Visual tactile sensor based on photonic crystal and preparation method thereof

Abstract

The invention relates to the technical field of sensor preparation, and provides a visual tactile sensor based on photonic crystals and a preparation method thereof, and the visual tactile sensor comprises a sensing unit, a sensing substrate and a camera unit. The sensing unit comprises a photonic crystal film, a transparent substrate and a protective elastic layer, the photonic crystal film is cured on the transparent substrate, mark points are marked on the surface of the photonic crystal film, and the protective elastic layer is cured on the surface, with the mark points, of the photonic crystal film; the sensing unit is embedded in one end face of the sensing base body, the camera unit is embedded in the other end face of the sensing base body, and a transparent substrate of the sensing unit faces the camera unit. The visual tactile sensor with the photonic crystal as the core is constructed, the comprehensive performance of the visual tactile sensor is remarkably optimized on the basis of guaranteeing continuous high sensing density, high resolution and multi-dimensional force sensing capacity, and the application scene of the visual tactile sensor in the intelligent field is expanded.

Description

Technical Field

[0001] This invention relates to the field of sensor fabrication technology, and more specifically, to a photonic crystal-based visual-tactile sensor and its fabrication method. Background Technology

[0002] In the current era of rapid development in embodied intelligence technology, tactile sensing technology, capable of detecting mechanical stimuli such as pressure and shape through physical interaction, provides crucial information for feedback control strategies and has become a core support for robots to perceive their external environment and achieve precise interaction. Meanwhile, machine vision technology, with its superior spatial resolution and dynamic tracking capabilities, can accurately capture multi-dimensional information such as the position and contour of target objects. The fusion of tactile sensing and machine vision to form a visual-tactile sensor, through the synergy of optical systems such as CCD / CMOS cameras and computer vision algorithms, possesses multi-modal perception capabilities for multi-dimensional forces, object shapes, and surface roughness. This meets the refined requirements of embodied intelligence for perceiving complex environments and plays an irreplaceable role in fields such as robot dexterity and intelligent interaction.

[0003] The core sensing mechanism of existing tactile flexible sensors revolves around the deformation and displacement of flexible sensing units. Their structure mainly consists of a flexible contact layer made of silicone, a sensing substrate, and optical detection components. The flexible contact layer is formed into a flexible structure of a specific thickness through coating or molding processes. It works in conjunction with the optical detection components to acquire force signals. Subsequent training with a large amount of data is required to train machine learning algorithms to infer the degree of contact layer deformation and then calculate the magnitude of the force, thus quantifying the force signal. However, the thickness of the silicone contact layer makes it prone to slippage during precise robotic operations, directly affecting the stability of sensing accuracy. Simultaneously, the force signal calculation relies on a data-driven machine learning model, which limits the accuracy of force decoupling calculations and generates significant computational power consumption. This situation restricts its widespread application in the field of embodied intelligence. Summary of the Invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems.

[0005] To address the above problems, this invention provides a visual-tactile sensor based on photonic crystals and its fabrication method.

[0006] In a first aspect, the present invention provides a photonic crystal-based visual-touch sensor, including a sensing unit, a sensing substrate, and a camera unit; The sensing unit includes a photonic crystal thin film, a transparent substrate, and a protective elastic layer. The photonic crystal thin film is solidified on the transparent substrate, and the surface of the photonic crystal thin film is marked with marking points. The protective elastic layer is solidified on the surface of the photonic crystal thin film with the marking points. The sensing unit is embedded in one end face of the sensing substrate, the camera unit is embedded in the other end face of the sensing substrate, and the transparent substrate of the sensing unit faces the camera unit.

[0007] Optionally, the transparent substrate includes a transparent elastic layer and a glass substrate, the transparent elastic layer is fixed on the glass substrate, and the photonic crystal film is fixed on the end face of the transparent elastic layer opposite to the glass substrate.

[0008] Optionally, the sensing substrate includes a base and a housing, the sensing unit is embedded in the base, and the base and the camera unit are respectively disposed on the two end faces of the housing.

[0009] Optionally, the sensing substrate further includes an LED light strip, which is arranged on the inner wall of the substrate and is used to provide an incident light source for information acquisition by the camera unit.

[0010] Optionally, the thickness of the photonic crystal film is 45μm-60μm.

[0011] Secondly, the present invention provides a method for fabricating a visual-touch sensor based on a photonic crystal, comprising: A photonic crystal film is solidified on a pre-configured transparent substrate, and marking points are affixed to the surface of the photonic crystal film. A protective slurry is prepared and coated onto the surface of the marked photonic crystal film to form a protective elastic layer, thereby obtaining a sensing unit. The sensing unit is embedded into the sensing substrate on which the camera unit is installed to obtain a visual-tactile sensor.

[0012] Optionally, before solidifying the photonic crystal film onto a pre-configured transparent substrate and marking the surface of the photonic crystal film with markers, the process includes: After preparing a substrate mixture solution and removing air bubbles, it is applied to a pre-prepared glass substrate and cured at high temperature to obtain the transparent substrate. The protective slurry is prepared and coated onto the surface of the marked photonic crystal thin film to form a sensing unit, including: After preparing a protective slurry and removing air bubbles, it is spin-coated onto the surface of the marked photonic crystal film and then cured at high temperature to form a protective elastic layer, thus obtaining the sensing unit.

[0013] Optionally, the substrate mixing solution includes polydimethylsiloxane and a crosslinking agent in a mixing mass ratio of 10:1, and after curing, forms a transparent elastic layer. The transparent substrate is composed of a transparent elastic layer and a glass substrate.

[0014] Optionally, the configuration of the protective slurry includes: Polydimethylsiloxane and crosslinking agent are mixed at a mass ratio of 10:1; Carbon black powder is added to the mixed slurry to obtain the protective slurry, wherein the mass of the carbon black powder accounts for 0.5% of the mass of the mixed slurry.

[0015] Optionally, before embedding the sensing unit into the sensing substrate to obtain the visual-touch sensor, the method further includes: The sensor substrate was 3D printed using photosensitive resin as the raw material.

