Passive radio frequency tactile sensor based on ferroelectric composite material and preparation method of passive radio frequency tactile sensor

Abstract

The invention relates to a passive radio frequency tactile sensor based on a ferroelectric composite material and a preparation method of the passive radio frequency tactile sensor, and belongs to the technical field of sensors. Comprising a multifunctional sensing unit used for non-contact dielectric sensing and contact type pressure sensing; wherein the multifunctional sensing unit comprises a first substrate layer, a first electrode layer, an elastic dielectric layer and a second electrode layer; the first electrode layer is arranged between the first substrate layer and the elastic dielectric layer; the sensing signal transmission unit comprises a second substrate layer and a communication coil; the communication coil is respectively connected with the first electrode layer and the second electrode layer; the communication coil is positioned on one side of the multifunctional sensing unit; wherein the second electrode layer is arranged between the elastic dielectric layer and the second substrate layer; at least one face of the elastic medium layer is of a porous microstructure. The pressure sensor not only has high-precision and high-sensitivity pressure sensing capability, but also shows excellent linear response characteristics, and effectively avoids a signal saturation phenomenon.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a passive radio frequency tactile sensor based on a ferroelectric composite material and a preparation method thereof. Background Art

[0002] In the field of passive radio frequency tactile sensors, the performance of the elastic dielectric layer is the core bottleneck that restricts the accuracy of pressure sensing. Due to the lack of effective microstructure design, the capacitance change of traditional homogeneous materials (such as PDMS) under contact pressure mainly depends on overall deformation, resulting in insufficient sensitivity in the low-pressure area, poor response linearity and easy signal saturation, which seriously limits the sensor's accurate measurement capability. In order to improve dielectric properties, existing technologies often increase the dielectric constant by increasing the proportion of functional fillers (such as BaTiO3 ferroelectric particles), but this method has significant drawbacks. The excessive introduction of fillers will cause the material stiffness to increase sharply (Young's modulus increases significantly), the flexibility to decrease significantly, and it is prone to brittle cracking, which directly sacrifices the core mechanical properties of the elastic dielectric layer as a flexible sensing unit, making it difficult to adapt to complex surface fitting or harsh application scenarios that require dynamic repeated loading (such as industrial automation sorting, robot dexterity, and medical rehabilitation monitoring). Therefore, developing a new type of composite dielectric layer that can improve pressure detection sensitivity and broaden the linear response range while maintaining excellent elastic deformation capacity and mechanical durability through synergistic optimization of its dielectric properties and micro-nanostructure design has become a key challenge that needs to be addressed urgently.

[0003] Furthermore, achieving passive, wireless, and highly sensitive identification capabilities is crucial in non-contact material identification applications (such as industrial sorting, robotic sensing, and medical applications). However, existing technologies have significant shortcomings. Contact sensing relies on physical contact, which can easily damage the target object and is limited in speed. Optical identification methods are susceptible to interference from surface characteristics and ambient lighting. Traditional passive wireless microwave sensing technologies (such as RFID or static near-field detection), while free from power supply wiring, typically rely on single-point static measurements (for example, monitoring frequency shift or signal strength changes at a fixed distance). This static measurement mode provides extremely limited material identification information and lacks sensitivity, making it difficult to accurately distinguish materials with similar dielectric constants. The ability to identify objects with small distance variations or weak dielectric responses is particularly limited. These methods fail to effectively capture the dynamic response characteristics (manifested as continuous curves of resonant frequency shift Δf and quality factor change ΔQ) generated by the complex coupling of distance and dielectric properties as the object approaches the sensor. These dynamic characteristics, rich in information, are the key to achieving highly sensitive and accurate material identification. Therefore, there is an urgent need to develop a new type of passive wireless sensing mechanism that can continuously extract and analyze the dynamic response curve of the object approaching process with high sensitivity, so as to achieve fast, robust and intelligent identification of the object material in a non-contact state, even before physical contact occurs, which surpasses traditional static microwave sensing. Summary of the Invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the problems in the existing technology of insufficient pressure perception accuracy, low sensitivity, poor linear response, easy signal saturation, and difficulty in balancing flexibility and mechanical durability caused by traditional material and design limitations of the elastic medium layer, as well as the problems in the existing technology of non-contact material identification such as low sensitivity, single information dimension, difficulty in accurately distinguishing materials, susceptibility to environmental interference, and reliance on single-point static measurement.

[0005] In a first aspect, to solve the above technical problems, the present invention provides a passive radio frequency tactile sensor based on a ferroelectric composite material, comprising:

[0006] Multifunctional sensing unit for non-contact dielectric sensing and contact pressure sensing;

[0007] The multifunctional sensing unit includes a first substrate layer, a first electrode layer, an elastic medium layer, and a second electrode layer; the first electrode layer is disposed between the first substrate layer and the elastic medium layer;

[0008] A sensing signal transmission unit includes a second substrate layer and a communication coil; the communication coil is connected to the first electrode layer and the second electrode layer respectively; the communication coil is located on one side of the multifunctional sensing unit; the second electrode layer is arranged between the elastic medium layer and the second substrate layer; at least one side of the elastic medium layer is set as a porous microstructure.

