A method and system for measuring pressure in a passive human cavity based on a multi-stable cell string

Abstract

The application provides a kind of passive human cavity pressure measurement method and system based on multi-stable cell string, including receiving the deformation data of multi-stable cell string, wherein the multi-stable cell string generates deformation according to the pressure change of the cavity to be measured;Stress analysis is carried out on the deformation of the multi-stable cell string, and cell stress data is obtained;The mapping relationship between the deformation field and the pressure field is established based on the cell stress data;According to the mapping relationship, the deformation data of the multi-stable cell string is pressure inversion, and the pressure data of the cavity to be measured is obtained.The application can respond to the pressure change in the human cavity through the deformation of the multi-stable cell string, then through the mapping relationship between the deformation field and the pressure field, the pressure data and the deformation data are calibrated or converted, the pressure indicators after pressure measurement are quickly read and converted, and the pressure measurement efficiency of the human cavity is improved.

Description

Technical Field

[0001] This invention relates to the field of medical testing technology, and in particular to a passive human body cavity pressure measurement method and system based on multistable cell strings. Background Technology

[0002] In clinical practice, it is frequently necessary to measure the pressure within human body cavities (e.g., heart chambers, thoracic cavity, abdominal cavity, bladder cavity, rectal cavity, anal canal, urethra, vagina, etc.) to diagnose diseases or assess organ function. For example, an anorectal manometry device is needed to assess anorectal function. Similarly, bladder manometry is performed to assess bladder function, and urethral manometry is performed for urodynamic analysis, and so on.

[0003] Current research on pressure measuring devices for human body cavities, both domestically and internationally, mainly focuses on sensor integration, lacking practical research on portable devices and failing to meet the needs for ease of use in clinical practice. A comprehensive analysis of existing technologies reveals that current pressure measurement methods require bulky data acquisition hardware to collect and decode the measured electric field, necessitating complex calculations and processing using specialized software, making it impossible to obtain measurement data directly.

[0004] Multistable cells are special structural units that can exhibit multiple stable configurations under different external conditions or stimuli. This characteristic makes multistable cells a promising candidate for applications in various fields, such as reconfigurable metamaterials, deformable structures, and energy-absorbing structures. However, multistable cells are rarely used in clinical settings in the medical field. The complexity of the human body structure necessitates recalculation and processing of the compressive deformation of multistable cells to obtain accurate data reflecting the pressure changes of human organs or anatomical structures in specific clinical scenarios. Furthermore, applying multistable cells to specific clinical scenarios requires first designing appropriate pressure processing and analysis algorithms based on the characteristics of the clinical setting before further designing portable devices suitable for those scenarios.

[0005] Therefore, there is a need to develop a method to reflect pressure changes within human body cavities by measuring and analyzing the deformation of multistable cells, i.e., a passive method for measuring pressure within human body cavities. Summary of the Invention

[0006] This invention provides a passive human body cavity pressure measurement method and system based on multistable cell strings to overcome the shortcomings of existing technologies.

[0007] This invention provides a passive human body cavity pressure measurement method based on multistable cell strings, comprising:

[0008] S1: Receive deformation data of a multistable cell string, wherein the multistable cell string deforms according to the pressure change of the cavity under test;

[0009] S2: Perform force analysis on the deformation of the multistable cell string to obtain cell force data;

[0010] S3: Establish a mapping relationship between the deformation field and the pressure field based on the cell force data;

[0011] S4: Based on the mapping relationship, pressure inversion is performed on the deformation data of the multistable cell string to obtain the pressure data of the cavity to be tested.

[0012] In this invention, the multistable cell string is composed of multiple multistable cells connected in series. The multistable cell can be a curved beam structure, which deforms when subjected to pressure.

[0013] In this invention, the human body cavity can be any of the various chambers of the heart, the thoracic cavity, the abdominal cavity, the bladder cavity, the urethra, the vagina, the rectum, the anal canal, or other natural cavities of the human body.

[0014] According to the present invention, a passive human body cavity pressure measurement method based on multistable cell strings is provided. In step S2, the stress analysis of the deformation of the multistable cell strings is performed by simulating the bending part of a single cell structure in the multistable cell string as an initially bent fixed Euler-Bernoulli beam, and assuming the unbent part of a single cell structure as rigid.

