Self-powered shoe sole and 4D printing method and application thereof

Abstract

The application provides a self-powered shoe sole and a 4D printing method and application thereof, and belongs to the field of multi-material additive manufacturing, and comprises a magnetic shoe sole, a flexible shoe midsole and a conductive coil, wherein the magnetic shoe sole is made of permanent magnetic ceramic and polymer composite and is used for generating a magnetic field; the flexible polymer shoe midsole is made of flexible polymer and comprises a three-dimensional porous structure and a dense structure, the three-dimensional porous structure is connected with the magnetic shoe sole and is used for compression or recovery under external force; the dense structure is connected with the three-dimensional porous structure, and a groove is formed at the bottom of the dense structure to embed the conductive coil. The application can convert the periodic external pressure generated during movement into electric energy to realize the self-power supply function, and can generate a voltage of 2V or above, which is five orders of magnitude higher than the micro-volt level output voltage of the previous magneto-electric piezoelectric sensor, so that the application can realize engineering application, and the self-powered shoe sole can also realize the step counting function by using the number of voltage waveforms.

Description

Technical Field

[0001] The present invention belongs to the field of multi-material additive manufacturing, and more specifically, relates to a self-powered sole and a 4D printing method and application thereof. Background Art

[0002] 4D printing is an additive manufacturing technology for intelligent components, whose shape, performance, or functionality change in a controlled manner over time and space in response to external energy fields (heat, magnetism, electricity, light, force, etc.). The latest academic view is that 4D printing and 3D printing are both additive manufacturing technologies, with 4D printing being a new branch of additive manufacturing. Unlike 3D-printed components, which are stable (shape, performance, and function are stable and do not change over time), 4D-printed components possess intelligent properties, meaning that at least one of their shape, performance, or function changes in a controlled manner over time in response to external energy fields.

[0003] Due to its intelligent, controllable, and adaptable nature, 4D printing, a disruptive manufacturing technology, holds broad application prospects in aerospace, biomedicine, soft robotics, sensors, and other fields. Consequently, 4D printing has sparked extensive research, resulting in numerous inventions. For example, CN113121256A discloses a method for 4D printing thermosetting epoxy resin-based composite materials, resulting in components exhibiting excellent shape memory properties. CN110788340A discloses a method for 4D printing copper-based shape memory alloys, and CN110434331A discloses a method for 4D printing intelligent components using functionally graded copper-based shape memory alloys, both of which exhibit significant shape memory effects. CN108587136A discloses a photoresponsive 4D printing material and its preparation method. These patents focus on the shape changes of 4D-printed components, neglecting changes in their performance and functionality. This is because most researchers limit themselves to using "stimulus-responsive" materials in additive manufacturing processes. The resulting components inherit the intelligent properties of the raw materials, perfectly accommodating the shape-shifting nature of 4D-printed components. This mindset has limited 4D printing research to the realm of component shape change, primarily demonstrating the process of shape change. This has kept 4D printing research confined to the laboratory stage, severely hampering its practical application in engineering. Only by achieving changes in component performance and functionality can 4D printing be applied.

[0004] To this end, CN111409284A discloses a flexible piezoelectric sensor based on 4D printing and its preparation method. The invention is based on the idea of ​​combining magnetoelectric materials, combining (splicing) the magnetic part and the conductive part of additive manufacturing together, and using the principle of electromagnetic induction, so that under the action of external force, the change of the magnetic flux of the conductive part leads to the generation of voltage. This newly generated piezoelectric performance indicates that the performance and function have changed, thus realizing 4D printing. However, the 4D printed piezoelectric sensor disclosed in the patent still has the following problems: (1) The preparation method uses the inevitable splicing process after additive manufacturing, which reduces the production efficiency and fails to fully reflect the advantages of additive manufacturing technology; (2) The piezoelectric voltage is low, only at the microvolt (μV) level, which is very easy to be confused with the noise of the voltage waveform, and the sensitivity is very low; (3) Although the invention has realized 4D printing with performance and function changes, it is still in the stage of idea verification and law exploration. The sensor formed by it is still far from real application due to the above defects. Therefore, in order to quickly promote the engineering application of 4D printing technology, new inventions are urgently needed. Summary of the Invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a self-powered sole and a 4D printing method and application thereof, aiming to solve the problem that existing 4D printing research is difficult to apply in engineering.

