Sensor, optical tactile sensing system and detection method

Abstract

The invention relates to the field of sensor design, and particularly provides a sensor, an optical tactile sensing system and a detection method.The sensor comprises a photoelectric detection unit, an elastic light path modulation unit, a light source unit and a capacitance touch control unit which are sequentially stacked; wherein the capacitive touch unit is used for sensing approaching or contact of a target; the light source unit is used for emitting light towards the elastic light path modulation unit when a target makes contact with the capacitive touch control unit. The elastic light path modulation unit is used for generating deformation when a target is in contact with the capacitive touch control unit, so that transmitted light is changed before and after the target is in contact with the capacitive touch control unit; and the photoelectric detection unit is used for collecting the transmitted light. According to the invention, the problems of signal interference and single-mode detection limitation of the tactile sensor in a complex photoelectromagnetic environment can be solved.

Description

Technical Field

[0001] This invention relates to the field of sensor design, and specifically provides a sensor, an optical tactile sensing system, and a detection method. Background Technology

[0002] In today's era of rapid technological advancement, tactile sensors play a crucial role as key components for intelligent devices to perceive their external environment. This is particularly true in fields such as intelligent robots, wearable devices, and medical rehabilitation equipment, where extremely high performance requirements are placed on tactile sensors. Traditional tactile sensors, such as piezoresistive and capacitive sensors, suffer from significant drawbacks, including low sensitivity, long response delays, and the ability to support only single-degree-of-freedom detection. For example, when robots perform precision grasping operations, existing sensors cannot accurately sense multi-directional pressure and subtle deformations in real time, leading to insufficient precision in grasping movements and a high risk of errors. Furthermore, in the field of medical rehabilitation, when rehabilitation robots assist patients in limb training, sensors need to accurately report contact force, a requirement that existing sensors struggle to meet.

[0003] In recent years, optical tactile sensors have gradually become a research hotspot due to their advantages such as electrical safety, chemical inertness, high sensitivity, and good flexibility. However, existing optical tactile sensors still have room for improvement in terms of structural design, cost control, and detection accuracy. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings, this invention proposes a sensor, an optical tactile sensing system, and a detection method, which can solve the problems of signal interference and single-mode detection limitations of tactile sensors in complex optoelectronic environments.

[0005] In a first aspect, the present invention discloses a sensor, comprising:

[0006] The photoelectric detection unit, the flexible optical path modulation unit, the light source unit, and the capacitive touch unit are stacked sequentially; among them...

[0007] The capacitive touch unit is used to sense when a target approaches or comes into contact with it;

[0008] The light source unit is used to emit light toward the elastic optical path modulation unit when the target touches the capacitive touch unit;

[0009] The elastic optical path modulation unit is used to generate deformation when the target contacts the capacitive touch unit, thereby causing the transmitted light to change before and after contact.

[0010] The photoelectric detection unit is used to collect the transmitted light.

[0011] Furthermore, the capacitive touch unit includes a metal mesh layer, a first metal reflective layer, and an insulating layer located between the two, wherein the first metal reflective layer is disposed closer to the light source unit than the metal mesh layer.

[0012] Furthermore, the capacitive touch unit also includes an encapsulation layer disposed on the surface of the metal mesh layer away from the light source unit.

[0013] Furthermore, the light source unit includes:

[0014] The light source and the second metal reflective layer, wherein

[0015] The light source is located between the first metal reflective layer and the second metal reflective layer;

[0016] The second metal reflective layer is closer to the elastic optical path modulation unit than the light source, and the second metal emitting layer is provided with a plurality of light-transmitting holes spaced apart, so that the light can enter the elastic optical path modulation unit.

[0017] Furthermore, the elastic optical path modulation unit includes: an elastic optical waveguide layer; wherein

[0018] The elastic optical waveguide layer includes several flexible optical waveguide structures, which are columnar structures arranged vertically between the light source unit and the photoelectric detection unit, with gaps between adjacent flexible optical waveguide structures.

[0019] Furthermore, the inner wall of the flexible optical waveguide structure is provided with a dielectric film.

[0020] Furthermore, the flexible optical path modulation unit also includes:

[0021] A lens layer is located between the elastic optical waveguide layer and the photoelectric detection unit;

[0022] The lens layer is used to focus the light transmitted through the flexible optical waveguide structure.

