Pressure measuring device and pressure measuring equipment

Abstract

The present invention relates to the technical field of medical equipment used in artificial knee replacement surgery, and discloses a pressure measuring device and a pressure measuring equipment, wherein the pressure measuring device comprises a bottom packaging layer, a piezoelectric electret layer and a top packaging layer which are sequentially stacked along a first direction, the piezoelectric electret layer has a plurality of microcavities, and a diaphragm is arranged in the microcavities, at least one bottom electrode block is arranged on the surface of the piezoelectric electret layer facing the bottom packaging layer, and at least one top electrode block is arranged on the surface of the piezoelectric electret layer facing the top packaging layer, the bottom electrode block and the top electrode block respectively cover at least one microcavity, and at least part of the microcavity is covered by the bottom electrode block and the top electrode block at the same time; the bottom electrode block and the top electrode block are respectively connected to an external circuit, and are used to output an electrical signal to the external circuit when the microcavity is deformed under the action of an external force.

Description

Technical Field

[0001] The present invention relates to the technical field of medical equipment applied to artificial knee replacement surgery, and in particular to a pressure measuring device and pressure measuring equipment. Background Art

[0002] With the aging of the population, the number of patients suffering from knee diseases has been on the rise in recent years. Knee diseases can cause knee pain, swelling, reduced range of motion and other discomforts, seriously affecting patients' daily lives. Artificial knee replacement surgery is currently a relatively effective method for treating knee diseases, which can relieve patients' pain and improve their quality of life.

[0003] When performing an artificial knee replacement, a tibial spacer is placed between the tibial component and the femoral component of the knee prosthesis. The force between the upper surface of the tibial spacer and the medial and lateral condyles of the femoral component is often unbalanced. During the operation, the doctor often adjusts the force balance by adjusting the tightness of the ligaments on both sides of the knee joint to make the force reasonable after the artificial knee joint is implanted in the human body, thereby improving the patient's quality of life after surgery.

[0004] In the existing technology, doctors are unable to accurately obtain the stress conditions between knee prostheses. Doctors usually insert their fingers into both sides of the knee joint cavity and adjust the tightness of the ligaments based on experience. This brings certain risks and unstable factors to artificial knee replacement surgery. Once improperly adjusted, it will affect the patient's postoperative recovery. Summary of the invention

[0005] The present invention provides a pressure measuring device and a pressure measuring equipment, which are used to solve the problem in the prior art that the force conditions between knee joint prostheses cannot be accurately obtained during artificial knee joint replacement surgery, and thus cannot provide guarantee for ligament adjustment.

[0006] In a first aspect, an embodiment of the present invention provides a pressure measurement device, comprising a thin film substrate, the thin film substrate being used to be attached to the surface of a tibial pad in an artificial knee joint prosthesis to measure the pressure applied by a femoral component in the artificial knee joint prosthesis to the surface of the tibial pad;

[0007] The thin film substrate comprises a bottom packaging layer, a piezoelectric electret layer and a top packaging layer which are sequentially stacked along a first direction, the piezoelectric electret layer comprises a plurality of microcavities, and a diaphragm is arranged in the microcavity, at least one bottom electrode block is arranged on the surface of the piezoelectric electret layer facing the bottom packaging layer, and at least one top electrode block is arranged on the surface of the piezoelectric electret layer facing the top packaging layer, the bottom electrode block and the top electrode block respectively cover at least one of the microcavities, and at least part of the microcavity is covered by the bottom electrode block and the top electrode block at the same time;

[0008] The bottom electrode block and the top electrode block are respectively connected to an external circuit, and are used to output an electrical signal to the external circuit when the microcavity is deformed under the action of an external force.

[0009] In the above embodiment, the piezoelectric electret layer of the pressure measuring device includes a plurality of microcavities. When the microcavities are deformed under the action of external force, the electric dipole moment changes, causing the compensation charge in the bottom electrode block and the top electrode block to change, thereby displaying a corresponding charge or voltage signal to the outside, and transmitting the piezoelectric effect to the external circuit. After the external circuit analyzes and processes the output electrical signal, it can determine the pressure information on the surface of the tibial pad, thereby providing data support for doctors during surgery.

