Preparation method of crossed pipeline type flexible piezoresistive sensor

Abstract

The invention relates to a preparation method of a crossed pipeline type flexible piezoresistive sensor, which belongs to the field of medical treatment, and comprises the following steps: firstly, obtaining a flexible film as a substrate based on an electrostatic spinning process, attaching a carbon nanotube to the film through an ultrasonic and impregnation method, and obtaining a tubular structure through a winding composite process; then electrospinning the TPU solution into filaments by using an electrospinning technology to form a scale-controllable film structure; then, selectively designing each tubular structure film on the TPU film to be arranged along x and y orthogonal axes to form a latticed structure; and finally, spinning a film covering net-shaped structure by adopting a TPU (Thermoplastic Polyurethane) solution through an electrostatic spinning technology for packaging, and receiving a signal by adopting a conductive adhesive tape, thereby finally forming the crossed tubular flexible piezoresistive sensor capable of realizing multi-dimensional force detection. According to the preparation method of the crossed pipeline type flexible piezoresistive sensor, the crossed pipeline type flexible piezoresistive sensor is successfully manufactured, and the manufacturing system has the advantages of being simple, efficient, easy to control, reliable, low in cost and the like.

Description

Technical Field

[0001] The invention relates to the technical field of medical instruments, and in particular to a method for preparing a cross-pipe flexible piezoresistive sensor. Background Art

[0002] Traditional biosensors are hindered by the rigidity of the material. In large bending or stretching deformation, the base material is prone to irreversible deformation, which can damage the electronic devices. In recent years, the research and development of flexible biosensors has attracted more and more attention, showing great development in the fields of electronic skin, new medical implants, wearable devices and bionic robots.

[0003] With the development of sensing technology, the flexibility, precision and intelligence of medical instruments, prostheses and other equipment have become key issues in the field. As a core sensing component, flexible pressure sensors should meet the multi-dimensional force perception needs of various application scenarios. Among them, flexible three-dimensional force sensors can identify the size and direction of force through structural design of materials, thereby achieving fine perception and control of the sensing object.

[0004] This patent focuses on the above-mentioned problems. By integrating technical features such as material modification, electrospinning, and winding composite, it innovatively proposes a design and preparation method for a cross-channel flexible piezoresistive sensor. Electrospinning has the ability to stretch and polarize the material during the spinning process and can produce ordered fiber films. Therefore, it is particularly suitable for the preparation of TPU films and channel sensors, with simple technical operations and high production efficiency. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a method for preparing a cross-channel flexible piezoresistive sensor, which has the advantages of flexibility, three-dimensional force detection, and the ability to detect various physiological activities of the human body. It solves the problems of realizing limb movement monitoring and analysis of dynamic forces on limbs, thereby better completing the perception and operation of the external environment.

[0006] (II) Technical solution To achieve the above object, the present invention provides the following technical solution: a method for preparing a cross-pipe flexible piezoresistive sensor, wherein the electrospinning system is composed of a feeding device, a collecting device, a three-axis motion platform and a computer control system, wherein the feeding device is composed of a micropump controller, a micropump actuator, a syringe piston cylinder and a syringe needle, and a TPU electrospinning solution in the syringe piston cylinder, and the collecting device is composed of a motor and a receiving plate, and comprises the following steps: Step 1), substrate of the multi-dimensional force sensor: dissolving TPU particles in a mixed solution of tetrahydrofuran and dimethylformamide to prepare a TPU electrospinning solution with a certain mass fraction, and electrospinning the TPU solution into filaments using electrospinning technology; Step 2), preparation of the pipeline sensor: prepare a TPU film by electrospinning, cut the film into a suitable size, put the film into a drying oven for drying, immerse the dried TPU film in a carbon nanotube dispersion and perform ultrasound to make the carbon nanotubes adhere to the surface of the TPU film, so that the film has conductivity; Step 3), preparation of x-axis sensor: placing the multiple pipe-type sensors obtained above on the TPU film substrate in an x-axis arrangement, and covering the entire x-axis sensor with a TPU electrospun film; Step 4), preparation of y-axis sensor: placing the multiple pipe-type sensors obtained in step 2) on the TPU film substrate in a manner orthogonal to the x-axis, i.e., the y-axis, to form an upper and lower composite cross-shaped mesh structure, and wrapping metal thin wires around both ends of the multiple pipe-type sensors arranged on the x-axis to perform composite treatment and fix them with conductive tape; Step 5), overall packaging: The sensor obtained after step 3) and step 4) is overall packaged by TPU electrospinning, the top TPU film is bonded to the base TPU film, and the composite metal wires led out in the above steps are left out, and the packaging is completed to form a single cross-pipe flexible piezoresistive sensor.