[0006] To achieve the above objectives, according to one aspect of the present invention, a self-powered sole is provided, comprising a magnetic sole, a flexible midsole, and a conductive coil, wherein the magnetic sole is made of a composite of permanent magnetic ceramic and polymer and is used to generate a magnetic field; the flexible polymer midsole is made of a flexible polymer and includes a three-dimensional porous structure and a dense structure, wherein the three-dimensional porous structure is connected to the magnetic sole and is used to compress or recover under the action of an external force; the dense structure is connected to the three-dimensional porous structure and has a groove at the bottom thereof for embedding the conductive coil;

[0007] During exercise, the flexible shoe midsole undergoes a periodic compression / recovery cycle under the action of external force, causing the distance between the conductive coil and the magnetic sole to change periodically, thereby changing the magnetic flux of the conductive coil and generating a voltage at its two ends, thereby converting the mechanical energy during exercise into electrical energy, thereby achieving self-power supply.

[0008] As a further preference, the conductive coil is two coils connected in series, one located at the forefoot position and the other located at the heel position.

[0009] As a further preferred embodiment, the permanent magnetic ceramic is neodymium iron boron or metal ferrite, and the mass fraction of the permanent magnetic ceramic in the magnetic sole is 40% to 60%; the polymer is nylon 12, nylon 6, nylon 66, polypropylene or thermoplastic polyurethane; the flexible polymer is thermoplastic polyurethane; and the conductive coil is a copper coil.

[0010] As a further preference, the three-dimensional porous structure is a three-periodic minimal surface structure, the volume fraction of the three-dimensional porous structure is 10% to 15%, and the unit size is 2 to 5 mm.

[0011] As a further preference, the height of the magnetic sole is 15 to 20 mm, the height of the three-dimensional porous structure is 10 to 15 mm, and the height of the dense structure is 5 to 10 mm.

[0012] According to another aspect of the present invention, a 4D printing method for the self-powered sole is provided, which comprises the following steps:

[0013] S1 uses a powder bed laser melting process to form permanent magnetic ceramic and polymer composite powders into magnetic soles;

[0014] S2 uses a powder bed laser melting process to sequentially form a three-dimensional porous structure and a dense structure on top of the magnetic sole using flexible polymer powder, and reserves slots at the bottom of the dense structure;

[0015] S3 embeds the conductive coil into the slots of the dense structure to obtain an integrated sole;

[0016] S4 magnetizes the integrated sole to obtain the self-powered sole.

[0017] As a further preferred embodiment, in step S4, the magnetization voltage is 1800-2000V.

[0018] According to another aspect of the present invention, there is provided a self-powered shoe comprising the self-powered sole and an upper, wherein the upper is sewn onto the self-powered sole.

[0019] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0020] 1. This invention provides a self-powered shoe sole. Through the interaction of a magnetic sole, a three-dimensional porous structure, and a conductive coil, it can convert periodic external pressure generated during exercise into electrical energy, thereby achieving self-powering. This self-powered shoe sole can generate a voltage of over 2V, a significant increase of five orders of magnitude compared to the microvolt output voltage of previous 4D-printed magnetoelectric piezoelectric sensors, making it suitable for engineering applications. Furthermore, this self-powered shoe sole can also implement a pedometer function by utilizing the number of voltage waveforms.

[0021] 2. In particular, by using two coils connected in series and placing them at the forefoot and heel, respectively, the present invention can generate different voltage waveforms for different running postures (forefoot first, last, and heel simultaneously). Gait analysis can then be performed based on the waveform display to adjust to the correct running posture.

[0022] 3. In addition, by optimizing the parameters of the self-powered sole, the present invention can significantly increase the output voltage, enabling the 4D-printed piezoelectric device to simultaneously perform sensing and power supply functions.