[0010] Optionally, the film-like matrix is ​​attached to a region of the surface of the tibial pad corresponding to the medial condyle or lateral condyle of the femoral component.

[0011] In the above embodiment, when the pressure measuring device is in use, the film substrate can be attached to a local area of ​​the tibial pad surface, and one or two film substrates can be used as needed, so that the film substrate can better adapt to the uneven surface structure of the tibial pad surface.

[0012] Optionally, the film-like matrix includes a first region, a second region, and an intermediate region arranged between the first region and the second region, the first region corresponds to the medial condyle of the femoral component, the second region corresponds to the lateral condyle of the femoral component, and the microcavities are distributed in the first region and the second region.

[0013] In the above embodiment, when the pressure measuring device is in use, the film-like substrate can be attached to the entire surface area of ​​the tibial pad, and by making the middle area wrinkled to an appropriate degree, the first area can correspond to the medial condyle of the femoral component and the second area can correspond to the lateral condyle of the femoral component.

[0014] Optionally, the microcavities are arranged in an array.

[0015] In the above embodiment, by arranging the microcavity array, the density of the microcavities can be increased and the sensitivity can be improved.

[0016] Optionally, the bottom electrode blocks and the top electrode blocks are cross-arranged along the row direction and the column direction of the array formed by the microcavities.

[0017] In the above embodiment, in terms of space, when the microcavity located in the intersection area of ​​the bottom electrode block and the top electrode block is squeezed, the bottom electrode block and the top electrode block can output electrical signals to the external circuit.

[0018] Optionally, the bottom electrode block extends along the row direction of the array formed by the microcavities, and one or more rows of the microcavities are arranged between two adjacent bottom electrode blocks, and / or, the top electrode block extends along the column direction of the array formed by the microcavities, and one or more columns of the microcavities are arranged between two adjacent top electrode blocks.

[0019] In the above embodiment, by arranging two adjacent bottom electrode blocks or top electrode blocks at intervals, series connection between different electrode blocks can be avoided, thereby facilitating the identification of the generating position of the electrical signal and determining the pressure area.

[0020] Optionally, the microcavity array includes a plurality of microcavity units, each of the bottom electrode blocks corresponds to at least one of the microcavity units, and each of the top electrode blocks corresponds to one of the microcavity units.

[0021] Optionally, the film-like substrate further includes a protective film, and the protective film is releasably disposed on the surfaces of the bottom packaging layer and the top packaging layer.

[0022] In the above implementation, the protective film can protect the surfaces of the bottom packaging layer and the top packaging layer during the transportation and storage stages of the pressure measuring device to prevent dust and other impurities in the air from contaminating the surfaces.

[0023] Optionally, the piezoelectric electret layer includes a first electret layer having pits, a second electret layer having pits, and a diaphragm layer arranged between the first electret layer and the second electret layer.

[0024] Optionally, the thickness of the film-like substrate is not greater than 1.0 mm.

[0025] In the above embodiment, the thickness of the pressure measuring device can be 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm and other values. During the operation, when the tightness of the ligaments on both sides of the knee joint is adjusted according to the measured pressure information, the film matrix can be peeled off from the tibial pad. Since the thickness of the film matrix is ​​relatively thin, the peeling will not affect the fit between the femoral component and the tibial pad.

[0026] In a second aspect, an embodiment of the present invention further provides a pressure measurement device, comprising the pressure measurement device described in any one of the above technical solutions, the pressure measurement device also comprising a signal processing device and a display device, the signal processing device is connected to the bottom electrode block and the top electrode block, and is used to determine the pressure information on the surface of the tibial pad according to the electrical signals transmitted by the bottom electrode block and the top electrode block;

[0027] The display device is connected to the signal processing device and is used to display the pressure information on the surface of the tibial pad.