[0007] Preferably, in step 1), during the electrospinning process, a syringe containing a composite TPU solution of a certain volume and a certain concentration is hung on the Z axis of the three-axis mobile platform, a 22G needle is installed on the syringe, and a receiving plate is directly below the needle, and aluminum foil is wrapped on the receiving plate. The distance between the syringe needle and the aluminum foil below is adjusted, and the power supply voltage is adjusted to meet the conditions for electrospinning. The positive electrode of the power supply is connected to the metal part of the syringe needle, and the negative electrode is connected to the aluminum foil, thereby forming a high-voltage electric field between the syringe needle and the aluminum foil. Under the combined action of the thrust of the micropump actuator and the electrostatic field force, the deposition of nanofibers is achieved, so that a dense and continuous TPU film is formed on the surface of the aluminum foil, which is used as the substrate of the multi-dimensional force sensor.

[0008] Preferably, in step 2), the receiving plate is fixed on the shaft platform, and a layer of aluminum foil is wrapped on the receiving plate. Through the computer control system, the syringe is docked just above the center of the receiving plate, the positive electrode of the high voltage voltage is connected to the metal needle of the syringe, and the negative electrode is connected to the aluminum foil on the receiving plate. Under the control of the micropump controller, the micropump actuator moves downward precisely to squeeze the TPU electrospinning solution in the syringe, so that the TPU mixed solution flows out evenly at a speed of 1 ml / h. The TPU mixed solution 4 flowing out of the syringe forms filaments under the action of high voltage electricity and is wound around the aluminum foil of the receiving plate in a fixed direction. Due to the reciprocating motion of the syringe, a whole piece of TPU film is formed on the receiving plate. The thickness of the TPU film can be controlled by controlling the spinning time.

[0009] Preferably, the flexible film soaked in carbon nanotubes has good conductivity, and its radial force response is enhanced after being bent and coiled. The composite mesh structure of orthogonal x and y axes enables it to selectively sense the strain components along the x and y axes. The tubular structure will also deform when under pressure, resulting in signal changes, thereby realizing multi-dimensional force detection; the electrospinning system is composed of a feeding device, a collecting device, a three-axis motion platform and a computer control system, wherein the feeding device is composed of a micropump controller, a micropump actuator, a syringe piston cylinder and a syringe needle, and the collecting device is composed of a motor, a receiving plate, etc.

[0010] Preferably, in step 3) and step 4), each tubular structure film on the TPU film is selectively designed to be arranged along the orthogonal x and y axes to form a grid structure.

[0011] (III) Beneficial effects Compared with the prior art, the present invention provides a method for preparing a cross-pipe flexible piezoresistive sensor, which has the following beneficial effects: 1. The preparation method of the cross-pipe flexible piezoresistive sensor utilizes a flexible structure and piezoresistive resistance technology. The x and y orthogonal axis arrangement structure can realize single-point and multi-point force resolution according to the change of resistance. The TPU film has high elasticity, corrosion resistance, and strong wear resistance. The structure and performance of the sensor can remain stable under large tensile or compressive deformation, thereby realizing limb movement monitoring and thus realizing the analysis of dynamic limb force.

[0012] 2. The preparation method of the cross-pipe flexible piezoresistive sensor has a simple sensor structure. The pipe structure can be formed by a mold. Flexible materials are used to make various parts of the sensor, so that the sensor has good tensile properties and a small geometric volume. It can cover a large area on the surface of smart devices, providing them with multi-dimensional force perception functions and enhancing their ability to recognize the external environment. The manufacturing method is simple and efficient, easy to control, reliable and low-cost. The cross-pipe flexible piezoresistive sensor has high sensitivity, can distinguish multi-dimensional strains in 3D space, and realize multi-dimensional force detection in 3D space. It is suitable for electronic skin, health testing, new medical implants, wearable devices and bionic robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a diagram of the preparation of the TPU piezoelectric film based on electrospinning of the present invention.

