the period is 150μm.

[0075] Performance testing: 5-20MHz acoustic insertion loss 0.9dB, 10MHz ultrasonic attenuation 1.8dB; phase delay deviation ±12% after 8% biaxial stretching, extinction ratio 10:1; 400-760nm transmittance 78%.

[0076] Example 3

[0077] This embodiment is an optical performance optimization embodiment. The raw materials and processes in this embodiment are basically the same as in Embodiment 1, with specific adjustments and performance as follows:

[0078] Parameter adjustments: the volume fraction of the acoustic matching layer hollow glass microspheres is 5%, the thickness is 30μm, and the equivalent acoustic impedance is 1.50MRayl; the total thickness of the optical polarization composite layer is 80μm, and the thickness ratio of the acoustic matching layer to the optical polarization composite layer is 1.5:1; the amplitude of the deployable wrinkled structure is 2μm and the period is 80μm.

[0079] Performance testing: 86% transmittance for 400-760nm; ±5% phase delay deviation after 8% biaxial stretching; 20:1 extinction ratio; 1.4dB insertion loss for 5-20MHz acoustic waves; 2.3dB attenuation for 10MHz ultrasonic waves.

[0080] Example 4

[0081] The raw materials and processes in this embodiment are basically the same as in Example 1. The purpose of this example is to verify the compatibility between the acoustic impedance of 1.50 MRayl and the wrinkle amplitude of 8 μm. The difference between this embodiment and Example 1 is: the volume fraction of hollow glass microspheres is 5% (K1 type, true density 0.125 g / cm³), the acoustic matching layer thickness is 30 μm, the equivalent acoustic impedance is 1.50 MRayl, the pre-tension strain is 25%, the wrinkle amplitude is 8 μm, and the period is 150 μm.

[0082] Performance testing: After biaxial stretching of 8%, the phase delay deviation is ±12% and the extinction ratio is 10:1; the insertion loss is 1.4dB in the 5-20MHz range and the attenuation is 2.3dB in the 10MHz range; the transmittance is 86%.

[0083] Example 5

[0084] The raw materials and processes in this embodiment are basically the same as in Example 1. The purpose of this example is to verify the compatibility between an acoustic impedance of 1.60 MRayl and a wrinkle amplitude of 2 μm. The difference between this embodiment and Example 1 is: the volume fraction of hollow glass microspheres is 20% (S38 type, true density 0.38 g / cm³), the acoustic matching layer thickness is 100 μm, the equivalent acoustic impedance is 1.60 MRayl, the pre-tension strain is 15%, the wrinkle amplitude is 2 μm, and the period is 80 μm.

[0085] Performance test: Performance: Phase delay deviation ±5% after biaxial stretching of 8%, extinction ratio 20:1; insertion loss 0.9dB from 5-20MHz, attenuation 1.8dB at 10MHz; transmittance 78%.

[0086] Comparative Example 6

[0087] This comparative example is based on Example 1. This example uses commercially available latex water bags, silicone water bags, and non-polarized PDMS water bags for experimental comparison to further illustrate the optical and ultrasonic performance of the present invention.

[0088] Test subjects: latex water bladder (200μm wall), silicone water bladder (180μm wall), and non-polarized PDMS water bladder (52μm wall, acoustic matching layer only).

[0089] Equipment: Olympus GF-UCT260 ultrasonic endoscope (7.5MHz), CV-190 electronic endoscope, standard acoustic impedance target (Z=1.52MRayl), USAF-1951 resolution plate, sine wave resolution plate (5-100lp / mm), spectrophotometer (Lambda950, with integrating sphere), pressure sensor (±0.1kPa), fresh pig stomach (obtained within 4 hours after slaughter, stored at 4℃, and restored to 37℃ before experiment).

[0090] Testing process:

[0091] 1. Sample installation: The water bag is installed in the slot at the front end of the endoscope probe. After vacuuming, 37°C degassed physiological saline is injected to remove air bubbles and allowed to stand for 5 minutes.

