Double-helix piezoelectric fiber array sensor and preparation method thereof

Abstract

The invention relates to the technical field of bionic touch, in particular to a double-helix piezoelectric fiber array sensor and a preparation method thereof. The double-helix piezoelectric fiber array sensor comprises an elastic base layer which is provided with a sensing area; the at least one sensing group is arranged in the sensing area of the elastic base layer, the sensing group comprises a first piezoelectric fiber and a second piezoelectric fiber, and the first piezoelectric fiber and the second piezoelectric fiber are the same in structure; and the first piezoelectric fiber and the second piezoelectric fiber are arranged in parallel. According to the embodiment, the two piezoelectric fibers of the double-helix structure are arranged side by side in the micro distance, when the sensor is triggered by the action of touching or sliding, the type of the trigger load can be analyzed according to the difference result by obtaining the charge signals of the two piezoelectric fibers of the double-helix structure and processing the difference value of the two charge signals through a difference method.

Description

Technical Field

[0001] This invention relates to the field of biomimetic tactile technology, specifically to a double-helix piezoelectric fiber array sensor and its fabrication method. Background Technology

[0002] With the continuous development of wearable devices, wearable devices now possess flexible functions such as bending, folding, and stretching. These characteristics make flexible wearable devices highly adaptable, giving them great application potential in smart scenarios such as healthcare, sports, and daily life.

[0003] In the process of developing this invention, the inventors discovered that existing tactile sensors struggle to effectively distinguish between normal and shear loads under simple structural conditions. Traditional solutions typically rely on multi-layer stacking or complex algorithms to differentiate between normal and shear loads, but these methods are costly and lack real-time performance. While PVDF-type piezoelectric polymers are now used for piezoelectric detection, offering the advantage of easy fiberization, straight fiber structures still suffer from aliasing in response to loads in different directions, making it difficult to achieve stable decoupled output. Summary of the Invention

[0004] One of the objectives of this invention is to provide a double-helix piezoelectric fiber array sensor and its fabrication method, so as to solve the problem that the prior art cannot effectively distinguish between normal and shear loads.

[0005] To solve the above-mentioned technical problems, the embodiments of the present invention are implemented as follows: In a first aspect, a dual-helix piezoelectric fiber array sensor is provided, comprising: An elastic base layer, wherein a sensing area is provided on the elastic base layer; At least one sensing group is disposed in the sensing area of ​​the elastic base layer, the sensing group comprising a first piezoelectric fiber and a second piezoelectric fiber, the first piezoelectric fiber and the second piezoelectric fiber having the same structure; and the first piezoelectric fiber and the second piezoelectric fiber are arranged side by side. Wherein, the first piezoelectric fiber comprises: at least two fiber strips, and the two fiber strips are configured with an anti-helical structure; and, Electrodes, which are disposed at both ends of the first piezoelectric fiber.

[0006] Furthermore, the spacing between the first piezoelectric fiber and the second piezoelectric fiber is controlled to be 2.0-3.0 mm.

[0007] Furthermore, the fiber strips in the first piezoelectric fiber are configured to have the same polarization direction.

[0008] Furthermore, the fiber tape is made of either PVDF fiber or PVDF-TrFE fiber.

[0009] The second aspect also provides a pressure detection method, which uses the aforementioned double-helix piezoelectric fiber array sensor for detection, and includes the following steps: Acquire the first charge signal of the first piezoelectric fiber and the second charge signal of the second piezoelectric fiber; The difference results between the first charge signal and the second charge signal are analyzed using a differential method; The detection result is obtained by judging the difference result; The discrimination process is as follows: if the difference between the first charge signal and the second charge signal is close to zero, it is normal pressure; if the difference between the first charge signal and the second charge signal is much greater than zero, it is lateral shear pressure.

[0010] Furthermore, when obtaining the detection result, the method further combines the difference value with the difference value to determine whether the charge values ​​of the first charge signal and the second charge signal are equal, thereby obtaining the detection result.

[0011] Furthermore, the differential analysis method calculates the difference between the first charge signal and the second charge signal using a differential formula, wherein the differential formula is: VΔ = V1 - V2; Where VΔ is the difference value; V1 is the first charge signal; and V2 is the second charge signal.

