A two-way fluid-structure interaction esophageal key point mechanical dynamic reconstruction method

Abstract

The application relates to a bidirectional fluid-structure coupling esophagus key point mechanical dynamic reconstruction method, and belongs to the technical field of tissue biomechanics detection. The method uses a system composed of a flexible liquid-filled balloon, a PVDF piezoelectric sensor, a traction guide tube, a signal processing and control terminal and the like to detect esophagus local key point stress; a collection system obtains a micro-variable piezoelectric matrix reflecting stress of four parts inside the balloon under a given frequency, and the micro-variable piezoelectric matrix is brought into a combined stress field-PVDF piezoelectric field calculation model, and finally the mechanical property reconstruction of the esophagus key point in a multi-level stress coupling field is realized. The application can reflect the biomechanics micro-variable properties of four nodes of the esophagus tube cavity under the balloon position, especially the active mechanical properties of the esophagus narrow part, can provide dynamic mechanical parameters for esophagus high-resolution pressure measurement, lumen mechanics reconstruction under the impedance area method, and thus can provide a scientific basis for esophagus dynamic function disease diagnosis.

Description

Technical Field

[0001] This invention belongs to the field of tissue biomechanical detection technology, and relates to a two-way fluid-structure interaction method for dynamic mechanical reconstruction of key points in the esophagus. Background Technology

[0002] Esophageal disorders, especially those related to motility, have a high incidence rate and are difficult to detect. Accurate detection of the biomechanical properties of the esophageal lining is crucial for diagnosing these disorders, but traditional detection methods have limitations. For example, endoscopic imaging-based gastroesophageal examinations focus on the morphological characteristics of the esophagus, primarily examining lesions of the esophageal mucosa. Other methods, such as esophageal manometry and distilled water perfusion manometry, are demanding and have significant limitations. Among emerging clinical testing technologies, high-resolution esophageal manometry (HRM) and functional luminal imaging probes (FLIP) are gaining acceptance due to their high-precision dynamic detection capabilities. FLIP uses a combination of balloon impedance area and in-band hydraulic pressure to morphologically reconstruct the balloon surface load, but it cannot capture the stress load and strain transfer of each component under dynamic micro-variations of the balloon. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a two-way fluid-structure interaction dynamic reconstruction method for esophageal key points. By using a flexible fluid-filled balloon catheter, the pressure changes at four longitudinal sections of the catheter inside the balloon during active strain movement are measured, thereby realizing the reconstruction of the mechanical properties of esophageal key points based on a combined stress field.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A bidirectional fluid-structure interaction method for dynamic reconstruction of esophageal critical points involves: using an esophageal critical point stress detection device to detect stress at local critical points in the esophagus; using a catheter of the active traction detection device to cause a balloon to undergo strain movement within the esophagus; and simultaneously, using a PVDF piezoelectric sensor in the detection device to output a time-series piezoelectric matrix reflecting the stress state of the detection device. This matrix is ​​input into a combined stress field-PVDF piezoelectric field calculation model to calculate the dynamic pressure load of the local critical points in the esophagus on the balloon, thereby reconstructing the mechanical properties of the local critical points in the esophagus.

[0006] Furthermore, the esophageal critical point stress detection device includes a catheter, a balloon, and a flexible PVDF piezoelectric sensor. The flexible PVDF piezoelectric sensor is attached to the front end of the catheter; the balloon completely seals the front end of the catheter to which the flexible PVDF piezoelectric sensor is attached.

[0007] Furthermore, the detection device is equipped with four flexible PVDF piezoelectric sensors to collect stress signals at different key points in the esophagus, outputting four sets of time-series piezoelectric signals, which are then processed to obtain the time-series piezoelectric matrix Y:

[0008]

[0009] In the formula, Y a Y b Y c and Y d These represent the signals collected by the four PVDF piezoelectric sensors. This represents the signals from frame 1 to frame n collected by the first PVDF piezoelectric sensor. Similarly, This represents the signals from frame 1 to frame n collected by the second PVDF piezoelectric sensor. This represents the signals from frame 1 to frame n collected by the third PVDF piezoelectric sensor. This indicates the signals from frame 1 to frame n collected by the fourth PVDF piezoelectric sensor.