[0092] 2. Ultrasonic testing: (1) Insertion loss: The water bladder is in vertical contact with the standard acoustic impedance target. The network analyzer emits a 10MHz pulse, records the echo amplitude, and calculates the attenuation value relative to no sample reference; (2) Resolution: The water bladder is covered with a USAF-1951 plate, the gain is adjusted to the point where the noise is just visible, and the minimum distinguishable linewidth group is recorded; (3) SNR: The probe is placed on the pig gastric mucosa, 10 frames of images are acquired, the homogeneous area in the submucosa is selected as the signal ROI, and the unstructured area 2mm away is selected as the background ROI. The SNR is calculated as 20 × log 10 (Signal mean / background standard deviation)

[0093] 3. Optical tests: (1) MTF: The water bladder covers the sine wave plate, and the white light mode is used for imaging. The 50 lp / mm area is selected. MTF = (I_max-I_min) / (I_max+I_min), where I is the gray value; (2) Transmittance / Haze: The sample is cut into 25mm×25mm pieces. The average T value of 400-760nm is measured by spectrophotometer. Haze H = diffuse transmittance / total transmittance × 100%.

[0094] 4. Operation test: The probe was inserted into the pig's stomach cavity and the water sac was slowly inflated until the ultrasound image clearly showed the five layers of the stomach wall (mucosa, muscularis mucosae, submucosa, muscularis propria, and serosa). The pressure was recorded. After the ultrasound scan was completed, the white light mode was switched to observe the mucosal surface, and the total time was recorded.

[0095] 5. Repeat testing: Three physicians with more than 5 years of EUS operation experience independently performed the test. Each physician repeated the above complete procedure 3 times for each sample. The sample order was randomized, resulting in a total of 9 sets of data / samples.

[0096] The results are as follows:

[0097]

[0098] Experimental tests showed that the ultrasonic insertion loss of Example 1 of the present invention was comparable to that of the non-polarized PDMS water bag, the MTF was significantly improved compared with the prior art, the low-pressure filling shortened the examination time, and the coefficient of variation was <10% in 9 repeated tests.

[0099] The above detailed description is a specific description of one feasible embodiment of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention. Of course, the above are only typical examples of the present invention. In addition, the present invention can have many other specific implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention.

Claims

1. A medical composite film material, characterized in that, It includes an acoustic matching layer and an optical polarization composite layer stacked together, with each layer bonded together by a medical-grade UV-curable optical adhesive. The optical adhesive has a visible light transmittance of ≥90% and a refractive index difference of ≤0.05 with the adjacent layer material. The acoustic matching layer consists of a light-transmitting elastomer matrix and acoustic impedance adjusting filler dispersed therein. The acoustic impedance adjusting filler is an isotropic hollow spherical particle with a particle size of 0.5-5 μm and a volume fraction of 5%-20%. The acoustic matching layer is optically isotropic, with an equivalent acoustic impedance of 1.50-1.60 MRayl and a thickness of 30-100 μm. The optical polarization composite layer includes a linear polarizing element and a quarter-wave plate element laminated together by optical adhesive, and an elastic buffer layer attached to the side of the linear polarizing element or the quarter-wave plate element away from the other element; the transmission axis of the linear polarizing element forms an angle of 45°±5° with the fast axis of the quarter-wave plate element; the storage modulus of the elastic buffer layer is 10-100MPa and the thickness is 5-15μm; the optical polarization composite layer has a deployable wrinkled structure, which is formed by pre-stretching the linear polarizing element or the quarter-wave plate element by 15%-25% and then attaching it to the elastic buffer layer, and releasing the prestress. The amplitude of the wrinkled structure is 2-8μm and the period is 80-150μm. It is configured to absorb strain by flattening the wrinkles when the composite film material is subjected to a biaxial tensile strain of no more than 8%, so as to maintain the deviation of its phase retardation relative to λ / 4 within ±15%, and the extinction ratio is maintained above 8:

1.