[0012] The third aspect also provides a preparation method for preparing the aforementioned double-helix piezoelectric fiber array sensor, characterized in that the steps include: To prepare fiber tape, the fiber material is polarized to increase the β phase content, and then the fiber tape is dissolved to obtain a spinnable solution. The spinnable solution is then made into fiber tape. Two fiber strips are spirally wound together to produce a reverse double-helix piezoelectric fiber. An inverted double-helix piezoelectric fiber is mounted on an elastic base layer, and electrodes are fabricated at both ends of the inverted double-helix piezoelectric fiber. The positions of the piezoelectric fibers with reverse double helixes in the elastic base layer are encapsulated and cured to obtain a double helix piezoelectric fiber array sensor.

[0013] Furthermore, the step of mounting the reverse double-helix piezoelectric fiber on the elastic base layer involves: setting a mounting groove on the elastic base layer, placing the reverse double-helix piezoelectric fiber in the mounting groove, and controlling the spacing error and parallelism error between the two reverse double-helix piezoelectric fibers.

[0014] The fourth aspect also provides a bionic skin, which includes the aforementioned double-helix piezoelectric fiber array sensor for detection; In addition, a flexible layer is provided on both sides of the double-helix piezoelectric fiber array sensor.

[0015] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following: This invention discloses a double-helix piezoelectric fiber array sensor, which consists of two double-helix piezoelectric fibers arranged side-by-side at a micro-distance. When the sensor is triggered by a touch or sliding action, the charge signals of the two double-helix piezoelectric fibers are acquired. The difference between the two charge signals is processed using a differential method, and the type of triggering load is analyzed based on the differential result. The tactile sensor structure designed in this invention can improve the sensor's sensitivity and distinguish the type of triggering pressure.

[0016] In this embodiment, two piezoelectric fibers with identical structures are arranged side by side on a flexible elastic base layer. The charge signals of the two piezoelectric fibers are then acquired, processed, and analyzed. Finally, the load pressure type can be quickly and easily obtained based on the results, and the pressure type can be efficiently distinguished.

[0017] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 A schematic diagram of a double-helix piezoelectric fiber array sensor provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the first piezoelectric fiber according to an embodiment of the present invention; Figure 3 This is a voltage response curve under normal pressure according to an embodiment of the present invention; Figure 4 This is a differential voltage curve obtained from the detection of normal pressure in an embodiment of the present invention. Figure 5 This is a voltage response curve under shear pressure according to an embodiment of the present invention; Figure 6 This is a differential voltage curve obtained by detecting shear pressure in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any implementation described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other implementations. The following description is provided to enable any person skilled in the art to implement and use this application. Details are set forth in the following description for illustrative purposes. It should be understood that those skilled in the art will recognize that this application can be implemented without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but rather to be consistent with the broadest scope of the principles and features disclosed in this application.

[0022] Bionic skin is an artificial material designed to mimic the structure and function of human skin, aiming to replicate the sensory, protective, and self-healing properties of real skin. It is typically made of elastic polymer composites (such as silicone-based polymers), possessing flexibility, stretchability, and biocompatibility. Its core functions include sensing external stimuli such as pressure, temperature, and humidity, and converting this information into electrical signals for applications in robotics, intelligent prosthetics, and medical monitoring. For example, bionic electronic skin can endow robots with tactile abilities, enhancing the human-computer interaction experience. Bionic skin has enormous application potential in consumer electronics, military, and healthcare industries. With the development of flexible electronics, novel attachable, wearable, portable, and foldable flexible electronic devices have become an important development direction in recent years.

[0023] Among them, tactile sensors play a core role in bionic skin. By simulating the tactile perception mechanism of human skin, bionic skin can detect and respond to mechanical stimuli from the external environment, including pressure, shear force, and vibration, as well as physical properties such as temperature, humidity, and texture.

[0024] Existing tactile sensors struggle to effectively distinguish between normal and shear loads even with simple structures. Traditional solutions typically rely on multi-layer stacking or complex algorithms to differentiate between normal and shear loads, but these methods are costly and lack real-time performance.

