A 3D printing preparation method for fiber-level pressure sensor

Abstract

The present invention belongs to the technical field of pressure sensor preparation, and relates to a 3D printing preparation method of a fiber-level pressure sensor. The 3D printing method is used to extrude ultrafine metal wires and pressure polymer materials from the same printing nozzle to obtain a fiber-level pressure sensor. The flow channel in the printing nozzle is composed of a vertical flow channel and an inclined flow channel. The vertical flow channel is divided into two sections, the middle of the upper section is connected to the lower end of the inclined flow channel, and a wire guide rod is provided in the upper section. A gap is left between the wire guide rod and the upper section, and a wire guide hole for ultrafine metal wire to pass through is provided in the wire guide rod. The ultrafine metal wire enters from the upper end of the vertical flow channel, and the pressure polymer material enters from the upper end of the inclined flow channel. The present invention adopts a 3D printing method to prepare a fiber-level pressure sensor, which can improve the performance of the pressure polymer material to obtain a high-sensitivity sensor, can accurately control the sensor structure and diameter, simplify the preparation process, improve efficiency and expand the application field.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure sensor preparation, and relates to a 3D printing preparation method of a fiber-level pressure sensor. Background Art

[0002] With the rapid development of science and technology, the demand for high-precision and high-stability sensors is growing, especially in cutting-edge fields such as smart wearables, medical health, environmental monitoring, and aerospace. Fiber-level pressure sensors have become an ideal choice to meet these needs with their unique advantages, such as highly integrated three-dimensional structural design, flexible and changeable pattern printing capabilities, and excellent environmental adaptability. It can not only significantly improve the sensitivity, response speed, and durability of the sensor, but also maintain stable performance output under extreme conditions, providing strong technical support for innovative applications in various fields. Therefore, accelerating the research and development and application of fiber-level pressure sensors is of vital importance to promoting scientific and technological progress, promoting industrial upgrading, and improving the quality of human life.

[0003] The current wet spinning, hot pressing, melt spinning and other technologies are mainly used to prepare sensors with sandwich structures. The sensing layer and the electrode layer need to be bonded. The electrodes used to output the charge are generally coated with silver paste, adhered with conductive tape, electroplated, etc., resulting in poor adhesion between interfaces, which greatly affects the output of the device charge. The device sensitivity is not high, and the process flow is long. The sensor device cannot be constructed in an integrated manner, resulting in poor stability of the sensor under extreme conditions, which hinders the widespread application of pressure sensors.

[0004] The literature (One-step and Continuous Fabrication of Coaxial Piezoelectric Fiber for Sensing Application; Chinese Journal of polymer science; 2023, 41,1778-1785.) uses screw extrusion technology to prepare one-dimensional coaxial piezoelectric fibers. First, a thin steel wire is passed through a die and fixed on a collecting roller as the inner core of the coaxial piezoelectric fiber. Then, polyvinylidene fluoride (PVDF) pellets are melt-extruded through a single-screw extruder, and the molten PVDF material is stretched at different speeds through a collecting roller to obtain one-dimensional flexible coaxial piezoelectric fibers of different diameters. Subsequently, these fibers are further processed and assembled into single-electrode bending vibration piezoelectric sensors. Finally, it is embedded in clothing through a weaving process, so that the sensor can be used as a wearable self-powered motion monitoring system.

[0005] Although the above literature has made some progress in the preparation of fiber-level pressure sensors, it still faces many challenges and shortcomings, which are specifically reflected in the following aspects:

[0006] 1. Performance bottleneck of fiber-level pressure sensors: Although fiber-level pressure sensors prepared by existing technologies show certain functionality in specific application scenarios, their sensitivity still needs to be further improved.

[0007] 2. The diameter control process is cumbersome and has high loss: During the preparation process, the diameter of the fiber-level pressure sensor is controlled by adjusting the stretching speed of the collecting roller. Although adjustability within a certain range is achieved, this process is relatively cumbersome and requires precise control of parameters such as stretching speed and temperature. It is also easy to increase material loss due to improper operation, reducing production efficiency and cost-effectiveness.