[0028] In the above embodiment, affected by the pressure, the microcavities distributed inside the thin film matrix will be deformed under the action of external force, changing the electric dipole moment, thereby causing the compensation charge in the bottom electrode block and the top electrode block to change, which is externally manifested as an electrical signal output to the signal processing device. The signal processing device determines the pressure information on the surface of the tibial pad based on the output electrical signal and transmits it to the display device, so that the pressure information on the surface of the tibial pad is displayed in real time on the screen through the display device, thereby facilitating the doctor's viewing and assisting the doctor in ligament adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the position of the pressure measuring device provided by an embodiment of the present invention during use;

[0030] Figure 2 for Figure 1 A cross-sectional view of a film-like substrate in the pressure measuring device shown;

[0031] Figure 3 A schematic diagram of the distribution of the bottom electrode block, the top electrode block and the microcavity provided in an embodiment of the present invention;

[0032] Figure 4 Another schematic diagram of the distribution of the bottom electrode block, the top electrode block and the microcavity provided in an embodiment of the present invention;

[0033] Figure 5 A regional distribution diagram of a thin film substrate in a pressure measuring device provided by an embodiment of the present invention;

[0034] Figure 6 A schematic diagram of the composition of a pressure measurement device provided in an embodiment of the present invention.

[0035] Reference numerals:

[0036] 1-thin film substrate; 101-first region; 102-second region; 103-middle region; 10-bottom encapsulation layer; 20-piezoelectric electret layer; 200-microcavity; 200a-microcavity unit; 21-first electret layer; 22-second electret layer; 23-diaphragm layer; 230-diaphragm; 30-top encapsulation layer; 40-bottom electrode block; 50-top electrode block;

[0037] 2-Signal processing device; 3-Display device;

[0038] 4-Femoral component; 5-Tibial spacer. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] An embodiment of the present invention provides a pressure measuring device, which aims to solve the problem of real-time monitoring of medial and lateral condyle pressure during joint replacement surgery. A microcavity structure is formed by a piezoelectric electret material with a high piezoelectric coefficient and flexibility. A directionally arranged macroscopic dipole is formed in the microcavity of the piezoelectric electret by corona needle polarization. Planned electrodes are plated by magnetron sputtering to form a dot matrix sensor array, thereby collecting pressure signals of irregular surfaces, providing a low-cost, highly sensitive, and highly biocompatible solution for knee joint pressure monitoring.

[0041] like Figure 2 As shown, the pressure measuring device includes a thin film substrate 1. From the application scenario, the artificial knee joint prosthesis includes a femoral component 4, a tibial component 6 and a tibial pad 5. The thin film substrate 1 is used to be attached to the surface of the tibial pad 5 in the artificial knee joint prosthesis to measure the pressure applied by the femoral component 4 in the artificial knee joint prosthesis to the surface of the tibial pad 5; from the structural point of view, the thin film substrate 1 has a thin film structure, specifically including a bottom packaging layer 10, a piezoelectric electret layer 20 and a top packaging layer 30 stacked in sequence along a first direction, the piezoelectric electret layer 20 includes a plurality of microcavities 200, and each microcavity 200 A diaphragm is arranged inside, which divides the microcavity 200 into two upper and lower sub-cavities; at least one bottom electrode block 40 is arranged on the surface of the piezoelectric electret layer 20 facing the bottom packaging layer 10, and at least one top electrode block 50 is arranged on the surface of the piezoelectric electret layer 20 facing the top packaging layer 30. The bottom electrode block 40 and the top electrode block 50 respectively cover at least one microcavity 200, and at least part of the microcavity 200 is covered by the bottom electrode block 40 and the top electrode block 50 at the same time. The bottom electrode block 40 and the top electrode block 50 are respectively connected to the external circuit, and are used to output electrical signals to the external circuit when the microcavity 200 is deformed under the action of external force.