[0025] Before describing the embodiments of the present invention in detail, the design concept of the present invention will be summarized below.

[0026] This invention provides a double-helix piezoelectric fiber array sensor, the specific implementation of which is as follows. Figure 1 As shown, the core of this invention includes: two piezoelectric fibers with double helix structures arranged side-by-side at a micro-distance. When the sensor is triggered by a touch or sliding action, the charge signals of the two piezoelectric fibers with double helix structures can be acquired. The difference between the two charge signals is processed using a differential method, and the type of trigger load is analyzed based on the differential result. The tactile sensor structure designed in this invention can improve the sensitivity of the sensor and distinguish the type of trigger pressure.

[0027] For the first aspect, which is based on the same inventive concept, please refer to the appendix. Figure 1 The diagram also discloses a double-helix piezoelectric fiber array sensor, comprising: Elastic base layer 2, on which a sensing area is provided; At least one sensing group 1 is provided in the sensing area of ​​the elastic base layer 2. The sensing group 1 includes a first piezoelectric fiber 10 and a second piezoelectric fiber 11. The first piezoelectric fiber 10 and the second piezoelectric fiber 11 have the same structure. Furthermore, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are arranged side by side. Wherein, the first piezoelectric fiber 10 comprises: at least two fiber strips, and the two fiber strips are configured with an anti-helical structure; and, Electrodes are disposed at both ends of the first piezoelectric fiber 10.

[0028] Understandably, when a touch sensor is subjected to normal sliding pressure, traditional sensors automatically couple / convert the sliding pressure into lateral pressure, which can easily lead to inaccurate sensing and difficulty in distinguishing between normal and lateral pressure.

[0029] In this embodiment, two piezoelectric fibers with identical structures are arranged side by side on a flexible elastic base layer 2. The charge signals of the two piezoelectric fibers are then acquired, processed, and analyzed. Finally, the load pressure type can be quickly and easily obtained based on the results, and the pressure type can be efficiently distinguished.

[0030] In this embodiment, the sensing group 1 uses two piezoelectric fibers arranged side by side. By acquiring the charge signals output by the deformation caused by pressure in two different directions of the piezoelectric fibers, it can effectively detect the pressure type of the load, that is, distinguish whether the pressure type is sliding or touching. Furthermore, the piezoelectric fibers adopt a helical structure, which can improve the deformation and sensitivity when force is applied to the piezoelectric fibers through the elastic properties of the helix.

[0031] To make the double-helix piezoelectric fiber array sensor flexible, an elastic base layer 2 is made of flexible material, and a sensing group 1 is installed on the elastic base layer 2, meaning that the elastic base layer 2 causes the sensing group 1 to deform. Electrodes are respectively placed at both ends of the two piezoelectric fibers, and the desired type can be obtained by detecting and analyzing the charge signals of the electrodes.

[0032] To improve the sensor's sensitivity, the piezoelectric fiber is configured as a double-reverse spiral structure of two fiber strips. This spiral structure enhances the sensitivity to deformation. Specifically, when a force is applied to the two fiber strips (a first fiber strip and a second fiber strip) on the spiral structure, they approach each other under the force, generating an electrical charge signal. Because the two identical first and second fiber strips approach each other, the deformation range is increased, thereby amplifying the deformation caused by pressure, increasing the amount of electrical charge signal generated, and improving the detection sensitivity.

[0033] In order to obtain the charge signal of each piezoelectric fiber individually, the embodiment sets electrodes at the two ends of the first piezoelectric fiber 10 and the second piezoelectric fiber 11, respectively, connects them to the outside through the electrodes, and then detects the charge signal generated by the electrodes individually.

[0034] Working principle: In this embodiment, two identical piezoelectric fibers 10 and 11 are arranged side by side. When a load pressure is applied to the piezoelectric fibers, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 generate two non-interfering charge signals. The two charge signals are then processed by a differential processing method to obtain a differential value. The load pressure can then be obtained by analyzing the differential value.