[0008] 3. The post-processing process is complex and time-consuming: Due to structural limitations, the one-dimensional fiber-level pressure sensor cannot be directly applied to the construction of sensors with complex shapes or special structures. In order to achieve special structures such as spiral structures and three-dimensional networks, subsequent complex processing processes such as heat setting and weaving must be carried out.

[0009] Therefore, it is necessary to seek new preparation technologies and methods to simplify the preparation process, improve production efficiency, reduce material loss, and further improve the performance of fiber-level pressure sensors, thereby promoting their application in a wider range of fields. Summary of the invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and to provide a 3D printing preparation method for a fiber-level pressure sensor.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A 3D printing preparation method for a fiber-level pressure sensor, wherein ultrafine metal wires (ultrafine copper wires, ultrafine silver wires, ultrafine gold wires, ultrafine platinum wires, etc.) and pressure polymer materials are extruded from the same printing nozzle by a 3D printing method to obtain a fiber-level pressure sensor;

[0013] The flow channel in the printing nozzle is composed of a vertical flow channel and an inclined flow channel. The vertical flow channel is divided into two sections, the middle of the upper section of the vertical flow channel is connected to the lower end of the inclined flow channel, a wire guide rod is provided in the upper section of the vertical flow channel, a gap is left between the wire guide rod and the upper section of the vertical flow channel, a wire guide hole for ultrafine metal wire to pass through is provided in the wire guide rod, the ultrafine metal wire enters from the upper end of the vertical flow channel, and the pressure polymer material enters from the upper end of the inclined flow channel. The two are compounded in the lower section of the vertical flow channel, and the pressure polymer material wraps the ultrafine metal wire to form a structure;

[0014] The diameter of the ultrafine metal wire is 0.01-0.03mm.

[0015] The present invention adopts the 3D printing method to prepare the fiber-level pressure sensor to solve the problems existing in the prior art for the following reasons:

[0016] Voltage needs to be applied during the 3D printing process. Voltage can cause the molecular chains of some pressure polymer materials (such as piezoelectric polymer materials) to polarize, form an ordered arrangement, increase the crystallinity, enhance the performance of the pressure polymer materials, and obtain a fiber-level pressure sensor with high output voltage and high sensitivity.

[0017] 3D printing technology can directly control the diameter of fiber-level pressure sensors and can directly print them into pyramid structures, honeycomb structures, woven structures, etc. 3D printing technology can directly increase the sensitivity by adjusting the printing process to increase the pore structure and expand the detection range of the sensor.

[0018] There is a problem in using ultrafine metal wire and pressure polymer materials as raw materials to prepare fiber-level pressure sensors by 3D printing - the ultrafine metal wire is too light and thin to enter the flow channel, and it is difficult to position it. The ultrafine metal wire easily floats on the surface of the fiber-level pressure sensor. The present invention solves this problem by redesigning the structure of the printing nozzle and adding a wire guide rod.

[0019] As the preferred technical solution:

[0020] In the 3D printing preparation method of a fiber-level pressure sensor as described above, the vertical flow channel, the inclined flow channel, and the guide wire rod are all cylindrical structures, the diameter of the guide wire rod is 1 / 5-2 / 5 of the diameter of the vertical flow channel, the diameter of the vertical flow channel is 0.1-0.5mm, and the diameter of the inclined flow channel is 1.75mm or 3mm.

[0021] In the 3D printing preparation method of a fiber-level pressure sensor as described above, the included angle between the vertical flow channel and the inclined flow channel is 60°.

[0022] In the 3D printing preparation method of a fiber-level pressure sensor as described above, in the upper section of the vertical flow channel, the length section located above the lower end of the inclined flow channel is recorded as the upper-upper section, and the length section located below the lower end of the inclined flow channel is recorded as the upper-upper section, the upper-lower section, and the lower section of the vertical flow channel have a length ratio of 4:3:3.

[0023] In the 3D printing preparation method of a fiber-level pressure sensor as described above, the guide wire rod is equal in length to the upper section of the vertical flow channel.

[0024] In the 3D printing preparation method of a fiber-level pressure sensor as described above, the diameter of the wire guide hole is 0.01 mm larger than the diameter of the ultrafine metal wire; the number of ultrafine metal wires and wire guide holes is 1, 2 or 3, and one ultrafine metal wire passes through one wire guide hole; the present invention utilizes the position of the wire guide hole to control the distribution of the ultrafine metal wire, thereby achieving directional distribution of the ultrafine metal wire in the fiber-level pressure sensor.