[0042] Specifically, the thin film substrate 1 is a sheet-like ultra-thin film layer, including a bottom packaging layer 10, a piezoelectric electret layer 20 and a top packaging layer 30, the bottom packaging layer 10, the piezoelectric electret layer 20 and the top packaging layer 30 are stacked in sequence along a first direction, wherein the first direction is the thickness direction of the thin film substrate 1, the bottom packaging layer 10 and the top packaging layer 30 respectively cover the upper and lower surfaces of the piezoelectric electret layer 20, thereby packaging the piezoelectric electret layer 20, and the packaging material used for the bottom packaging layer 10 and the top packaging layer 30 can be polydimethylsiloxane (PDMS) Or Parylene, optionally, the PDMS encapsulation layer can be prepared by spin coating, and the Parylene encapsulation layer can be prepared by deposition. Under the sealing effect of the bottom encapsulation layer 10 and the top encapsulation layer 30, the tissue fluid in the human body can be prevented from entering the piezoelectric electret layer 20, thereby causing short circuits and other effects on the various electrode blocks distributed on the surface of the piezoelectric electret layer 20. At the same time, during the transportation and storage stages of the pressure measuring device, the bottom encapsulation layer 10 and the top encapsulation layer 30 can also prevent moisture in the environment from entering the piezoelectric electret layer 20.

[0043] The piezoelectric electret layer 20 has a plurality of microcavities 200 inside, and these microcavities 200 are independent and closed cavity structures. After the piezoelectric electret layer 20 is polarized, the upper and lower surfaces of the microcavity 200 are distributed with opposite charges. The microcavity 200 has a diaphragm 230, which divides the microcavity 200 into two upper and lower sub-cavities, and isolates the upper and lower surfaces of the microcavity 200 to avoid neutralization of positive and negative charges distributed on the two surfaces. When the microcavity 200 is squeezed, the microcavity 200 will deform, resulting in a change in the dipole moment per unit volume; the surface of the piezoelectric electret layer 20 facing the bottom encapsulation layer 10 is set There is at least one bottom electrode block 40, and the bottom electrode block 40 can cover one microcavity 200 or multiple microcavities 200. At least one top electrode block 50 is arranged on the surface of the piezoelectric electret layer 20 facing the top packaging layer 30. Similarly, the top electrode block 50 can also cover one microcavity 200 or multiple microcavities 200, and at least part of the microcavity 200 is covered by the bottom electrode block 40 and the top electrode block 50 at the same time. When the microcavity 200 covered by the bottom electrode block 40 and the top electrode block 50 is squeezed, the compensation charges in the bottom electrode block 40 and the top electrode block 50 will change, which is manifested as an output of an electrical signal to the external circuit.

[0044] like Figure 1As shown, the film-like matrix 1 is used to be attached to the surface of the tibial pad 5 in the artificial knee joint prosthesis. When the femoral component 4 applies pressure to the surface of the tibial pad 5, part of the microcavity 200 will be squeezed and deformed, thereby changing the electric dipole moment, so that the compensation charge in the bottom electrode block 40 and the top electrode block 50 covering the surface of this part of the microcavity 200 changes, which is manifested externally as an electrical signal output to the external circuit. After the external circuit analyzes and processes the output electrical signal, it can determine the pressure information on the surface of the tibial pad 5. The pressure information includes the size of the pressure and the distribution of the pressure. In other words, it can determine which part of the tibial pad 5 is under pressure, the size of the pressure, and other information. In this way, the doctor can adjust the tightness of the knee joint ligament according to the obtained pressure information, so that the tibial pad 5 is subjected to a balanced force, avoid excessive local friction, and ensure the patient's postoperative recovery.

[0045] The film-like substrate 1 does not require power to drive when working, so there is no need to set up a power supply component, and the structure is simple. In addition, the film-like substrate 1 is a sheet-like ultra-thin film layer, which is flexible and can collect pressure information of the irregular and uneven surfaces of the two condyles of the femoral component 4, and adapt to the special service environment of the knee joint.

[0046] During the operation, the film-like matrix 1 can be pasted onto the tibial pad 5 in the artificial knee joint prosthesis, and the signal transmission channel between the film-like matrix 1 and the external circuit is connected, so that the pressure information applied by the two condyles of the femoral component 4 to the tibial pad 5 can be measured, and the tightness of the ligaments on both sides of the knee joint can be adjusted according to the measured pressure information. After the adjustment is completed, the film-like matrix 1 can be peeled off from the surface of the tibial pad 5. It is easy to use, safe and hygienic, and will not cause cross contamination. In addition, the film-like matrix 1 is a thin film structure with flexibility, so it can be suitable for tibial pads 5 with different structures produced by different merchants, and has strong adaptability.