[0016] The beneficial effects of the photonic crystal-based visual-touch sensor of this invention are as follows: A photonic crystal thin film is solidified on a transparent substrate. Its ultra-thin thickness replaces the thicker silicone contact layer in existing technologies, significantly reducing the risk of slippage during delicate robotic operations and ensuring the stability of sensing accuracy. Simultaneously, the helical arrangement of the photonic crystal thin film molecules strictly follows Bragg's law of reflection. Its reflection wavelength has a strict underlying physical relationship with the magnitude of the force, eliminating the need for machine learning training based on large amounts of data. This lays a core foundation for accurate force signal calculation and solves the problem of lacking underlying physical relationships in force calculation in existing technologies. Marking points on the surface of the photonic crystal thin film form a clear displacement reference. When the sensor is subjected to tangential or sliding forces, the marked points shift synchronously with the shear deformation of the photonic crystal thin film. The displacement vector can be accurately tracked using algorithms such as Farneback optical flow, providing a reliable physical basis for the quantitative calculation of tangential forces. This avoids the drawbacks of relying on complex algorithms to infer deformation in existing technologies, improving the accuracy of tangential force detection and further reducing computational power consumption. A protective elastic layer is cured onto the surface of the photonic crystal film with marked points, forming a protective layer that prevents the photonic crystal film and marked points from directly contacting external objects, thus avoiding wear and damage and extending the sensor's lifespan. Simultaneously, the protective elastic layer, made of an elastic material with controllable thickness, does not impede the transmission of force signals to the photonic crystal film, ensuring that the film can respond promptly to external forces and produce uniform deformation, guaranteeing the normal operation of the sensing function. Adding functional components (such as carbon black powder) to the protective elastic layer can further optimize optical contrast, making it easier to capture optical signals related to marked point displacement and changes in the wavelength reflected by the photonic crystal, further improving the accuracy of signal acquisition. The sensing unit is embedded in one end face of the sensing substrate, and the camera unit is embedded in the other end face, with the transparent substrate facing the camera unit. This mounting method ensures coaxial alignment between the camera unit and the sensing unit, allowing the reflected light signal from the photonic crystal film to be transmitted to the camera unit without attenuation or deviation, ensuring the accuracy of optical detection. Meanwhile, the integrated structure of the sensing substrate provides a stable installation position for both, avoiding component displacement or loosening during sensor stress or movement, and further improving the stability of sensing accuracy.

[0017] This invention comprehensively solves the key technical problems existing in current visual-touch sensors through the synergistic cooperation of various structures and connections. Regarding sensing stability, the combination of an ultra-thin photonic crystal film and a protective elastic layer completely improves the slippage problem caused by traditional thick silicone contact layers, resulting in more stable sensing accuracy during fine operations. In terms of signal processing, relying on the physical properties of the photonic crystal itself to establish a direct correlation between force and wavelength changes, combined with displacement tracking of marker points, ensures that the calculation of normal and tangential forces has a strict underlying physical logic, eliminating the need for data-driven machine learning, significantly reducing computational power consumption, and significantly improving the accuracy of force decoupling calculations. Regarding structural reliability, the protective elastic layer and the stable support of the sensing substrate ensure the durability and long-term stability of the sensor. In summary, this invention significantly optimizes the overall performance of visual-touch sensors while maintaining continuous high sensing density, high resolution, and multi-dimensional force sensing capabilities, effectively expanding their application scenarios in the field of embodied intelligence. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart of the photonic crystal-based visual-touch sensor method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the sensor unit according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the sensor structure according to an embodiment of the present invention; Figure 4 The image shows the test results of an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1-Protective elastic layer; 2-Marker point; 3-Photonic crystal thin film; 4-Transparent substrate; 41-Transparent elastic layer; 42-Glass substrate; 5-Sensing unit; 6-Base; 7-LED light strip; 8-Housing; 9-Camera unit. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit this application. The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. 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 indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0022] like Figure 2 and Figure 3 As shown in the figure, an embodiment of the present invention provides a photonic crystal-based visual-touch sensor, including a sensing unit 5, a sensing substrate, and a camera unit 9.

[0023] The sensing unit includes a photonic crystal film 3, a transparent substrate 4, and a protective elastic layer 1. The photonic crystal film 3 is solidified on the transparent substrate 4, and the surface of the photonic crystal film 3 is marked with marking points 2. The protective elastic layer 1 is solidified on the surface of the photonic crystal film 3 with the marking points 2. The sensing unit 5 is embedded in one end face of the sensing substrate, and the camera unit 9 is embedded in the other end face of the sensing substrate, with the transparent substrate 4 of the sensing unit 5 facing the camera unit 9.

[0024] Specifically, the sensing substrate can be a one-piece block structure, with a cylindrical or square shape. Its dimensions are precisely matched to the specifications of the sensing unit 5 and the camera unit 9. The internal end faces are respectively provided with recessed grooves adapted to the contours of the sensing unit 5 and the camera unit 9. The sensing substrate can be made of resin, a material with good mechanical strength and light-shielding properties, providing stable support for the internal components and reducing interference from external stray light. The sensing unit 5 can be embedded in the recessed groove on one end face of the sensing substrate through methods such as interference fit or UV adhesive bonding, ensuring a tight, gapless fit. The camera unit 9 is a miniaturized CCD or CMOS camera module, cylindrical in shape, with its lens focal length precisely matched to the distance between the sensing unit 5 and the camera unit 9. The camera unit 9 is also embedded in a groove on the other end face of the sensing substrate, with its lens facing the transparent substrate 4 of the sensing unit 5. The lens axis of the camera unit 9 coincides with the central axis of the sensing unit 5, ensuring a clear optical detection path. It acquires real-time images of the reflected wavelength changes of the photonic crystal thin film 3 and the displacement of the marker point 2, transmitting the image data to the subsequent signal processing module to provide raw data for force signal calculation. The sensing substrate provides a precise positioning and stable installation environment for the sensing unit 5 and the camera unit 9, while its own light-shielding properties ensure the stability of the optical detection.

[0025] The transparent substrate 4 has a sheet-like structure, and its shape matches the mounting surface of the sensing unit 5. It can be designed to be circular or square, and can be made of a highly transparent elastomer or highly transparent borosilicate glass. If an elastomer is used, it can provide both support and slight flexibility; if glass is used, it has higher structural stability. One side of the transparent substrate 4 serves as a curing carrier for the photonic crystal film 3, and is firmly bonded to the photonic crystal film 3 by means of a UV adhesive, etc. The other side faces the camera unit 9, providing stable support for the photonic crystal film 3. At the same time, thanks to its excellent light transmittance, it ensures that the reflected light signal of the photonic crystal film 3 is transmitted to the camera unit 9 without attenuation.