[0025] As described above, a 3D printing preparation method for a fiber-level pressure sensor, the 3D printing process parameters include: electric field voltage 20kV, filling rate 60%-100%, layer thickness 0.2-0.4mm; the 3D printed filling path is a straight line, honeycomb, square wave, woven structure or concentric circle; when the filling path is a straight line, the printing angle is 0°, 90° or ±45°.

[0026] In the 3D printing preparation method of a fiber-level pressure sensor as described above, the pressure polymer material is a piezoelectric polymer material such as PVDF, polyacrylonitrile (PAN), polylactic acid (PLLA) or a thermoplastic polymer (PLA) containing piezoelectric fillers (barium titanate, zinc oxide, carbon nanotubes); the fiber-level pressure sensor is a fiber-level piezoelectric sensor with a sensitivity of 2-8V / kPa and a detection range of 1-75kPa.

[0027] In the 3D printing preparation method of a fiber-level pressure sensor as described above, the pressure polymer material is a piezoresistive polymer material such as polyethylene elastomer, polycaprolactone, polyamide elastomer or thermoplastic polyurethane elastomer containing conductive filler (carbon black, carbon nanotubes, silver nanowires); the fiber-level pressure sensor is a fiber-level piezoresistive sensor with a sensitivity of 80-160 kPa -1 , the detection range is 1-180kPa.

[0028] Beneficial Effects

[0029] (1) The present invention applies voltage during the 3D printing process to polarize the molecular chains of the pressure polymer material to form an orderly arrangement, thereby improving the crystallinity, thereby improving the performance of the pressure polymer material and obtaining a fiber-level pressure sensor with high output voltage and high sensitivity. At the same time, 3D printing technology can accurately control the diameter of the sensor and print complex structures to meet diverse application needs.

[0030] (2) The present invention redesigns the printing nozzle structure and adds a wire guide rod, thereby solving the problem that the ultrafine metal wire is too light and too thin to enter the flow channel, cannot be positioned, and easily floats on the sensor surface, thereby achieving the directional distribution of the ultrafine metal wire in the fiber-level pressure sensor.

[0031] (3) The present invention does not require complicated post-processing processes, simplifies the preparation process, improves production efficiency, reduces material loss, and promotes the wider application of fiber-level pressure sensors in smart wearables, medical health, environmental monitoring, aerospace and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of an ultra-fine metal wire passing through a wire guide rod; wherein a corresponds to Example 1, and b corresponds to Example 3;

[0033] Figure 2 A schematic diagram of the flow path of the ultra-fine metal wire and the pressure polymer material entering the printing nozzle (the wire guide rod is not shown in the figure);

[0034] Figure 3 A schematic diagram of preparing a fiber-level pressure sensor by 3D printing (the guide wire rod is not shown in the figure);

[0035] Figure 4 Schematic diagram of the cross section of the extruded fuse during 3D printing (the distance unit in the figure is mm); wherein a corresponds to Example 1 and Example 7; b corresponds to Example 2; c corresponds to Example 3; d corresponds to Example 5; e corresponds to Example 8, f corresponds to Example 4, and g corresponds to Example 6;

[0036] Figure 5 Fill the path diagram for the braided structure;

[0037] Among them, 1-ultrafine metal wire, 2-heating platform, 3-copper sheet, 4-printing platform, 5-upper section, 6-lower section, 7-upper-upper section, 8-upper and lower sections. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0039] The following are the test methods for the relevant performance indicators in each embodiment:

[0040] Sensitivity and detection range of fiber-level piezoelectric sensor: First, use a universal testing machine to apply a pressure of 1-75kPa to the fiber-level piezoelectric sensor, and set the compression rate of the universal testing machine to 1-5mm / min. Then, the output signal generated by the fiber-level piezoelectric sensor during the compression process is transmitted to the digital multimeter in real time. The digital multimeter directly displays the strength of the output voltage signal. Finally, based on the obtained data, the sensitivity S (V / kPa) of the fiber-level piezoelectric sensor is calculated according to the following formula:

[0041] S = ΔV / ΔP;

[0042] Where ΔV is the relative change in the output voltage of the fiber-level piezoelectric sensor (V), and ΔP is the relative change in the pressure applied by the fiber-level piezoelectric sensor (kPa);

[0043] The test process was repeated three times, and the average of the three calculation results was taken to obtain the sensitivity of the fiber-level piezoelectric sensor;

[0044] The pressure range where signal output is detected is the detection range.