[0047] In addition, the overall thickness of the film-like matrix 1 is relatively thin. After the tightness of the ligaments on both sides of the knee joint is adjusted and the film-like matrix 1 is peeled off from the surface of the tibial pad 5, it will not affect the cooperation between the femoral component 4 and the tibial pad 5.

[0048] Optionally, the thickness of the film substrate 1 is not greater than 1.0 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc.

[0049] The film-like substrate 1 may further include a protective film, which is removably disposed on the surface of the bottom packaging layer 10 and the top packaging layer 30. The protective film can protect the surface of the bottom packaging layer 10 and the top packaging layer 30 during the transportation and storage stages of the pressure measuring device to prevent dust and other impurities in the air from contaminating the surface, thereby meeting the high requirements of medical supplies for sanitary conditions.

[0050] In the pressure measurement device, the microcavities 200 are arranged in an array on the piezoelectric electret layer 20. By arraying the microcavities 200, more microcavities 200 can be arranged in a limited area, increasing the density of the microcavities 200 and improving the sensitivity. At the same time, the arrangement of the microcavities 200 can be regularized, so that when the microcavities 200 are compressed, it is easy to identify the position of the microcavities 200 and lock the compressed area. Of course, the microcavities 200 can also be arranged in other ways, such as random arrangement, which will not be listed here one by one.

[0051] In some embodiments, Figure 3 As shown, the microcavities 200 are arranged in a matrix structure with multiple rows and columns along the row direction and the column direction, respectively, and the bottom electrode block 40 and the top electrode block 50 are arranged crosswise along the row direction and the column direction of the array formed by the microcavities 200, wherein the row direction is the X-axis direction and the column direction is the Y-axis direction. In order to clearly show the relative positional relationship between the bottom electrode block 40, the top electrode block 50 and the microcavity 200, Figure 3 The drawing is performed in a partially transparent manner, and the middle layer 20 is omitted.

[0052] The bottom electrode block 40 is located on the surface of the piezoelectric electret layer 20 facing the bottom packaging layer 10, and the bottom electrode block 40 extends in the row direction and covers a portion of the microcavity 200 in this direction. The top electrode block 50 is located on the surface of the piezoelectric electret layer 20 facing the top packaging layer 30, and the top electrode block 50 extends in the column direction and covers a portion of the microcavity 200 in this direction. In terms of space, when the microcavity 200 located in the intersection area of ​​the bottom electrode block 40 and the top electrode block 50 is squeezed, the bottom electrode block 40 and the top electrode block 50 can output electrical signals to the external circuit.

[0053] like Figure 3 As shown, each bottom electrode block 40 can form a cross in space with one or more top electrode blocks 50. Similarly, each top electrode block 50 can also form a cross in space with one or more bottom electrode blocks 40. Since the microcavity 200 located in the intersection area can be covered by the bottom electrode block 40 and the top electrode block 50 at the same time, when this part of the microcavity 200 is squeezed, the bottom electrode block 40 and the top electrode block 50 can output electrical signals to the external circuit. This can reduce the number of bottom electrode blocks 40 and top electrode blocks 50 and simplify the circuit structure inside the thin film substrate 1.

[0054] Continue to refer Figure 3 One or more rows of microcavities 200 are arranged between two adjacent bottom electrode blocks 40, and / or one or more columns of microcavities 200 are arranged between two adjacent top electrode blocks 50. By arranging two adjacent bottom electrode blocks 40 or top electrode blocks 50 at intervals, it is possible to avoid being connected in series with each other, thereby facilitating the identification of the generating position of the electrical signal and determining the pressure-bearing area.

[0055] In other embodiments, Figure 4 As shown, the array formed by the microcavity 200 includes a plurality of microcavity units 200a, each microcavity unit 200a includes one or more microcavities 200, wherein each bottom electrode block 40 corresponds to at least one microcavity unit 200a, and each top electrode block 50 corresponds to a microcavity unit 200a one-to-one.

