A flexible ultrasound patch for monitoring corneal elastic modulus and a method of manufacturing the same

Abstract

The application discloses a flexible ultrasonic patch for monitoring corneal elastic modulus and a preparation method thereof, the patch comprises, from top to bottom, a top flexible packaging layer, a top electrode layer, a piezoelectric layer, a bottom electrode layer, a bottom flexible base material isolation layer and a bottom flexible packaging layer; the piezoelectric layer is internally provided with an air column. Compared with a traditional medical hard probe for measuring corneal mechanical properties, the application has good flexibility, and the tensile property and bending resistance are greatly improved; the patch can be dynamically attached to the surface of an eyelid, and long-time corneal health monitoring of a human body can be realized; meanwhile, a non-invasive monitoring mode widens the application scene of the device, and real-time monitoring of corneal elastic modulus during a sleep process at night can be realized, and other eye features such as intraocular pressure can be further obtained.

Description

Technical Field

[0001] This invention belongs to the field of flexible electronics technology, and in particular relates to a flexible ultrasonic patch for monitoring the elastic modulus of the cornea and its preparation method. Background Technology

[0002] Corneal elastic modulus is a crucial parameter for assessing corneal health. Measuring it is clinically vital, as it helps in more accurately assessing intraocular pressure, which is essential for the diagnosis and monitoring of glaucoma. It also aids in the early identification of corneal diseases such as keratoconus, allowing for timely treatment. Understanding corneal elastic modulus before refractive surgery helps doctors develop personalized surgical plans, improving surgical safety and outcomes. For researchers, measuring corneal elastic modulus contributes to a deeper understanding of corneal biomechanical properties and their impact on eye health, providing theoretical support for the development of new diagnostic tools and technologies. For patients who have undergone corneal surgery, regular corneal elastic modulus monitoring is an effective way to evaluate surgical outcomes and monitor potential complications. Therefore, corneal elastic modulus measurement plays a key role in multiple aspects.

[0003] Currently, technologies used to monitor corneal elastic modulus include ultrasound imaging, corneal topography, optical coherence tomography (OCT), Scheimpflug imaging, and corneal biomechanical analysis. Among these, ultrasound imaging, as a widely used technology in the field of medical monitoring, is characterized by its non-invasiveness, high resolution, and real-time imaging capabilities. It can image corneal tissue in real time with high precision, monitor corneal elastic modulus, and thus assess corneal health.

[0004] Currently, most ultrasound devices in the medical monitoring field use rigid ultrasound probes, which are applied to the patient's eyelids with coupling gel. This requires operation by professional medical personnel, and manually moving the probe not only affects the patient's tactile experience but also leads to monitoring errors due to staff negligence. For air-based elastography, direct contact with the cornea causes discomfort and prevents real-time measurement. For patients with glaucoma, keratoconus, and other conditions, monitoring corneal elastic modulus during nighttime sleep is particularly important. The biggest challenge for ultrasound devices is to achieve non-invasive, real-time, high-precision, and nearly imperceptible dynamic monitoring of corneal elastic modulus. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a flexible ultrasonic patch for monitoring the elastic modulus of the cornea, comprising, from top to bottom, a top flexible encapsulation layer, a top electrode layer, a piezoelectric layer, a bottom electrode layer, a bottom flexible substrate isolation layer, and a bottom flexible encapsulation layer; an air column is provided inside the piezoelectric layer; an array composed of several ultrasonic transducer units is also provided inside the piezoelectric layer, with the ultrasonic transducer units separated by air columns; the materials of the flexible ultrasonic patch are all composed of polymers and their composites.

[0006] Specifically, the bottom electrode layer and the top electrode layer serve as ports for receiving and transmitting signals, respectively, and both the bottom electrode layer and the top electrode layer are patterned.

[0007] Specifically, the materials of the bottom flexible encapsulation layer include silicone elastomer Ecoflex-0030, polyurethane elastomer, PET film, and PDMS elastomer.