[0045] Sensitivity and detection range of fiber-level piezoresistive sensor: First, the fiber-level piezoresistive sensor was installed on an electronic universal testing machine and connected to a digital multimeter. Then, the pressure range was set to 1-180 kPa and the tensile rate of the electronic universal testing machine was set to 10 mm / min for testing. During the test, the resistance change of the fiber-level piezoresistive sensor during the tensile process was transmitted to the digital multimeter in real time, and the digital multimeter directly displayed the resistance value. Finally, based on the obtained data, the sensitivity S (kPa) of the fiber-level piezoresistive sensor was calculated according to the following formula -1 ):

[0046] S = (ΔR / R0) / ΔP;

[0047] Where ΔR is the absolute change in resistance (the ratio ΔR / R0 to the initial resistance R0 represents the resistance change rate), R0 is the initial resistance (Ω), and ΔP is the pressure change applied to the fiber-level piezoresistive sensor (kPa);

[0048] The test process was repeated three times, and the average of the three calculation results was taken to obtain the sensitivity of the fiber-level piezoresistive sensor;

[0049] The pressure range where signal output is detected is the detection range.

[0050] like Figure 2 As shown, the flow channel in the printing nozzle in the following embodiments consists of a vertical flow channel and an inclined flow channel; the vertical flow channel is divided into an upper section 5 and a lower section 6; in the upper section 5, the length section located above the lower end of the inclined flow channel is recorded as the upper-upper section 7, and the length section located below the lower end of the inclined flow channel is recorded as the upper-lower section 8, and the length ratio of the upper-upper section 7, the upper-lower section 8, and the lower section 6 is 4:3:3; the middle part of the upper section 5 is connected to the lower end of the inclined flow channel, and a wire guide rod of the same length as the upper section 5 is provided in the upper section 5, and a gap is left between the wire guide rod and the upper section 5; the number of wire guide holes is the same as that of the ultrafine metal wire, and the two correspond one to one; the vertical flow channel, the inclined flow channel, and the wire guide rod are all cylindrical structures, and the angle between the vertical flow channel and the inclined flow channel is 60°.

[0051] Example 1

[0052] A 3D printing preparation method for a fiber-level piezoelectric sensor, the specific steps are as follows:

[0053] (1) Preparation of raw materials;

[0054] Ultrafine metal wire: ultrafine copper wire, diameter 0.01mm;

[0055] Piezoelectric polymer material: PVDF, manufacturer is Zhejiang Funolin Chemical New Materials Co., Ltd., model number is FL2008;

[0056] (2) If Figure 3 As shown, a 3D printing method is used to extrude an ultra-fine metal wire and a piezoelectric polymer material from the same printing nozzle onto a printing platform (a printing platform 4 is located on a copper sheet 3, and a copper sheet 3 is located on a heating platform 2), thereby obtaining a fiber-level piezoelectric sensor; Figure 1 As shown in a, the ultra-fine metal wire 1 enters from the upper end of the wire guide rod in the upper section of the vertical flow channel through the corresponding wire guide hole. Figure 2 or Figure 3 As shown, the piezoelectric polymer material enters from the upper end of the inclined flow channel;

[0057] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.1mm, the diameter of the inclined flow channel is 1.75mm, the diameter of the wire guide rod is 0.04mm, the number of wire guide holes is 1, and the diameter of the wire guide hole is 0.02mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 100% (filling path is a straight line), printing angle 0°, and layer thickness 0.2mm.

[0058] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in a, the fiber-level piezoelectric sensor finally obtained is a planar structure; the sensitivity of the fiber-level piezoelectric sensor is 2V / kPa, and the detection range is 5-40kPa.

