Three-dimensional force tactile sensing system based on photoelectric impedance imaging device and preparation method of three-dimensional force tactile sensing system

Abstract

The invention discloses a three-dimensional force tactile sensing system based on a photoelectric impedance imaging device and a preparation method, the three-dimensional force tactile sensing system comprises the photoelectric impedance imaging device, a light source module, a light scattering deformation layer and a data acquisition and processing module, the photoelectric impedance imaging device comprises a substrate, and a photoelectric sensitive layer is constructed at the upper part of the substrate; a specific number of conductive electrode arrays are arranged on the periphery of the sensing area, a light distribution image is reconstructed by collecting electrical signals when the tactile sensing system is under pressure and a photoelectric impedance imaging device, a light spot position and a standard deviation parameter are extracted through Gaussian function fitting, tangential force and normal force are calculated respectively, and three-dimensional force sensing is achieved. In addition, effective classification of the tactile system under different tactile conditions is realized by using an artificial intelligence algorithm. The three-dimensional force tactile sensing system is low in interconnection complexity and high in damage fault tolerance, effectively solves the problems that a traditional optical tactile sensor is large in rigidity, complex in structure and high in cost, and is suitable for robot flexible operation and artificial limb tactile perception.

Description

Technical Field

[0001] This invention relates to the field of tactile sensing technology, and in particular to a three-dimensional force tactile sensing system and its fabrication method based on a photoelectric impedance imaging device. Background Technology

[0002] Tactile sensing technology with three-dimensional force perception capability is key to enabling precise operation of intelligent robots. Currently, the main technological approaches to achieving three-dimensional force perception include: capacitive / piezoresistive sensors based on multi-sensor unit integration, Hall effect sensors based on magnetic induction, and tactile sensors based on optical imaging.

[0003] Among these, optical tactile sensing solutions (such as Gelsight) have attracted widespread attention due to their high spatial resolution and resistance to electromagnetic interference. These solutions generally rely on CMOS array image sensors and require complex optical markings on the elastomer to achieve three-dimensional force sensing. Recently, Professor Takao Someya's team at the University of Tokyo replaced the rigid and bulky silicon photodetector-based rigid CMOS imager with an organic photodetector based on a CMOS matrix to achieve a certain degree of mechanical flexibility. The tactile sensor, integrating backlighting, light-scattering rubber, and a flexible image sensor, can accurately detect normal pressures up to 360 kPa and tangential pressures up to 100 kPa, respectively. However, the independent interconnecting leads for each pixel based on CMOS image sensors cause the number of leads to increase exponentially with resolution, increasing manufacturing complexity and cost, easily causing signal crosstalk, and a single lead failure can lead to the failure of an entire row or column. Furthermore, its cost increases significantly with size.

[0004] Therefore, there is an urgent need in this field for a tactile sensing system that can take into account large area, low interconnect complexity, high robustness, and efficient three-dimensional force decoding. Summary of the Invention

[0005] This invention provides a three-dimensional force tactile sensing system and its fabrication method based on a photoelectric impedance imaging device. It solves the problems of high interconnection complexity, high manufacturing cost, and difficulty in three-dimensional force decoding caused by the use of array-type imagers in existing optical tactile sensors. It is suitable for robot dexterity operation, prosthetic tactile feedback and human-computer interaction systems that require simultaneous detection of normal force and tangential force.

[0006] A first aspect of the present invention provides a three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device, comprising: a photoelectric impedance imaging device, a light source module, a light scattering deformation layer, and a data acquisition and processing module, wherein the photoelectric impedance imaging device, the light scattering deformation layer, and the light source module are stacked and packaged. The light source module is used to provide uniform illumination; The light scattering deformation layer is disposed between the photoelectric impedance imaging device and the light source module. When an external force is applied, the light scattering deformation layer deforms, and its internal light scattering characteristics change with the applied force. The photoelectric impedance imaging device includes a substrate, a photosensitive layer on the upper part of the substrate, and a conductive electrode array. The conductivity of the photosensitive layer varies with the incident light intensity. The conductive electrode array is spaced apart at the edge of the photosensitive layer and is used to inject excitation current and measure voltage response. The data acquisition and processing module is connected to the conductive electrode array of the photoelectric impedance imaging device. When pressure is applied, it sequentially selects the electrodes of the conductive electrode array, applies a constant current excitation, acquires the voltage response data between all electrode pairs, converts the voltage response data into a photoelectric impedance image, fits the Gaussian function parameters of the photoelectric impedance image, calculates the tangential force and normal force, and performs three-dimensional force sensing.