[0008] Specifically, the materials for the flexible substrate isolation layer include polyimide and epoxy resin.

[0009] Specifically, the materials of the top flexible encapsulation layer include parylene, parylene C, polyimide, polytetrafluoroethylene, and polybenzoxazole, and the thickness of the top flexible encapsulation layer is 5-10 micrometers.

[0010] Specifically, the thickness of the piezoelectric layer is 80-150 micrometers.

[0011] A method for preparing a flexible ultrasonic patch is also provided, wherein the flexible ultrasonic patch is any of the above-mentioned flexible ultrasonic patches, specifically including the following steps:

[0012] Prepare a bottom flexible substrate isolation layer;

[0013] A bottom electrode layer is deposited and patterned on a bottom flexible substrate isolation layer;

[0014] The piezoelectric layer was prepared using a thermal embossing method;

[0015] A top electrode layer is deposited and patterned on top of the piezoelectric layer;

[0016] A top flexible encapsulation layer is fabricated on top of the top electrode layer;

[0017] The bottom of the package is a flexible encapsulation layer.

[0018] Specifically, the preparation of the piezoelectric layer using the hot imprinting method includes the following steps:

[0019] A master mold with a columnar structure is created using photolithography. The attributes of the columnar structure include shape, pattern, and height. The master mold is then cast and cured using PDMS to produce a PDMS stamp with a columnar cavity.

[0020] A thin film is pressed onto the bottom electrode layer, the film is heated to soften it, and a PDMS stamp is pressed into the film so that the softened film fills the columnar cavity of the PDMS stamp. After the stamping is completed, the PDMS stamp is released. Another thin film is laminated on top to form an air column and an ultrasonic transducer unit, and finally a piezoelectric layer is made.

[0021] The film is subjected to oxygen plasma treatment before being pressed onto the bottom electrode layer.

[0022] Specifically, the material of the main mold is epoxy resin; the material of the film is one of polyvinylidene fluoride and its copolymers, or flexible piezoelectric ceramics.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The flexible ultrasound patch for monitoring corneal elastic modulus provided by this invention can be used for, but is not limited to, monitoring corneal elastic modulus. Compared with traditional rigid ultrasound probes and traditional corneal measurement tools, this invention is soft and comfortable, does not directly contact the cornea, can conform to the eyelid, broadens the application scenarios of corneal elastic modulus monitoring, and fills the gap in the field of nighttime corneal elastic modulus monitoring. Attached Figure Description

[0025] Figure 1 This is a schematic cross-sectional view of the flexible ultrasonic patch according to an embodiment of the present invention.

[0026] Figure 2 This is a top view of the piezoelectric layer of the flexible ultrasonic patch according to an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram illustrating the working principle of the flexible ultrasonic patch according to an embodiment of the present invention.

[0028] The diagram is marked as follows:

[0029] Top flexible encapsulation layer 1, top electrode layer 2, piezoelectric layer 3, air column 4, bottom electrode layer 5, bottom flexible substrate isolation layer 6, bottom flexible encapsulation layer 7, ultrasonic transducer unit 8, flexible ultrasonic patch 10, eyelid 11, cornea 12, ultrasonic pulse 13, shear wave 14, displacement 15. Detailed Implementation