[0023] 4. At the same time, the present invention provides a 4D printing method for self-powered soles, which adopts a multi-material additive manufacturing process to achieve integrated continuous printing, effectively improving production efficiency. The voltage generated by the prepared self-powered sole changes controllably over time, and provides a new manufacturing idea for 4D printing with changing performance and functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of a self-powered shoe provided by a preferred embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the principle of achieving self-power supply of the self-powered sole provided by the preferred embodiment of the present invention;

[0026] Figure 3 The present invention provides a 4D printing method for self-powered shoes according to a preferred embodiment of the present invention;

[0027] Figure 4 This is a physical picture of the self-powered shoes provided by the preferred embodiment of the present invention;

[0028] Figure 5 is a graph showing the change in voltage over time generated by the self-powered shoe prepared in Example 1 of the present invention during running;

[0029] Figure 6 : This is a comparison of the LED light before and after the voltage generated by the self-powered shoe prepared in Example 1 of the present invention during running is driven by the LED light, where (a) is before the light is turned on, and (b) is after the light is turned on;

[0030] Figure 7 1 is a schematic diagram of the principle of the self-powered shoes prepared in Example 1 of the present invention having a gait analysis function, wherein (a1) is a running posture in which the heel touches the ground first, (a2) is a running posture in which the forefoot and the heel touch the ground at the same time, (a3) ​​is a running posture in which the forefoot touches the ground first, (b1) is a voltage waveform diagram in which the heel touches the ground first, (b2) is a voltage waveform diagram in which the forefoot and the heel touch the ground simultaneously, and (b3) is a voltage waveform diagram in which the forefoot touches the ground first.

[0031] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0032] 1-Magnetic sole, 2-Conductive coil, 3-Flexible midsole, 4-Upper. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The present invention provides a self-powered sole, the specific structure of which can be referred to Figure 1 The exploded view shows that the self-powered sole includes a magnetic sole 1, a flexible midsole 3 and a conductive coil 2, wherein the magnetic sole 1 is made of a composite of permanent magnetic ceramics and polymers and is used to generate a magnetic field; the flexible polymer midsole 3 is made of a flexible polymer and includes a three-dimensional porous structure and a dense structure, and the three-dimensional porous structure is connected to the magnetic sole 1 and is used to compress / recover under the action of an external force; the dense structure is connected to the three-dimensional porous structure, and its bottom is grooved to embed the conductive coil 2.

[0035] Figure 2 This is a schematic diagram of the self-powered sole converting biomechanical energy into electrical energy during human running. The conductive coil 2 is in the magnetic field generated by the magnetic sole 1. During running, the flexible midsole 3 undergoes a periodic compression / recovery cycle under the action of an external force, causing the distance between the conductive coil 2 and the magnetic sole 1 to change periodically. This in turn changes the magnetic flux of the conductive coil 2, generating a voltage at both ends of the coil, thereby realizing the self-powered function. A voltage waveform is generated with each step, so the number of steps can be obtained by the number of waveforms, thereby realizing the pedometer function.

[0036] The voltage generated by the self-powered sole provided by the present invention can reach above 2V. By leading two wires from the conductive coil 2 and connecting them to an LED lamp, the LED lamp can be driven to flash.

[0037] Furthermore, the conductive coils consist of two coils connected in series, one located at the forefoot and the other at the heel. Different running postures (forefoot first, heel first, and both) produce different voltage waveforms. Users can analyze their gait based on the waveforms and adjust to the correct gait (forefoot first is generally considered the healthiest). Therefore, this self-powered sole has both step counting and gait analysis functions, making it ready for immediate use.

[0038] Furthermore, the permanent magnetic ceramic is neodymium iron boron or metal ferrite such as barium ferrite or strontium ferrite, and the mass fraction of the permanent magnetic ceramic in the magnetic sole 1 is 40% to 60%. This ratio can ensure the smooth formation of the magnetic sole while enabling it to generate a sufficiently high magnetic induction intensity; the polymer is nylon 12 (PA12), nylon 6 (PA6), nylon 66 (PA66), polypropylene (PP) or thermoplastic polyurethane (TPU); the flexible polymer is preferably thermoplastic polyurethane (TPU); the conductive coil 2 is a copper coil, and the number of turns of each coil is 5000 to 6000, thereby generating a higher output voltage in the conductive coil.