[0007] Optionally, in one embodiment of the present invention, the light source module includes an array of light-emitting diodes.

[0008] Optionally, in one embodiment of the present invention, the scattering structure of the light scattering deformation layer is a porous structure with a porosity greater than 30% and a pore size range of 10-500 micrometers; and / or, the surface is provided with microstructures, the characteristic size of the microstructures is 5-200 micrometers, and the shape of the microstructures includes at least one of hemispherical, pyramidal, cylindrical or random concave-convex shapes.

[0009] Optionally, in one embodiment of the present invention, the photoelectric impedance imaging device has a photoconductive response to at least one of ultraviolet, visible, and infrared light.

[0010] Optionally, in one embodiment of the present invention, the data acquisition and processing module includes: The data acquisition unit is used to sequentially select different electrode pairs through a multiplexed switch array to inject constant current excitation and measure the voltage response data between each electrode pair. The image reconstruction unit is used to convert the measured voltage response data into a photoelectric impedance image based on the photoelectric impedance imaging algorithm; The force calculation unit is used to fit the photoelectric impedance image into a Gaussian function, extract the spot position center parameter and standard deviation of the Gaussian function, calculate the tangential force based on the spot position center parameter, and calculate the normal force based on the standard deviation parameter.

[0011] Optionally, in one embodiment of the invention, the EIDORS toolbox is used to convert the measured voltage response data into a photoelectric impedance image.

[0012] Optionally, in one embodiment of the present invention, the photoelectric impedance image is fitted to a Gaussian function using a trust region algorithm: ; in, To fit the light intensity value, x and y Here are the coordinate indices of the PIT imager, where A is the amplitude, which is related to the absolute light intensity. and This is the position parameter of the light spot center, used to reflect the amplitude and direction of the tangential component of the applied pressure. The standard deviation of the Gaussian function is used to reflect the magnitude of the normal component of the applied pressure.

[0013] Optionally, in one embodiment of the present invention, under normal force, the light scattering deformation layer deforms, the distance between the light source and the photoelectric impedance imager decreases, and the standard deviation decreases; under tangential force, the center of the light spot position shifts, and the magnitude and direction of the applied pressure are derived based on the calibrated quantitative relationship.

[0014] Optionally, in one embodiment of the present invention, the data acquisition and processing module is further configured to perform scene recognition on the photoelectric impedance image according to the trained neural network model to obtain a three-dimensional force tactile scene classification result, wherein the trained neural network model includes at least one of ResNET, VGGNet, MobileNet and EfficientNet.

[0015] A second aspect of the present invention provides a method for fabricating a three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device, used in the three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device described in the above embodiment, comprising the following steps: Step 1, Prepare the light source module: Solder the light-emitting diodes on the circuit board, and complete the series connection of the current-limiting resistors and circuit testing; Step 2, Preparation of light scattering deformation layer: Soluble template particles are mixed with elastomer, and the particles are dissolved after solidification to form a porous structure; or 3D printing technology is used to prepare an elastomer with microstructure; or template method and 3D printing technology are used to prepare an elastomer with microstructure on the surface; Step 3: The photoelectric impedance imaging device, the light scattering deformation layer, and the light source module are stacked and packaged.

[0016] The three-dimensional force-tactile sensing system and its fabrication method based on photoelectric impedance imaging devices according to the present invention have the following beneficial effects: First, this invention innovatively applies photoelectric impedance imaging technology to three-dimensional force-tactile sensing. By using a conductive electrode array arranged around the sensing area, it achieves the measurement of the light distribution across the entire region, fundamentally eliminating the design paradigm of traditional array-type imagers that require independent interconnecting leads for each pixel. This ensures that the interconnecting complexity and manufacturing cost do not significantly increase when the sensor is made larger, effectively solving the problems of a dramatic increase in the number of leads, increased crosstalk, and high costs associated with increasing resolution in traditional optical tactile sensors.

[0017] Secondly, the photoelectric impedance sensor of this invention exhibits excellent damage tolerance. Because it operates based on the principle of topological reconstruction, even if local puncture damage occurs inside the sensing area, it can still effectively image and sense force through the surrounding electrodes, thus solving the vulnerability problem of traditional array sensors that suffer overall functional failure due to local damage.