[0014] Figure 2 This is a schematic diagram of making a thin film into a pipeline sensor.

[0015] Figure 3 This is a schematic diagram of the production of a cross-pipe structure.

[0016] Figure 4 This is a three-dimensional view of the cross-channel flexible piezoresistive sensor.

[0017] Figure 5 This is the schematic diagram of the cross-pipe flexible piezoresistive sensor.

[0018] In the figure: 1. micropump controller; 2. micropump actuator; 3. TPU electrospinning solution; 4. computer control system; 5. receiving board. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of 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.

[0020] Embodiment 1: A method for preparing a cross-pipe flexible piezoresistive sensor, wherein the electrospinning system is composed of a feeding device, a collecting device, a three-axis motion platform and a computer control system 4, wherein the feeding device is composed of a micropump controller 1, a micropump actuator 2, a syringe piston cylinder and a syringe needle, and a TPU electrospinning solution 3 in the syringe piston cylinder, and the collecting device is composed of a motor and a receiving plate 5, and comprises the following steps: The substrate of the flexible piezoresistive sensor is obtained by electrospinning. First, weigh 2g of TPU particles, and then immediately put the particles into 10ml of a composite solution of tetrahydrofuran (THF): dimethylformamide (DMF) in a ratio of 3:2, and stir at 300rpm for 4h to make the TPU particles completely dissolved and uniform. Use a syringe to draw 5ml of the solution for use.

[0021] The receiving plate 5 is fixed on the 3-axis platform, and a layer of aluminum foil is wrapped on the receiving plate 5. The computer control system 4 allows the syringe to stop just above the center of the receiving plate 5. The positive electrode of the high voltage voltage is connected to the metal needle of the syringe, and the negative electrode is connected to the aluminum foil on the receiving plate 5. Under the control of the micropump controller 1, the micropump actuator 2 moves downward precisely to squeeze the TPU electrospinning solution 3 in the syringe, so that the TPU mixed solution flows out evenly at a speed of 1 ml / h. The TPU mixed solution 4 flowing out of the syringe forms filaments under the action of high voltage electricity and is wound around the aluminum foil of the receiving plate 5 in a fixed direction. Due to the reciprocating motion of the syringe, a whole piece of TPU film is formed on the receiving plate 5. The thickness of the TPU film can be controlled by controlling the spinning time.

[0022] After spinning, the aluminum foil with the TPU film on the receiving plate 5 is removed and placed in an oven at 30°C for 6 hours to completely evaporate the remaining solvent, and the soft TPU film is successfully prepared. The TPU film is cut into a 5×5 cm square for later use.

[0023] The TPU film was prepared by electrospinning process, and the film was cut into 1.5×3cm strips and placed in a drying oven for drying. 0.6g of carbon nanotubes were weighed and placed in 30ml of anhydrous ethanol solution to prepare a carbon nanotube dispersion. The dried strip TPU film was immersed in the carbon nanotube dispersion and ultrasonicated for 15min, and then immersed at room temperature for 48h to allow the carbon nanotubes to adhere to the surface of the TPU film, thereby making the film conductive. The impregnated composite film was placed in an oven at 30°C and baked for 4h to obtain a dry conductive film. The conductive film was placed in a tubular mold to bend it into a pipe structure for shaping.

[0024] Three finalized pipeline sensors were selected and placed on the TPU film base at even intervals and arranged on the x-axis. The viscosity of the TPU film was used to stick the pipeline sensors on the base film without displacement. Fine metal wires were wrapped around both ends of the multiple pipeline sensors arranged on the x-axis for composite treatment and fixed with conductive tape. The entire x-axis sensor was covered with TPU electrospun film again.

[0025] Three finalized pipeline sensors were selected and placed on the TPU film base at even intervals and arranged on the y-axis. The TPU film's own viscosity was used to stick the pipeline sensors on the base film without displacement. Fine metal wires were wrapped around both ends of the multiple pipeline sensors arranged on the y-axis to perform a composite treatment and then fixed with conductive tape.

[0026] The sensor obtained after the above steps is packaged as a whole by TPU electrospinning. The total amount of electrospinning liquid used for packaging is set to 2 ml. The top TPU film is bonded to the base TPU film, and the composite metal wire led out in the above steps is left out. The packaging is completed to form a single cross-channel flexible piezoresistive sensor.