[0010] Furthermore, the combined stress field-PVDF piezoelectric field calculation model includes a balloon cavity strain model, a balloon internal flow field micro-variation model, a catheter tip elastic strain model, and a balloon dynamic load reconstruction PVDF force-electric conversion model.

[0011] Furthermore, the balloon cavity strain model is used to calculate the balloon membrane wall stress, which is divided into cylindrical stress calculation and arc-shaped balloon wall stress calculation;

[0012] The stress calculation for the cylinder is shown in the following formula:

[0013]

[0014] In the formula, σ m σ represents axial stress. θ denoted by circumferential stress, P represents the hydraulic pressure inside the bladder under transient steady state, D represents the diameter of the bladder cylinder, and S represents the cross-sectional area of ​​the bladder cylinder.

[0015] The stress calculation for the arc-shaped capsule wall is shown in the following formula:

[0016]

[0017] In the formula, σ top σ represents the stress on the upper arc-shaped wall of the cyst cavity. bottom R represents the stress of the arc-shaped wall at the lower end of the sac cavity, R1 and R2 represent the first and second radii of curvature at any point within the arc-shaped sac wall, respectively, L represents the length of the arc-shaped wall, δ represents the thickness of the sac membrane wall, θ represents the calculated cutoff angle, V represents the volume of the fluid inside the sac, ρ represents the fluid density, and g represents the gravitational acceleration.

[0018] Furthermore, the micro-variation model of the flow field inside the balloon is used to calculate the stress of the fluid inside the balloon cavity. Combined with the stress calculation results of the balloon cavity wall, the axial strain and circumferential strain of the cylindrical balloon wall can be calculated.

[0019] The relationship between the strain of the cylindrical balloon wall and the stress of the balloon is shown in the following equation:

[0020]

[0021] In the formula, E is the Young's modulus of the balloon material, and v is the Poisson's ratio of the balloon material;

[0022] The fluid shear stress on the surface of the piezoelectric sensor is derived from the static Navier-Stokes equations, and the calculation of the fluid shear stress on the surface of the piezoelectric sensor is shown in the following formula:

[0023]

[0024] In the formula, P represents the fluid pressure distribution, and μ represents the fluid dynamic viscosity. Let τ be the gradient operator, u be the fluid velocity field, K be the bulk modulus, and τ be the mass modulus. turb Let be the fluid shear stress, and y be the direction perpendicular to the hose surface. This indicates that the derivative value is calculated on the surface of the hose.

[0025] Furthermore, the elastic strain model at the catheter tip is used to calculate the internal stress of the catheter caused by the elastic strain that occurs during the strain process of the detection device. The elastic strain is divided into axial tensile strain and bending strain, and the calculation method is as follows:

[0026]

[0027] In the formula, F N(拉伸) M represents the constant axial tensile force under axial tensile strain, where A represents the cross-sectional area of ​​the conduit, and M represents the axial constant tensile force. Z y represents the bending moment applied to a plane by an external force when the duct experiences bending strain. max I represents the maximum longitudinal deformation value. Z(弯曲) This represents the moment of inertia of the duct about the Z-axis of its cross-section.

[0028] Furthermore, the PVDF force-to-electric conversion model for balloon dynamic load reconstruction is used to calculate the output voltage value of stress conversion on the surface of the PVDF film material. The stress on the PVDF film surface is a linear superposition of the duct stress and the shear force of the fluid inside the balloon, and the calculation method is as follows:

[0029]

[0030] In the formula, σ PVDF The g value represents the surface stress of the PVDF film, s represents the surface area of ​​a single PVDF film, and g represents the surface stress of the PVDF film.31 The piezoelectric coefficient of a sensor, V, is expressed as a voltage constant. out This represents the theoretical output voltage of the piezoelectric sensor.