[0023] Furthermore, the lens layer is an elastic hemispherical or aspherical lens structure.

[0024] Furthermore, the elastic optical path modulation unit also includes a transparent elastic film for encapsulation, located between the elastic optical waveguide layer and the light source unit.

[0025] Secondly, the present invention discloses an optical tactile sensing system, comprising:

[0026] The sensor as described in the first aspect;

[0027] An analog-to-digital converter, used to convert the analog signals acquired by the sensor into digital signals; and

[0028] A microcontroller is used to process the digital signals.

[0029] Furthermore, the microcontroller also includes an artificial intelligence model that identifies the target when it approaches or comes into contact with it.

[0030] Furthermore, the artificial intelligence model is a support vector machine model.

[0031] Furthermore, it also includes a grounding circuit, wherein when the capacitive touch unit senses the approach of a target, the microcontroller connects the grounding circuit to release static electricity.

[0032] Thirdly, the present invention discloses a detection method employing the system described in the second aspect, comprising:

[0033] The capacitive touch unit senses when the target approaches or comes into contact with it;

[0034] When the capacitive touch unit senses a target contact, the light source unit emits light toward the elastic optical path modulation unit;

[0035] The elastic optical path modulation unit deforms, causing the transmitted light to change before and after contact.

[0036] The photoelectric detection unit collects the transmitted light;

[0037] The analog-to-digital converter converts the analog signals acquired by the sensor into digital signals; and

[0038] The microcontroller processes the digital signal to obtain the detection result.

[0039] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects:

[0040] In the technical solution of this invention, the sensor comprises a photoelectric detection unit, an elastic optical path modulation unit, a light source unit, and a capacitive touch unit. The capacitive touch unit has dual functions: first, it isolates electromagnetic interference to ensure the stability of the optical signal; second, it enables non-contact proximity detection. The elastic optical path modulation unit employs a columnar flexible optical waveguide structure to amplify the minute deformations generated when a target object comes into contact with it, thereby enabling the sensor to achieve more accurate detection results. This invention overcomes the limitations of traditional tactile sensors in signal interference and single-mode detection under complex electromagnetic environments. Attached Figure Description

[0041] The disclosure of this invention will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Furthermore, similar numbers in the drawings are used to denote similar components, wherein:

[0042] Figure 1 This is a schematic diagram of the main structure of a sensor according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the main structure of a sensor according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the main structure of a capacitive touch unit according to an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the main structure of a light source unit according to an embodiment of the present invention;

[0046] Figure 5 This is a schematic diagram of the main structure of an elastic optical path modulation unit according to an embodiment of the present invention;

[0047] Figure 6 This is a schematic diagram of the main structure of a photoelectric detection unit according to an embodiment of the present invention;

[0048] Figure 7 This is a schematic diagram of the main structure of an optical tactile sensing system according to an embodiment of the present invention;

[0049] Figure 8 This is a schematic diagram of the main flow of a detection method according to an embodiment of the present invention.

[0050] List of reference numerals :

[0051] 1: Photodetector unit; 1-1: Rigid substrate; 1-2: Flexible substrate; 1-3: First electrode structure; 1-4: Gate insulating layer; 1-5: Active structure; 1-6: Second electrode structure; 1-7: First insulating material layer; 1-8: Photodiode layer; 1-9: Metal light-shielding structure; 1-10: Second insulating material layer; 2: Elastic optical path modulation unit; 2-1: Flexible optical waveguide structure; 2-2: Dielectric film; 2-3: Lens layer; 2-4: Transparent planarization layer; 3: Light source unit; 3 -1: Second metal reflective layer; 3-2: Insulating layer; 3-3: Anode layer; 3-4: Hole transport layer; 3-5: R pixel light-emitting layer; 3-6: G pixel light-emitting layer; 3-7: B pixel light-emitting layer; 3-8: Pixel definition layer; 3-9: Electron transport layer; 3-10: Cathode; 3-11: Planarization layer; 3-12: Second insulating layer; 311: Light-transmitting hole; 4: Capacitive touch unit; 4-1: Metal mesh layer; 4-2: First metal reflective layer; 4-3: Insulating layer; 4-4: Encapsulation layer; Detailed Implementation

[0052] Some embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0053] This invention provides a sensor, more specifically, a tactile sensor, and further, in terms of technical details, it is an innovative design of an optical tactile sensor.