[0026] The photonic crystal film 3 has a sheet-like structure, with a shape completely identical to the transparent substrate 4. The molecules of the photonic crystal film 3 are arranged in a helical pattern, and the material is a photonic crystal material with selective reflection characteristics of specific wavelengths. The photonic crystal film 3 is uniformly coated on the surface of the transparent substrate 4 away from the camera unit 9. After curing, it forms a tightly bonded interface with the transparent substrate 4 without bubbles or wrinkles. It is the core component for force-to-light signal conversion. When subjected to force, the deformation of the helical structure causes a change in the reflected wavelength or drives the displacement of the marker point 2, realizing the signal conversion between normal force and tangential force.

[0027] The marker 2 is a circular dot structure, marked in a regular array on the surface of the photonic crystal film 3 away from the transparent substrate 4. The marker 2 can be formed by laser marking process, forming a firm bond with the photonic crystal film 3. The color of the marker 2 forms a clear optical contrast with the surface of the photonic crystal film 3, serving as a displacement reference for tangential force sensing. When the photonic crystal film 3 undergoes shear deformation, the marker 2 moves synchronously, providing a clear displacement signal for tangential force calculation.

[0028] The protective elastic layer 1 has a sheet-like thin film structure that completely covers the surface of the photonic crystal film 3 and the marker point 2. It is applied to the surface of the photonic crystal film 3 using a spin-coating process and then cured to form an elastomer. The protective elastic layer 1 adheres tightly to the photonic crystal film 3, does not impede the transmission of external forces, and prevents the photonic crystal film 3 and the marker point 2 from directly contacting external objects, thus avoiding wear and damage. Simultaneously, carbon black powder optimizes optical contrast, improving the detectability of the marker point 2.

[0029] In this embodiment of the invention, a photonic crystal film 3 is solidified on a transparent substrate 4. Its ultra-thin thickness replaces the thicker silicone contact layer in existing technologies, significantly reducing the risk of slippage during delicate robotic operations and ensuring the stability of sensing accuracy. Simultaneously, the molecules of the photonic crystal film 3 are arranged in a helical pattern, strictly adhering to Bragg's law of reflection. Its reflection wavelength has a strict underlying physical relationship with the magnitude of the force, eliminating the need for machine learning training based on large amounts of data. This lays a core foundation for accurate force signal calculation and solves the problem of lacking underlying physical relationships in force calculation in existing technologies. Marking points 2 are affixed to the surface of the photonic crystal film 3 to form a clear displacement reference. When the sensor is subjected to tangential or sliding forces, the marking points 2 shift synchronously with the shear deformation of the photonic crystal film 3. The displacement vector can be accurately tracked using algorithms such as Farneback optical flow, providing a reliable physical basis for the quantitative calculation of tangential forces. This avoids the drawbacks of relying on complex algorithms to infer deformation in existing technologies, improving the accuracy of tangential force detection and further reducing computational power consumption. A protective elastic layer 1 is cured on the surface of the photonic crystal film 3 with the marker points 2, forming a protective layer that prevents the photonic crystal film 3 and the marker points 2 from directly contacting external objects, thus avoiding wear and damage and extending the sensor's lifespan. Simultaneously, the protective elastic layer 1, made of an elastic material with controllable thickness, does not hinder the transmission of force signals to the photonic crystal film 3, ensuring that the photonic crystal film 3 can respond promptly to external forces and produce uniform deformation, guaranteeing the normal operation of the sensing function. Adding functional components such as carbon black powder to the protective elastic layer 1 can further optimize optical contrast, making it easier to capture optical signals from the displacement of the marker points 2 and changes in the reflected wavelength of the photonic crystal film 3, further improving the accuracy of signal acquisition. The sensing unit 5 is embedded in one end face of the sensing substrate, and the camera unit 9 is embedded in the other end face of the sensing substrate, with the transparent substrate 4 facing the camera unit 9. This installation method ensures the coaxial alignment of the camera unit 9 and the sensing unit 5, allowing the reflected light signal from the photonic crystal film 3 to be transmitted to the camera unit 9 without attenuation or deviation, ensuring the accuracy of optical detection. Meanwhile, the integrated structure of the sensing substrate provides a stable installation position for both, avoiding component displacement or loosening during sensor stress or movement, and further improving the stability of sensing accuracy.

[0030] This invention comprehensively solves the key technical problems existing in current visual-touch sensors through the synergistic cooperation of various structures and connections. Regarding sensing stability, the combination of the ultra-thin photonic crystal film 3 and the protective elastic layer 1 completely improves the slippage problem caused by traditional thick silicone contact layers, resulting in more stable sensing accuracy during fine operations. In terms of signal processing, a direct correlation between force and wavelength change is established based on the physical properties of the photonic crystal film 3. Combined with displacement tracking of the marker point 2, the calculation of normal and tangential forces possesses strict underlying physical logic, eliminating the need for data-driven machine learning, significantly reducing computational power consumption, and substantially improving the accuracy of force decoupling calculations. Regarding structural reliability, the protective elastic layer 1 and the stable support of the sensing substrate ensure the sensor's durability and long-term stability. In summary, this invention significantly optimizes the overall performance of visual-touch sensors while maintaining continuous high sensing density, high resolution, and multi-dimensional force sensing capabilities, effectively expanding its application scenarios in the field of embodied intelligence.

[0031] Optionally, the transparent substrate 4 includes a transparent elastic layer 41 and a glass substrate 42, the transparent elastic layer 41 is fixed on the glass substrate 42, and the photonic crystal film 3 is fixed on the end face of the transparent elastic layer 41 away from the glass substrate 42.