[0009] In one embodiment of the present invention, the elastic dielectric layer is a polydimethylsiloxane layer doped with ferroelectric ceramic nanowires.

[0010] In one embodiment of the present invention, the porous microstructure is a porous pyramid structure.

[0011] In one embodiment of the present invention, both the first base layer and the second base layer are polyimide films.

[0012] In one embodiment of the present invention, the first electrode layer and the second electrode layer are both made of metallic copper.

[0013] In a second aspect, to solve the above technical problems, the present invention provides a method for preparing a passive radio frequency tactile sensor based on a ferroelectric composite material, comprising:

[0014] Etching is performed on the polyimide copper-clad film to obtain a first electrode layer and a second electrode layer;

[0015] preparing a BCZT ferroelectric ceramic sol and converting the BCZT ferroelectric ceramic sol into a precursor solution; and electrospinning the precursor solution to obtain BCZT nanowires;

[0016] performing photoreduction on the BCZT nanowires to obtain an Ag-BCZT nanowire heterostructure;

[0017] Selecting a flexible polymer and performing microstructural optimization on the flexible polymer to obtain an elastic layer; utilizing the Ag-BCZT nanowire heterostructure to perform dielectric optimization on the elastic layer to obtain an elastic dielectric layer;

[0018] placing the elastic medium layer between the first electrode layer and the second electrode layer;

[0019] A first base layer, a second base layer and a communication coil are selected, the first base layer is connected to the first electrode layer, and the second base layer is connected to the second electrode layer; the communication coil is connected to the first electrode layer and the second electrode layer to prepare a passive radio frequency tactile sensor.

[0020] In one embodiment of the present invention, the steps of photoreducing the BCZT nanowires to obtain the Ag-BCZT nanowire heterostructure are as follows:

[0021] placing the BCZT nanowires into a mixed solution of alcohol and water, and dispersing them by ultrasound and stirring to obtain a BCZT nanowire solution;

[0022] Controlling the loading amount of silver nanoparticles by adjusting the concentration of the AgNO3 solution, and adding the AgNO3 solution to the BCZT nanowire solution to obtain a first solution;

[0023] The first solution is irradiated with ultraviolet light in a nitrogen environment to promote the reduction of silver ions into silver particles, and the Ag-BCZT nanowire heterostructure is obtained by filtration and drying.

[0024] In one embodiment of the present invention, a flexible polymer is selected, and microstructure optimization is performed on the flexible polymer to obtain an elastic layer; and the elastic layer is dielectrically optimized using the Ag-BCZT nanowire heterostructure to obtain an elastic dielectric layer. The steps are as follows:

[0025] mixing the flexible polymer and the cross-linking agent in a predetermined ratio to obtain a first mixture;

[0026] adding salt particles to the first mixture and magnetically stirring until uniform to obtain a second mixture;

[0027] placing the Ag-BCZT nanowires into the second mixture according to a preset mass ratio to obtain a second solution;

[0028] The second solution is poured into a mold, and demoulded after being cured to obtain an elastic medium layer.

[0029] In one embodiment of the present invention, the method of performing etching on the polyimide copper-clad film to obtain the first electrode layer and the second electrode layer is a wet etching process.

[0030] In a third aspect, to solve the above technical problems, the present invention provides a manipulator comprising:

[0031] A passive radio frequency tactile sensor based on a ferroelectric composite material as described above;

[0032] The identification module is used to obtain a response curve of the passive radio frequency tactile sensor when it approaches the object to be measured; and identify the material of the object to be measured according to the response curve.

[0033] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0034] (1) The passive radio frequency tactile sensor based on ferroelectric composite materials and its preparation method described in the present invention can realize the combination of non-contact dielectric sensing and contact pressure detection by integrating a multifunctional sensing unit, which greatly improves the environmental adaptability and stability of the sensor. The use of a microstructure-optimized Ag-BCZT-PDMS elastic medium layer gives the sensor high sensitivity and good mechanical flexibility, making it easy to use in complex scenarios. The sensor separates the detection area and the communication area in space, and the sensing electrodes are placed in areas where mechanical deformation is concentrated. Placing the communication coil in areas with slight deformation can achieve stable wireless communication, which solves the problem of unstable parameter reading of traditional radio frequency passive pressure sensors.

[0035] (2) By integrating radio frequency technology, the present invention enables the sensor to perform non-contact environmental sensing and material identification, demonstrating significant potential for intelligent applications. Its simple and cost-effective preparation process lays a solid foundation for the widespread promotion and practical application of this technology.