[0054] The sensor disclosed in this invention refers to... Figures 1-2 Its core structure mainly comprises the following key components, which are stacked sequentially in a specific order: from bottom to top, they are a photoelectric detection unit 1, an elastic optical path modulation unit 2, a light source unit 3, and a capacitive touch unit 4. The main function of the capacitive touch unit is to sense whether a target object is approaching or directly contacting the sensor surface. The light source unit undertakes another important task: when a target object touches the capacitive touch unit, the light source unit emits light towards the elastic optical path modulation unit. Specifically, the light source unit emits an array of light spots; the image of this array of light spots constitutes a special light signal, namely the light spot array signal. This design effectively avoids prolonged continuous illumination by the light source, thus preventing the elastic optical path modulation unit, made of elastic material, from malfunctioning due to overheating, and consequently avoiding a decrease in sensor sensitivity.

[0055] The elastic optical path modulation unit plays an indispensable role in the entire sensor operation. When a target object comes into contact with the capacitive touch unit, this unit undergoes corresponding deformation. This deformation causes a significant change in the light spot image signal transmitted through it before and after contact, reflected in both light intensity and the position of the light spot image signal. The unique feature of this component is its ability to amplify the minute deformation caused by the target object's contact, enabling the sensor to achieve more accurate detection. Within the photodetector unit, there is a crucial component: a pixel photodiode (PD) array. This array has the ability to receive light spots and detect changes in their intensity and position. Specifically, when an array light spot appears, the pixel photodiode array can sensitively capture the spot and accurately detect changes in its intensity or position. The primary task of the photodetector unit is to collect light, which is the light transmitted through the elastic optical path modulation unit. The photodetector unit then converts these collected light signals into data that can be used in subsequent applications. In this way, the photoelectric detection unit provides reliable and stable data support for the normal operation of the entire sensor system, thereby ensuring that the sensor system can function accurately and efficiently in various application scenarios.

[0056] The various components described above do not exist independently, but rather work together closely to form this high-performance optical tactile sensor. Each component performs its specific function while cooperating with others to ensure that the sensor can accurately and efficiently complete tactile sensing tasks in various application scenarios. This structure not only improves the sensor's sensitivity and reliability but also lays a solid foundation for its widespread adoption in practical applications.

[0057] The specific structure and function of each of the above components are explained in detail below.

[0058] Capacitive touch unit

[0059] Reference Figure 3 The capacitive touch unit 4 includes a metal mesh layer 4-1, a first metal reflective layer 4-2, and an insulating layer 4-3 located between the two. It should be noted that the first metal reflective layer 4-2 is positioned closer to the light source unit 3 in space than the metal mesh layer 4-1. These three layers together constitute a composite layer structure combining metal mesh shielding and capacitive sensing.

[0060] In one specific embodiment, the top layer uses a 20nm thick silver nanowire / PDMS composite film with a grid period of 200μm. Even when the tensile strain reaches 50%, the sheet resistance can still be maintained at ≤5Ω / □ (ohms per square or ohms per block). This material can form a regular and uniform conductive grid structure through advanced nanoimprinting technology or traditional screen printing process, thereby ensuring that it has good conductivity and mechanical stability.

[0061] The intermediate layer uses a dielectric elastomer as the insulating layer. The dielectric elastomer can be made of nanoparticles such as PDMS doped with TiO2. The thickness of the insulating layer can be controlled at 50μm, and it has a dielectric constant of 3.2. This parameter selection allows the layer to effectively adjust the capacitance characteristics of the overall structure while ensuring good insulation performance.

[0062] The bottom layer uses Ag metal electrodes, which not only form a capacitor structure together with the upper metal mesh layer, but also undertake the important function of the reflective layer of the light source unit, thus realizing an integrated design with multiple functions. The bottom Ag metal electrodes can be fabricated as Ag reflective layers using screen printing or magnetron sputtering.