[0031] The beneficial effects of this invention are as follows: This invention reflects the biomechanical micro-change characteristics of four nodes of the esophageal lumen under the balloon position by measuring the stress load and strain transmission of each component under dynamic micro-change of the balloon, especially the main dynamic characteristics at the esophageal stenosis. It can provide dynamic mechanical parameters for high-resolution esophageal manometry and lumen mechanical reconstruction under impedance area method, thereby providing a scientific basis for the diagnosis of esophageal motility disorders.

[0032] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0034] Figure 1 The following are schematic diagrams of the detection device and system architecture of the present invention: (a) is a schematic diagram of the balloon structure, and (b) is a schematic diagram of the system architecture.

[0035] Figure 2 The diagram shows the stress field of multi-level fluid-structure interaction. (a) is a schematic diagram of the stress load and strain of the balloon membrane wall, (b) is a schematic diagram of the strain of the fluid inside the balloon, and (c) is a schematic diagram of the stress load and strain of the duct.

[0036] Figure 3 Reconstructing the framework for the mechanical properties of key points in the esophagus;

[0037] Figure 4 This is the strain output model for the PVDF sensing unit. Detailed Implementation

[0038] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0039] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0040] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0041] like Figure 1 The diagram shown illustrates the composition of the detection system of this invention. Figure 1 (a) shows the balloon structure. As shown in the figure, four PVDF piezoelectric sensors are evenly distributed on the surface of the catheter, which is sealed and wrapped by a high-toughness thin-film balloon cavity. This is the front end of the catheter insertion part. The flexible PVDF piezoelectric sensors operate at a frequency of 1Hz to 20Hz. The volume of liquid inside the sealed balloon cavity can be adaptively adjusted according to the detection requirements, allowing the balloon cavity to flexibly conform to the esophageal wall tissue. The four PVDF piezoelectric sensors are used to detect the stress changes at four stress detection points inside the balloon under tensile and torsional strain. By introducing the detection data into the combined stress field-PVDF piezoelectric field calculation model, the dynamic pressure load on the balloon cavity at four key local points of the esophagus that are coplanar with the four stress detection points inside the balloon can be obtained, thus completing the reconstruction of the mechanical properties of the key local points of the esophagus.

[0042] like Figure 1 (b) shows the system architecture of the detection device, which consists of a detection catheter, a signal processing and control terminal, and a host computer with a calculation model. The signal processing and control terminal processes the raw data collected by the PVDF piezoelectric sensor and transmits it to the host computer. The host computer with the combined stress field-PVDF piezoelectric field calculation model will complete the calculation of the stress load on the surface of the balloon membrane wall, thereby intuitively reflecting the dynamic mechanical characteristics of the key points of the esophagus where the balloon is located.

[0043] To facilitate the balloon structure in performing the corresponding detection work, this invention incorporates a circuit system integrating data acquisition, aspiration fluid control, and piezoelectric signal transmission modules in the signal processing and control terminal. The data acquisition module circuit consists of four stages: front-end charge amplification, voltage two-stage amplification, low-pass filtering, and 50Hz power frequency notch filtering. Under the control of the system MCU or CPU, it dynamically acquires multi-mode piezoelectric signals at different frequencies. After equivalent simplification of the charge source circuit under substeady state, the output charge of the PVDF sensor is calculated by the following formula:

[0044]

[0045] In the formula, C f Q represents the front-end equivalent matching capacitance of the circuit system. PVDF U represents the actual charge collected by the PVDF piezoelectric sensor. o This indicates the actual voltage output of the PVDF piezoelectric sensor.

[0046] The time-series piezoelectric matrix acquired by the detection device is defined as Y(4×n), where its four row vectors represent the time-series signal outputs of the first to fourth PVDF piezoelectric sensors from left to right. This reflects the pressure changes at the four longitudinal sections of the catheter within the sac during the current movement period, resulting from the combined effects of tensile and shear forces generated by catheter strain and shear forces generated by turbulent flow within the sac. The time-series piezoelectric matrix Y is shown in the following equation:

[0047]