[0030] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0032] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0033] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0034] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that terms such as “comprising / including” or “having” specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0036] The flexible ultrasonic patch for monitoring corneal elastic modulus provided in this embodiment consists of a multi-layer structure, from bottom to top: a bottom flexible encapsulation layer 7 made of elastomer for bonding with the eyelid 11; a bottom flexible substrate isolation layer 6 made of polyimide of about 10 micrometers as the electrode substrate; a 200-nanometer gold electrode layer deposited on top of the polyimide; a piezoelectric layer 3 fabricated by thermoimaging, the structure of which includes an array of 64 ultrasonic transducers made of 80-150 micrometers thick polyvinylidene fluoride and its copolymer P (VDF-TrFE); an electrode layer of 200-400 nanometers thick deposited on top of the piezoelectric layer 3; and finally, a C-type polyethylene oxide layer of about 5-10 micrometers thick. A xylene film is used for encapsulation to form a top flexible encapsulation layer 1. In one specific example, each electrode of the flexible ultrasonic patch 10 is connected to an external electronic control system. The input power is changed by the electronic control system, and the time delay and phase difference of each piezoelectric unit in each piezoelectric layer 3 are calculated. The emission time and direction of each unit of the 16 central ultrasonic transducers are then set to emit high-energy ultrasonic pulses with the same focal point, which are precisely focused on a point on the cornea. All 64 ultrasonic transducer units 8 of the piezoelectric layer 3 receive the reflected ultrasonic signals, detect the displacement 15 of the tissue due to strain, and image these displacements 15 to construct a spatiotemporal map. The propagation speed of the shear wave is calculated by algorithms such as linear fitting, and then the elastic modulus of the corneal tissue is calculated.

[0037] Specifically, such as Figure 1 and Figure 3 As shown, the internal structure of the flexible ultrasonic patch 10 includes a top flexible encapsulation layer 1, a top electrode layer 2, a piezoelectric layer 3, a bottom electrode layer 5, a bottom flexible substrate isolation layer 6, and a bottom flexible encapsulation layer 7. An air column 4 is provided inside the piezoelectric layer 3 (the piezoelectric layer 3 is composed of an ultrasonic transducer unit 8 and the air column 4; the material of the ultrasonic transducer unit 8 is the piezoelectric layer material). From bottom to top: the bottom flexible encapsulation layer 7, as a functional layer directly attached to the eyelid 11, is placed at the bottom. The bottom electrode layer 5 is patterned and vapor-deposited onto the bottom flexible substrate isolation layer 6 made of polyimide. The piezoelectric layer 3 forms the air column 4 through thermal imprinting. Electrode deposition continues above the piezoelectric layer 3 to form the top electrode layer 2. Finally, the entire device is encapsulated, and a top flexible encapsulation layer 1 is fabricated on top.

[0038] To further improve the applicability of this embodiment in monitoring corneal elastic modulus, the thickness of the piezoelectric layer 3 (i.e., the thickness of the ultrasonic transducer) is adjusted, thereby changing the ultrasonic frequency so that the piezoelectric resonant frequency is in the range of 4-10MHz, which can adapt to different eyelid 11 thicknesses and corneal depths.

[0039] The purpose of the bottom flexible encapsulation layer 7 is to encapsulate the internal structure, avoid external interference, and be soft and comfortable, so as to fit the eyelid 11.

[0040] The purpose of the bottom flexible substrate isolation layer 6 is to serve as a substrate for the electrode material, enabling better evaporation and adhesion of the electrode, and as a substrate, it can be better transferred from the glass.

[0041] The bottom electrode layer 5 and the top electrode layer 2 are intended to serve as ports for receiving and transmitting signals, wherein the bottom electrode layer 5 and the top electrode layer 2 are patterned.

[0042] The piezoelectric layer 3 is located between the bottom electrode layer 5 and the top electrode layer 2. Its purpose is to transmit and receive ultrasonic waves. It can convert voltage signals into ultrasonic signals or convert ultrasonic signals into voltage signals and output them. The columnar structure is to reduce signal crosstalk between them.

[0043] The flexible ultrasonic patch 10 described in this embodiment is composed of polymers and their composites, and has good stretchability and bendability. Specifically:

[0044] The bottom flexible encapsulation layer 7 is made of materials including, but not limited to, silicone elastomer Ecoflex-0030, polyurethane elastomer, PET film, PDMS elastomer, etc.

[0045] The bottom flexible substrate isolation layer 6 is made of materials including but not limited to polyimide, epoxy resin, etc.

[0046] The bottom electrode layer 5 and the top electrode layer 2 are made of materials including, but not limited to, metallic materials such as gold, silver, and copper.