[0063] This structural design possesses a dual-functional mechanism. On one hand, it effectively addresses high-frequency interference through electromagnetic shielding. Specifically, it utilizes the skin effect to reflect and absorb electromagnetic interference above 1 GHz (shielding effectiveness ≥45 dB), and through a grounding loop design, it can safely discharge static electricity, achieving a protection level of ±8 kV. On the other hand, it also enables proximity sensing. Through a parallel-plate capacitor structure formed by the metal mesh layer and the reflective layer's metal electrodes, it detects changes in capacitance (resolution up to 0.01 pF), thereby accurately estimating the approach distance of objects with an error strictly controlled within less than 5%. This dual-functional mechanism makes this structure widely applicable and highly practical.

[0064] In one embodiment, reference is still made to Figure 3 The capacitive touch unit further includes an encapsulation layer 4-4 disposed on the surface of the metal mesh layer away from the light source unit.

[0065] Light source unit

[0066] Still refer to Figure 2 The light source unit 3 includes:

[0067] The light source and the second metal reflective layer 3-1, wherein

[0068] The light source is located between the first metal reflective layer 4-2 and the second metal reflective layer 3-1;

[0069] The second metal reflective layer is closer to the elastic optical path modulation unit than the light source, and the second metal emitting layer is provided with a plurality of light-transmitting holes 311 spaced apart, so that the light can enter the elastic optical path modulation unit.

[0070] In one embodiment, the light source used is an OLED light source integrated inside the device. Figure 2 (Not shown in the image). This OLED light source possesses numerous excellent characteristics. After the sensor is completely encapsulated, light from the external environment cannot penetrate it, ensuring the entire sensor remains opaque. Due to this opacity, optical signal interference is eliminated during practical applications, which is crucial for ensuring the stability and accuracy of the sensor's operation. Furthermore, when the light emitted from the OLED light source passes through multiple light-transmitting holes, these light rays form an array of light spots. This array of light spots provides the necessary optical foundation for subsequent operations or detection.

[0071] The top reflective layer, also known as the first metal reflective layer 4-2, uses a silver-plated flexible reflective film. This film has a reflectivity greater than or equal to 90%. It works in conjunction with the diffuser plate to achieve a reflective optical path design. This design effectively reduces the power consumption of the light source, making the operating current less than or equal to 10 mA.

[0072] The intermediate light source layer is a three-channel wavelength-tunable RGB OLED with wavelengths of 450 nm, 525 nm, and 630 nm. This light source layer configuration can provide light of multiple colors and allows for wavelength adjustment to meet different application scenarios.

[0073] The bottom-layer light-transmitting aperture, or light-transmitting aperture 311, is also composed of a silver-plated flexible reflective film, which also has a reflectivity greater than or equal to 90%. An array of apertures is created on the silver reflective layer, each aperture measuring 300 micrometers × 300 micrometers, with a spacing of 200 micrometers between the apertures. When light passes through these apertures, a fixed-size light spot array can be collected on the detector array, which facilitates subsequent detection and analysis of the optical signal.

[0074] In one embodiment, the light source unit can be adopted Figure 4 The structure shown is referenced. Figure 4 The light source unit 3 includes:

[0075] A second metal reflective layer 3-1 is formed on the elastic optical path modulation unit 2. In this embodiment, the second metal reflective layer is an Ag reflective light-transmitting aperture layer. This Ag reflective light-transmitting aperture layer can be formed by first forming a thin film using magnetron sputtering, followed by a series of operations including exposure, development, and etching to obtain the Ag reflective layer light-transmitting aperture structure; alternatively, screen printing can be used to obtain the Ag reflective layer structure.

[0076] A first insulating layer 3-2 is formed on the second metal reflective layer 3-1. In this embodiment, the insulating layer is a SiOx insulating layer, used to isolate moisture and other contaminants, thus protecting the OLED light-emitting layer. The SiOx film can be formed using a PECVD device.

[0077] An array of light-emitting structures is formed on the insulating layer 3-2. Adjacent light-emitting structures are spaced apart.

[0078] Each light-emitting structure includes:

[0079] An anode layer 3-3 is formed on the insulating layer 3-2. In this embodiment, the anode layer 3-3 is an ITO anode layer, which is formed by magnetron sputtering of an ITO thin film and then patterned by photolithography.