[0032] Specifically, such as Figure 3As shown, the shape of the glass substrate 42 is adapted to the installation of the sensing unit 5. The side length or diameter is determined according to the specifications of the sensing unit 5, and the thickness is controlled within 1-2 mm. The material is high-transparency borosilicate glass or quartz glass, possessing excellent mechanical strength, light transmittance, and dimensional stability. The surface is ultrasonically cleaned and dried to ensure no impurities remain, providing rigid support for the entire transparent substrate 4 and the transparent elastic layer 41 and photonic crystal film 3 above it. This prevents deformation or damage to the sensing unit 5 during stress or installation, ensuring structural stability. The transparent elastic layer 41 has a shape completely consistent with the glass substrate 42, and is prepared to form a tightly bonded, bubble-free, and wrinkle-free elastomer. The transparent elastic layer 41 combines flexibility and light transmittance, buffering the impact of external forces on the glass substrate 42 while providing suitable flexible support for the photonic crystal film 3, and ensuring uninterrupted transmission of reflected light signals from the photonic crystal film 3. The transparent substrate 4 is formed into an integrated structure through the stacking and curing of a glass substrate 42, a transparent elastic layer 41, and a photonic crystal film 3. Specifically, the transparent elastic layer 41 is directly cured onto the flat end face of the glass substrate 42 without any intermediate layers. The photonic crystal film 3 is uniformly coated onto the end face of the transparent elastic layer 41 facing away from the glass substrate 42 using UV adhesive. After curing, it is tightly bonded to the transparent elastic layer 41, ensuring that external forces can be smoothly transmitted through the transparent elastic layer 41 to the photonic crystal film 3, causing its helical structural deformation. Simultaneously, the end face of the glass substrate 42 facing away from the transparent elastic layer 41 faces the camera unit 9, ensuring a smooth optical signal transmission path.

[0033] Optionally, the sensing substrate includes a base 6 and a housing 8, the sensing unit 5 is embedded in the base 6, and the base 6 and the camera unit 9 are respectively disposed on the two end faces of the housing 8.

[0034] Specifically, such as Figure 2As shown, the sensing substrate consists of two parts: a base 6 and a housing 8. The base 6 is a hollow cylindrical or block-shaped structure with openings at both ends. Its shape precisely matches one opening of the housing 8. It can be designed as a cylinder or a square, and its axial length is determined by the thickness of the sensing unit 5, while its radial dimension matches the contour of the sensing unit 5. The sensing unit 5 is embedded in the inner cavity of the base 6 via an interference fit or UV adhesive bonding. The two fit tightly without gaps, achieving stable positioning of the sensing unit 5. The base 6 provides a precise installation reference and rigid support for the sensing unit 5, preventing displacement or deformation during stress or assembly. It also serves as the connection carrier between the sensing unit 5 and the housing 8, ensuring the assembly accuracy of the overall structure. The housing 8 is a hollow cylindrical or box-shaped structure with openings at both ends. One opening is for mounting the base 6, and the other opening is for mounting the camera unit 9. The inner cavity dimensions are adapted to the shape of the base 6 and the installation requirements of the camera unit 9. The outer shell 8 is made of a light-shielding material, effectively preventing stray light from entering the inner cavity. One end of the outer shell 8 has a snap-fit ​​or threaded structure on its inner wall. The base 6 is fixed to this opening via snap-fit ​​or threaded connection, and after installation, the end face of the base 6 is flush with the end face of the outer shell 8. The other end of the outer shell 8 has a fixing structure, such as a slot or thread, adapted to the camera unit 9. After the camera unit 9 is inserted into this opening, it is locked in place by the fixing structure, with the lens of the camera unit 9 facing the inner cavity of the outer shell 8 and coaxially aligned with the sensing unit 5 embedded in the base 6. The outer shell 8 creates a closed optical detection environment, isolating external stray light interference, while protecting the internal sensing unit 5, base 6, and camera unit 9 from external impacts and wear, ensuring the structural integrity of the sensor.

[0035] Optionally, the sensing substrate further includes an LED light strip 7, which is arranged on the inner wall of the base 6 and is used to provide an incident light source for the information acquisition of the camera unit 9.

[0036] Specifically, the LED strip 7 has a ring-shaped flexible strip structure, with its circumference precisely matching the circumferential length of the inner wall of the base 6. It exhibits excellent overall flexibility and can conform to the arc or square contour of the inner wall of the base 6. The encapsulation shell is made of materials such as polyvinyl chloride (PVC), with micro-LED beads evenly arranged inside. The encapsulation shell possesses good insulation and temperature resistance, making it suitable for the sensor's operating environment. The power supply lines of the LED strip 7 are integrated into the edge of the encapsulation, and the wire material can be copper core wire. The LED strip 7 can be tightly attached to the inner wall of the base 6 using high-temperature resistant double-sided adhesive or a clip, positioned between the mounting interface of the sensing unit 5 embedded in the base 6 and the housing 8, surrounding the outer periphery of the sensing unit 5. The power supply lines of the LED strip 7 extend along the pre-reserved wiring groove on the inner wall of the base 6 to the outside of the sensing substrate, without obstructing the optical path between the camera unit 9 and the sensing unit 5, nor affecting the assembly and fixation of the base 6 and the housing 8. After installation, the light-emitting surface of the LED strip 7 faces the center of the sensing unit 5, ensuring that the light can be uniformly irradiated onto the surface of the photonic crystal film 3 of the sensing unit 5. The LED strip 7 provides a uniform and stable incident light source for the information acquisition of the camera unit 9. After the emitted light shines on the surface of the photonic crystal film 3, it is selectively reflected by the photonic crystal film 3. The reflected light signal is transmitted to the camera unit 9 through the transparent substrate 4, providing the necessary optical conditions for the camera unit 9 to capture the reflection wavelength change of the photonic crystal film 3 and the displacement image of the marker point 2.

[0037] Optionally, the thickness of the photonic crystal film is 45μm-60μm.

[0038] Specifically, the preferred thickness range of the photonic crystal film in this embodiment of the invention is 45μm-60μm, and can be specifically set to 50μm. This embodiment sets the thickness of the photonic crystal film 3 to 50μm, precisely matching the sensor's sensing function, structural stability, and application requirements. On one hand, the 50μm thickness balances the film's flexibility and mechanical strength, enabling rapid and uniform deformation in response to external forces while avoiding the problems of excessive thinness leading to breakage and excessive thickness hindering force signal transmission. It also ensures a stable bond with the transparent substrate 4, guaranteeing the regularity of reflected wavelength changes. On the other hand, it ensures that the wavelength blue shift amplitude under normal force and the displacement trajectory of the marker point 2 under tangential force are both within the precise capture range of the optical detection device (i.e., camera unit 9). This significantly reduces the slippage problem of traditional thick silicone contact layers and provides reliable support for the accurate calculation of normal and tangential forces, while simultaneously ensuring the repeatability and durability of the sensor.