[0015] According to the present invention, a passive human body cavity pressure measurement method based on a multistable cell string is provided, wherein the governing equation of the fixed Euler-Bernoulli beam is expressed as follows:

[0016]

[0017] in, It is Young's module. It is the moment of inertia of the beam's surface. For differential operators, It is the lateral deflection of the beam. It's pressure. It is the span of the beam. This is the initial shape of the beam. The position of the beam, It is the Dirac increment function. Let be the transverse force acting on the midpoint of the beam.

[0018] According to the present invention, a passive human body cavity pressure measurement method based on a multistable cell string is provided. In step S2, the cell force data is the compressive force of the multistable cell string, and the expression for the compressive force is:

[0019]

[0020]

[0021] in, For compressive force, For the change in beam length, The initial beam length, Let be the cross-sectional area of ​​the beam.

[0022] According to the passive human body cavity pressure measurement method based on multistable cell strings provided by the present invention, the expression of the deformation field in step S3 is as follows:

[0023]

[0024]

[0025]

[0026] in, For the normalized deformation field, The modal index value of the multistable cell string. For the first Modal coefficients of each mode, For a normalized pressure field, For the first The coefficients of the first mode shape, The compressive force on a normalized multistable cell string;

[0027] The expression for the quadratic equation of the pressure field is:

[0028]

[0029]

[0030]

[0031]

[0032] in, is the first coefficient of the quadratic equation for the pressure field. is the second coefficient of the quadratic equation for the pressure field. is the third coefficient of the quadratic equation for the pressure field. These are the coefficients of the first-order mode shape. The coefficients of the third-order mode shape. This is the ratio of the height to the thickness of the bending beam. This represents the modal defect size.

[0033] According to the passive human body cavity pressure measurement method based on multistable cell strings provided by the present invention, step S3 further includes:

[0034] S31: Solve the quadratic equation of the pressure field by taking multiple terms of the vector of compressive forces on the normalized multistable cell string, and obtain multiple equation roots;

[0035] S32: Multiple modal coefficient values ​​and multiple deformation field values ​​are obtained by calculating multiple equation roots;

[0036] S33: Based on multiple modal coefficient values ​​and multiple deformation field values, plot the function curves of the pressure field and the deformation field to obtain the mapping relationship between the deformation field and the pressure field.

[0037] According to the passive human body cavity pressure measurement method based on multistable cell strings provided by the present invention, in step S31, when solving the quadratic equation of the pressure field, the discriminant of the quadratic equation of the pressure field is analyzed. When the discriminant is less than 0, the quadratic equation of the pressure field is solved by the next term of the vector of the compressive force on the normalized multistable cell string; when the discriminant is greater than 0, the solution of the quadratic equation of the pressure field is output as the root of the equation.

[0038] According to the passive human body cavity pressure measurement method based on multistable cell strings provided by the present invention, step S4 further includes:

[0039] S41: Convert deformation data into pressure result data using mapping relationships;

[0040] S42: Visualize the pressure results data.

[0041] This invention also provides a passive human body cavity pressure measurement system based on multistable cell strings, comprising:

[0042] Multistable cell strings, computing devices;

[0043] When the multistable cell string is placed in the cavity to be tested, it can generate deformation data based on the pressure change of the cavity to be tested. The processor in the computing device executes steps S1-S4 of any one of claims 1-8 to calculate the pressure data of the cavity to be tested.

[0044] According to the present invention, a passive human body cavity pressure measurement system based on multistable cell strings is provided, wherein the computing device specifically includes:

[0045] Deformation calibration module and calculation module;

[0046] The deformation calibration module is used to detect the deformation data of the multistable cell string;

[0047] The computing module further includes:

[0048] Force analysis unit: Used to perform force analysis on the deformation of multistable cell strings and obtain cell force data;

[0049] Mapping relationship establishment unit: used to establish a mapping relationship between the deformation field and the pressure field based on the cell force data;

[0050] Pressure inversion unit: used to perform pressure inversion on the deformation data of the multistable cell string according to the mapping relationship, and obtain the pressure data of the cavity under test.

[0051] This invention provides a passive human body cavity pressure measurement method and system based on multistable cell strings. It senses the pressure changes in the cavity under test by observing the multi-level deformation behavior of a multistable pressure measurement structure formed by multiple multistable cells connected in series. Subsequently, a mapping relationship between the deformation field and the pressure field under the action of a nonlinear external force field is established. The deformation of the multistable cell string is then rapidly calibrated, and the pressure data is obtained by inverting the deformation data through the mapping relationship. Through the calibration or conversion of this pressure measurement method, various key indicators after pressure measurement can be quickly read and calculated, improving the accuracy and efficiency of human body cavity pressure measurement. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of a passive human body cavity pressure measurement method based on multistable cell strings provided in an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of a passive human body cavity pressure measurement system based on a multistable cell string, provided in an embodiment of the present invention.