[0027] Embodiment 2: A method for preparing a cross-pipe flexible piezoresistive sensor, wherein the electrospinning system is composed of a feeding device, a collecting device, a three-axis motion platform and a computer control system 4, wherein the feeding device is composed of a micropump controller 1, a micropump actuator 2, a syringe piston cylinder and a syringe needle, and a TPU electrospinning solution 3 in the syringe piston cylinder, and the collecting device is composed of a motor and a receiving plate 5, and comprises the following steps: The substrate of the flexible piezoresistive sensor was obtained by an electrospinning process. First, 2 g of TPU particles were weighed, and then the particles were immediately placed in 10 ml of a composite solution of tetrahydrofuran (THF): dimethylformamide (DMF) in a ratio of 3:2. The solution was formed and stirred at 300 rpm for 4 hours to completely dissolve the TPU particles. 5 ml of the solution was drawn with a syringe for standby use.

[0028] The receiving plate 5 is fixed on the 3-axis platform, and a layer of aluminum foil is wrapped on the receiving plate 5; the computer control system 4 is used to make the syringe stop just above the center of the receiving plate 5; the positive electrode of the high voltage voltage is connected to the metal needle of the syringe, and the negative electrode is connected to the aluminum foil on the receiving plate 5; under the control of the micropump controller 1, the micropump actuator 2 moves downward accurately to squeeze the TPU electrospinning solution 3 in the syringe, so that the TPU mixed solution flows out evenly at a speed of 1 ml / h, and the TPU mixed solution 4 flowing out of the syringe forms filaments under the action of high voltage electricity, which are wound on the aluminum foil of the receiving plate 5 in a fixed direction. Due to the reciprocating motion of the syringe, a whole piece of TPU film is formed on the receiving plate 5. The thickness of the TPU film can be controlled by controlling the spinning time; after the spinning is completed, the aluminum foil with the TPU film on the receiving plate 5 is removed and placed in an oven at 30°C for 6 hours to completely evaporate the remaining solvent, and the soft TPU film is successfully prepared; the TPU film is trimmed into a square of 5×5 cm for standby use.

[0029] Weigh 1.2g of PCL particles, and then immediately put the particles into 10ml of DMF: dichloromethane = 1:2 solvent to prepare a PCL electrospinning solution with a mass fraction of 12%, and stir at 600rpm for 4h to completely dissolve the PCL particles. Draw 5ml of the solution with a syringe and set aside. The receiving plate 5 is fixed on the 3-axis platform, and a layer of aluminum foil is wrapped on the receiving plate 5. The computer control system 4 is used to make the syringe stop just above the center of the receiving plate 5. The positive electrode of the high voltage is connected to the metal needle of the syringe, and the negative electrode is connected to the aluminum foil on the receiving plate 5. Under the control of the micropump controller 1, the micropump actuator 2 moves downward precisely to squeeze the PCL electrospinning solution 3 in the syringe, so that the PCL mixed solution flows out evenly at a speed of 0.8ml / h. The PCL mixed solution 4 flowing out of the syringe forms filaments under the action of high voltage electricity and winds around the aluminum foil of the receiving plate 5 in a fixed direction. Due to the reciprocating motion of the syringe, a whole PCL film is formed on the receiving plate 5. The thickness of the PCL film can be controlled by controlling the spinning time. After the spinning is completed, the aluminum foil with the PCL film on the receiving plate 5 is removed and placed in an oven at 30°C for 6 hours to completely evaporate the remaining solvent, and the soft PCL film is successfully prepared.

[0030] The PCL film was trimmed into a 1.5×3cm strip shape, 0.6g of carbon nanotubes were weighed and placed in 30ml of anhydrous ethanol solution to prepare a carbon nanotube dispersion, the dried strip PCL film was immersed in the carbon nanotube dispersion and ultrasonicated for 15min, then immersed at room temperature for 48h to allow the carbon nanotubes to adhere to the surface of the PCL film, thereby making the film conductive. The impregnated composite film was placed in an oven at 30°C and baked for 4h to obtain a dry conductive film. The conductive film was placed in a tubular mold to bend it into a pipe structure for shaping.