[0036] (3) The present invention integrates a neural network material recognition model, enabling the sensor to not only sense changes in external pressure but also accurately identify target materials. This feature greatly broadens its application potential in multiple fields, including robotic tactile sensing, intelligent detection, and object recognition, while also providing strong support for the advancement of intelligent sensing and human-computer interaction technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0038] Figure 1 Schematic diagram of the structure of a passive radio frequency tactile sensor based on ferroelectric composite materials in a preferred embodiment of the present invention;

[0039] Figure 2 Schematic diagram of electrodes and conductive coils of a passive radio frequency tactile sensor in a preferred embodiment of the present invention;

[0040] Figure 3 This is a flow chart of a method for preparing a passive radio frequency tactile sensor based on a ferroelectric composite material in a preferred embodiment of the present invention;

[0041] Figure 4 This is a flow chart for preparing the elastic medium layer in a preferred embodiment of the present invention;

[0042] Figure 5 A schematic diagram of the principle of pressure detection by a passive radio frequency tactile sensor in a preferred embodiment of the present invention;

[0043] Figure 6Schematic diagram of S parameter changes of the passive radio frequency tactile sensor when different pressures are applied in a preferred embodiment of the present invention;

[0044] Figure 7 Graph showing the sensitivity of a sensor based on an Ag-BCZT-PDMS dielectric layer in a preferred embodiment of the present invention;

[0045] Figure 8 Schematic diagram of signal changes when a passive radio frequency tactile sensor detects bending of a knee joint model in a preferred embodiment of the present invention;

[0046] Figure 9 Schematic diagram of the principle of non-contact detection of object material by a passive radio frequency tactile sensor in a preferred embodiment of the present invention;

[0047] Figure 10 Schematic diagram of the S parameter change of the passive radio frequency tactile sensor when approaching an object in a preferred embodiment of the present invention;

[0048] Figure 11 Schematic diagram of frequency response curve and amplitude response curve of the passive radio frequency tactile sensor when approaching objects of different materials in a preferred embodiment of the present invention.

[0049] Explanation of the reference numerals in the specification: 10. Multifunctional sensing unit; 11. First substrate layer; 12. First electrode layer; 13. Elastic medium layer; 14. Second electrode layer; 20. Sensing signal transmission unit; 21. Second substrate layer; 22. Communication coil. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0051] Example 1

[0052] Reference Figure 1 As shown, an embodiment of the present invention provides a passive radio frequency tactile sensor based on a ferroelectric composite material, comprising:

[0053] Multifunctional sensing unit 10, used for non-contact dielectric sensing and contact pressure sensing;

[0054] The multifunctional sensing unit 10 includes a first substrate layer 11, a first electrode layer 12, an elastic medium layer 13, and a second electrode layer 14; the first electrode layer 12 is disposed between the first substrate layer 11 and the elastic medium layer 13;

[0055] The sensing signal transmission unit 20 includes a second substrate layer 21 and a communication coil 22; the communication coil 22 is connected to the first electrode layer 12 and the second electrode layer 14 respectively; the communication coil 22 is located on one side of the multifunctional sensing unit 10; the second electrode layer 14 is arranged between the elastic medium layer 13 and the second substrate layer 21; at least one side of the elastic medium layer 13 is set as a porous microstructure.

[0056] An embodiment of the present invention provides a passive radio frequency tactile sensor based on a ferroelectric composite material. By integrating a multifunctional sensing unit 10, it can realize the combination of non-contact dielectric sensing and contact pressure detection, greatly improving the flexibility, stability, environmental adaptability and sensitivity of the sensor. The use of a microstructure-optimized elastic medium layer 13 makes the sensor have high sensitivity and good mechanical flexibility, which is convenient for application in complex scenarios. The sensor separates the detection area and the communication area in space, and the sensing electrodes are placed in the area where mechanical deformation is concentrated. The communication coil 22 is arranged in the area with slight deformation to achieve stable wireless communication, which solves the problem of unstable parameter reading of traditional radio frequency passive pressure sensors. Therefore, the sensor described in the embodiment of the present invention not only has high-precision and high-sensitivity pressure sensing capabilities, but also exhibits excellent linear response characteristics, effectively avoiding signal saturation. In addition, the sensor also combines excellent flexibility and durability, so that it can maintain stable performance in various application environments.

[0057] Specifically, the multifunctional sensing unit 10 is used for non-contact dielectric sensing and contact pressure sensing, and its structure includes a base layer (including a first base layer 11 and a second base layer 21), a first electrode layer 12, an elastic medium layer 13 and a second electrode layer 14. Among them, the elastic medium layer 13 is preferably a polydimethylsiloxane layer (abbreviated as PDMS layer) with a porous pyramid structure doped with ferroelectric ceramic nanowires (silver-coated barium calcium zirconium titanate, Ag-BCZT NWs). The preparation material of the base layer can be selected from polyurethane (PU) nanofibers, polyetheretherketone (PEEK), polyphenylene sulfide (PPS), etc. However, polyimide (PI) film can adapt to various shapes and mechanical stresses due to its high strength, high modulus and good flexibility. In addition, the material also has excellent high temperature resistance and can remain stable even in a high temperature environment above 200°C. It also has a low thermal expansion coefficient, ensuring high dimensional stability. Therefore, in an embodiment of the present invention, polyimide (PI) film is preferably used as the material of the base layer.