[0048] The combined stress field-PVDF piezoelectric field calculation model in this invention is a mathematical and physical calculation model based on the multi-level fluid-structure interaction stress field, establishing the relationship between the outputs of four PVDF piezoelectric sensors and the stress of the balloon membrane wall, as follows: Figure 2 As shown. This model allows for the direct reconstruction of subtle changes in the mechanical properties of key points in the esophagus based on the detection data from the detection system. Specifically, by introducing the time-series piezoelectric matrix Y obtained by the detection system into a multi-field coupled computational model, the output is the dynamic load on the balloon surface, as shown. Figure 3 As shown, the detection system introduces the preprocessed time-series piezoelectric matrix Y into the coupled computation framework. The obtained process output can reflect the dynamic pressure on the four key points of the balloon cavity. By further fitting it, the final value output obtained is the dynamic pressure load of the four local key points of the esophagus on the balloon cavity, that is, the mechanical property reconstruction of the local key points of the esophagus.

[0049] During the tensile strain motion of the balloon, the superimposed stress field of the balloon strain is decomposed into five parts: the strain model of the PVDF piezoelectric film material, the strain model of the balloon cavity, the micro-variation model of the flow field inside the balloon, the elastic strain model of the catheter tip, and the PVDF force-electric conversion model of the balloon dynamic load reconstruction. The five parts are described in detail below.

[0050] (1) Strain model of PVDF piezoelectric thin film material

[0051] During the strain motion, the main strains are tensile strain, bending strain, and fluid shear strain. These are the stresses caused by the circumferential arching bending strain of the film due to the bending of the conduit, the stresses caused by the axial tensile strain of the film due to the stretching of the conduit, and the annular wrapping turbulent shear stress on the film surface caused by the turbulence within the closed balloon cavity. The strain model calculation for PVDF piezoelectric thin film materials is as follows: Figure 4 As shown, the stress generated by external traction will directly cause elastic strain in the catheter tip and PVDF. The two are coupled to each other, which is PVDF output component 1. The balloon cavity deforms under the load of the esophageal wall, generating an approximately turbulent fluid field in the balloon. The fluid shear stress under the metasteady state is PVDF output component 2. The two output components are superimposed and coupled in the sensor. After preprocessing, they will be used as the process output result and enter the coupling calculation framework.

[0052] When the conduit is stretched and bent, the PVDF piezoelectric sensor material satisfies the polarization stretching condition, which is supported by the generalized strain equation D for piezoelectric materials. i =∑ i,j d ij *T j The equation for the PVDF piezoelectric effect under external solid-state stress loading can be derived as follows:

[0053]

[0054] In the formula, D i d represents the actual piezoelectric coefficient of PVDF. 31 d 32 d 33 d 24 d 15 T1 to T6 represent the theoretical piezoelectric coefficients under various strain conditions, and T1 to T6 represent the stress calibration values ​​of the material under various strain conditions.

[0055] (2) Strain model of balloon cavity

[0056] like Figure 2 As shown in (a), under the tensile strain motion of the balloon pulled by the catheter, the dynamic stress loading condition of the esophagus on the balloon is decomposed into a non-uniform transverse annular pressure that varies with time and a constant axial double-end tension. In order to reduce the difficulty of analysis, it is necessary to ignore the secondary elastic deformation caused by the reaction shear stress of turbulence on the balloon membrane during the motion strain process.

[0057] The stress components of the balloon membrane wall under ideal conditions need to be decomposed into cylindrical stress and arc-shaped balloon wall stress for separate calculation. The calculation of cylindrical stress needs to consider the axial stress σ. mWith circumferential stress σ θ Let P be the hydraulic pressure inside the balloon under transient steady-state conditions, which can be estimated from piezoelectric detection data; D be the diameter of the balloon cylinder; and S be the cross-sectional area of ​​the balloon cylinder. The stress calculation equations for the balloon cavity cylinder are as follows:

[0058]