[0018] Third, the photoelectric impedance sensor of the present invention can be manufactured on an ultrathin flexible substrate, and the fabrication method has good scalability, enabling a low-cost, flexible, large-area, and high-performance three-dimensional force tactile sensor system.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the features of the flexible photoelectric impedance sensor according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the photoelectric sensing performance of the flexible photoelectric impedance sensor according to an embodiment of the present invention. Figure 4 This is a schematic diagram of a photoelectric impedance imager for multi-size, multi-point, and multi-transmittance detection according to an embodiment of the present invention. Figure 5 This is a photographic schematic diagram of transparent and porous elastomers according to an embodiment of the present invention; Figure 6 This is a photographic schematic diagram of a flexible LED array according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the photoelectric impedance imaging reconstruction results under oblique force in the range of 30° to 60° according to an embodiment of the present invention. Figure 8This is a schematic diagram of a robot hand with a fixed three-dimensional force sensor contacting different surfaces, and a schematic diagram of the corresponding PIT photoelectric impedance imaging reconstruction results, according to an embodiment of the present invention. Figure 9 The recognition accuracy using the ResNet-18 neural network in this embodiment of the invention is shown. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] Figure 1 This is a schematic diagram of a three-dimensional force tactile sensing system based on a photoelectric impedance imaging device according to an embodiment of the present invention.

[0023] like Figure 1 As shown, the three-dimensional force tactile sensing system based on photoelectric impedance imaging device includes: photoelectric impedance imaging device, light source module, light scattering deformation layer and data acquisition and processing module, wherein the photoelectric impedance imaging device, light scattering deformation layer and light source module are stacked and packaged.

[0024] The light source module is used to provide uniform illumination. In a specific embodiment, the light source module can be an array of light-emitting diodes.

[0025] The light scattering deformation layer is disposed between the photoelectric impedance imaging device and the light source module. When an external force is applied, the light scattering deformation layer deforms, and its internal light scattering characteristics change with the applied force.

[0026] In a specific embodiment, the scattering structure of the light scattering deformation layer can be one or a combination of the following: (a) It has a porous structure with a porosity greater than 30% and a pore size range of 10-500 micrometers; (b) The surface is provided with microstructures, the characteristic size of which is 5-200 micrometers and the shape is at least one of hemispherical, pyramidal, cylindrical or random concave-convex.

[0027] like Figure 2 As shown, the photoelectric impedance imaging device includes a substrate, a photosensitive layer on the substrate, and a conductive electrode array. The conductivity of the photosensitive layer varies with the incident light intensity. The conductive electrode array is spaced apart at the edge of the photosensitive layer and is used to inject excitation current and measure voltage response.

[0028] Photoelectric impedance imaging devices exhibit photoconductive responses to one or more of ultraviolet, visible, and infrared light.

[0029] The data acquisition and processing module is connected to the conductive electrode array of the photoelectric impedance imaging device. When pressure is applied, it sequentially selects the electrodes of the conductive electrode array and applies a constant current excitation to acquire the voltage response data between all electrode pairs. The voltage response data is converted into a photoelectric impedance image, and the Gaussian function parameters of the photoelectric impedance image are fitted to calculate the tangential force and normal force for three-dimensional force sensing.

[0030] In one embodiment of the present invention, the data acquisition and processing module includes: The data acquisition unit is used to sequentially select different electrode pairs through a multiplexed switch array to inject constant current excitation and measure the voltage response data between each electrode pair. The image reconstruction unit is used to convert the measured voltage response data into a photoelectric impedance image based on the photoelectric impedance imaging algorithm; The force calculation unit is used to fit the photoelectric impedance image to a Gaussian function, extract the spot position center parameter and standard deviation of the Gaussian function, calculate the tangential force based on the spot position center parameter, and calculate the normal force based on the standard deviation parameter.

[0031] Furthermore, the data acquisition and processing module is also used to perform scene recognition on the photoelectric impedance image based on the trained neural network model to obtain the three-dimensional force tactile scene classification result.

[0032] Understandably, after obtaining the photoelectric impedance image, a neural network model can be used to identify the image and directly determine the three-dimensional force-tactile context to which the currently applied pressure belongs. The neural network model includes at least one of ResNet, VGGNet, MobileNet, and EfficientNet. A training dataset is constructed to train the neural network model, and a test dataset is used to test the trained neural network, continuously optimizing the neural network parameters. The training dataset includes the photoelectric impedance image and its corresponding context label.