[0058] The embodiments of the present invention utilize a microstructure-optimized Ag-BCZT-PDMS elastic dielectric layer, which not only enhances the sensor's sensitivity but also imparts exceptional mechanical flexibility. These properties enable the sensor to adapt to diverse and complex application scenarios, demonstrating excellent performance and reliability. This optimization allows the sensor to withstand deformations such as bending and twisting during everyday use while maintaining high-precision detection capabilities, resulting in wider applicability and durability in practical applications.

[0059] Furthermore, given copper's excellent electrical conductivity, it can ensure efficient and stable signal transmission between the electrode and the external circuit, reducing resistance, thereby improving the sensor's response speed and measurement accuracy. At the same time, copper has good thermal conductivity and can quickly conduct heat, ensuring uniform temperature distribution during electrode operation and preventing local overheating from affecting performance. Furthermore, copper has high chemical stability under normal operating conditions and is not easily oxidized or corroded, which helps extend the service life of the electrode and ensure long-term stable operation of the sensor. Therefore, in the embodiment of the present invention, both the first electrode layer 12 and the second electrode layer 14 are made of metallic copper.

[0060] Specifically, the sensing signal transmission unit 20 is used to couple with the reading antenna connected to the vector network analyzer to achieve sensor excitation and efficient signal transmission. The structure of the sensing signal transmission unit 20 includes a base layer and a flexible conductive coil (i.e., a communication coil 22), wherein the two ends of the flexible conductive coil are respectively connected to the upper electrode (i.e., the first electrode layer 12) and the lower electrode (i.e., the second electrode layer 14) of the sensor, together forming an LC resonant structure, referring to Figure 2 As shown. Among them, Figure 2 The flexible conductive coil measures 2.0 mm x 2.0 mm, and the electrode layer measures 1.5 mm x 1.5 mm. Copper is used for the flexible conductive coil due to its excellent electrical conductivity, ensuring stable and efficient signal transmission, thereby improving the sensor's overall performance.

[0061] The embodiment of the present invention proposes a passive radio frequency tactile sensor based on a ferroelectric composite material, which has significant technical advantages and application prospects, and is particularly suitable for application scenarios such as pressure detection and material identification. By integrating a multifunctional sensing unit 10, the sensor can realize the combination of non-contact dielectric sensing and contact pressure detection, greatly improving the environmental adaptability and stability of the sensor. The use of a microstructure-optimized Ag-BCZT-PDMS elastic medium layer gives the sensor high sensitivity and good mechanical flexibility, making it easy to use in complex scenarios. The sensor separates the detection area and the communication area in space, and the sensing electrodes are placed in areas where mechanical deformation is concentrated. Placing the communication coil 22 in areas with slight deformation can achieve stable wireless communication, which solves the problem of unstable parameter reading of traditional radio frequency passive pressure sensors.

[0062] Example 2

[0063] Reference Figure 3 As shown, this embodiment provides a method for preparing a passive radio frequency tactile sensor based on a ferroelectric composite material, including but not limited to the following steps:

[0064] S1, etching the polyimide copper-clad film to obtain a first electrode layer 12 and a second electrode layer 14;

[0065] S2, preparing a BCZT ferroelectric ceramic sol and converting the BCZT ferroelectric ceramic sol into a precursor solution; electrospinning the precursor solution to obtain BCZT ferroelectric ceramic nanowires;

[0066] S3, photoreducing the BCZT nanowires to obtain Ag-BCZT nanowire heterostructures;

[0067] S4, selecting a flexible polymer, performing microstructural optimization on the flexible polymer, and obtaining an elastic layer; performing dielectric optimization on the elastic layer using an Ag-BCZT nanowire heterostructure, and obtaining an elastic dielectric layer 13;

[0068] S5. Place the elastic medium layer 13 between the first electrode layer 12 and the second electrode layer 14; select the first base layer 11, the second base layer 21 and the communication coil 22, connect the first base layer 11 to the first electrode layer 12, and connect the second base layer 21 to the second electrode layer 14; connect the communication coil 22 to the first electrode layer 12 and the second electrode layer 14 to prepare a passive radio frequency tactile sensor.