[0035] The two piezoelectric fibers generate two complementary charge signals as follows: When sliding, since the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are arranged side by side with a very small gap, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 undergo the same deformation, that is, two symmetrical charge signals are obtained. Two synchronous and equal-intensity electrical signals are obtained through the detection electrode. A difference value close to zero is obtained through differential calculation, which indicates that the sensor is subjected to normal pressure. When touching, since the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are arranged side by side and the touch is lateral, the first piezoelectric fiber 10 is compressed and the second piezoelectric fiber 11 is stretched. At this time, the two charge signals of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 with the same amplitude but different signs are obtained through differential calculation, which indicates that the sensor is subjected to lateral shear pressure.

[0036] It should be noted that when subjected to lateral force, the sensor can be understood as a beam structure. That is, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are located on both sides of the neutral layer of the beam. Under the action of force, the first piezoelectric fiber 10 is compressed and the second piezoelectric fiber 11 is stretched, thereby generating two different charge signals.

[0037] Here, as attached Figure 1 The normal pressure x shown is perpendicular to the lateral shear pressure y.

[0038] In a further embodiment, the spacing between the first piezoelectric fiber 10 and the second piezoelectric fiber 11 is controlled to be 2.0-3.0 mm.

[0039] Understandably, in order to ensure that the first piezoelectric fiber 10 and the second piezoelectric fiber 11, which are arranged side by side, can obtain the same deformation in the normal direction and thus obtain symmetrical charge signals, in this embodiment, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are arranged side by side, and the interval between them is controlled within a certain range, so that the first piezoelectric fiber 10 and the second piezoelectric fiber 11 produce the same deformation, thus obtaining two symmetrical charge signals. Two synchronous and equal-intensity electrical signals are obtained through the detection electrode.

[0040] In some embodiments, the spacing between the first piezoelectric fiber 10 and the second piezoelectric fiber 11 is controlled to be 2.5 mm; in other embodiments, the spacing between the first piezoelectric fiber 10 and the second piezoelectric fiber 11 is controlled to be 2.0 mm; and in still other embodiments, the spacing between the first piezoelectric fiber 10 and the second piezoelectric fiber 11 is controlled to be 3.0 mm.

[0041] In a further embodiment, the fiber strips in the first piezoelectric fiber 10 are configured to have the same polarization direction.

[0042] Understandably, in order to ensure that the piezoelectric fiber composed of two fiber strips can generate charge, in this embodiment, the polarization directions of the first fiber strip and the second fiber strip included in the first piezoelectric fiber 10 are set to be the same, so that the first fiber strip and the second fiber strip generate the same charge signal when deformed, and finally converge to the electrode, and the charge signal of the electrode can be detected.

[0043] In a further embodiment, the fiber tape is made of either PVDF fiber or PVDF-TrFE fiber.

[0044] Based on the same inventive concept, a second aspect discloses a pressure detection method, which uses the aforementioned double-helix piezoelectric fiber array sensor for detection, comprising the following steps: Step 010: Obtain the first charge signal of the first piezoelectric fiber 10 and the second charge signal of the second piezoelectric fiber 11.

[0045] In use, the double-helix piezoelectric fiber array sensor is placed on bionic skin. When force is applied to the double-helix piezoelectric fiber array sensor, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 deform, thereby generating two independent charge signals. In this embodiment, these two charge signals are acquired for analysis in subsequent steps. That is, through structural design, two independent electrical signals under different environments can be easily acquired, thereby quickly distinguishing the type of pressure.

[0046] In actual operation, when sliding, since the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are arranged side by side with a very small gap between them, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 produce the same deformation, that is, they obtain two symmetrical charge signals. Two synchronous and equal-intensity electrical signals are obtained through the detection electrode. When touching, since the direction of the applied pressure is such that the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are arranged longitudinally side by side, under the action of the touch side, the first piezoelectric fiber 10 is compressed and the second piezoelectric fiber 11 is stretched. At this time, the first piezoelectric fiber 10 and the second piezoelectric fiber 11 have two charge signals with the same amplitude but different signs.