[0055] Figure 3 This is a schematic diagram of a single multistable cell string embodiment used in a passive human body cavity pressure measurement method based on multistable cell strings according to the present invention.

[0056] Figure 4 This is a schematic diagram illustrating the parameter identification of a single cell structure in a multistable cell string provided in an embodiment of the present invention;

[0057] Figure 5This is a schematic diagram of the equivalent stress deformation of the cell structure at the midpoint of the beam in a multistable cell string provided by an embodiment of the present invention when subjected to a transverse force. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] The following is combined Figures 1 to 5 Description of embodiments of the present invention.

[0060] like Figure 1 As shown, this invention provides a passive human body cavity pressure measurement method based on multistable cell strings, comprising:

[0061] S1: Receive deformation data of a multistable cell string, wherein the multistable cell string deforms according to the pressure change of the cavity under test.

[0062] S2: Perform force analysis on the deformation of the multistable cell string to obtain cell force data.

[0063] In step S2, the stress analysis of the deformation of the multistable cell string is performed by simulating the bent part of a single cell structure in the multistable cell string as an initially bent fixed Euler Bernoulli beam, and assuming the unbent part of a single cell structure as rigid.

[0064] The governing equation of the fixed Euler Bernoulli beam is expressed as follows:

[0065]

[0066] in, It is Young's module. It is the moment of inertia of the beam's surface. For differential operators, It is the lateral deflection of the beam. It's pressure. It is the span of the beam. This is the initial shape of the beam. The position of the beam, It is the Dirac increment function. Let be the transverse force acting on the midpoint of the beam.

[0067] In step S2, the cell force data is the compressive force of the multistable cell string, and the expression for the compressive force is:

[0068]

[0069]

[0070] in, For compressive force, For the change in beam length, The initial beam length, Let be the cross-sectional area of ​​the beam.

[0071] Furthermore, such as Figure 4 As shown, this invention simulates the curved portion of the cell structure as an initially curved, fixed Euler-Bernoulli beam, while assuming the other parts of the cell to be rigid, such as... Figure 5 As shown, the lateral force It is applied at the midpoint of the beam.

[0072] Based on the governing equations of the beam described above, assuming the model has no pattern defects, the initial shape of the beam is... It is given by the following formula:

[0073]

[0074] In the formula Let be the initial vertex height of the beam. For the first buckling mode of the fixed-fixed Euler-Bernoulli beam, in order to obtain a definite deformation sequence, a model that is not completely proportional to the third buckling mode was also considered. In the model of the third buckling mode, It then becomes:

[0075]

[0076] In the formula, It is a mode shape defect, and its specific expression is:

[0077]

[0078] In the formula, It is the third buckling mode of a fixed-support beam. It is the modal defect size; the case of a model without defects corresponds to... This makes a model with pattern defects a generalization of a model without defects.

[0079] For a single unit cell, the compressive force Caused by the reduction in the total length of the beam, the specific expression is:

[0080]

[0081] in It is the cross-sectional area of ​​the beam. It is the change in beam length. This refers to the initial beam length and the changed beam length. It is given by the following formula:

[0082]

[0083] when and When this is the case, the following approximation holds:

[0084]

[0085]

[0086] Therefore, the compressive force can be obtained from the four calculation formulas above. The expression.

[0087] The lateral deflection of the beam at its midpoint It is given by the following formula:

[0088]

[0089] because Corresponding to the change in cell height when a transverse load is applied, therefore we will This is called a cell-based transformation.

[0090] S3: Establish a mapping relationship between the deformation field and the pressure field based on the cell force data.

[0091] The expression for the deformation field in step S3 is as follows:

[0092]

[0093]

[0094]

[0095] in, For the normalized deformation field, The modal index value of the multistable cell string. For the first Modal coefficients of each mode, For a normalized pressure field, For the first The coefficients of the first mode shape, The compressive force on a normalized multistable cell string;

[0096] The expression for the quadratic equation of the pressure field is:

[0097]

[0098]

[0099]

[0100]

[0101] in, is the first coefficient of the quadratic equation for the pressure field. is the second coefficient of the quadratic equation for the pressure field. is the third coefficient of the quadratic equation for the pressure field. These are the coefficients of the first-order mode shape. The coefficients of the third-order mode shape. This is the ratio of the height to the thickness of the bending beam. This represents the modal defect size.