[0047] The piezoelectric layer 3 is made of materials including, but not limited to, polyvinylidene fluoride and its copolymer P (VDF-TrFE), flexible piezoelectric ceramics, and other flexible piezoelectric materials.

[0048] The top flexible encapsulation layer 1 includes, but is not limited to, encapsulation materials such as parylene N, parylene C, polyimide (PI), polytetrafluoroethylene (PTFE), and polybenzoxazole (PBO).

[0049] The flexible ultrasound patch provided in this embodiment for monitoring corneal elastic modulus is only 200-400 micrometers thick and weighs only 1-5 grams. It is soft, lightweight, and can fit well with the eyelid 11.

[0050] This embodiment also provides a method for preparing the above-mentioned flexible ultrasonic patch, including the following steps:

[0051] (a) First, a polyimide film with a thickness of about 10 micrometers is spin-coated and cured on a temporary glass slide to prepare a bottom flexible substrate isolation layer 6;

[0052] (b) A 200-nanometer-thick composite material layer was deposited on a polyimide film using sputtering as the bottom electrode, and then a patterned bottom electrode layer 5 was prepared by photolithography.

[0053] (c) Preparation of the Imprint Stamp: The mold for the stamp is formed by patterning epoxy resin on a separate glass substrate using photolithography to create a master mold with a columnar structure, including shape (e.g., square, hexagonal, and circular), pattern, and height. Then, PDMS (polydimethylsiloxane) is poured into the master mold and cured (PDMS is a liquid substance composed of a bulk and a crosslinking agent, cured by heating at 80 degrees Celsius for 60 minutes; the melting point of the cured PDMS stamp is 200-300°C) to create the imprint stamp, i.e., the PDMS stamp with a columnar cavity structure. The PDMS stamp is a soft mold, which is more suitable for large-area imprinting than a hard mold because it allows for a gentler release of the mold from the edge, gradually covering the entire panel.

[0054] (d) A P(VDF-TrFE) film layer approximately 50 micrometers thick was laminated onto the prepared bottom electrode layer 5. To improve adhesion strength, the P(VDF-TrFE) film was directly treated with oxygen plasma before lamination to enhance adhesion. The P(VDF-TrFE) film layer was heated to 160°C (slightly above the melting point of P(VDF-TrFE)) to soften it, and the PDMS stamp was pressed into the P(VDF-TrFE) film layer so that the material of the P(VDF-TrFE) film layer filled the cavity in the PDMS stamp. After imprinting is completed, the PDMS stamp is released slowly and uniformly. After the PDMS stamp is removed, a columnar structure about 70 micrometers high and a P(VDF-TrFE) thin film layer about 10 micrometers thick are formed below the columnar structure. After the PDMS stamp is released, another P(VDF-TrFE) thin film about 20 micrometers thick is laminated on top of the columnar structure, finally forming the piezoelectric layer 3 and air columns 4. The top 20-micrometer P(VDF-TrFE) thin film will partially flow into the columnar structure on the bottom substrate after being softened by heating, thus providing a flat surface to facilitate the subsequent deposition of the top electrode. The piezoelectric layer 3 formed here consists of an array of ultrasonic transducer units 8 and air columns 4 that separate each ultrasonic transducer unit 8.

[0055] (e) A patterned common top electrode layer 2 is deposited by physical vapor deposition, and C-type parylene is used as the top flexible encapsulation layer 1 to protect the internal structure from the influence of the external environment.

[0056] like Figure 2 The piezoelectric layer 3 comprises multiple arrayed hexagonal air columns 4 that mechanically isolate adjacent ultrasonic transducer units 8. This significantly reduces acoustic crosstalk between adjacent acoustic elements, and the structure of the air columns 4 and the absence of piezoelectric ceramics increase the mechanical flexibility of the entire array, enhancing its bendability and providing the possibility of conforming to curved surfaces. Simultaneously, the hexagonal column shape and appropriate air spacing increase the effective piezoelectric area.