[0047] Please refer to the attached document. Figure 3 The figure shows the voltage signal curves of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 under normal pressure. Specifically, to simulate sliding of the sensor, a normal pressure of 0-50 kPa is gradually applied, and the voltage signal curves of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are detected. Figure 3 It can be observed that the outputs of the two channels of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 almost overlap, with a linear sensitivity of about 0.020-0.021 mV / kPa, which characterizes the structural symmetry and repeatability.

[0048] Please refer to the attached document. Figure 5 The figure shows the voltage signal curves of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 under shear pressure. Specifically, by simulating touch on the sensor, a shear pressure of 0-20 kPa is gradually applied, and the voltage signal curves of the first piezoelectric fiber 10 under compression and the second piezoelectric fiber 11 under tension are detected. Figure 5 It can be observed that the outputs of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 are almost symmetrical, that is, the absolute values ​​of their output voltages are almost equal, but the directions are opposite.

[0049] It should be noted that the charge signal here includes voltage signal or current signal. That is, the voltage signal or current signal generated by the deformation of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 can be obtained by detecting the electrodes at both ends of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 respectively.

[0050] Step 020: Analyze the difference results between the first charge signal and the second charge signal using the difference method.

[0051] In a further embodiment, the differential method analysis calculates the difference between the first charge signal and the second charge signal using a differential formula, wherein the differential formula is: VΔ = V1 - V2; Where VΔ is the difference value; V1 is the first charge signal; and V2 is the second charge signal.

[0052] Understandably, after acquiring the first charge signal and the second charge signal, in order to more intuitively observe and identify what kind of pressure caused the deformation, the embodiment uses a differential processing method, that is, calculates the difference value between the two independent charge signals through a differential formula, and then the pressure type can be identified based on the difference value.

[0053] For example: In an embodiment, when a double-helix piezoelectric fiber array sensor is used in bionic skin, such as robotic tactile bionic skin, the first piezoelectric fiber 10 is closer to the inside of the robot, and the second piezoelectric fiber 11 is further away. When the bionic skin is touched, the second piezoelectric fiber 11 is compressed and the charge signal of the channel detected is a negative voltage V2, and the first piezoelectric fiber 10 is stretched and the charge signal of the channel detected is a positive voltage V1.

[0054] In an example, when a 10 kPa positive shear pressure is applied to the bionic skin to simulate touch, the voltage signals of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 can be detected. The first charge signal V1 is 0.21 mV, and the second charge signal V2 is -0.2 mV. Using the above differential formula, VΔ = 0.21 - (-0.2) = 0.41 mV. The differential value obtained after differential calculation is much greater than zero.

[0055] When the bionic skin is subjected to a sliding motion and a normal pressure of 10 kPa is applied, the voltage signals of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 can be detected. The first charge signal V1 is 0.20 mV, and the second charge signal V2 is 0.21 mV. Using the aforementioned differential formula, VΔ = 0.21 - 0.2 = 0.01 mV is calculated. The differential value obtained after differential calculation is close to zero.

[0056] Please refer to the attached document. Figure 4 The figure shows a voltage signal curve representing the difference between the first charge signal and the second charge signal under normal pressure. Specifically, by simulating sliding, a shear pressure of 0-50 kPa is gradually applied to the sensor, the first charge signal of the first piezoelectric fiber 10 and the first charge signal of the second piezoelectric fiber are detected, and the difference value curve obtained through differential processing is shown. Figure 4 It can be observed that the voltage of the differential value remains close to zero even as the normal pressure continuously increases.

[0057] Please refer to the attached document. Figure 6 The figure shows a voltage signal curve representing the difference between the first charge signal and the second charge signal under shear pressure. Specifically, by simulating a touch, a shear pressure of 0-20 kPa is gradually applied to the sensor, the first charge signal of the first piezoelectric fiber 10 and the first charge signal of the second piezoelectric fiber are detected, and the difference value curve obtained through differential processing is used to... Figure 6 It can be observed that the voltage of the differential value increases linearly with the increase of shear pressure, and all of them are greater than zero.

[0058] Step 030: Determine the detection result based on the difference results; The discrimination process is as follows: if the difference between the first charge signal and the second charge signal is close to zero, it is normal pressure; if the difference between the first charge signal and the second charge signal is much greater than zero, it is lateral shear pressure.