[0039] When the sensor is running, it relies on the transmission logic of "force-structural deformation-optical signal-data processing" to achieve accurate sensing of normal and tangential forces. The specific process is as follows: Initial preparation stage: LED light strip 7 is activated and emits a stable light source. The light shines evenly onto the surface of the functional layer photonic crystal film 3 of the sensing unit 5. The photonic crystal film 3 maintains the initial spiral structure without external force and reflects light of a specific wavelength (in accordance with Bragg's law of reflection). The camera unit 9 collects the initial reflected light signal and the initial position image of the marker point 2 in real time as reference data. Force Application and Signal Generation Stage: When the protective elastic layer 1 of the sensing unit 5 comes into contact with the object being measured and is subjected to a force, the force signal is transmitted to the photonic crystal film 3 through the protective elastic layer 1, causing corresponding structural deformation. Under normal force (Z-axis direction), the helical structure of the photonic crystal film 3 is compressed, the pitch decreases, causing its reflected wavelength to blue shift as the pitch decreases, and the center wavelength of the reflected light changes; under tangential force (X / Y-axis direction) or sliding force, the photonic crystal film 3 undergoes shear deformation, causing the array of marker points 2 on the surface to move synchronously, and the spatial position of the marker points 2 changes relative to the initial state; Signal acquisition stage: Camera unit 9 continuously captures the reflected light signal of photonic crystal thin film 3 and the real-time image of marker point 2, and continuously transmits wavelength change information and displacement image information to signal processing module to ensure signal changes during dynamic tracking force application process; Signal processing and output stage: The signal processing module analyzes and processes the acquired optical signals. For the normal force, based on Bragg's law of reflection and combined with the pre-calibrated correspondence between "wavelength change and force magnitude", the specific value and location of the normal force are calculated. For the tangential force: the Farneback optical flow algorithm is used to track the displacement vector (fx, fy) of marker point 2 in adjacent frames, and the distribution characteristics and resultant force (Fx, Fy) of the tangential force are inferred from the displacement vector. Finally, the signal processing module outputs multi-dimensional force sensing results, providing data support for the feedback control of robots and other equipment.

[0040] Reset phase: When the external force disappears, the spiral structure of the photonic crystal thin film 3 returns to its initial state, the reflected wavelength and the position of the marker point 2 return to the reference value, and the sensor waits for the next force signal input and enters the cyclic sensing state.

[0041] like Figure 1 As shown in the figure, an embodiment of the present invention also provides a method for fabricating a visual-touch sensor based on a photonic crystal, comprising: The photonic crystal film 3 is solidified on a pre-configured transparent substrate 4, and marking points 2 are affixed to the surface of the photonic crystal film 3.

[0042] Specifically, the pre-configured transparent substrate 4 provides a stable supporting interface for the photonic crystal thin film 3, and its excellent light transmittance ensures attenuated optical signal transmission, providing a structural basis for subsequent optical detection of force signals. The transparent substrate 4 can be a highly transparent glass (such as...) Figure 3 Glass substrate 42), high transparency glass (such as Figure 3 The glass substrate 42 in the middle has high light transmittance and support stability, which can provide light transmission for subsequent visual and tactile sensors and buffer against external impacts; in addition, the transparent substrate 4 can also be prepared from materials with certain flexibility and chemical inertness, such as an elastic layer prepared by mixing polymethyl methacrylate (PMMA) with a curing agent (e.g., Figure 3 The transparent elastic layer 41 provides physical protection for the photonic crystal film 3 and can simulate the tactile interaction characteristics of human skin. The molecules of the photonic crystal film 3 are arranged in a helical pattern, giving it the physical property of selectively reflecting specific wavelengths and strictly adhering to Bragg's law of reflection. This property allows the force applied to be directly converted into a detectable optical signal, establishing a fundamental physical relationship between force and wavelength changes. The photonic crystal film 3 can be uniformly adhered to the surface of the transparent substrate 4 using an optical adhesive and then cured, ensuring a gapless bond between the two. The thickness of the photonic crystal film 3 can be 45μm-60μm.

[0043] A protective slurry is prepared and coated on the surface of the marked photonic crystal film 3 to form a protective elastic layer 1, thereby obtaining the sensing unit 5.

[0044] Specifically, an ultraviolet laser marking machine is used to mark the surface of the cured photonic crystal film 3, forming a uniform array of marking points 2. This micro-array of marking points 2 serves as a reference for tangential force sensing. When the photonic crystal film 3 is subjected to tangential force and undergoes shear deformation, the marking points 2 will shift synchronously with the deformation, providing a clear displacement reference for the quantitative detection of tangential force. A protective slurry forms a protective elastic layer 1, which can prevent damage to the photonic crystal film 3 caused by external friction and impact, while not affecting the transmission of its force deformation. The protective slurry can be prepared by mixing polycarbonate (PC) with a crosslinking agent. After curing, this mixed slurry forms a protective elastic layer 1 with high elasticity and transparency, ensuring optical signal transmission while precisely matching the deformation characteristics of the underlying photonic crystal response layer (i.e., the photonic crystal film 3), forming a complete sensing unit 5, such as... Figure 2 As shown. In addition, in order to improve the optical contrast between marker point 2 and the background, a certain amount of graphite powder can be added to the mixed slurry to optimize the displacement detection accuracy.

[0045] The sensing unit 5 is embedded into the sensing substrate on which the camera unit 9 is installed to obtain a visual-tactile sensor.

[0046] Optionally, the sensor substrate can be 3D printed using photosensitive resin as the raw material.