[0059] The stress on the arcuate wall of the balloon membrane needs to be analyzed from the upper and lower ends of the balloon cavity separately. Let R1 and R2 be the first and second radii of curvature at any point within the arcuate wall, respectively; L be the length of the arcuate wall; δ be the thickness of the balloon membrane; θ be the calculated truncated angle; P be the intra-balloon hydraulic pressure under transient steady-state conditions; V be the fluid volume; ρ be the fluid density; and g be the gravitational acceleration. The stress σ on the arcuate wall at the upper end of the balloon cavity is... top Stress σ at the lower curved wall bottom They are respectively:

[0060]

[0061] (3) Micro-variation model of the flow field inside the bladder

[0062] Under strain motion, the resulting turbulent structure is extremely complex, requiring a reasonable simplification of its changes. Specifically, this involves analyzing the turbulent flow field within the balloon cavity when a constant load is applied to a 10mm wide area at the center of the balloon surface. The stress loading positions are then adjusted to the corresponding lateral positions of the 1st, 2nd, 3rd, and 4th piezoelectric sensors. The constant load is then modified to a time-series dynamic load based on the esophageal wall structure. Finally, the subtle variations in the turbulent flow field within the balloon cavity are fitted, as shown below. Figure 2 As shown in (b), τ turb(2) With τ turb(3) The fluid shear stresses of the second and third piezoelectric sensors are given. F0 and F0′ are the annular pressure loads exerted locally by the esophageal inner wall on the outer wall of the balloon cavity, considered as equal forces pointing towards the central axis of the balloon cavity, directly generating the transient steady-state equivalent hydraulic pressure P of the fluid inside the balloon. Combining the stress calculation results of the balloon cavity wall, the axial strain and circumferential strain of the cylindrical balloon wall can be calculated:

[0063]

[0064] In the formula, E is the Young's modulus of the balloon material, and v is the Poisson's ratio of the balloon material;

[0065] The fluid shear stress on the surface of the piezoelectric sensor is derived from the static Navier-Stokes equations, and the calculation of the fluid shear stress on the surface of the piezoelectric sensor is shown in the following formula:

[0066]

[0067] In the formula, P represents the fluid pressure distribution, and μ represents the fluid dynamic viscosity. Let τ be the gradient operator, u be the fluid velocity field, K be the bulk modulus, and τ be the mass modulus. turb Let be the fluid shear stress, and y be the direction perpendicular to the hose surface. This indicates that the derivative value is calculated on the surface of the hose.

[0068] (4) Elastic strain model of catheter tip

[0069] The conduit tip is structurally directly coupled to four PVDF piezoelectric sensors. The elastic strain under solid-state load corresponds to the PVDF piezoelectric sensor unit, such as... Figure 2 As shown in (c), the conduit can be simplified as an elastic rod with a large Young's modulus. The tensile strain of the hose under axial tension and the bending strain of the hose under equivalent cross-sectional pressure are analyzed. The internal stress calculation equations are as follows:

[0070]

[0071] In the formula, σ represents the internal stress of the duct under two strains, and F N(拉伸) M represents the constant axial tensile force under tensile strain, A represents the actual cross-sectional area of ​​the catheter lumen, and M represents the tensile strain. Z y represents the bending moment on the plane of external force application when the duct experiences bending strain. max I represents the maximum longitudinal deformation value. z(弯曲) This represents the moment of inertia of the duct about the Z-axis of its cross-section.

[0072] (5) PVDF force-to-electric conversion model for reconstructing dynamic load on a balloon

[0073] This model is used to calculate the output voltage value of stress transformation on the surface of PVDF film material. The stress on the PVDF film surface is a linear superposition of the duct stress and the shear force of the fluid inside the bladder. The calculation method is as follows:

[0074]