[0059] In a further embodiment, when obtaining the detection result, the method further determines whether the charge values ​​of the first charge signal and the second charge signal are equal, and then combines this with the difference value for further determination to obtain the detection result. After obtaining the difference value, further determination is performed based on whether the charge values ​​of the first charge signal and the second charge signal are equal. Specifically: If the first charge signal and the second charge signal are equal and the difference is very close to zero, it is determined to be normal pressure; if the first charge signal and the second charge signal are not equal and the difference is much greater than zero, it is determined to be lateral shear pressure.

[0060] For example, When the bionic skin is subjected to simulated sliding and a normal pressure of 10 kPa is applied, the voltage signals of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 can be detected. The first charge signal V1 is 0.20 mV, and the second charge signal V2 is 0.21 mV. The difference formula described above is used to calculate VΔ = 0.21 - 0.2 = 0.01 mV. The determination process includes: the difference value after differential calculation is close to zero, and the first charge signal V1 is approximately equal to the second charge signal V2; therefore, it is determined to be normal pressure.

[0061] When a 10 kPa positive shear pressure is applied to the bionic skin to simulate touch, the voltage signals of the first piezoelectric fiber 10 and the second piezoelectric fiber 11 can be detected. The first charge signal V1 is 0.21 mV, and the second charge signal V2 is -0.2 mV. Using the aforementioned difference formula, VΔ = 0.21 - (-0.2) = 0.41 mV is calculated. The determination process includes: the difference value after differential calculation is much greater than zero, and the negative value of the first charge signal V1 is not equal to the positive value of the second charge signal V2; therefore, it is determined to be a positive shear pressure.

[0062] It should be noted that, due to the fact that the detection equipment and operation usually have a certain error in the detection results during the actual detection process, there may be slight discrepancies in the actual detection results of the charge signal.

[0063] Based on the same inventive concept, a third aspect discloses a preparation method, the steps of which include: Step 001: Prepare fiber tape. The fiber material is polarized to increase the β phase content, and then the fiber tape is dissolved to obtain a spinnable solution. The spinnable solution is then made into fiber tape.

[0064] Fiber ribbons are obtained by electrospinning, wherein the fiber ribbons comprise PVDF or PVDF-TrFE fiber bundles and are subjected to polarization treatment to increase the β-phase content of the fiber ribbons.

[0065] Specifically, firstly, PVDF or PVDF-TrFE is dissolved in a polar solvent system, wherein the PVDF or PVDF-TrFE content is 70 / 30–80 / 20 mol%, with a solid content of 14–20 wt%; the solvent is a binary system, such as DMF / acetone or DMF / MEK, with a mass ratio controlled at 6 / 4–7 / 3, to prepare a spinnable solution. Next, electrospinning is performed under controlled temperature and humidity to obtain oriented or random fiber bundles. The spinning conditions are controlled as follows: nozzle voltage 12–20 kV, flow rate 0.4–1.0 mL / h, distance between the nozzle and the collecting plate 12–20 cm, ambient temperature 22–26 °C, and RH 35–50%. The resulting fiber ribbon has a diameter of 0.3–2.0 µm.

[0066] Subsequently, thermal / electric field combined polarization was used to improve the β phase and piezoelectric coefficient. The polarization conditions were controlled as follows: temperature 70-90°C, electric field 60-100 MV / m, and polarization time 20-40 min. Finally, cooling was performed under an electric field.

[0067] Step 002: The two fiber strips are spirally wound to produce a reverse double helix piezoelectric fiber.

[0068] Two fiber strips with the same polarization direction are selected and spirally wound in opposite directions to form a double-helix piezoelectric fiber. During spiral winding, the core diameter of the two fiber strips is controlled at 0.3–0.8 mm, the helix angle (θ) is controlled at 30°–55°, the pitch (p) is controlled at 0.5–2.0 mm, the twist density is controlled at 150–400 TPM, and the pre-stretch is controlled at 1–3%.