[0059] Example 2

[0060] A 3D printing preparation method for a fiber-level piezoelectric sensor, the specific steps are as follows:

[0061] (1) Preparation of raw materials;

[0062] Ultrafine metal wire: ultrafine silver wire, diameter 0.01mm;

[0063] Piezoelectric polymer material: PAN, manufactured by Hubei Dechao Chemical Co., Ltd., model P60C;

[0064] (2) Using a 3D printing method, an ultrafine metal wire and a piezoelectric polymer material are extruded from the same printing nozzle onto a printing platform to obtain a fiber-level piezoelectric sensor; the ultrafine metal wire enters from the upper end of the wire guide rod in the upper section of the vertical flow channel through the corresponding wire guide hole, and the piezoelectric polymer material enters from the upper end of the inclined flow channel; the printing platform is located on a copper sheet, and the copper sheet is located on a heating platform;

[0065] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.2mm, the diameter of the inclined flow channel is 3mm, the diameter of the wire guide rod is 0.04mm, the number of wire guide holes is 1, and the diameter of the wire guide hole is 0.02mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 100% (filling path is a straight line), printing angle 0°, and layer thickness 0.2mm.

[0066] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in b, the final fiber-grade piezoelectric sensor is a columnar structure; the sensitivity of the fiber-grade piezoelectric sensor is 4V / kPa, and the detection range is 5-45kPa.

[0067] Example 3

[0068] A 3D printing preparation method for a fiber-level piezoelectric sensor, the specific steps are as follows:

[0069] (1) Preparation of raw materials;

[0070] Ultrafine metal wire: Ultrafine gold wire, diameter 0.02mm;

[0071] Piezoelectric polymer material: PLLA, manufactured by Zhejiang Hisun Biomaterials Co., Ltd., brand name REVODE190;

[0072] (2) Using the 3D printing method, two ultra-fine metal wires and piezoelectric polymer materials are extruded from the same printing nozzle onto the printing platform to obtain a fiber-level piezoelectric sensor; Figure 1 As shown in b, two ultra-fine metal wires 1 respectively enter from the upper ends of the wire rods in the upper section of the vertical flow channel through the corresponding wire guide holes, and the piezoelectric polymer material enters from the upper end of the inclined flow channel; the printing platform is located on the copper sheet, and the copper sheet is located on the heating platform;

[0073] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.3mm, the diameter of the inclined flow channel is 1.75mm, the diameter of the wire guide rod is 0.08mm, the number of wire guide holes is 2, and the diameter of the 2 wire guide holes is 0.03mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 80% (filling path is concentric circles), and layer thickness 0.4mm.

[0074] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in c, the final fiber-grade piezoelectric sensor is a hemispherical structure. The sensitivity of the fiber-grade piezoelectric sensor is 5V / kPa, and the detection range is 1-50kPa.

[0075] Example 4

[0076] A 3D printing preparation method for a fiber-level piezoelectric sensor, the specific steps are as follows:

[0077] (1) Preparation of raw materials;

[0078] Ultrafine metal wire: ultrafine platinum wire, diameter 0.02mm;

[0079] Piezoelectric polymer material: PLA containing barium titanate (20wt%); the manufacturer of PLA is Nature Works, model number is 4060D;

[0080] (2) Using a 3D printing method, two ultrafine metal wires and a piezoelectric polymer material are extruded from the same printing nozzle onto a printing platform to obtain a fiber-level piezoelectric sensor; the two ultrafine metal wires are respectively inserted from the upper ends of the wire guide rods in the upper section of the vertical flow channel through corresponding wire guide holes, and the piezoelectric polymer material is inserted from the upper end of the inclined flow channel; the printing platform is located on a copper sheet, and the copper sheet is located on a heating platform;

[0081] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.3mm, the diameter of the inclined flow channel is 1.75mm, the diameter of the wire guide rod is 0.08mm, the number of wire guide holes is 2, and the diameter of the 2 wire guide holes is 0.03mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 80% (filling path is square wave), and layer thickness 0.2mm.

[0082] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in f, the final fiber-level piezoelectric sensor is a truncated cone structure; the sensitivity of the fiber-level piezoelectric sensor is 6V / kPa, and the detection range is 1-55kPa.