[0075] In the formula, σ PVDF The g value represents the surface stress of the PVDF film, s represents the surface area of ​​a single PVDF film, and g represents the surface stress of the PVDF film. 31 The piezoelectric coefficient of a sensor, V, is expressed as a voltage constant. out This represents the theoretical output voltage of the piezoelectric sensor. The axial tensile stress of the duct is negligible due to its small value. The mechanical properties of the esophageal wall can be obtained from the output voltage of the PVDF piezoelectric sensor.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A two-way fluid-structure interaction dynamic reconstruction method for key points of the esophagus, characterized in that: The method is as follows: stress detection is performed at local key points in the esophagus using an esophageal key point stress detection device. The balloon is subjected to strain movement in the esophagus by actively traction of the catheter of the detection device. At the same time, the time-series piezoelectric matrix reflecting the stress situation of the detection device is output by the PVDF piezoelectric sensor in the detection device. This matrix is ​​input into the combined stress field-PVDF piezoelectric field calculation model to calculate the dynamic pressure load of the local key points in the esophagus on the balloon, thus completing the reconstruction of the mechanical properties of the local key points in the esophagus. The esophageal key point stress detection device includes a catheter, a balloon, and a flexible PVDF piezoelectric sensor; the flexible PVDF piezoelectric sensor is attached to the front end of the catheter; the balloon completely seals the front end of the catheter to which the flexible PVDF piezoelectric sensor is attached. The combined stress field-PVDF piezoelectric field calculation model includes a balloon cavity strain model, an intra-balloon flow field micro-variation model, a catheter tip elastic strain model, and a balloon dynamic load reconstruction PVDF force-electric conversion model. The balloon cavity strain model is used to calculate the balloon membrane wall stress, which is divided into cylindrical stress calculation and arc-shaped balloon wall stress calculation. The stress calculation for the cylinder is shown in the following formula: In the formula, Indicates axial stress. Indicates circumferential stress. P This indicates the hydraulic pressure inside the bladder under transient steady-state conditions. D Indicates the diameter of the balloon cylinder. S This represents the cross-sectional area of ​​the balloon cylinder; The stress calculation for the arc-shaped capsule wall is shown in the following formula: In the formula, This indicates the stress on the arc-shaped wall at the upper end of the cyst cavity. This indicates the stress on the arc-shaped wall at the lower end of the cyst cavity. and Let represent the first radius of curvature and the second radius of curvature at any point within the arcuate cyst wall, respectively. L Indicates the length of the curved wall. Indicates the thickness of the balloon membrane wall. This indicates the calculation of the intercept angle. V Indicates the volume of liquid inside the capsule. Indicates the density of the liquid. g Represents gravitational acceleration; The micro-variation model of the intracapsular flow field is used to calculate the stress of the fluid inside the balloon cavity, based on static... Navier-Stokes The equation derives the fluid shear stress on the surface of the piezoelectric sensor, which is calculated as follows: In the formula, P For fluid pressure distribution, For fluid dynamic viscosity, For gradient operators, u For the fluid velocity field, K Bulk modulus For fluid shear stress, y The direction perpendicular to the surface of the hose. This indicates that the derivative value is calculated on the surface of the hose; The elastic strain model at the catheter tip is used to calculate the internal stress of the catheter caused by the elastic strain that occurs during the strain process of the detection device. The elastic strain is divided into axial tensile strain and bending strain, and the calculation method is as follows: In the formula, This represents the constant axial tensile force under axial tensile strain. A Indicates the cross-sectional area of ​​the conduit. This represents the bending moment applied to a plane by an external force when the duct experiences bending strain. This represents the maximum longitudinal deformation value. This represents the moment of inertia of the duct about the Z-axis of its cross-section; The PVDF force-to-electric conversion model for balloon dynamic load reconstruction is used to calculate the output voltage value of stress conversion on the surface of the PVDF film material. The stress on the PVDF film surface is a linear superposition of the catheter stress and the shear force of the fluid inside the balloon, and the calculation method is as follows: In the formula, Indicates the surface stress of the PVDF film. s This represents the surface area of ​​a single PVDF film. The piezoelectric coefficient of a sensor is expressed in the form of a voltage constant. This represents the theoretical output voltage of the piezoelectric sensor.

2. The method for dynamic reconstructing the biomechanics of key points in the esophagus according to claim 1, characterized in that: Four flexible PVDF piezoelectric sensors were used to detect pressure loads at different key points in the esophagus, outputting four sets of time-series piezoelectric signals. After processing, the time-series piezoelectric matrix was obtained. Y : In the formula, , , and These represent the signals collected by four flexible PVDF piezoelectric sensors.

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