[0033] The fabrication method of the three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device according to this invention includes the following steps: Step 1, Prepare the light source module: Solder the light-emitting diodes on the circuit board, and complete the series connection of the current-limiting resistors and circuit testing; Step 2, Preparation of light scattering deformation layer: Soluble template particles are mixed with elastomer, and the particles are dissolved after solidification to form a porous structure; or 3D printing technology is used to prepare an elastomer with microstructure; or template method and 3D printing technology are used to prepare an elastomer with microstructure on the surface; Step 3: The photoelectric impedance imaging device, the light scattering deformation layer, and the light source module are stacked and packaged.

[0034] A specific embodiment is provided to illustrate the fabrication method of a three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device.

[0035] 1) Substrate Preparation: An n-type silicon wafer with a 300 nm thick silica coating was selected as the rigid support substrate. First, the silicon wafer was ultrasonically cleaned sequentially in acetone and isopropanol for 30 minutes each, and then dried with nitrogen. Subsequently, a polyacrylic acid (PAA) precursor solution was diluted with N,N-dimethylformamide to a concentration of 10 wt% and spin-coated onto the treated silicon wafer at 600 rpm for 60 seconds. Then, a stepped-temperature heat treatment was performed in a nitrogen glove box to complete imidization, ultimately forming a polyimide substrate with a thickness of approximately 5 μm.

[0036] 2) Preparation of the indium zinc oxide photosensitive layer: Indium nitrate and zinc nitrate were dissolved in 2-methoxyethanol at a molar ratio of 6:4. Then, appropriate amounts of acetylacetone and ammonia were added, and the mixture was stirred for 12 hours to obtain a precursor solution. After filtration through a 0.22 μm filter membrane, the solution was spin-coated onto a substrate at 3000 rpm for 60 seconds, pre-annealed at 120°C for 60 seconds, and then annealed at 300°C for 10 minutes. The spin-coating of the precursor solution was then repeated, followed by pre-annealing at 120°C for 60 seconds and annealing at 300°C for 2 hours to obtain an indium zinc oxide film approximately 60 nm thick.

[0037] 3) Patterning process: Spin-coat nLOF 2020 negative photoresist, pre-bake at 115°C for 105 seconds, then expose to UV light through a mask, and post-bake at 115°C for 60 seconds. Treat with NMD-3 developer for 30 seconds to form a circular photoresist protective layer. Then, etch the unprotected areas with a 10 wt% oxalic acid aqueous solution, and finally remove the photoresist with acetone to obtain the patterned photosensitive area.

[0038] 4) Electrode preparation: A 100nm thick aluminum electrode array was deposited around the sensitive area using a thermal evaporation process, with 16 electrodes evenly distributed around the circumference, each electrode measuring 0.25mm × 0.25mm.

[0039] 5) Quantum dot modification: CdSe / ZnS quantum dot toluene solution (10 mg / mL) was spin-coated at 2000 rpm for 30 seconds, then immersed in 1,7-diaminoheptane methanol solution (20 mM) at 60 °C for 15 minutes. After cleaning with methanol and isopropanol, it was annealed at 180 °C in a nitrogen atmosphere for 30 minutes to form a stable heterojunction.

[0040] 6) Device release: Carefully peel the device prepared above from the support substrate to obtain a flexible photoelectric impedance sensor.

[0041] like Figure 3As shown, under a 5V bias voltage and ultraviolet light of varying intensities, the current between the two electrodes of the flexible photoelectric impedance sensor exhibits a strong linear relationship with the light intensity, with a light-to-dark current ratio >10. 4 .

[0042] like Figure 4 As shown, when the light source is blocked by polyimide film layers of the same diameter but different thicknesses (50µm and 125µm), the reconstructed images show similar spatial coverage but different intensity levels. When two to four polyimide film layers of the same thickness are used for blocking, these differences can be visually confirmed by impedance reconstruction, demonstrating the device's excellent resolution independently within a single sensing area.

[0043] In an embodiment of the present invention, the porous flexible light-scattering deformable layer is prepared as follows: sieved sugar particles are mixed with Ecoflex 00-31 silicone rubber at a mass ratio of 3:1, sandwiched between two glass plates spaced 2 mm apart, and cured at 50°C for 2 hours. Subsequently, the sugar particles are dissolved in water, and after drying, an opaque porous Ecoflex rubber with an average pore size of 50 μm is obtained. This porous structure exhibits higher elongation at break and lower tensile strength compared to dense Ecoflex, while also possessing excellent light-scattering properties.

[0044] like Figure 5 The image shows photographs of transparent Ecoflex and porous Ecoflex, demonstrating that the porous structure alters the optical properties.