[0069] Specifically, in step S1, in the preparation of the electrode layer (including the first electrode layer 12 and the second electrode layer 14) and the flexible conductive coil (i.e., the communication coil 22), a variety of processes such as photolithography, dry etching, and laser etching can be used to process materials such as polyimide (PI) silver-coated film (PI@75um, Ag@25um), polyimide (PI) aluminum-coated film (PI@75um, Al@25um), and polyimide (PI) nickel-coated film (PI@75um, Ni@25um). However, considering the cost-effectiveness, process maturity, and the excellent conductivity and moderate mechanical properties of the copper material itself, the embodiment of the present invention preferably adopts a wet etching process for preparation on the PI copper-coated film (PI@75um, Cu@25um). The prepared electrode layer and flexible conductive coil are as follows. Figure 2 shown.

[0070] Specifically, in step S2, BCZT nanowires are preferably prepared by electrospinning, and the specific steps are as follows:

[0071] S210. Prepare BCZT ferroelectric ceramic sol. Dissolve barium acetate, calcium acetate monohydrate, and zirconium acetylacetonate in a mixed solvent of acetic acid and ethylene glycol methyl ether to form solution A. Mix tetrabutyl titanate and acetylacetone to prepare solution B.

[0072] S220. Slowly drop solution B into solution A, heat and stir at 45°C for 6 hours to obtain a uniform light yellow sol.

[0073] S230, taking 10 ml of the sol, adding 0.55 g of polyvinyl pyrrolidone (PVP), and stirring at 40° C. until the sol is completely dissolved to prepare an electrospinning precursor solution.

[0074] S240. BCZT nanowires (NWs) were prepared by electrospinning with the spinning temperature controlled at 40°C, the humidity not exceeding 20%, the needle tip 10 cm from the roller, and the voltage 10 kV. The specific steps were as follows: the fiber membrane obtained by spinning was dried at 40°C for 48 hours, and then calcined at 800°C for 2 hours to finally obtain BCZT nanowires.

[0075] It should be noted that the parameters set above are optimized values ​​to ensure the best performance, but they are not fixed. Based on specific application requirements and environmental conditions, these parameters can be flexibly adjusted to achieve the best adaptability and performance optimization.

[0076] Specifically, in step S3, the BCZT nanowires are photoreduced by a photoreduction method to prepare an Ag-BCZT nanowire heterostructure, and the specific steps are as follows:

[0077] S310, placing the BCZT nanowires into a mixed solution of alcohol and water, and dispersing them by ultrasound and stirring to obtain a BCZT nanowire solution.

[0078] For example, BCZT NWs were added to a mixed solution of alcohol and water, ultrasonicated for 1 minute, and then stirred at room temperature to disperse them evenly.

[0079] S320, controlling the loading amount of silver nanoparticles by adjusting the concentration of the AgNO3 solution, and adding the AgNO3 solution to the BCZT nanowire solution to obtain a first solution.

[0080] For example, the loading amount of Ag nanoparticles was regulated by controlling the concentration of the AgNO3 solution. An appropriate amount of AgNO3 crystals was weighed to a concentration of 0.04 mol / L, and nitrogen was introduced into the solution for 10 minutes to fully remove oxygen from the water.

[0081] S330, irradiating the first solution with ultraviolet light in a nitrogen environment to reduce the silver ions into silver particles, and obtaining an Ag-BCZT nanowire heterostructure by filtration and drying.

[0082] For example, after irradiating with ultraviolet light for 45 minutes, the sample was filtered and dried for more than 24 hours to finally obtain Ag-BCZTNWs.

[0083] The Ag-BCZT NWs heterostructure prepared using steps S310 to S330 exhibits enhanced piezoelectric properties and conductivity while maintaining good flexibility and mechanical strength. The introduction of silver nanoparticles enhances the polarization effect, optimizes the microstructure, reduces resistance, and improves signal transmission efficiency. Furthermore, the oxidation resistance and corrosion resistance of the silver nanoparticles further enhance the chemical stability of the material and extend its service life. The entire preparation process is simple to operate, cost-effective, and environmentally friendly, making it particularly suitable for high-performance applications such as flexible sensors and biomedical sensors.

[0084] Specifically, refer to Figure 4 As shown, in step S4, a reverse molding method is used to precisely fabricate microstructures within a flexible polymer elastic matrix. Meanwhile, silver-barium calcium zirconium titanate (Ag-BCZT) nanowires are integrated into the elastic layer to enhance the dielectric properties of the material. The flexible polymer used to prepare the elastic layer can be a variety of high-performance elastomers, such as polydimethylsiloxane (PDMS), Ecoflex, and thermoplastic polyurethane (TPU). This optimized design of materials and structures can enhance the performance of the sensor, improving its adaptability and reliability in complex environmental conditions.