[0031] Three shaped pipeline films were selected and placed on the TPU film base at uniform intervals and arranged on the x-axis. The TPU film's own viscosity was used to stick the pipeline sensor on the base film without displacement. Fine metal wires were wrapped around both ends of the multiple pipeline sensors arranged on the x-axis for composite treatment and fixed with conductive tape. The entire x-axis sensor was covered with TPU electrospun film again.

[0032] Three shaped pipeline films were selected and placed on the TPU film base at even intervals and arranged on the y-axis. The TPU film's own viscosity was used to stick the pipeline sensor on the base film without displacement. Fine metal wires were wrapped around both ends of the multiple pipeline sensors arranged on the y-axis to compound them and then fixed with conductive tape.

[0033] The sensor obtained after the above steps is packaged as a whole by TPU electrospinning. The total amount of electrospinning liquid used for packaging is set to 2 ml. The top TPU film is bonded to the base TPU film, and the composite metal wire led out in the above steps is left out. The packaging is completed to form a single cross-channel flexible piezoresistive sensor.

[0034] It should be noted that the sensing principle is: In order to explain the three-dimensional force measurement principle of the sensor, we establish the coordinate axis with the upper surface of the sensor. The z-axis is perpendicular to the center of the surface and points upward. The x-axis is located on the upper surface of the sensor and is perpendicular to the z-axis and points to the right. The y-axis is located on the upper surface of the sensor and is perpendicular to the z-axis and points to the back. Figure 4 When a three-dimensional force acts on the sensor unit, the resistance will change accordingly: (a) In the free state without force, each sensor unit is not subjected to force, the length and diameter of the tubular sensor remain unchanged, and the resistance value of each sensor unit is the initial resistance, as shown in Figure 5 (a) (b) Under the action of vertical compressive stress F, if Figure 5 As shown in (b), the x-axis and y-axis sensing units are subjected to pressure, the tubular sensor is squeezed and deformed, and the conductivity is enhanced, resulting in a decrease in the resistance value of each sensing unit.

[0035] (c) Under the action of shear force F in the x direction, if Figure 5 As shown in (c), assuming that the shear force is converted into friction force through the force-bearing contact, the shear force in the x direction causes the sensor unit to be compressed by the compressive stress. Since the force direction is from right to left, the resistance of the right sensor decreases more than the resistance of the right sensor.

[0036] The magnitude and direction of the detection force can be determined by mathematical relationships. A three-dimensional coordinate system is established along the upper surface of the sensor. When the force is applied to the force loading block, the force is decomposed into three components along the three coordinate axes: Fx, Fy, and Fz.

[0037] Fz can be calculated by the following equation:

[0038] Wherein, Fz1, Fz2, and Fz3 are the normal force components measured by the four force-sensitive units.

[0039] The transverse components Fx and Fy can be calculated by the following equations:

[0040]

[0041] Where h is the diameter height of the pipeline piezoresistive sensor The beneficial effects of the present invention are: 1. The preparation method of the cross-pipe flexible piezoresistive sensor utilizes a flexible structure and piezoresistive resistance technology. The x and y orthogonal axis arrangement structure can realize single-point and multi-point force resolution according to the change of resistance. The TPU film has high elasticity, corrosion resistance, and strong wear resistance. The structure and performance of the sensor can remain stable under large tensile or compressive deformation, thereby realizing limb movement monitoring and thus realizing the analysis of dynamic limb force.