[0057] like Figure 2 In some embodiments, the piezoelectric layer 3 is arranged in a columnar array structure with a total of 64 ultrasonic transducer units 8, preferably polyvinylidene fluoride and its copolymer P (VDF-TrFE). This material has an acoustic impedance similar to human tissue, resulting in superior matching performance. Therefore, no coupling layer is required, and no coupling agent needs to be applied to the patient's eyelid 11 for acoustic coupling. In some embodiments, the piezoelectric layer 3 is composed of 80-150 micrometers thick polyvinylidene fluoride and its copolymer P (VDF-TrFE). In one specific example, the piezoelectric layer 3 is 80 micrometers thick polyvinylidene fluoride and its copolymer P (VDF-TrFE). In some embodiments, the top electrode layer 2 has a thickness of 200-400 nanometers. In one specific example, the top electrode layer 2 has a thickness of 400 nanometers. In some embodiments, the top flexible encapsulation layer 1 is a 5-10 micrometer thick C-type parylene film. In one specific example, the top flexible encapsulation layer 1 is a 5-micrometer thick C-type parylene film.

[0058] The bottom flexible encapsulation layer 7 is made of a flexible material, preferably the silicone elastomer Ecoflex-0030 in some embodiments, which is used to fit the surface of the eyelid 11 when worn by the patient and to encapsulate the internal structure, isolating it from interference from the external environment. The thickness is about 200 micrometers.

[0059] like Figure 3 In this embodiment, when measuring the elastic modulus of the cornea, the flexible ultrasonic patch 10 is tightly attached to the eyelid 11. By emitting a focused ultrasonic pulse 13 to a point on the cornea 12 through the flexible ultrasonic patch 10, the point on the cornea undergoes elastic deformation, generating a shear wave 14. Subsequently, the flexible ultrasonic patch switches to receiving mode to receive the reflected ultrasonic waves and detect the displacement 15 of the focal tissue. By constructing a spatiotemporal map of the displacement 15, the shear wave velocity is obtained through algorithms such as linear fitting, and then the elastic modulus of the corneal tissue is calculated.

[0060] The principle of this invention for monitoring corneal elastic modulus is as follows: A flexible ultrasonic patch is placed on the eyelid 11 of a lying patient, ensuring that the patch adheres tightly to the patient's closed eyelid 11. A signal generator and a power amplifier are connected to the electrodes of the flexible ultrasonic patch. The emission time and phase of the 16 ultrasonic transducer units 8 in the center of the piezoelectric layer 3 are calculated by a program algorithm, causing the signal generator to generate different voltage signals at both ends of the electrodes. The ultrasonic power is then amplified by the power amplifier, thereby causing the piezoelectric layer 3 to emit a high-power ultrasonic pulse signal to the same point on the corneal tissue, causing the cornea to undergo a slight elastic deformation. The ultrasonic waves reflected by the corneal tissue are then received by all the ultrasonic transducer units 8, constructing a displacement image of the tissue 15. The propagation velocity of the shear wave is obtained through algorithms such as linear fitting, and the elastic modulus of the cornea is calculated using the formula for calculating the elastic modulus.

[0061] The formula for calculating the corneal elastic modulus using the shear wave elastography method in this invention is as follows:

[0062] ,in The elastic modulus of the cornea. The density of the cornea, This represents the propagation speed of the shear wave.

[0063] The flexible ultrasound patch for monitoring corneal elastic modulus provided by this invention can be used for, but is not limited to, monitoring corneal elastic modulus. Compared with traditional rigid ultrasound probes and traditional corneal measurement tools, this invention is soft and comfortable, does not directly contact the cornea, can conform to the eyelid, broadens the application scenarios of corneal elastic modulus monitoring, and fills the gap in the field of nighttime corneal elastic modulus monitoring.