[0085] Furthermore, a flexible polymer is selected and microstructure optimized to obtain an elastic layer; and the elastic layer is dielectrically optimized using an Ag-BCZT nanowire heterostructure to obtain an elastic dielectric layer 13. The specific steps are as follows:

[0086] S410, mixing the flexible polymer and the cross-linking agent in a preset ratio to obtain a first mixture;

[0087] S420, adding salt particles (NaCl) to the first mixture and performing magnetic stirring until uniform, to obtain a second mixture (i.e., an unsolidified mixture);

[0088] S430, adding Ag-BCZT nanowires to the second mixture according to a preset mass ratio to obtain a first solution;

[0089] S440: Pour the first solution into a mold, solidify it at a certain temperature, and then demold it. Then, soak it in hot water to completely dissolve the salt particles, thereby obtaining the elastic medium layer 13. The mold (e.g., a micro-pyramid mold) can be prepared by 3D printing technology, and its material is preferably white resin.

[0090] S450 , ultrasonically treating the obtained Ag-BCZT-PDMS dielectric layer in ethanol, and then drying it to remove residues.

[0091] Exemplarily, first, the flexible polymer is preferably polydimethylsiloxane (PDMS), and polydimethylsiloxane (PDMS) is mixed with a cross-linking agent in a mass ratio of 10:1, and the mass ratio of salt to PDMS is about 2:1, and magnetic stirring is performed for 1 hour. Then, according to the optimal mass ratio of Ag-BCZT NWs to PDMS of 0.06, Ag-BCZT NWs are added to the uncured mixture of salt particles and PDMS and stirred thoroughly. Next, the mixed PDMS solution is poured into the pyramid mold, and after curing at 60°C for 2 hours, the cured composite material is demolded from the container and placed in 60°C water for 2 hours to fully dissolve the salt particles. Finally, the Ag-BCZT-PDMS dielectric layer is placed in ethanol for ultrasonic treatment, and then placed in an oven and dried at 80°C for 1 hour to fully remove the residue.

[0092] The embodiment of the present invention utilizes an Ag-BCZT-PDMS elastic dielectric layer with an optimized microstructure, resulting in a sensor with high sensitivity and good mechanical flexibility, facilitating its application in complex scenarios. Furthermore, during the manufacturing process, 3D printing technology was used to create the mold, combined with wet etching and photoreduction techniques, reducing production costs while improving process applicability and flexibility.

[0093] Specifically, in step S5, the Ag-BCZT-PDMS dielectric layer is used as the intermediate layer of the passive RF tactile sensor, assembled using a simple folding method, and encapsulated using polyimide (PI) tape to produce the passive RF tactile sensor. This method is significantly cost-effective and demonstrates high manufacturing versatility, simplicity, and compatibility.

[0094] Furthermore, the selection of materials for the first substrate layer 11, the second substrate layer 21, and the communication coil 22 can be referred to the relevant description in Example 1 and will not be repeated here. Finally, the prepared first substrate layer 11 is connected to the first electrode layer 12, the prepared second substrate layer 21 is connected to the second electrode layer 14, and the prepared communication coil 22 is connected to the first electrode layer 12 and the second electrode layer 14, completing the sensor assembly.

[0095] Specifically, the prepared sensor is divided into tactile receptors (pressure electrodes) and sensory neurons (communication coil 22) based on functional differences. Among them, the pressure electrode integrated with the Ag-BCZT-PDMS dielectric layer can respond to pressure stimulation, read the coupling between the antenna and the communication coil 22 to activate the sensor and read its changing S parameters, such as Figure 5 shown. Figure 5 The symbol C represents capacitance. This structural design ensures stable readout of detection parameters when the sensor is subjected to pressure-induced deformation and in spatially confined scenarios such as slits, thereby improving the stability and environmental adaptability of the RF pressure sensor.

[0096] The equivalent circuit of the sensor system can be expressed as a series RLC circuit. The resonant frequency of the sensor is f res And the quality factor Q can be expressed as:

[0097]

[0098] Among them, L sensor is the coil inductance, which is determined by the design drawing; R D is the parasitic resistance; π is the symbol of pi; C D represents the equivalent capacitance of the pressure electrode, and its expression is:

[0099]

[0100] Where ε0 is the dielectric constant of vacuum, ε eff is the relative dielectric constant of the dielectric layer, A is the plate area, and d is the plate spacing. It can be seen that capacitance is proportional to the dielectric constant of the substrate, the size of the conductor, and the gap between the two conductors.

[0101] Furthermore, when the sensor is subjected to pressure, the effective dielectric constant ε is mainly causedeff and the change of the electrode plate spacing d, s, t c 、l g The change in capacitance ΔC can be ignored, and the capacitance change ΔC can be equivalent to:

[0102]

[0103] Where, ΔC d The capacitance change caused by the change in electrode spacing is is the capacitance change caused by the change in dielectric constant.

[0104] Specifically, by connecting the near-field coil to a vector network analyzer (VNA), the sensor's status can be monitored through the reflection coefficient (S11) curve. Observing the minimum return loss (S11) value confirms the sensor's resonant frequency, reflecting the external pressure at the electrode.