[0056] That is, the microcavity unit 200a, the bottom electrode block 40, and the top electrode block 50 may correspond one to one, or each microcavity unit 200a may correspond one to one with the top electrode block 50, and a plurality of microcavity units 200a may correspond to one bottom electrode block 40.

[0057] The number of microcavities 200 contained in the microcavity unit is not limited, for example, it can be two, four, six or other numbers. When the size of the microcavity 200 is determined, the number of microcavities 200 contained in the microcavity unit is related to the detection accuracy. The more microcavities 200 there are, the larger the locked pressure area is and the lower the accuracy is. Conversely, the fewer microcavities 200 there are, the smaller the locked pressure area is and the higher the accuracy is.

[0058] like Figure 4 As shown, the four microcavities in the dotted frame form a microcavity unit 200a, and there are multiple microcavity units 200a and top electrode blocks 50, and the two correspond one to one, while the bottom electrode block 40 is a whole and covers all the microcavities 200. When the microcavity unit 200a between the bottom electrode block 40 and one of the top electrode blocks 50 is squeezed, the bottom electrode block 40 and the top electrode block 50 can output electrical signals to the external circuit. Since the bottom electrode block 40 is a whole, only one wire is required to connect to the external circuit. Therefore, the circuit structure inside the thin film substrate 1 is relatively simple.

[0059] In some embodiments, the film-like matrix 1 can be attached to a local area of ​​the surface of the tibial pad 5 when in use, such as the area corresponding to the medial condyle or lateral condyle of the tibial pad 5 and the femoral component 4. This is because the surface of the tibial pad 5 facing the femoral component 4 often has an uneven surface structure. By attaching the film-like matrix 1 to a local area of ​​the tibial pad 5, the surface structure of the tibial pad 5 can be adapted. During the operation, two film-like matrices 1 can be used to attach to the areas on the surface of the tibial pad 5 corresponding to the medial condyle and lateral condyle of the femoral component 4, respectively, so as to simultaneously detect the pressure applied to the surface of the tibial pad 5 by the two condyles of the femoral component 4. Of course, only one film-like matrix 1 can be used to detect the pressure applied to the surface of the tibial pad 5 by the femoral component 4 on one side.

[0060] Alternatively, the film-like substrate 1 may also be attached to the entire surface of the tibial pad 5, and accordingly, Figure 5 As shown, the film-like matrix 1 includes a first region 101, a second region 102, and an intermediate region 103 arranged between the first region and the second region, the first region 101 corresponds to the medial condyle of the femoral component 4, the second region 102 corresponds to the lateral condyle of the femoral component 4, and the microcavity 200 is distributed in the first region 101 and the second region 102.

[0061] Specifically, the microcavity 200 can be distributed in the first area 101 and the second area 102 in an array form or in other forms. During the operation, it can be determined whether the force on the two condyles of the femoral component 4 is balanced based on the pressure information collected by the microcavity 200 in the first area 101 and the microcavity 200 in the second area 102.

[0062] The middle area 103 is between the first area 101 and the second area 102. Compared with the first area 101 and the second area 102, the middle area 103 is a blank area, that is, the microcavity 200 is not provided in the middle area 103. In this way, when the film-like matrix 1 is attached to the surface of the tibial pad 5, the middle area 103 is wrinkled to a certain extent, so that the first area 101 corresponds to the medial condyle of the femoral component 4, and the second area 102 corresponds to the lateral condyle of the femoral component 4.

[0063] In addition, the surface of the tibial pad 5 facing the femoral component 4 is often not flat, and the middle portion of the tibial pad 5 is higher than the two side portions. This structure of the tibial pad 5 can be accommodated by providing the middle region 103. At the same time, since the microcavity 200 is not provided in the middle region 103, when the femoral component 4 rolls on the surface of the tibial pad 5, the middle region 103 will not output electrical signals to the outside, that is, it will not interfere with the measurement results.

[0064] Optionally, the piezoelectric electret layer 20 includes a first electret layer 21 having pits, a second electret layer 22 having pits, and a diaphragm layer 23 disposed between the first electret layer 21 and the second electret layer 22 .