[0047] Specifically, after the sensing substrate is modeled using computer-aided design software such as SolidWorks, the model is imported into a photopolymer 3D printer for resin printing. An internal mounting slot is pre-drilled to precisely match the dimensions of the sensing unit 5. The complete sensing unit 5 is then embedded into the mounting slot of the sensing substrate, completing the assembly of the visual-tactile sensor. The light-shielding design of the sensing substrate prevents external stray light from interfering with optical detection, ensuring the stability of signal acquisition. Figure 3 As shown, the sensor substrate includes a base 6, an LED light strip 7, and a housing 8. The base 6 adopts an integrated molding structure with a pre-reserved mounting groove that precisely matches the size of the sensing unit 5, used to fix the sensing unit 5 and provide it with a stable support foundation to ensure structural stability under stress. The LED light strip 7 is arranged in a ring on the inner wall of the base 6, surrounding the sensing unit 5, providing a uniform and stable incident light source for the sensing unit 5, ensuring that the reflected light signal of the photonic crystal film 3 has good detectability and avoiding the impact of uneven illumination on signal accuracy. The housing 8 is wrapped around the base 6 and the sensing unit 5 and is made of light-shielding material, which can isolate external stray light interference, create a closed optical detection environment, ensure the purity of the light signal captured by the camera unit 9, and improve detection accuracy. The camera unit 9 is installed on the top of the housing 8, opposite to the sensing unit 5, with the lens facing the transparent elastomer (i.e., transparent elastic layer 41) of the observation layer of the sensing unit 5, used to collect the image information of the reflection wavelength change of the photonic crystal film 3 and the displacement of the marker point 2 in real time, and transmit the data to the subsequent signal processing module.

[0048] The beneficial effects of the method for fabricating the photonic crystal-based visual-touch sensor of the present invention are the same as those of the aforementioned photonic crystal-based visual-touch sensor, and will not be repeated here.

[0049] Optionally, before solidifying the photonic crystal film 3 onto the pre-configured transparent substrate 4 and marking the surface of the photonic crystal film 3 with marker points 2, the following steps are included: After preparing the substrate mixture solution and removing air bubbles, it is scraped onto the pre-prepared glass substrate 42 and cured at high temperature to obtain the transparent substrate 4.

[0050] Optionally, the substrate mixing solution includes polydimethylsiloxane and a crosslinking agent in a mass ratio of 10:1, and after curing, a transparent elastic layer 41 is formed. The transparent substrate 4 is composed of the transparent elastic layer 41 and a glass substrate 42.

[0051] Specifically, the preparation of the transparent substrate 4 begins with the preparation of the substrate mixture solution. Polydimethylsiloxane is selected as the main substrate material, and it is mixed with a crosslinking agent at a mass ratio of 10:1 to form a stable substrate mixture solution. This ensures the coating fluidity of the mixture solution and imparts good mechanical strength and light transmittance to the final transparent substrate 4 through the crosslinking reaction, providing reliable support for the subsequent curing of the photonic crystal film 3. The prepared substrate mixture solution needs to be degassed by placing it in a vacuum drying oven and letting it stand in a vacuum environment for 5 minutes to allow the dissolved air in the solution to fully overflow and be expelled, avoiding defects such as depressions and pores on the surface of the transparent elastic layer 41 formed by subsequent scraping. The degassed mixture solution is evenly applied to a borosilicate glass substrate 42 with a side length of 2 cm (the side length is determined according to the sensor size) that has been ultrasonically cleaned and dried using a precision scraper. During the scraping process, the scraper movement speed is kept consistent to ensure that the substrate mixture solution coating thickness is uniform, laying the foundation for the smooth adhesion of the photonic crystal film 3. After the coating is completed, the borosilicate glass substrate 42 containing the substrate mixture solution is placed in a high-temperature oven for high-temperature curing. The high-temperature environment accelerates the cross-linking reaction, allowing the substrate mixture solution to form a uniform and structurally stable transparent elastic layer 41. Simultaneously, it enhances the bonding strength between the transparent elastic layer 41 and the borosilicate glass substrate 42, preventing delamination or peeling during subsequent processing or use, and ensuring the long-term stability of the transparent substrate 4. After fabrication, a transparent substrate 4 is formed, consisting of the transparent elastic layer 41 and the glass substrate 42, as shown below. Figure 2 As shown.

[0052] Optionally, the protective slurry is applied to the surface of the marked photonic crystal film 3 to form a sensing unit 5, comprising: After preparing a protective slurry and removing air bubbles, it is spin-coated onto the marked surface of the photonic crystal film 3 and then cured at high temperature to obtain the sensing unit 5.

[0053] Optionally, the configuration of the protective slurry includes: Polydimethylsiloxane and crosslinking agent are mixed at a mass ratio of 10:1; Carbon black powder is added to the mixed slurry to obtain the protective slurry, wherein the mass of the carbon black powder accounts for 0.5% of the mass of the mixed slurry.

[0054] Specifically, the protective slurry is prepared using polydimethylsiloxane (PDMS) as the base material, combined with a suitable crosslinking agent, and mixed at a mass ratio of 10:1 to ensure thorough integration and a homogeneous base slurry system. PDMS provides good flexibility and elasticity, while the crosslinking agent enhances the structural stability and mechanical strength of the slurry through subsequent curing reactions. Together, they provide suitable protective support for the photonic crystal film 3. Carbon black powder is added to the homogeneously mixed base slurry, with the carbon black powder accounting for 0.5% of the total mass of the mixed slurry. Stirring continues until the carbon black powder is uniformly dispersed in the slurry without agglomeration, resulting in the final protective slurry. The addition of carbon black powder does not affect the flexibility and coating performance of the protective slurry, while optimizing the optical contrast of the slurry, providing a clear background reference for the subsequent optical detection of the displacement of marker point 2 (i.e., detection by camera unit 9). The prepared protective slurry needs to undergo a de-airing process. It is placed in a vacuum drying oven and left to stand for 5 minutes to allow dissolved air to fully escape and be expelled. This prevents residual air bubbles from causing pores and defects in the subsequently coated protective elastic layer 1, ensuring the integrity and uniformity of the protective elastic layer 1. After de-airing, the protective slurry is spin-coated evenly onto the marked photonic crystal film 3. During spin-coating, equipment parameters are controlled to ensure consistent coating thickness, ensuring complete coverage of the photonic crystal film 3 and surface markings 2. After spin-coating, the device carrying the protective slurry is placed in a high-temperature oven for high-temperature curing. The high-temperature environment accelerates the cross-linking reaction, allowing the protective slurry to form a uniform and structurally stable protective elastic layer 1 that firmly bonds to the photonic crystal film 3. Simultaneously, it ensures that the protective elastic layer 1 possesses good elasticity and deformation transmission capabilities, without hindering the transmission of external forces to the photonic crystal film 3.

[0055] Optionally, the curing temperature for high-temperature curing is 80°C, and the curing time is 10 minutes.