[0105] Furthermore, in a specific operation, the reading antenna is connected to a vector network analyzer (VNA) and the reflection coefficient (S11) parameter is used for detection. During the measurement process, the S11 curve is scanned to observe its characteristics that vary with frequency. Figure 6 As shown, the sensor's resonant frequency will shift under different pressure conditions, which is manifested as the minimum position of the S11 curve moving. By confirming the minimum frequency of S11, the external pressure changes can be quickly determined. Figure 6 The symbol Unit:kPa indicates that the unit is kilopascal (kPa).

[0106] Further, refer to Figure 7 As shown, 0.6% wt Ag-BCZT NWs was determined to be the optimal doping ratio, and the sensitivity of the sensor was as high as 2.644 MHz / kPa (0-20 kPa) and 0.544 MHz / kPa (20-100 kPa). Figure 7 Symbol Unit: MHz / kPa MHz stands for MegaHertz, which is the unit of frequency.

[0107] It is worth noting that the sensor has the potential for implantable stress detection due to its wireless and passive nature and the separation of communication and sensing. The sensor was used in a knee joint model to demonstrate implantable joint stress. The results are as follows: Figure 8As shown in the figure, as the bending angle increases, the stress between the knee joint models gradually decreases, and the frequency of the sensor increases. Because this demonstration experiment was manually controlled by the experimenter, the frequency response will produce some spikes and instabilities, but this does not affect the evaluation of the sensor's detection capabilities. In summary, the proposed sensor demonstrates the potential for inter-articular stress detection, helping patients after joint replacement surgery to achieve real-time monitoring of inter-articular stress, avoiding excessive load on the joints during the recovery process, reducing the risk of recurrence, and helping patients to better recover from training.

[0108] Example 3

[0109] This embodiment provides a robot arm, comprising:

[0110] A passive radio frequency tactile sensor based on a ferroelectric composite material provided in embodiment 1;

[0111] The identification module is used to obtain the response curve of the passive radio frequency tactile sensor when it approaches the object to be measured; and identify the material of the object to be measured based on the response curve.

[0112] Reference Figure 9 As shown in the figure, due to the radiation characteristics of electromagnetic signals, radio frequency tactile sensors can achieve non-contact perception of the external environment. When the sensor is installed on a manipulator, the material of the object can be identified by monitoring the sensor's resonant frequency shift Δf and return loss ΔS11 during the approach process. This design enables the manipulator to have the ability to identify the material of the object non-contact without the need for additional wiring. When the material under test (MUT) approaches the sensor, the resonant frequency will shift. There is a clear relationship between the offset of the resonant frequency and the dielectric constant of the material under test. As the sensor gradually approaches the object, the dielectric constant ε in the detection field c It can be simply expressed as:

[0113] ε c =p mut ε MUT +(1-p mut )ε air ;

[0114] Among them, ε air is the dielectric constant of air, ε MUT is the dielectric constant of the object to be measured, p mut is the proportional coefficient.

[0115] Reference Figure 10 As shown in the figure, the S-parameter curve of the sensor shifts to the upper left when it approaches an object. According to perturbation theory, when the sensor approaches an object with a different dielectric constant, the sensor produces a different response.

[0116] Specifically, when the material under test (MUT) is close to the sensor, its dielectric constant is different from that of the surrounding medium, which causes the dielectric constant in the electromagnetic field around the sensor to change, thereby affecting the resonant frequency of the sensor. The frequency shift Δf is related to the distance d between the material and the device. MUT And the dielectric constant ε of the object to be measured MUT The relationship is expressed as:

[0117] Δf∝K×d MUT (ε MUT +ε air ); (5)

[0118] Where K is a constant, ε air is the dielectric constant of air, ∝ indicates that it is proportional to. In addition, according to the description of formulas (1) and (2), the change of the sensor during the approaching object can also be equivalent to the change of capacitance. And because the object approaches the sensor itself R D The influence of is very small, so the expression of the quality factor change ΔQ is:

[0119]

[0120] Therefore, by monitoring the sensor's resonant frequency shift Δf and return loss ΔS11 as an object approaches, accurate identification of the object's material can be achieved.

[0121] In order to accurately identify different materials, the recognition module does not rely solely on a single change value, but extracts dynamic response curves in two dimensions, frequency and amplitude, as input to the neural network model. Figure 11 As shown in Figure 3, different materials (including copper, glass, polyurethane (PU), plastic, and wood) have significantly different response curves when placed close to the sensor. Figure 11 The vertical axis ΔFreq in the graph represents the frequency change. After analyzing these response curves with a trained neural network, the material properties of an object can be determined in advance, enabling preliminary material identification before the robot arm even touches the object. By collecting sensor response data before the robot arm touches the object and inputting it into a neural network-based material recognition model, the object's material can be identified before actual contact. Therefore, the combination of the proposed sensor and neural network technology demonstrates remarkable capabilities in sensing and identifying the material properties of different objects as the sensor approaches them.