[0069] Next, the two ends of the double-helix piezoelectric fiber are cured while maintaining the deformability of the middle section of the double-helix piezoelectric fiber. The curing of the double-helix piezoelectric fiber ends is performed using a dispensing process, with the curing temperature controlled at 60-80 °C and the curing time controlled at 5-15 min.

[0070] Step 003: Install the reverse double helix piezoelectric fiber on the elastic base layer 2, and make electrodes at both ends of the reverse double helix piezoelectric fiber.

[0071] In a further embodiment, the mounting of the anti-double-helix piezoelectric fibers on the elastic base layer 2 involves: setting a mounting groove 3 on the elastic base layer 2, placing the anti-double-helix piezoelectric fibers within the mounting groove 3, and controlling the spacing error and parallelism error between the two anti-double-helix piezoelectric fibers. The spacing and parallelism of the piezoelectric fibers can be controlled through the mounting groove 3.

[0072] First, mounting grooves 3 matching the piezoelectric fibers are prepared on the elastic base layer 2. The reverse double-helix piezoelectric fibers are then embedded parallel to each other into the mounting grooves 3, ensuring consistent channel spacing and row / column alignment. The elastic base layer 2 is made of PDMS or TPU, and its thickness is controlled to be 200–500 µm. When creating the mounting grooves 3 on the elastic base layer 2, the groove width is controlled to be 1.2–2.0 mm, the groove depth to be 0.4–0.8 mm, and the spacing between the mounting grooves 3 to be 2.0–3.0 mm. The positioning tolerances between the paired mounting grooves 3 are controlled, with a parallelism error ≤0.5° and a center distance error ≤±50 µm. Finally, when installing the reverse double-helix piezoelectric fibers into the mounting grooves 3, the surface of the mounting grooves 3 needs to be activated using O2 plasma at 50–100 W for 30–60 s.

[0073] After installing the reverse double-helix piezoelectric fiber into mounting groove 3, electrodes need to be fabricated at both ends of the fiber. Specifically, an independent electrode is formed at the end of each piezoelectric fiber, and a lead wire is led out. The piezoelectric fibers are electrically isolated from each other, and a differential / bus connection is then made at the rear end. The electrodes are formed using silver paste printing or metal / ITO sputtering processes. The silver paste curing temperature is controlled at 100-140°C, the curing time is controlled at 10-20 min, and the electrode metal thickness is controlled at 100-200 nm. The electrode gap at both ends is controlled at ≥300 µm, and the edge distance between adjacent piezoelectric fibers is ≥500 µm. Next, leads are fabricated on the electrodes using gold wire, aluminum wire, or flexible copper foil. These leads are then soldered using welding and ultrasonic bonding. The low-temperature solder paste is used, with the soldering temperature controlled at 150–170 °C. Finally, a 1-2 mm stress buffer adhesive is applied to the solder joint. Alternatively, insulation or shielding can be added to the leads, using PI / UV adhesive film with a thickness of 10–20 µm, and the back shielding layer thickness ≤20 µm.

[0074] Step 004: Encapsulate and solidify the positions of the piezoelectric fibers with reverse double helixes on the elastic base layer 2 to obtain a double helix piezoelectric fiber array sensor.

[0075] An elastic capping layer 4 is encapsulated on an elastic base layer 2, ensuring a limited cavity or flexible layer above the piezoelectric fibers to maintain sensitivity and durability. The leads are sealed and interfaces are provided, resulting in the desired double-helix piezoelectric fiber array sensor. PDMS or TPU is used as the encapsulation material for the capping layer 4, with a thickness controlled at 100-300µm. The gap between the capping layer 4 and the piezoelectric fibers is controlled at 30-100µm. PDMS curing / lamination is performed at a controlled temperature of 80–120 °C for 15–45 min, while TPU hot-pressing is performed at 85–110 °C with a strength controlled at 0.1–0.3 MPa for 2–5 min. The ports are sealed with black glue / silicone, with a water absorption rate controlled to ≤0.5%.

[0076] It should be noted that the length of the mounting groove 3 is determined based on the piezoelectric fiber of the reverse double helix, and the piezoelectric fiber of the reverse double helix is ​​determined based on the actual product. For example, when a wristband is used, the piezoelectric fiber of the reverse double helix is ​​the width of the wristband, and when it is a bionic glove for a robotic hand, the mounting groove 3 is set according to the length of the fingers.