[0102] To determine the normalized force-normalized deformation curve, that is, to establish the deformation field under the action of a nonlinear external force field. With pressure field The mapping relationship between the two decomposes the beam deflection into the sum of the buckling modes of the initially straight-fixed and fixed-supported beams, specifically expressed as:

[0103]

[0104] in It is a modal shape. It is the modal amplitude. For numerical results, only the first 13 modes are considered.

[0105] in, The expression is:

[0106]

[0107]

[0108] Based on the above formula, the modal amplitude can be obtained using the variational method. The nonlinear equation system.

[0109] And total potential energy The change is given by the following formula:

[0110]

[0111] in , and These represent the changes in bending strain energy, compressive strain energy, and external potential energy, respectively, which are given by the following equations:

[0112]

[0113]

[0114]

[0115] The following standardizations were also introduced:

[0116]

[0117]

[0118] Using the formula above , , And from the above-mentioned normalized equations, we can obtain the normalized transformation. and normalized compressive force It can be represented as normalized modal amplitude. Functions:

[0119]

[0120]

[0121] in In addition, the change in total potential energy It can be represented as:

[0122]

[0123] Using the minimum potential energy theorem The following set of nonlinear equations can be obtained:

[0124]

[0125]

[0126]

[0127]

[0128]

[0129] For the theoretical model of the initial bending beam, when the second mode is constrained, i.e., only the symmetric solution is considered, which means that... Regarding the shortcomings of the third mode There is only one form of solution, which leads to the normalized modal amplitude being given by the following equation:

[0130]

[0131]

[0132]

[0133]

[0134] From the above and We can obtain the normalizing force. The quadratic equation is expressed as follows:

[0135]

[0136] in:

[0137]

[0138]

[0139]

[0140] Step S3 further includes:

[0141] S31: Solve the quadratic equation of the pressure field by taking multiple terms of the vector of compressive forces on the normalized multistable cell string, and obtain multiple equation roots;

[0142] In step S31, when solving the quadratic equation of the pressure field, the discriminant of the quadratic equation of the pressure field is analyzed. When the discriminant is less than 0, the quadratic equation of the pressure field is solved by the next term of the vector of the compressive force on the normalized multistable cell string. When the discriminant is greater than 0, the solution of the quadratic equation of the pressure field is output as the root of the equation.

[0143] S32: Multiple modal coefficient values ​​and multiple deformation field values ​​are obtained by calculating multiple equation roots;

[0144] In steps S31 to S32, in step S31, the normalized compressive force is first formed. Given a vector, solve for the normalized force for each term of that vector. The quadratic equation, if the discriminant of the equation is... A negative value means that a normalized compressive force value is impossible if... If it is positive, then the normalizing force can be obtained. The two roots, and for each of these roots, the corresponding mode coefficient All can be obtained from the expression for the normalized modal amplitude, normalized deformation It can also be obtained from the above equation.

[0145] S33: Based on multiple modal coefficient values ​​and multiple deformation field values, plot the function curves of the pressure field and the deformation field to obtain the mapping relationship between the deformation field and the pressure field.

[0146] After step S2, the value of the normalized force can be plotted as a function of the normalized deformation at each root, corresponding to... of Connecting the points obtained from each term of the vector, a pressure field can be obtained for each of the two root families. With deformation field The two curves converge to the curve corresponding to the curve. By connecting these two curves, we obtain a single curve representing the normalized force and normalized deformation, thus obtaining the deformation field under the action of a nonlinear external force field. With pressure field The mapping relationship curve between them.

[0147] S4: Based on the mapping relationship, pressure inversion is performed on the deformation data of the multistable cell string to obtain the pressure data of the cavity to be tested.

[0148] Step S4 further includes:

[0149] S41: The deformation data is converted into pressure result data using the mapping relationship;

[0150] S42: Visualize the pressure results data.

[0151] After steps S1 to S3, the deformation field under the action of the obtained nonlinear external force field can be used as a basis. With pressure field The mapping relationship curve between the two is based on the deformation data calibrated by the deformation measurement rapid calibration technology, which transforms the deformation field data into pressure field data, enabling convenient acquisition of clinical pressure indicators, and the results can be displayed to users in a visual or other form.

[0152] like Figure 2 As shown, the present invention also provides a passive human body cavity pressure measurement system based on multistable cell strings, for performing a passive human body cavity pressure measurement method based on multistable cell strings as described in any of the above claims, comprising:

[0153] Multistable cell string 100, computing device;

[0154] When the multistable cell string 100 is placed in the cavity to be tested, it can generate deformation data based on the pressure change of the cavity to be tested. The processor in the computing device executes any of the above S1-S4 steps to calculate and obtain the pressure data of the cavity to be tested.