[0045] The design and system integration of the light source module are explained in detail through a specific embodiment. Four UV-LEDs with a peak wavelength of 370nm are mounted at the four corners of the circuit board with a 5mm spacing. Each LED is connected in series with a 200Ω current-limiting resistor, and the parallel components are powered by 5V DC. The LED light source (light source module), porous rubber (light scattering deformation layer), and photoelectric impedance sensor (photoelectric impedance imaging device) are sequentially bonded together using an optically transparent adhesive to form a three-dimensional force-tactile sensor with a total thickness of approximately 2mm, which can be easily attached to the fingertip of a robot. Figure 6 As shown.

[0046] The data acquisition and processing system is described in detail through a specific embodiment. The data acquisition system uses a Keysight 34970A switching unit in conjunction with a Keithley 2400 source meter, and two 16-channel multiplexers to control current excitation and voltage detection respectively. An adjacent measurement protocol is implemented: a 1mA current is sequentially injected into 16 pairs of adjacent electrodes, and the voltage of all adjacent pairs is simultaneously detected, obtaining 256 measurement values / frame. A 500ms sampling interval is set, and the average of 5 measurements is taken for each data point.

[0047] When an external force is applied, the light scattering deformation layer deforms, altering its internal light scattering properties: 1) Normal pressure causes deformation of the light scattering deformation layer, reducing the distance between the light source and the photoelectric impedance imager, thus decreasing the standard deviation;

[0048] 2) The tangential force causes the center of the light spot in the light scattering deformation layer to shift. This optical change is captured by the PIT imaging device and converted into force information through a reconstruction algorithm.

[0049] Specifically, when the data acquisition and processing module converts the measured voltage response data into a photoelectric impedance image, it uses the EIDORS toolbox for image reconstruction, reconstructing the voltage data into a 1280×256 pixel light intensity distribution map. After normalization, the reconstructed image is fitted to a Gaussian function using a trust region algorithm. ; in, To fit the light intensity value, x and y Here are the coordinate indices of the PIT imager, where A is the amplitude, which is related to the absolute light intensity. and This is the position parameter of the light spot center, used to reflect the amplitude and direction of the tangential component of the applied pressure. The standard deviation of the Gaussian function is used to reflect the magnitude of the normal component of the applied pressure.

[0050] Based on the calibrated quantitative relationship, the center position of the light spot is extracted ( μ ) and standard deviation ( σ It enables three-dimensional force calculation and derives the magnitude and direction of the applied pressure.

[0051] To verify the response characteristics under external forces at different angles, the same force was applied to the three-dimensional force tactile sensing system at tilt angles of 30°, 45°, and 60°. The corresponding reconstruction results from the photoelectric impedance imaging device are as follows: Figure 7 As shown in the figure, the center position of the light spot shifts significantly and the size of the light spot changes accordingly as the tilt angle increases, verifying the sensor's ability to simultaneously solve for both axial and tangential forces.

[0052] like Figure 8 As shown, to verify the tactile sensing capability of the triaxial tactile sensor, the sensor was mounted on the robot's index finger, and the contact response of the spherical surface, the surface of the cube, the edge, and the vertex were tested, along with the corresponding photoelectric impedance imaging reconstruction results. The results show that the area and position of the formed photoelectric impedance image are significantly different under different pressing conditions, indicating that the sensor can effectively distinguish different tactile modalities.

[0053] like Figure 9As shown, a tactile classification framework based on ResNet-18 was constructed to verify the system's practicality. The network employs the ReLU activation function and the Adam optimizer, with dropout regularization used to prevent overfitting. After 150 epochs of training using 2000 photoelectric impedance image samples for each tactile modality, and evaluation with 200 test samples, the overall classification accuracy reached 96.5%, confirming that the ResNet-enhanced 3D force tactile sensing system based on photoelectric impedance imaging possesses excellent tactile modality discrimination capabilities.

[0054] The three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device proposed in this invention includes a photoelectric impedance imaging device, a light source module, a light scattering deformation layer, and a data acquisition and processing module. The photoelectric impedance imaging device comprises a substrate, a photosensitive layer constructed on the substrate, and a specific number and arrangement of conductive electrode arrays surrounding the sensing area. The light scattering deformation layer typically employs a porous elastomer structure or microstructure surface elasticity. By acquiring the electrical signals of the tactile sensing system under pressure, the photoelectric impedance imaging device reconstructs a light distribution image and extracts the position and size parameters of the light spot using Gaussian function fitting. Tangential and normal forces are then calculated to achieve three-dimensional force sensing. This three-dimensional force-tactile sensing system has advantages such as low interconnect complexity and strong damage tolerance, effectively solving the problems of high rigidity, complex structure, and high cost of traditional optical tactile sensors. It is suitable for robot dexterity operation and prosthetic tactile sensing.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