[0083] Example 5

[0084] A 3D printing preparation method for a fiber-level piezoelectric sensor, the specific steps are as follows:

[0085] (1) Preparation of raw materials;

[0086] Ultrafine metal wire: ultrafine copper wire, diameter 0.03mm;

[0087] Piezoelectric polymer material: PLA containing zinc oxide (15wt%); the manufacturer of PLA is Nature Works, model number is 4060D;

[0088] (2) Using a 3D printing method, three ultrafine metal wires and a piezoelectric polymer material are extruded from the same printing nozzle onto a printing platform to obtain a fiber-level piezoelectric sensor; the three ultrafine metal wires are respectively inserted from the upper ends of the wire guide rods in the upper section of the vertical flow channel through corresponding wire guide holes, and the piezoelectric polymer material is inserted from the upper end of the inclined flow channel; the printing platform is located on a copper sheet, and the copper sheet is located on a heating platform;

[0089] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.4mm, the diameter of the inclined flow channel is 1.75mm, the diameter of the wire rod is 0.16mm, the number of wire holes is 3, and the diameter of the three wire holes is 0.04mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 70% (such as Figure 5 As shown, the filling path is a woven structure) with a layer thickness of 0.3mm.

[0090] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in (d), the fiber-grade piezoelectric sensor finally obtained has an arch bridge structure; the sensitivity of the fiber-grade piezoelectric sensor is 7V / kPa, and the detection range is 1-60kPa.

[0091] Example 6

[0092] A 3D printing preparation method for a fiber-level piezoelectric sensor, the specific steps are as follows:

[0093] (1) Preparation of raw materials;

[0094] Ultrafine metal wire: ultrafine platinum wire, diameter 0.03mm;

[0095] Piezoelectric polymer material: PLA containing carbon nanotubes (5wt%); the manufacturer of PLA is Nature Works, model number is 4060D;

[0096] (2) Using a 3D printing method, three ultrafine metal wires and a piezoelectric polymer material are extruded from the same printing nozzle onto a printing platform to obtain a fiber-level piezoelectric sensor; the three ultrafine metal wires are respectively inserted from the upper ends of the wire guide rods in the upper section of the vertical flow channel through corresponding wire guide holes, and the piezoelectric polymer material is inserted from the upper end of the inclined flow channel; the printing platform is located on a copper sheet, and the copper sheet is located on a heating platform;

[0097] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.5mm, the diameter of the inclined flow channel is 3mm, the diameter of the wire guide rod is 0.2mm, the number of wire guide holes is 3, and the diameter of the three wire guide holes is 0.04mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 60% (filling path is honeycomb), and layer thickness 0.4mm.

[0098] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in g, the final fiber-level piezoelectric sensor is a pyramid structure; the sensitivity of the fiber-level piezoelectric sensor is 8V / kPa, and the detection range is 1-75kPa.

[0099] Example 7

[0100] A 3D printing preparation method for a fiber-level piezoresistive sensor, the specific steps are as follows:

[0101] (1) Preparation of raw materials;

[0102] Ultrafine metal wire: ultrafine copper wire, diameter 0.01mm;

[0103] Piezoresistive polymer material: polyolefin elastomer, manufacturer is ExxonMobil, model is POE 0203;

[0104] (2) Using a 3D printing method, an ultrafine metal wire and a piezoresistive polymer material are extruded from the same printing nozzle onto a printing platform to obtain a fiber-level piezoresistive sensor; the ultrafine metal wire enters from the upper end of the wire guide rod in the upper section of the vertical flow channel through the corresponding wire guide hole, and the piezoresistive polymer material enters from the upper end of the inclined flow channel; the printing platform is located on a copper sheet, and the copper sheet is located on a heating platform;

[0105] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.1mm, the diameter of the inclined flow channel is 1.75mm, the diameter of the wire guide rod is 0.04mm, the number of wire guide holes is 1, and the diameter of the wire guide hole is 0.02mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 100% (filling path is a straight line), printing angle 90°, and layer thickness 0.2mm.

[0106] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in a; the fiber-level piezoresistive sensor finally obtained is a cylindrical structure; the sensitivity of the fiber-level piezoresistive sensor is 80kPa -1 , the detection range is 1-100kPa.