[0065] like Figure 2 As shown, the piezoelectric electret layer 20 is formed by pressing a first electret layer 21, a diaphragm layer 23 and a second electret layer 22, wherein the first electret layer 21 and the second electret layer 22 both have pits, and the two pits are arranged on the upper and lower sides of the diaphragm layer 23 to form a microcavity 200 together, and the diaphragm layer 23 is partially located inside the microcavity 200, which can avoid the neutralization of the positive and negative charges carried by the first electret layer 21 and the second electret layer 22.

[0066] The first electret layer 21 and the second electret layer 22 are both polymer materials, which can be one of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), soluble polytetrafluoroethylene (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), PVDF derivatives PVDF-TrFE and P (VDF / TFE), polyethylene (PE), polypropylene (PP), polyimide (PI), and polyethylene terephthalate (PET).

[0067] The diaphragm layer 23 may be one of FEP, PFA, PE, PP, PI, and PET, and the melting point of the diaphragm layer 23 is lower than the melting points of the first electret layer 21 and the second electret layer 22 .

[0068] The thickness of the entire piezoelectric electret layer 20 is less than or equal to 100 μm, and the material of each film layer can be selected according to the thickness requirement.

[0069] The main process steps of the film-like substrate 1 are briefly described with a specific embodiment:

[0070] Step 1: preparing a first electret layer 21 and a second electret layer 22;

[0071] Step 2: a heat insulating pad is placed between the first electret layer 21 and the second electret layer 22, and the first electret layer 21 and the second electret layer 22 are clamped by using a stainless steel template with both upper and lower layers having a concave-convex texture structure and placed on a hot press stamping table, and hot-pressed at a pressure of 10-20 MPa and a temperature of 100-140° C. for 5 minutes to prepare a first electret layer 21 and a second electret layer 22 with a concave-convex texture structure;

[0072] Step 3: Take the first electret layer 21 and the second electret layer 22 prepared in the second step, and take another diaphragm layer 23 and place it between the first electret layer 21 and the second electret layer 22, wherein the diaphragm layer 23 has no texture structure and has a flat surface, and the extension direction of the concave-convex texture of the first electret layer 21 and the extension direction of the concave-convex texture of the second electret layer 22 are perpendicular to each other, and then clamp them with two stainless steel templates without concave-convex texture structures, and hot press them at a relatively low pressure (1.0 MPa) at 340° C. for 1 min to form a piezoelectric electret layer 20 with a microcavity 200;

[0073] Step 4: Use DC magnetron sputtering to plate a layer of copper with a thickness of 100-150nm on the surface of the first electret layer 21 and the surface of the second electret layer 22 as the bottom electrode block 40 and the top electrode block 50, wherein the sputtering power is 100W and the time is 10-15min. The distribution of the bottom electrode block 40 and the top electrode block 50 is carried out according to the pre-designed plan, and the wires are connected to the corresponding electrode blocks using silver paste or other methods (solder);

[0074] Step 5: forming a directional dipole in the microcavity 200 of the piezoelectric electret layer 20 by corona needle polarization;

[0075] Step six: Spin coating is used to cover the surfaces of the first electret layer 21 and the second electret layer 22 with PDMS material to form a bottom encapsulation layer 10 and a top encapsulation layer 30 .

[0076] Optionally, the first electret layer 21 and the second electret layer 22 are PTFE / PFA polymer films formed by laminating a PTFE film and a PFA film.

[0077] Based on the same technical concept, the embodiment of the present invention also provides a pressure measuring device, such as Figure 6 As shown, the pressure measuring device includes any one of the above technical solutions. In addition to the pressure measuring device, the pressure measuring device also includes a signal processing device 2 and a display device 3. The signal processing device 2 is connected to the bottom electrode block 40 and the top electrode block 50, and is used to determine the pressure information on the surface of the tibial pad 5 according to the electrical signal transmitted by the bottom electrode block 40 and the top electrode block 50; the display device 3 is connected to the signal processing device 2, and is used to display the pressure information on the surface of the tibial pad 5.