[0056] Specifically, in the preparation of the transparent substrate 4, a glass substrate 42 coated with a mixture of polydimethylsiloxane and a crosslinking agent is placed in an 80°C oven and cured for 10 minutes. The 80°C temperature effectively activates the crosslinking agent, promoting the formation of a stable crosslinked structure between the polydimethylsiloxane molecular chains. The 10-minute curing time ensures the crosslinking reaction proceeds fully, avoiding incomplete reactions that could lead to insufficient mechanical strength and a loose structure in the transparent elastic layer 41. It also prevents the transparent elastic layer 41 from yellowing or experiencing a decrease in light transmittance due to excessively high temperatures or prolonged curing times. In the curing of the protective slurry, the device coated with the protective slurry (a mixture of polydimethylsiloxane, crosslinking agent, and carbon black powder) is placed in an 80°C oven and cured for 10 minutes. This combination of temperature and time enables the protective slurry to form a uniform and elastic protective layer 1, while ensuring the strong bond between the protective elastic layer 1 and the photonic crystal film 3, preventing delamination and peeling. At the same time, the mild curing conditions do not damage the spiral structure and optical properties of the photonic crystal film 3, ensuring the regularity of its reflection wavelength change after being subjected to force.

[0057] Optionally, marking the surface of the photonic crystal thin film 3 with marking points 2 includes: Marking point 2 is applied according to a diameter of 100μm and a spacing of 200μm.

[0058] Specifically, when marking the marking points 2 on the surface of the photonic crystal thin film 3, a laser marking machine is used to uniformly mark the points according to the parameters of 100 μm in diameter and 200 μm in spacing. Before marking, the surface of the photonic crystal thin film 3 needs to be cleaned to ensure that no impurities affect the formation of the marking points 2. During the marking process, the laser landing accuracy is controlled by a positioning device to make the marking points 2 distributed in a regular array on the thin film surface. The center-to-center distance between adjacent marking points 2 is strictly controlled to be 200 μm, and the diameter deviation of a single marking point 2 does not exceed ±5 μm. The design of marker point 2, with its specific parameters, is precisely matched to the sensing characteristics of the photonic crystal film 3. The 100μm diameter ensures sufficient optical discernibility for clear capture by the camera unit 9, while avoiding excessive surface space occupation due to a large diameter, which could negatively impact the overall deformation response of the photonic crystal film 3. The 200μm spacing balances the distribution density of marker points 2 with deformation detection sensitivity. This ensures that when shear deformation occurs in any area of ​​the film, a corresponding marker point 2 generates a traceable displacement, while avoiding interference between displacement signals due to excessively small spacing or blind spots in deformation detection due to excessively large spacing. Marker points 2 are formed using laser marking, resulting in a strong bond between them and the photonic crystal film 3. They will not detach or become blurred during stress deformation or long-term use, ensuring the continuity and reliability of displacement detection. Simultaneously, the color of marker point 2 provides a clear optical contrast with the photonic crystal film 3 and the subsequently coated protective elastic layer 1, further enhancing the clarity of image acquisition (i.e., acquisition by the camera unit 9) and providing a foundation for accurate calculation of the displacement vector.

[0059] like Figure 3 As shown, an embodiment of the present invention provides a photonic crystal-based visual-touch sensor, which is manufactured using the photonic crystal-based visual-touch sensor method described above. The visual-touch sensor includes a sensing unit 5 and a sensing substrate. The sensing unit 5 is embedded in the base 6 of the sensing substrate. The outer shell 8 of the sensing substrate wraps around the base 6 and the sensing unit 5. An LED light strip 7 is arranged in a ring on the inner wall of the base 6. A camera unit 9 is installed on the top of the outer shell 8 and is positioned opposite to the sensing unit 5.

[0060] The present invention will be further described below with reference to specific embodiments.

[0061] Example 1 This embodiment provides a visual-tactile sensor based on a photonic crystal, the fabrication method of which includes the following steps: 1.1 Fabrication of sensor housing 8 and base 6 A one-piece shell 8 and base 6 model was constructed using SolidWorks software. The shell 8 was designed as a light-shielding structure, and the base 6 had a pre-drilled mounting slot that precisely matches the size of the sensing unit 5, ensuring a seamless fit after the sensing unit 5 was embedded. The completed 3D model was imported into a photopolymer 3D printer, and photosensitive resin was used as the printing material. The model was printed according to preset parameters. After printing, the surface was cleaned to remove residual support material, resulting in a complete light-shielding shell 8 and base 6.

[0062] 1.2 Preparation of transparent substrate 4 Weigh 1g of polydimethylsiloxane (PDMS) as the substrate material, and mix it with 0.1g of epoxy crosslinking agent. Place the mixture in a mixing container at a mass ratio of 10:1 and stir for 15 minutes using a high-speed stirrer to ensure thorough and uniform mixing. Place the mixed solution in a vacuum drying oven and evacuate under vacuum for 5 minutes to completely remove dissolved air bubbles. Then, apply the degassed mixture onto a 2cm side-length glass substrate 42 that has been ultrasonically cleaned and dried, controlling the coating thickness to 100μm. Place the coated glass substrate 42 in an 80℃ oven and cure at a constant temperature for 10 minutes. After cooling, a smooth, transparent substrate 4 (containing a transparent elastic layer 41 and a glass substrate 42) with good light transmittance is obtained.

[0063] 1.3 Attachment of photonic crystal thin film 3 A 50μm thick photonic crystal film 3 was selected, and a layer of UV adhesive was uniformly applied to the effective area (i.e., the surface of the transparent elastic layer 41) of the transparent substrate 4. The photonic crystal film 3 was then smoothly and evenly adhered to the substrate surface coated with UV adhesive. A scraper was used to gently press the film and substrate together to remove air bubbles, ensuring a tight, bubble-free bond. The bonded device was then placed under a UV curing device and cured for 3 minutes to firmly bond the photonic crystal film 3 to the transparent substrate 4.

[0064] 1.4 Preparation of Marker Point 2 The device with the photonic crystal attached is fixed on the worktable of the laser marking machine, and its position is adjusted so that the surface of the photonic crystal film 3 faces the laser emitter. Laser marking parameters are set, and markings are uniformly applied to the surface of the photonic crystal film 3 according to a diameter of 100 μm and a spacing of 200 μm, forming a regularly distributed array of marking dots 2. During the marking process, the laser power and irradiation time are controlled to ensure that the marking dots 2 are clearly distinguishable without damaging the internal structure of the photonic crystal film 3.