[0039] Furthermore, the three-dimensional porous structure is a three-periodic minimal surface structure, which is composed of a minimum unit cell (similar to the unit cell of a crystal) arrayed in three-dimensional space. It has two important parameters: volume fraction and unit size. By regulating these two parameters, the compression modulus of the three-dimensional lattice structure 2 can be precisely controlled, thereby controlling its strain under a given pressure. Therefore, the volume fraction of the three-dimensional porous structure in the present invention is 10% to 15%, and its unit size is preferably 2 to 5 mm. This parameter range can ensure that the three-dimensional porous structure has a lower modulus, generates greater strain when subjected to pressure, and has a faster deformation process.

[0040] Furthermore, the height a of the magnetic sole 1 is preferably 15 to 20 mm, the height b of the three-dimensional porous structure is preferably 10 to 15 mm, the height c of the dense structure is preferably 5 to 10 mm, and the height of the slots in the dense structure is preferably 1 to 2 mm, so that the sole has sufficient strength and is conducive to the continuous compression / recovery process.

[0041] According to another aspect of the present invention, a 4D printing method for the self-powered sole is provided, and the process is as follows: Figure 3 , specifically including the following steps:

[0042] S1 imports the sole model into the powder bed laser melting equipment, and uses the powder bed laser melting process to form the permanent magnetic ceramic and polymer composite powder into the magnetic sole 1;

[0043] S2 uses a powder bed laser melting process to sequentially form a three-dimensional porous structure and a dense structure on top of the magnetic sole 1 using flexible polymer powder. Slots are reserved at the bottom of the dense structure. Since the upper surface of the dense structure is in close contact with the shoe upper, in order to enhance the fit and wearing comfort and achieve personalized customization, the user's foot surface data can be obtained through a 3D scanner, and then the adapted shoe upper model can be obtained through reverse calculation.

[0044] S3 embeds the conductive coils into the slots reserved in the dense structure to obtain an integrated sole. It is preferred to use two conductive coils connected in series, one in front and one behind, one at the forefoot and the other at the heel.

[0045] S4 magnetizes the integrated sole continuously printed in steps S1 to S3, with the magnetization voltage being 1800 to 2000 V, thereby producing a self-powered sole.

[0046] According to another aspect of the present invention, a self-powered shoe is provided, which comprises the self-powered sole and the upper 4, the upper being sewn onto the self-powered sole. Figure 4 shown.

[0047] The technical solution provided by the present invention is further described below with reference to specific embodiments.

[0048] Example 1

[0049] (1) Material and structural design of self-powered shoes

[0050] The magnetic sole 1 is made of a NdFeB / thermoplastic polyurethane mixed powder, with the NdFeB mass fraction being 50%. The flexible midsole 3 is made of thermoplastic polyurethane powder. The three-dimensional porous structure preferably utilizes a three-periodic minimal surface structure with a volume fraction of 10%, a cell size of 3 mm, a forming height of a = 15 mm, b = 10 mm, and c = 8 mm, and a slot height of 1 mm. The conductive coil is a copper coil with 6000 turns. A 3D scanner is used to obtain the user's foot data (e.g., size 43). A reverse calculation is then performed to obtain the appropriate upper model. The personalized sole model (combined model of the magnetic sole and flexible midsole) is then imported into the powder bed laser melting equipment.

[0051] (2) 4D printing of self-powered shoes

[0052] S1 forms a magnetic sole 1, using NdFeB / thermoplastic polyurethane composite powder material to print the magnetic sole 1, with a forming height of a;

[0053] S2 Forming flexible shoe midsole 3, change the powder feeding cylinder to thermoplastic polyurethane powder, and adjust the process parameters of the equipment. Continue to form the three-dimensional porous structure with height b and the dense structure with height c on the magnetic shoe sole 1, and reserve a slot hole below the dense structure;

[0054] S3 Embedding coil, embed two conductive coils 2 in series at the reserved slot hole position of the flexible shoe midsole 3 to obtain an integrated sole. The conductive coils 2 are placed in front and back, one at the forefoot position and the other at the heel position.