[0122] The embodiments of the present invention, combined with radio frequency technology, enable the sensor to achieve non-contact environmental perception and material identification, with strong intelligent potential. Its simple preparation process and high cost-effectiveness provide a solid foundation for large-scale promotion and practical application. In addition, combined with the material recognition model of the neural network, the sensor can not only sense changes in external pressure but also accurately identify the target material, greatly expanding its application range in fields such as robot touch, intelligent detection, and object recognition, and helping to promote the development of intelligent perception and human-computer interaction technology.

[0123] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0124] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0125] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0126] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0127] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A passive radio frequency tactile sensor based on ferroelectric composite material, characterized in that: include: Multifunctional sensing unit for non-contact dielectric sensing and contact pressure sensing; The multifunctional sensing unit includes a first substrate layer, a first electrode layer, an elastic medium layer, and a second electrode layer; the first electrode layer is disposed between the first substrate layer and the elastic medium layer; A sensing signal transmission unit includes a second substrate layer and a communication coil; the communication coil is connected to the first electrode layer and the second electrode layer respectively; the communication coil is located on one side of the multifunctional sensing unit; the second electrode layer is arranged between the elastic medium layer and the second substrate layer; at least one side of the elastic medium layer is set as a porous microstructure.

2. The passive radio frequency tactile sensor based on ferroelectric composite material according to claim 1, characterized in that: The elastic medium layer is a polydimethylsiloxane layer doped with ferroelectric ceramic nanowires.

3. The passive radio frequency tactile sensor based on ferroelectric composite material according to claim 1, characterized in that: The porous microstructure is a porous pyramid structure.

4. The passive radio frequency tactile sensor based on ferroelectric composite material according to claim 1, characterized in that: The first base layer and the second base layer are both polyimide films.

5. The passive radio frequency tactile sensor based on ferroelectric composite material according to claim 1, characterized in that: The first electrode layer and the second electrode layer are both made of metal copper.

6. A method for preparing a passive radio frequency tactile sensor based on ferroelectric composite materials, characterized in that ,include: Etching is performed on the polyimide copper-clad film to obtain a first electrode layer and a second electrode layer; preparing a BCZT ferroelectric ceramic sol and converting the BCZT ferroelectric ceramic sol into a precursor solution; and electrospinning the precursor solution to obtain BCZT ferroelectric ceramic nanowires; performing photoreduction on the BCZT nanowires to obtain an Ag-BCZT nanowire heterostructure; Selecting a flexible polymer and performing microstructural optimization on the flexible polymer to obtain an elastic layer; utilizing the Ag-BCZT nanowire heterostructure to perform dielectric optimization on the elastic layer to obtain an elastic dielectric layer; placing the elastic medium layer between the first electrode layer and the second electrode layer; A first base layer, a second base layer and a communication coil are selected, the first base layer is connected to the first electrode layer, and the second base layer is connected to the second electrode layer; the communication coil is connected to the first electrode layer and the second electrode layer to prepare a passive radio frequency tactile sensor.

7. The method for preparing a passive radio frequency tactile sensor based on a ferroelectric composite material according to claim 6, characterized in that: The steps of photoreducing the BCZT nanowires to obtain the Ag-BCZT ferroelectric ceramic nanowire heterostructure are as follows: placing the BCZT nanowires into a mixed solution of alcohol and water, and dispersing them by ultrasound and stirring to obtain a BCZT nanowire solution; Controlling the loading amount of silver nanoparticles by adjusting the concentration of the AgNO3 solution, and adding the AgNO3 solution to the BCZT nanowire solution to obtain a first solution; The first solution is irradiated with ultraviolet light in a nitrogen environment to promote the reduction of silver ions into silver particles, and the Ag-BCZT nanowire heterostructure is obtained by filtration and drying.

8. The method for preparing a passive radio frequency tactile sensor based on a ferroelectric composite material according to claim 6, wherein: The steps of selecting a flexible polymer, performing microstructural optimization on the flexible polymer to obtain an elastic layer, and performing dielectric optimization on the elastic layer using the Ag-BCZT nanowire heterostructure to obtain an elastic dielectric layer are as follows: mixing the flexible polymer and the cross-linking agent in a predetermined ratio to obtain a first mixture; adding salt particles to the first mixture and magnetically stirring until uniform to obtain a second mixture; placing the Ag-BCZT ferroelectric ceramic nanowires into the second mixture according to a preset mass ratio to obtain a second solution; The second solution is poured into a mold, and demoulded after being cured to obtain an elastic medium layer.

9. The method for preparing a passive radio frequency tactile sensor based on a ferroelectric composite material according to claim 6, wherein: The method of etching the polyimide copper-clad film to obtain the first electrode layer and the second electrode layer is a wet etching process.

10. A robot, characterized in that: include: The passive radio frequency tactile sensor based on ferroelectric composite material according to any one of claims 1 to 5; The identification module is used to obtain a response curve of the passive radio frequency tactile sensor when it approaches the object to be measured; and identify the material of the object to be measured according to the response curve.

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