[0065] 1.5 Preparation of protective elastic layer 1 Weigh 1g of polydimethylsiloxane (PDMS) and 0.1g of epoxy crosslinking agent, and mix them evenly at a mass ratio of 10:1 to obtain a base slurry. Add 0.5% carbon black powder to the base slurry and continue stirring for 20 minutes to ensure that the carbon black powder is evenly dispersed in the slurry without agglomeration. Place the mixed protective slurry in a vacuum drying oven and evacuate for 5 minutes to remove air bubbles. Then pour it onto the surface of the photonic crystal film 3 marked with point 2. Place the device in a spin coater and spin coat at 1000 rpm for 30 seconds to ensure that the protective slurry evenly covers the film surface, forming a protective elastic layer 1 of uniform thickness. Place the spin-coated device in an 80℃ oven and cure for 10 minutes to obtain a complete sensing unit 5.

[0066] 1.6 Sensor Overall Assembly The prepared sensing unit 5 is embedded into the pre-formed mounting groove of the base 6, ensuring a tight fit and fixed position between the sensing unit 5 and the base 6. An LED strip 7 is wrapped around the inner wall of the base 6 to provide a uniform incident light source for the sensing unit 5. The camera unit 9 is fixed to a preset mounting position on the top of the light-shielding housing 8. The angle of the camera unit 9 is adjusted so that its lens axis is aligned with the center of the sensing unit 5, enabling precise capture of the reflected light signal from the photonic crystal film 3 and the image of the marker point 2. Finally, the housing 8 is fastened to the base 6 using a snap-fit ​​structure, completing the overall assembly of the visual-tactile sensor.

[0067] 1.7 Performance Testing The assembled sensor underwent 50,000 repeatability tests, and the test results showed that... Figure 4 As shown, the sensor exhibits zero-point drift of less than 1% and maximum drift of less than 5%, demonstrating excellent stability. Under the action of normal and tangential forces, it can accurately capture the changes in the reflected wavelength of the photonic crystal film 3 and the displacement of the marker point 2. The force signal is accurately calculated, and the computing power consumption is significantly lower than that of traditional silicone contact layer sensors, meeting the refined sensing needs in the field of embodied intelligence.

[0068] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A visual-tactile sensor based on a photonic crystal, characterized in that, Includes a sensing unit (5), a sensing substrate, and a camera unit (9); The sensing unit includes a photonic crystal film (3), a transparent substrate (4), and a protective elastic layer (1). The photonic crystal film (3) is solidified on the transparent substrate (4), and the surface of the photonic crystal film (3) is marked with marking points (2). The protective elastic layer (1) is solidified on the surface of the photonic crystal film (3) with the marking points (2). The sensing unit (5) is embedded in one end face of the sensing substrate, the camera unit (9) is embedded in the other end face of the sensing substrate, and the transparent substrate (4) of the sensing unit (5) faces the camera unit (9).

2. The photonic crystal-based visual-tactile sensor according to claim 1, characterized in that, The transparent substrate (4) includes a transparent elastic layer (41) and a glass substrate (42). The transparent elastic layer (41) is solidified on the glass substrate (42), and the photonic crystal film (3) is solidified on the end face of the transparent elastic layer (41) away from the glass substrate (42).

3. The photonic crystal-based visual-tactile sensor according to claim 1, characterized in that, The sensing substrate includes a base (6) and a housing (8). The sensing unit (5) is embedded in the base (6). The base (6) and the camera unit (9) are respectively disposed on the two end faces of the housing (8).

4. The photonic crystal-based visual-tactile sensor according to claim 3, characterized in that, The sensing substrate also includes an LED light strip (7), which is arranged on the inner wall of the base (6) and is used to provide an incident light source for the information acquisition of the camera unit (9).

5. The photonic crystal-based visual-tactile sensor according to claim 1, characterized in that, The thickness of the photonic crystal thin film (3) is 45μm-60μm.

6. A method for fabricating a visual-tactile sensor based on a photonic crystal, characterized in that, The method for fabricating a photonic crystal-based visual-touch sensor as described in any one of claims 1 to 5 includes: The photonic crystal film (3) is solidified on a pre-configured transparent substrate (4), and marking points (2) are affixed to the surface of the photonic crystal film (3). Prepare a protective slurry and coat it on the surface of the photonic crystal film (3) after marking to form a protective elastic layer (1) and obtain a sensing unit (5). The sensing unit (5) is embedded into the sensing substrate on which the camera unit (9) is installed to obtain a visual-tactile sensor.

7. The method for fabricating a photonic crystal-based visual-touch sensor according to claim 6, characterized in that, Before the photonic crystal film (3) is solidified on a pre-configured transparent substrate (4) and before marking points (2) are affixed to the surface of the photonic crystal film (3), the following steps are included: After preparing the substrate mixture solution and removing air bubbles, it is scraped onto the pre-prepared glass substrate (42) and cured at high temperature to obtain the transparent substrate (4). The protective slurry is applied to the surface of the marked photonic crystal thin film (3) to form a sensing unit (5), including: After preparing a protective slurry and removing air bubbles, it is spin-coated onto the surface of the marked photonic crystal film (3) and cured at high temperature to form a protective elastic layer (1), thus obtaining the sensing unit (5).

8. The method for fabricating a photonic crystal-based visual-touch sensor according to claim 7, characterized in that, The substrate mixture solution includes polydimethylsiloxane and a crosslinking agent in a mass ratio of 10:

1. After curing, it forms a transparent elastic layer (41). The transparent substrate (4) is composed of the transparent elastic layer (41) and a glass substrate (42).

9. The method for fabricating a photonic crystal-based visual-touch sensor according to claim 7, characterized in that, The protective slurry configuration includes: Polydimethylsiloxane and crosslinking agent are mixed at a mass ratio of 10:1; Carbon black powder is added to the mixed slurry to obtain the protective slurry, wherein the mass of the carbon black powder accounts for 0.5% of the mass of the mixed slurry.

10. The method for fabricating a photonic crystal-based visual-touch sensor according to claim 6, characterized in that, Before embedding the sensing unit (5) into the sensing substrate to obtain the visual-touch sensor, the method further includes: The sensor substrate was 3D printed using photosensitive resin as the raw material.

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