[0078] During use, affected by pressure, the microcavities 200 distributed inside the thin film matrix 1 will be deformed under the action of external force, changing the electric dipole moment, thereby causing the compensation charge in the bottom electrode block 40 and the top electrode block 50 to change, which is manifested externally as an electrical signal output to the signal processing device 2. The signal processing device 2 determines the pressure information on the surface of the tibial pad 5 based on the output electrical signal and transmits it to the display device 3, so that the pressure information on the surface of the tibial pad 5 is displayed in real time on the screen through the display device 3, thereby facilitating the doctor's viewing and assisting the doctor in ligament adjustment.

[0079] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A pressure measuring device, characterized in that: The invention comprises a film-like substrate, wherein the film-like substrate is used to be attached to the surface of a tibial pad in an artificial knee joint prosthesis to measure the pressure applied by the femoral component in the artificial knee joint prosthesis to the surface of the tibial pad; The thin film substrate comprises a bottom packaging layer, a piezoelectric electret layer and a top packaging layer which are sequentially stacked along a first direction, the piezoelectric electret layer has a plurality of microcavities, and a diaphragm is arranged in the microcavity, at least one bottom electrode block is arranged on the surface of the piezoelectric electret layer facing the bottom packaging layer, and at least one top electrode block is arranged on the surface of the piezoelectric electret layer facing the top packaging layer, the bottom electrode block and the top electrode block respectively cover at least one of the microcavities, and at least part of the microcavity is covered by the bottom electrode block and the top electrode block at the same time; The bottom electrode block and the top electrode block are respectively connected to an external circuit, and are used to output an electrical signal to the external circuit when the microcavity is deformed under the action of an external force; The piezoelectric electret layer includes a first electret layer having pits, a second electret layer having pits, and a diaphragm layer disposed between the first electret layer and the second electret layer.

2. The pressure measuring device according to claim 1, characterized in that: The film-like matrix is ​​attached to the surface of the tibial pad in an area corresponding to the medial condyle or lateral condyle of the femoral component.

3. The pressure measuring device according to claim 1, characterized in that: The film-like matrix includes a first region, a second region and an intermediate region arranged between the first region and the second region, the first region corresponds to the medial condyle of the femoral component, the second region corresponds to the lateral condyle of the femoral component, and the microcavities are distributed in the first region and the second region.

4. The pressure measuring device according to any one of claims 1 to 3, characterized in that: The microcavity array is arranged.

5. The pressure measuring device according to claim 4, characterized in that: The bottom electrode blocks and the top electrode blocks are cross-arranged along the row direction and the column direction of the array formed by the microcavities.

6. The pressure measuring device according to claim 5, characterized in that: The bottom electrode block extends along the row direction of the array formed by the microcavities, and one or more rows of the microcavities are arranged between two adjacent bottom electrode blocks, and / or the top electrode block extends along the column direction of the array formed by the microcavities, and one or more columns of the microcavities are arranged between two adjacent top electrode blocks.

7. The pressure measuring device according to claim 4, characterized in that: The array formed by the microcavities includes a plurality of microcavity units, each of the bottom electrode blocks corresponds to at least one of the microcavity units, and each of the top electrode blocks corresponds to one of the microcavity units.

8. The pressure measuring device according to any one of claims 1 to 3, characterized in that: The film-shaped substrate further includes a protective film, and the protective film is disposed on the surfaces of the bottom encapsulation layer and the top encapsulation layer in a releasable manner.

9. The pressure measuring device according to any one of claims 1 to 3, characterized in that: The thickness of the film-like substrate is not greater than 1.0 mm.

10. A pressure measuring device, characterized in that: comprising the pressure measuring device according to any one of claims 1 to 9, further comprising a signal processing device and a display device, wherein the signal processing device is connected to the bottom electrode block and the top electrode block, and is used to determine the pressure information on the surface of the tibial pad according to the electrical signals transmitted by the bottom electrode block and the top electrode block; The display device is connected to the signal processing device and is used to display the pressure information on the surface of the tibial pad.

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