[0107] Example 8

[0108] A 3D printing preparation method for a fiber-level piezoresistive sensor, the specific steps are as follows:

[0109] (1) Preparation of raw materials;

[0110] Ultrafine metal wire: ultrafine silver wire, diameter 0.02mm;

[0111] Piezoresistive polymer material: polycaprolactone, manufacturer: Perstorp AB, model: CAPA6500;

[0112] (2) Using the 3D printing method, three ultrafine metal wires and piezoresistive polymer materials are extruded from the same printing nozzle onto a printing platform to obtain a fiber-level piezoresistive sensor; the three ultrafine metal wires respectively enter from the upper ends of the wire guide rods in the upper section of the vertical flow channel through the corresponding wire guide holes, and the piezoresistive polymer material enters from the upper end of the inclined flow channel; the printing platform is located on a copper sheet, and the copper sheet is located on a heating platform;

[0113] Among them, the parameters related to the printing nozzle are: the diameter of the vertical flow channel is 0.5mm, the diameter of the inclined flow channel is 3mm, the diameter of the wire guide rod is 0.1mm, the number of wire guide holes is 3, and the diameter of the three wire guide holes is 0.03mm; the process parameters of 3D printing are: electric field voltage 20kV, filling rate 60% (filling path is honeycomb), and layer thickness 0.4mm.

[0114] During 3D printing, the cross section of the extruded filament is as follows: Figure 4 As shown in e; the final fiber-level piezoresistive sensor is a hemispherical structure; the sensitivity of the fiber-level piezoresistive sensor is 160kPa -1 , the detection range is 1-180kPa.

Claims

1. A 3D printing preparation method for a fiber-level pressure sensor, characterized in that: Using 3D printing method, ultra-fine metal wire and pressure polymer material are extruded from the same printing nozzle to obtain fiber-level pressure sensor; The flow channel in the printing nozzle is composed of a vertical flow channel and an inclined flow channel. The vertical flow channel is divided into two sections, the middle of the upper section of the vertical flow channel is connected to the lower end of the inclined flow channel. A wire guide rod is provided in the upper section of the vertical flow channel. A gap is left between the wire guide rod and the upper section of the vertical flow channel. A wire guide hole for ultrafine metal wire to pass through is provided in the wire guide rod. The ultrafine metal wire enters from the upper end of the vertical flow channel, and the pressure polymer material enters from the upper end of the inclined flow channel. The diameter of the ultrafine wire is 0.01-0.03mm; The pressure polymer material is PLA containing piezoelectric filler; the fiber-level pressure sensor is a fiber-level piezoelectric sensor with a sensitivity of 6-8V / kPa and a detection range of 1-75kPa.

2. The 3D printing preparation method of a fiber-level pressure sensor according to claim 1, characterized in that: The vertical flow channel, the inclined flow channel and the wire guide rod are all cylindrical structures. The diameter of the wire guide rod is 1 / 5-2 / 5 of the diameter of the vertical flow channel. The diameter of the vertical flow channel is 0.1-0.5 mm, and the diameter of the inclined flow channel is 1.75 mm or 3 mm.

3. The 3D printing preparation method of a fiber-level pressure sensor according to claim 2, characterized in that: The included angle between the vertical flow channel and the inclined flow channel is 60°.

4. The 3D printing preparation method of a fiber-level pressure sensor according to claim 1, characterized in that: In the upper section of the vertical channel, the length section located above the lower end of the inclined channel is recorded as the upper-upper section, and the length section located below the lower end of the inclined channel is recorded as the upper-upper section. The length ratio of the upper-upper section, the upper-upper section, and the lower section of the vertical channel is 4:3:

3.

5. The 3D printing preparation method of a fiber-level pressure sensor according to claim 1, characterized in that: The wire guide rod is equal in length to the upper section of the vertical flow channel.

6. The 3D printing preparation method of a fiber-level pressure sensor according to claim 1, characterized in that: The diameter of the wire guide hole is 0.01 mm larger than the diameter of the ultrafine metal wire; the number of the ultrafine metal wire and the wire guide hole are both 1, 2 or 3, and one ultrafine metal wire passes through one wire guide hole.

7. The 3D printing preparation method of a fiber-level pressure sensor according to claim 1, characterized in that: The process parameters of 3D printing include: electric field voltage 20kV, filling rate 60%-100%, layer thickness 0.2-0.4mm; the filling path of 3D printing is straight line, honeycomb, square wave, woven structure or concentric circle; when the filling path is a straight line, the printing angle is 0°, 90° or ±45°.

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