[0042] 2. The preparation method of the cross-pipe flexible piezoresistive sensor has a simple sensor structure. The pipe structure can be formed by a mold. Flexible materials are used to make various parts of the sensor, so that the sensor has good tensile properties and a small geometric volume. It can cover a large area on the surface of smart devices, providing them with multi-dimensional force perception functions and enhancing their ability to recognize the external environment. The manufacturing method is simple and efficient, easy to control, reliable and low-cost. The cross-pipe flexible piezoresistive sensor has high sensitivity, can distinguish multi-dimensional strains in 3D space, and realize multi-dimensional force detection in 3D space. It is suitable for electronic skin, health testing, new medical implants, wearable devices and bionic robots.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a cross-pipe flexible piezoresistive sensor, characterized in that: The electrospinning system is composed of a feeding device, a collecting device, a three-axis motion platform and a computer control system (4), wherein the feeding device is composed of a micropump controller (1), a micropump actuator (2), a syringe piston cylinder and a syringe needle, and a TPU electrospinning solution (3) in the syringe piston cylinder, and the collecting device is composed of a motor and a receiving plate (5), and includes the following steps: Step 1), substrate of the multi-dimensional force sensor: dissolving TPU particles in a mixed solution of tetrahydrofuran and dimethylformamide to prepare a TPU electrospinning solution with a certain mass fraction, and electrospinning the TPU solution into filaments using electrospinning technology; Step 2), preparation of the pipeline sensor: prepare a TPU film by electrospinning, cut the film into a suitable size, put the film into a drying oven for drying, immerse the dried TPU film in a carbon nanotube dispersion and ultrasonicate it to make the carbon nanotubes adhere to the surface of the TPU film, so that the film has conductivity, and process it into a tube shape with a special mold; Step 3), preparation of x-axis sensor: placing the multiple pipe-type sensors obtained above on the TPU film substrate in an x-axis arrangement, and covering the entire x-axis sensor with a TPU electrospun film; Step 4), preparation of y-axis sensor: placing the multiple pipe-type sensors obtained in step 2) on the TPU film substrate in a manner orthogonal to the x-axis, i.e., the y-axis, to form an upper and lower composite cross-shaped mesh structure, and wrapping metal thin wires around both ends of the multiple pipe-type sensors arranged on the x-axis to perform composite treatment and fix them with conductive tape; Step 5), overall packaging: The sensor obtained after step 3) and step 4) is packaged as a whole by TPU electrospinning, the top TPU film is bonded to the base TPU film, and the composite metal wires led out in the above steps are left out, and the packaging is completed to form a single cross-pipe flexible piezoresistive sensor.

2. The method for preparing a cross-pipe flexible piezoresistive sensor according to claim 1, characterized in that: In step 1), during the electrospinning process, a syringe containing a concentrated composite TPU solution (3) is hung on the Z axis of the 3-axis mobile platform, a 22G needle is installed on the syringe, and a receiving plate (5) is directly below the needle. The receiving plate (5) is wrapped with aluminum foil. The distance between the syringe needle and the aluminum foil below is adjusted, and the power supply voltage is adjusted to meet the conditions for electrospinning. The positive electrode of the power supply is connected to the metal part of the syringe needle, and the negative electrode is connected to the aluminum foil, so that a high-voltage electric field is formed between the syringe needle and the aluminum foil. Under the combined action of the thrust of the micropump actuator and the electrostatic field force, the deposition of nanofibers is achieved, so that a dense and continuous TPU film is formed on the surface of the aluminum foil, which is used as the substrate of the multi-dimensional force sensor.

3. The method for preparing a cross-pipe flexible piezoresistive sensor according to claim 1, characterized in that: Step 2), the receiving plate (5) is fixed on the 3-axis platform, and a layer of aluminum foil is wrapped on the receiving plate (5). Through the computer control system 4, the syringe is parked just above the center of the receiving plate (5). The positive electrode of the high voltage is connected to the metal needle of the syringe, and the negative electrode is connected to the aluminum foil on the receiving plate (5). Under the control of the micropump controller (1), the micropump actuator (2) moves downward accurately to squeeze the TPU electrospinning solution (3) in the syringe, so that the TPU mixed solution (4) flows out evenly at a speed of 1 ml / h. The TPU mixed solution (4) flowing out of the syringe forms filaments under the action of high voltage electricity and is wound around the aluminum foil of the receiving plate (5) in a fixed direction. Due to the reciprocating motion of the syringe, a whole piece of TPU film is formed on the receiving plate (5). The thickness of the TPU film can be controlled by controlling the spinning time.

4. The method for preparing a cross-pipe flexible piezoresistive sensor according to claim 1, characterized in that: in, The flexible film soaked in carbon nanotubes has good conductivity. Bending and rolling it enhances its radial force response. The orthogonal x- and y-axis composite network structure enables it to selectively sense the strain components along the x- and y-axes. The tubular structure will also deform when under pressure, resulting in signal changes, thereby realizing multi-dimensional force detection.

5. The method for preparing a cross-pipe flexible piezoresistive sensor according to claim 1, characterized in that: In step 3) and step 4), each tubular structure film on the TPU film is selectively designed to be arranged along the x and y orthogonal axes to form a grid structure.

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