Claims

1. A three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device, characterized in that, include: The device comprises an opto-impedance imaging device, a light source module, a light scattering deformation layer, and a data acquisition and processing module, wherein the opto-impedance imaging device, the light scattering deformation layer, and the light source module are stacked and packaged. The light source module is used to provide uniform illumination; The light scattering deformation layer is disposed between the photoelectric impedance imaging device and the light source module. When an external force is applied, the light scattering deformation layer deforms, and its internal light scattering characteristics change with the applied force. The photoelectric impedance imaging device includes a substrate, a photosensitive layer on the upper part of the substrate, and a conductive electrode array. The conductivity of the photosensitive layer varies with the incident light intensity. The conductive electrode array is spaced apart at the edge of the photosensitive layer and is used to inject excitation current and measure voltage response. The data acquisition and processing module is connected to the conductive electrode array of the photoelectric impedance imaging device. When pressure is applied, it sequentially selects the electrodes of the conductive electrode array, applies a constant current excitation, acquires the voltage response data between all electrode pairs, converts the voltage response data into a photoelectric impedance image, fits the Gaussian function parameters of the photoelectric impedance image, calculates the tangential force and normal force, and performs three-dimensional force sensing.

2. The system according to claim 1, characterized in that, The light source module includes an array of light-emitting diodes.

3. The system according to claim 1, characterized in that, The light scattering deformation layer has a porous structure with a porosity greater than 30% and a pore size ranging from 10 to 500 micrometers; and / or, the surface is provided with microstructures with a characteristic size of 5 to 200 micrometers and a shape including at least one of hemispherical, pyramidal, cylindrical, or random concave-convex shapes.

4. The system according to claim 1, characterized in that, The photoelectric impedance imaging device has a photoconductive response to at least one of ultraviolet, visible, and infrared light.

5. The system according to claim 1, characterized in that, The data acquisition and processing module includes: The data acquisition unit is used to sequentially select different electrode pairs through a multiplexed switch array to inject constant current excitation and measure the voltage response data between each electrode pair. The image reconstruction unit is used to convert the measured voltage response data into a photoelectric impedance image based on the photoelectric impedance imaging algorithm; The force calculation unit is used to fit the photoelectric impedance image into a Gaussian function, extract the spot position center parameter and standard deviation of the Gaussian function, calculate the tangential force based on the spot position center parameter, and calculate the normal force based on the standard deviation parameter.

6. The system according to claim 5, characterized in that, The measured voltage response data was converted into an opto-impedance image using the EIDORS toolbox.

7. The system according to claim 5, characterized in that, The photoelectric impedance image is fitted to a Gaussian function using the trust region algorithm. ； in, To fit the light intensity value, x and y Here are the coordinate indices of the PIT imager, where A is the amplitude, which is related to the absolute light intensity. and This is the position parameter of the light spot center, used to reflect the amplitude and direction of the tangential component of the applied pressure. The standard deviation of the Gaussian function is used to reflect the magnitude of the normal component of the applied pressure.

8. The system according to claim 5, characterized in that, Under normal force, the light scattering deformation layer deforms, the distance between the light source and the photoelectric impedance imager decreases, and the standard deviation decreases; under tangential force, the center of the light spot position shifts, and the magnitude and direction of the applied pressure are deduced based on the calibrated quantitative relationship.

9. The system according to claim 1, characterized in that, The data acquisition and processing module is also used to perform scene recognition on the photoelectric impedance image according to the trained neural network model to obtain the three-dimensional force tactile scene classification result. The trained neural network model includes at least one of ResNET, VGGNet, MobileNet and EfficientNet.

10. A method for fabricating a three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device, used in the three-dimensional force-tactile sensing system based on a photoelectric impedance imaging device as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1, Prepare the light source module: Solder the light-emitting diodes on the circuit board, and complete the series connection of the current-limiting resistors and circuit testing; Step 2, Preparation of light scattering deformation layer: Soluble template particles are mixed with elastomer, and the particles are dissolved after solidification to form a porous structure; or 3D printing technology is used to prepare an elastomer with microstructure; or template method and 3D printing technology are used to prepare an elastomer with microstructure on the surface; Step 3: The photoelectric impedance imaging device, the light scattering deformation layer, and the light source module are stacked and packaged.

Images