[0155] Furthermore, the structure of a multistable cell string of 100 is as follows: Figure 3 As shown, when subjected to external stimuli, cell 110 in the cell string can deform according to changes in external pressure. This deformation includes not only the microscopic changes in the relative positions between cells 110, but also the macroscopic changes in the shape of the entire cell string. In pressure measurement of human cavities (e.g., heart cavity, thoracic cavity, bladder cavity, rectal cavity, urethra, vagina, etc.), the multistable cell string, as a sensitive element, converts the pressure changes in the area to be measured into measurable deformation.

[0156] By setting up multiple multistable cell strings and connecting them in parallel along the length of the shell, a more comprehensive and refined measurement of the pressure distribution in the area to be measured can be achieved. Since each cell string can independently sense and respond to pressure changes, more accurate and reliable pressure field information can be obtained by integrating the measurement data of multiple cell strings.

[0157] In one embodiment, the multistable cell can be a curved beam structure, which deforms under pressure. Curved beams exhibit more complex characteristics under stress, including the coupling of axial deformation and in-plane bending, the coupling of vertical deflection and torsion, and the coupling with cross-sectional distortion. Among these, the coupling of deflection and torsional deformation is the most significant; that is, under vertical loads and torque, the curved beam simultaneously generates bending and torsional moments, which influence each other.

[0158] When subjected to external pressure, the curved beam structure can undergo significant deformation or displacement. Therefore, in one embodiment, this deformation or displacement can be directly captured by pressure sensors mounted on the curved beam and converted into electrical signals or other forms of processable data. In other words, when the curved beam is subjected to pressure, due to the "bending-torsion" coupling effect, its principal tensile stress is greater, thereby increasing its sensitivity to pressure changes.

[0159] According to the present invention, a passive human body cavity pressure measurement system based on multistable cell strings is provided, wherein the computing device specifically includes:

[0160] Deformation calibration module 200, calculation module 300;

[0161] The deformation calibration module 200 is used to detect the deformation data of the multistable cell string;

[0162] The computing module 300 specifically includes:

[0163] Force analysis unit 310: used to perform force analysis on the deformation of multistable cell strings and obtain cell force data;

[0164] Mapping relationship establishment unit 320: used to establish a mapping relationship between the deformation field and the pressure field based on the cell force data;

[0165] Pressure inversion unit 330: used to perform pressure inversion on the deformation data of the multistable cell string according to the mapping relationship, and obtain the pressure data of the cavity to be tested.

[0166] This invention provides a passive human cavity pressure measurement system based on a multistable cell string. The multistable cell string enables a passive design, eliminating the need for external power supplies or complex electronic devices for direct intervention in the human body. This significantly reduces surgical risks, infection risks, and the impact on patients' daily lives, improving measurement safety and patient comfort. The multistable cell string, as a pressure sensing element, possesses high precision and stable deformation characteristics, accurately responding to pressure changes within the measured cavity. These changes are precisely measured by a deformation calibration module, providing reliable input data for the calculation module, thereby retrieving high-precision pressure data. Furthermore, due to the system's passive nature and excellent performance... Its biocompatibility allows for long-term, even long-term, implantation within the body to continuously monitor changes in cavity pressure, providing continuous and dynamic reference data for clinical diagnosis and treatment. Furthermore, the system structure is relatively simple, facilitating integration with existing medical equipment or diagnostic procedures. It can be widely applied to pressure monitoring in various human cavities such as the heart, chest, abdomen, bladder, vagina, urethra, and rectum, providing doctors with more comprehensive diagnostic information. It also offers real-time feedback and rapid response: through real-time processing and inversion of deformation data via a calculation module, the system can quickly generate pressure data, providing doctors with immediate feedback and helping to promptly assess changes in the patient's condition and formulate treatment plans.

[0167] This invention provides a passive human cavity pressure measurement method based on multistable cell strings. By simulating the curved portion of the cell structure as an initially bent, fixed Euler-Bernoulli beam, while assuming the other parts of the cell are rigid, the method performs force analysis on the beam using its governing equations. Subsequently, by decomposing the beam's deflection and using modal amplitude and potential energy changes, expressions for normalized force, normalized compressive force, and normalized deformation are established. This establishes a mapping relationship between the deformation field and pressure field under a nonlinear external force field. Finally, this mapping relationship enables rapid calibration and conversion of deformation and pressure data. This eliminates the need for external hardware for data acquisition and decoding in human cavity pressure measurement. Through mechanical principles, the method utilizes the body's own deformation response, and then, based on calibration or conversion, quickly reads and calculates various key indicators after pressure measurement, completing the measurement and improving simplicity and efficiency in reading pressure indicators.