2. The medical composite film material according to claim 1, characterized in that, The light-transparent elastomer matrix is ​​an addition-type polydimethylsiloxane or an aliphatic medical polyurethane; The acoustic impedance regulating filler is a hollow glass microsphere or a hollow polymer microsphere. The particle size distribution of the filler is D50 = 1-3 μm, the maximum particle size does not exceed 5 μm, and the wall thickness is 5%-15% of the particle size.

3. The medical composite film material according to claim 1, characterized in that, The linear polarizing element is a moisture-resistant dye-based polarizing film or a hydrophobically treated polyvinyl alcohol polarizing film with an initial extinction ratio ≥100:1 and a thickness of 20-40μm. The quarter-wave plate element is a birefringent polymer film or a liquid crystal polymer film, with a phase retardation of λ / 4±10% and a thickness of 10-30μm.

4. The medical composite film material according to claim 1, characterized in that, The total thickness of the optical polarization composite layer is 40-80 μm, and the thickness ratio of the acoustic matching layer to the optical polarization composite layer is 1.5-2.5:

1.

5. The medical composite film material according to claim 1, characterized in that, It also includes a protective layer covering the outer surface of the optical polarization composite layer. The protective layer is made of transparent thermoplastic polyurethane or polyether block amide, with a thickness of 15-25 μm and a visible light transmittance of ≥85%.

6. The medical composite film material according to claim 1, characterized in that, The material has an acoustic insertion loss of less than 1.5 dB at ultrasonic frequencies of 5 MHz to 20 MHz and an ultrasonic attenuation of less than 2.5 dB at a frequency of 10 MHz; the material has a transmittance of ≥75% in the visible light band of 400-760 nm.

7. A method for preparing the medical composite film material according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Preparation of acoustic matching layer: The transparent elastomer prepolymer is mixed with hollow spherical fillers with a particle size of 0.5-5μm. After vacuum degassing, a uniform film layer with a thickness of 30-100μm is formed by precision scraping or casting process. After heating and curing, the acoustic matching layer is obtained. (2) Fabrication of optical polarization composite layer: (2a) Align the linear polarizing film and the phase retardation film at an angle of 45°±5° between the transmission axis and the fast axis; (2b) A UV-curable optical adhesive is coated between the linear polarization film and the phase retardation film, and a double-layer composite structure is formed by roll pressing. The structure is then cured by UV irradiation, and the curing energy density is 400-800 mJ / cm². (2c) The side of the linear polarization film or phase retardation film away from the other film layer in the bilayer composite structure obtained in step (2b) is attached to the surface of the elastic buffer layer; during attachment, a pre-stretch strain of 15%-25% is applied to the linear polarization film or the phase retardation film, and the elastic buffer layer does not stretch. After bonding, the prestress is slowly released, causing the linear polarization film or the phase retardation film to retract and form a deployable wrinkled structure with an amplitude of 2-8 μm and a period of 80-150 μm, thus obtaining an optical polarization composite layer. (3) Interlayer bonding: The optical polarization composite layer prepared in step (2) is bonded to the surface of the acoustic matching layer prepared in step (1) using UV-curable optical adhesive. The bonding pressure is controlled at 0.1-0.5 MPa and the temperature is 25-40℃. After bonding, it is cured by UV irradiation with a curing energy density of 500-1000 mJ / cm².

8. The preparation method according to claim 7, characterized in that, It also includes step (4) protective layer forming: a transparent thermoplastic polyurethane or polyether block amide solution is cast and coated on the outer surface of the optical polarization composite layer, and then dried and cured to form a protective layer with a thickness of 15-25μm.

9. An endoscopic-assisted water bag, characterized in that, Made from the medical composite film material as described in any one of claims 1-7.

10. The endoscopic-assisted water bag according to claim 9, characterized in that, The total wall thickness of the water bladder is 100-250 μm, and the sound path delay generated at a 10 MHz ultrasonic working frequency is less than 0.3 μs.

Images