[0064] Compared with the prior art, the significant advantages of this invention are:

[0065] The flexible ultrasound patch for monitoring corneal elastic modulus provided by this invention can be used for, but is not limited to, monitoring corneal elastic modulus. Compared with traditional rigid ultrasound probes and traditional corneal measurement tools, this invention is soft and comfortable, does not directly contact the cornea, can conform to the eyelid, broadens the application scenarios of corneal elastic modulus monitoring, and fills the gap in the field of nighttime corneal elastic modulus monitoring.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible ultrasonic patch for monitoring the elastic modulus of the cornea, characterized in that, From top to bottom, it includes a top flexible encapsulation layer (1), a top electrode layer (2), a piezoelectric layer (3), a bottom electrode layer (5), a bottom flexible substrate isolation layer (6), and a bottom flexible encapsulation layer (7); the piezoelectric layer (3) has an air column (4) inside; the piezoelectric layer (3) also has an array assembled from several ultrasonic transducer units (8) inside, and the ultrasonic transducer units (8) are separated by air columns (4). The material of the flexible ultrasonic patch is composed of polymers and their composites; the thickness of the piezoelectric layer (3) is 80-150 micrometers.

2. The flexible ultrasonic patch for monitoring corneal elastic modulus according to claim 1, characterized in that, The bottom electrode layer (5) and the top electrode layer (2) serve as ports for receiving and transmitting signals, respectively, and both the bottom electrode layer (5) and the top electrode layer (2) are patterned.

3. The flexible ultrasonic patch for monitoring corneal elastic modulus according to claim 1, characterized in that, The materials of the bottom flexible encapsulation layer (7) include silicone elastomer Ecoflex-0030, polyurethane elastomer, PET film, and PDMS elastomer.

4. The flexible ultrasonic patch for monitoring corneal elastic modulus according to claim 1, characterized in that, The materials of the flexible substrate isolation layer (6) include polyimide and epoxy resin.

5. The flexible ultrasonic patch for monitoring corneal elastic modulus according to claim 1, characterized in that, The materials of the top flexible encapsulation layer (1) include parylene, parylene C, polyimide, polytetrafluoroethylene, and polybenzoxazole, and the thickness of the top flexible encapsulation layer (1) is 5-10 micrometers.

6. A method for preparing a flexible ultrasonic patch, characterized in that, The flexible ultrasonic patch is the flexible ultrasonic patch according to any one of claims 1-5, and specifically includes the following steps: Prepare a bottom flexible substrate isolation layer (6); A bottom electrode layer (5) is deposited and patterned on the bottom flexible substrate isolation layer (6); A piezoelectric layer was prepared by hot embossing (3); A top electrode layer (2) is deposited on top of the piezoelectric layer (3) and patterned; A top flexible encapsulation layer (1) is prepared on top of the top electrode layer (2); The bottom flexible encapsulation layer is encapsulated (7).

7. The method for preparing a flexible ultrasonic patch according to claim 6, characterized in that, The preparation of the piezoelectric layer (3) using the hot embossing method specifically includes the following steps: A master mold with a columnar structure is created using photolithography. The attributes of the columnar structure include shape, pattern, and height. The master mold is then cast and cured using PDMS to produce a PDMS stamp with a columnar cavity. A thin film is pressed onto the bottom electrode layer (5), the film is heated to soften it, and the PDMS stamp is pressed into the film so that the softened film fills the columnar cavity of the PDMS stamp. After the stamping is completed, the PDMS stamp is released. A thin film is laminated on top to form an air column (4) and an ultrasonic transducer unit (8), and finally a piezoelectric layer (3) is made.

8. The method for preparing a flexible ultrasonic patch according to claim 7, characterized in that, The film is subjected to oxygen plasma treatment before being pressed onto the bottom electrode layer (5).

9. The method for preparing a flexible ultrasonic patch according to claim 7, characterized in that, The main mold is made of epoxy resin; the film is made of polyvinylidene fluoride and its copolymers, or flexible piezoelectric ceramics.

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