[0055] S4 Magnetizing, place the integrated sole printed continuously in steps S1-S3 parallel to the horizontal plane, make the magnetic shoe sole close to the magnetizing machine, set the magnetizing voltage to 1920V, and the sole obtains permanent magnetism at the moment of starting the magnetizing machine, thereby obtaining a self-powered sole;

[0056] S5 Stitching upper 4, stitch the commercialized upper to the self-powered sole prepared in steps S1-S4 to obtain a self-powered shoe.

[0057] Example 2

[0058] (1) Material and structure design of self-powered shoe

[0059] The magnetic shoe sole 1 uses barium ferrite / nylon 12 mixed powder, of which the mass fraction of barium ferrite is 40%, and the flexible shoe midsole 3 uses thermoplastic polyurethane powder. The three-dimensional porous structure preferably uses a three-period minimal surface structure, with a volume fraction of 15%, a unit size of 2mm, a forming height a=20mm, b=15mm, c=5mm, and a slot hole height of 2mm. The conductive coil uses a copper coil with 5000 turns. The foot surface data of the user (such as 43 inches) is obtained by a three-dimensional scanner, and the adaptive upper model is obtained by reverse operation. The personalized sole model (including the overall model of the magnetic shoe sole and the flexible shoe midsole) is imported into the powder bed laser melting equipment.

[0060] (2) 4D printing of self-powered shoe

[0061] The preparation process of Example 1 is used, and the magnetizing voltage is set to 2000V.

[0062] Example 3

[0063] (1) Material and structure design of self-powered shoe

[0064] The magnetic sole 1 is made of a strontium ferrite / polypropylene mixed powder, with the mass fraction of strontium ferrite being 60%. The flexible midsole 3 is made of thermoplastic polyurethane powder. The three-dimensional porous structure preferably utilizes a three-periodic minimal surface structure with a volume fraction of 12%, a cell size of 5 mm, a forming height of a = 18 mm, b = 13 mm, and c = 10 mm, and a slot height of 1.5 mm. The conductive coil is a copper coil with 5500 turns. A 3D scanner is used to obtain the user's foot data (e.g., size 43). A reverse calculation is then performed to obtain the appropriate upper model. The personalized sole model (including the integrated model of the magnetic sole and flexible midsole) is then imported into the powder bed laser melting equipment.

[0065] (2) 4D printing of self-powered shoes

[0066] The preparation process of Example 1 was adopted, and the magnetizing voltage was set to 1800V.

[0067] Example 4

[0068] (1) Material and structural design of self-powered shoes

[0069] The magnetic sole 1 is made of a strontium ferrite / thermoplastic polyurethane mixed powder, with the mass fraction of strontium ferrite being 55%. The flexible midsole 3 is made of thermoplastic polyurethane powder. The three-dimensional porous structure preferably uses a three-periodic minimal surface structure with a volume fraction of 13%, a cell size of 4 mm, a forming height of a = 16 mm, b = 12 mm, and c = 7 mm, a slot height of 2 mm, and a copper coil as the conductive coil. A three-dimensional scanner is used to obtain the user's foot data (e.g., size 43). A reverse calculation is then performed to obtain the appropriate upper model. The personalized sole model (including the integrated model of the magnetic sole and flexible midsole) is then imported into the powder bed laser melting equipment.

[0070] (2) 4D printing of self-powered shoes

[0071] The preparation process of Example 1 was adopted, and the magnetization voltage was set to 1900 V. The performance test and function verification process of the self-powered shoes prepared in Example 1 were carried out as follows:

[0072] The tester wore the self-powered shoes prepared in Example 1 and ran on a treadmill at a uniform speed of 8 km / h. The voltage generated by the change of magnetic flux in the conductive coil 2 exceeded 2V. The curve of voltage change over time is shown in FIG. Figure 5 As shown. A voltage above 2V is enough to drive the LED light to light up. Connect the two coils in series with the LED light. Since the peak value of the AC current exceeds 2V during the running process, the LED continues to flash. The comparison before and after the flash is shown in the figure below. Figure 6 The self-powered shoe also has the functions of step counting and gait analysis and correction. The principle is as follows Figure 7 As shown. Each step, a voltage waveform will be generated, so the number of steps is the number of waveforms. Figure 7 are three common running postures and the voltage waveform diagrams generated by them, wherein (a1) and (b1) are the rear heel landing first, (a2) and (b2) are the front palm and the rear heel landing at the same time, and (a3) and (b3) are the front palm landing first. In the three gaits, the voltage waveforms generated by the front and rear coils are different. It is generally considered that the front palm landing first is the healthiest posture, at which time the coil at the front palm generates a strong voltage, and the rear heel generates a weak voltage, as shown in (b3) of FIG. 4. Figure 7 If the waveform is the same as the diagram, it indicates that the gait is correct; if the waveform is different from (b3) (or the same as (b1) and (b2)), it indicates that the gait is incorrect, and the gait can be adjusted in real time to the voltage waveform of "front strong and rear weak" to achieve gait correction. Figure 7

[0073] The above tests show that the self-powered shoes prepared according to the technical scheme provided by the present application have the functions of self-power supply, step counting, gait analysis and correction, can convert biomechanical energy into electrical energy output, the force-electricity conversion performance and function change controllably with time, provides a new scheme for realizing the performance and function change of 4D printing, and provides a directly usable product manufactured by the 4D printing technology, greatly promotes the application of the 4D printing technology.

[0074] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A self-powered sole, characterized in that: The self-powered sole comprises a magnetic sole (1), a flexible midsole (3) and a conductive coil (2), wherein the magnetic sole (1) is made of a composite of permanent magnetic ceramic and polymer and is used to generate a magnetic field; the flexible midsole (3) is made of a flexible polymer and comprises a three-dimensional porous structure and a dense structure, the three-dimensional porous structure is connected to the magnetic sole (1) and is used to be compressed or restored under the action of an external force; the dense structure is connected to the three-dimensional porous structure and has a groove at its bottom for embedding the conductive coil (2); the conductive coil (2) is two coils connected in series, one located at the forefoot position and the other located at the heel position, and is used for gait analysis; During exercise, the flexible midsole (3) undergoes a periodic compression / recovery cycle under the action of an external force, causing the distance between the conductive coil (2) and the magnetic sole (1) to change periodically, thereby changing the magnetic flux of the conductive coil (2) to generate a voltage at both ends thereof, thereby converting the mechanical energy during the exercise into electrical energy, thereby achieving self-power supply.

2. The self-powered sole according to claim 1, characterized in that The permanent magnetic ceramic is neodymium iron boron or metal ferrite, and the mass fraction of the permanent magnetic ceramic in the magnetic sole (1) is 40% to 60%; the polymer is nylon 12, nylon 6, nylon 66, polypropylene or thermoplastic polyurethane; the flexible polymer is thermoplastic polyurethane; and the conductive coil (2) is a copper coil.

3. The self-powered sole according to claim 1, characterized in that The three-dimensional porous structure is a three-periodic minimal surface structure, the volume fraction of the three-dimensional porous structure is 10% to 15%, and the unit size is 2 to 5 mm.

4. The self-powered sole according to any one of claims 1 to 3, characterized in that: The height of the magnetic sole (1) is 15 to 20 mm, the height of the three-dimensional porous structure is 10 to 15 mm, and the height of the dense structure is 5 to 10 mm.

5. The 4D printing method of the self-powered sole according to any one of claims 1 to 4, characterized in that: The 4D printing method includes the following steps: S1 uses powder bed laser melting process to form permanent magnetic ceramic and polymer composite powder into magnetic soles (1); S2 utilizes a powder bed laser melting process to sequentially form a three-dimensional porous structure and a dense structure on the magnetic sole (1) using flexible polymer powder, and reserves slots at the bottom of the dense structure; S3 embeds the conductive coil into the slots of the dense structure to obtain an integrated sole; S4 magnetizes the integrated sole to obtain the self-powered sole.

6. The 4D printing method of the self-powered sole according to claim 5, characterized in that: In step S4, the magnetization voltage is 1800-2000V.

7. A self-powered shoe, characterized in that: The self-powered shoe comprises the self-powered sole according to any one of claims 1 to 4 and a shoe upper (4), wherein the shoe upper (4) is sewn onto the self-powered sole.

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