[0077] Based on the same inventive concept, the fourth aspect discloses a bionic skin, which includes the aforementioned double-helix piezoelectric fiber array sensor for detection. In addition, a flexible layer is provided on both sides of the double-helix piezoelectric fiber array sensor.

[0078] Based on the same inventive concept, the fourth aspect also discloses an application method of a double-helix piezoelectric fiber array sensor, which is applied in wearable health monitoring, robot tactile sensing and human-computer interaction and other application scenarios.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A double-helix piezoelectric fiber array sensor, characterized in that, include: An elastic base layer, wherein a sensing area is provided on the elastic base layer; At least one sensing group is disposed in the sensing area of ​​the elastic base layer, the sensing group comprising a first piezoelectric fiber and a second piezoelectric fiber, the first piezoelectric fiber and the second piezoelectric fiber having the same structure; and the first piezoelectric fiber and the second piezoelectric fiber are arranged side by side. Wherein, the first piezoelectric fiber comprises: at least two fiber strips, and the two fiber strips are configured with an anti-helical structure; and, Electrodes, which are disposed at both ends of the first piezoelectric fiber.

2. The double-helix piezoelectric fiber array sensor according to claim 1, characterized in that, The spacing between the first piezoelectric fiber and the second piezoelectric fiber is controlled to be 2.0-3.0 mm.

3. The double-helix piezoelectric fiber array sensor according to claim 1, characterized in that, The fiber bands in the first piezoelectric fiber are configured to have the same polarization direction.

4. The double-helix piezoelectric fiber array sensor according to claim 1, characterized in that, The fiber tape is made of either PVDF fiber or PVDF-TrFE fiber.

5. A pressure detection method, characterized in that, The detection is performed using the double-helix piezoelectric fiber array sensor as described in claims 1-4, and the steps include: Acquire the first charge signal of the first piezoelectric fiber and the second charge signal of the second piezoelectric fiber; The difference results between the first charge signal and the second charge signal are analyzed using a differential method; The detection result is obtained by judging the difference result; The discrimination process is as follows: if the difference between the first charge signal and the second charge signal is close to zero, it is normal pressure; if the difference between the first charge signal and the second charge signal is much greater than zero, it is lateral shear pressure.

6. The pressure detection method according to claim 5, characterized in that, When obtaining the detection result, the method further combines the difference value with the first charge signal and the second charge signal to make a judgment based on whether their charge values ​​are equal, thereby obtaining the detection result.

7. The pressure detection method according to claim 5, characterized in that, The differential analysis method involves calculating the difference between the first charge signal and the second charge signal using a differential formula, where the differential formula is: VΔ = V1 - V2; Where VΔ is the difference value; V1 is the first charge signal; and V2 is the second charge signal.

8. A preparation method for preparing the double-helix piezoelectric fiber array sensor according to claims 1-4, characterized in that the step... include: To prepare fiber tape, the fiber material is polarized to increase the β phase content, and then the fiber tape is dissolved to obtain a spinnable solution. The spinnable solution is then made into fiber tape. Two fiber strips are spirally wound together to produce a reverse double-helix piezoelectric fiber. An inverted double-helix piezoelectric fiber is mounted on an elastic base layer, and electrodes are fabricated at both ends of the inverted double-helix piezoelectric fiber. The positions of the piezoelectric fibers with reverse double helixes in the elastic base layer are encapsulated and cured to obtain a double helix piezoelectric fiber array sensor.

9. The preparation method according to claim 8, characterized in that, The process of mounting the reverse double-helix piezoelectric fiber on the elastic base layer involves: setting an mounting groove on the elastic base layer, placing the reverse double-helix piezoelectric fiber in the mounting groove, and controlling the spacing error and parallelism error between the two reverse double-helix piezoelectric fibers.

10. A bionic skin, characterized in that, The detection is performed using the double-helix piezoelectric fiber array sensor as described in claims 1-4; In addition, a flexible layer is provided on both sides of the double-helix piezoelectric fiber array sensor.

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