[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive human body cavity pressure measurement method based on multistable cell strings, characterized in that, include: S1: Receive deformation data of a multistable cell string, wherein the multistable cell string deforms according to the pressure change of the cavity under test; S2: Perform force analysis on the deformation of the multistable cell string to obtain cell force data; In step S2, the stress analysis of the deformation of the multistable cell string is performed by simulating the bent part of a single cell structure in the multistable cell string as an initially bent fixed Euler Bernoulli beam, and assuming the unbent part of a single cell structure as rigid. The governing equations of the fixed Euler Bernoulli beam are expressed as follows: in, It is Young's module. It is the moment of inertia of the beam's surface. For differential operators, It is the lateral deflection of the beam. It's pressure. It is the span of the beam. This is the initial shape of the beam. The position of the beam, It is the Dirac increment function. The transverse force acting on the midpoint of the beam; The cell force data is the compressive force of the multistable cell string, and the expression for the compressive force is: in, For compressive force, For the change in beam length, The initial beam length, Let be the cross-sectional area of ​​the beam; S3: Establish a mapping relationship between the deformation field and the pressure field based on the cell force data; The expression for the deformation field in step S3 is: in, For the normalized deformation field, The modal index value of the multistable cell string. For the first Modal coefficients of each mode, For a normalized pressure field, For the first The coefficients of the first mode shape, The compressive force on a normalized multistable cell string; The expression for the quadratic equation of the pressure field is: in, is the first coefficient of the quadratic equation for the pressure field. is the second coefficient of the quadratic equation for the pressure field. is the third coefficient of the quadratic equation for the pressure field. These are the coefficients of the first-order mode shape. The coefficients of the third-order mode shape. This is the ratio of the height to the thickness of the bending beam. The size of the modal defect; S4: Based on the mapping relationship, pressure inversion is performed on the deformation data of the multistable cell string to obtain the pressure data of the cavity to be tested.

2. The passive human body cavity pressure measurement method based on multistable cell strings according to claim 1, characterized in that, Step S3 further includes: S31: Solve the quadratic equation of the pressure field by taking multiple terms of the vector of compressive forces on the normalized multistable cell string, and obtain multiple equation roots; S32: Multiple modal coefficient values ​​and multiple deformation field values ​​are obtained by calculating multiple equation roots; S33: Based on multiple modal coefficient values ​​and multiple deformation field values, plot the function curves of the pressure field and the deformation field to obtain the mapping relationship between the deformation field and the pressure field.

3. The passive human body cavity pressure measurement method based on multistable cell strings according to claim 2, characterized in that, In step S31, when solving the quadratic equation of the pressure field, the discriminant of the quadratic equation of the pressure field is analyzed. When the discriminant is less than 0, the quadratic equation of the pressure field is solved by the next term of the vector of the compressive force on the normalized multistable cell string. When the discriminant is greater than 0, the solution to the quadratic equation of the pressure field is output as the root of the equation.

4. The passive human body cavity pressure measurement method based on multistable cell strings according to claim 2, characterized in that, Step S4 further includes: S41: Convert deformation data into pressure result data using mapping relationships; S42: Visualize the pressure results data.

5. A passive human body cavity pressure measurement system based on multistable cell strings, characterized in that, include: Multistable cell strings, computing devices; When the multistable cell string is placed in the cavity to be tested, it can generate deformation data based on the pressure change of the cavity to be tested. The processor in the computing device executes steps S1-S4 of any one of claims 1 to 4 to calculate the pressure data of the cavity to be tested.

6. A passive human body cavity pressure measurement system based on multistable cell strings according to claim 5, characterized in that, The computing device specifically includes: Deformation calibration module and calculation module; The deformation calibration module is used to detect the deformation data of the multistable cell string; The computing module further includes: Force analysis unit: Used to perform force analysis on the deformation of multistable cell strings and obtain cell force data; Mapping relationship establishment unit: used to establish a mapping relationship between the deformation field and the pressure field based on the cell force data; Pressure inversion unit: used to perform pressure inversion on the deformation data of the multistable cell string according to the mapping relationship, and obtain the pressure data of the cavity under test.

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