[0080] Hole transport layer 3-4, or HTL (Hole Transport Layer), is formed on anode layer 3-3. The pattern is formed using vacuum evaporation.

[0081] A light-emitting layer is formed on the hole transport layer 3-4. In this embodiment, the light-emitting layer is a REG OLED organic light-emitting layer, and the R pixel light-emitting layer 3-5, G pixel light-emitting layer 3-6, and B pixel light-emitting layer 3-7 are formed layer by layer by vacuum evaporation. The R pixel light-emitting layer 3-5, G pixel light-emitting layer 3-6, and B pixel light-emitting layer 3-7 are arranged side by side.

[0082] Pixel definition layers 3-8 are formed between R, G, and B pixels, and are organic light-emitting materials used to separate the light-emitting layers of R, G, and B pixels.

[0083] Electron transport layers 3-9 are formed on the light-emitting layer, and ETL uses vacuum evaporation to form the pattern.

[0084] In this embodiment, the cathode 3-10 formed on the electron transport layer 3-9 is formed by magnetron sputtering of a metal Ag or Al thin film, and then patterned by photolithography.

[0085] A planarization layer 3-11 is formed between the light-emitting layers. In this embodiment, the planarization layer 3-11 is a resin planarization layer.

[0086] The second insulating layer 3-12, formed on the planarization layer 3-11, serves as an insulating layer. In this embodiment, a PECVD device can be used to form the SiOx film.

[0087] The first metal reflective layer 4-2 is formed on the second insulating layer 3-12. The first metal reflective layer 4-2 can be fabricated as an Ag reflective layer by screen printing or magnetron sputtering.

[0088] Flexible optical path modulation unit

[0089] Reference Figure 5 The elastic optical path modulation unit 2 includes: an elastic optical waveguide layer; wherein

[0090] The elastic optical waveguide layer includes several flexible optical waveguide structures 2-1. The flexible optical waveguide structures are columnar structures, vertically arranged between the light source unit and the photoelectric detection unit, and adjacent flexible optical waveguide structures are fitted with gaps.

[0091] In one embodiment, the inner wall of the flexible optical waveguide structure is provided with a dielectric film 2-2.

[0092] In one embodiment, the elastic optical path modulation unit further includes a transparent elastic film for encapsulation, located between the elastic optical waveguide layer and the light source unit.

[0093] The modulator theory of the flexible optical waveguide layer of this invention is described as follows:

[0094] As a core component of the elastic optical path modulation unit, the flexible optical waveguide layer's modulation mechanism is based on the geometric deformation and optical property changes of the elastic medium under stress. When external pressure or shear force is applied to the sensor, the PDMS-based elastic optical waveguide layer deforms, and the built-in micron-sized hollow columnar structure changes its shape accordingly. Under normal pressure, the hollow column tilts along the pressure direction. Due to the change in the angle between the column and the normal to the waveguide surface, the light that originally propagated according to the principle of total internal reflection within the waveguide shifts in its reflection angle, causing some light leakage or a change in the transmission path, thus altering the light intensity or optical path. Under tangential stress, the hollow column, in addition to tilting, also undergoes lateral displacement. This displacement affects the propagation path length and direction of light within the waveguide layer, similarly causing attenuation or enhancement of light intensity. By detecting and analyzing changes in light intensity and spot size, the decoupling and quantification of tactile information such as pressure and shear force can be achieved, thereby completing the conversion and modulation of tactile signals into optical signals.

[0095] Physical structural design features

[0096] The flexible optical waveguide layer employs a multi-layered composite structure design to enhance its performance and stability. The bottom layer is a flexible substrate, providing mechanical support for the entire waveguide layer. Utilizing low-modulus PDMS material, it possesses excellent flexibility and elastic recovery, enabling it to adapt to varying degrees of bending and deformation. On the flexible substrate, a regularly arranged array of micron-sized hollow columnar structures is fabricated using microfabrication processes such as photolithography and micro-injection molding. The diameter of these hollow columns is controlled between 50-100 μm, and their height is adjusted within the range of 200-500 μm according to specific design requirements. The spacing between the columns is precisely calculated to ensure that they can deform independently under stress while also working collaboratively to accurately reflect external tactile information. The top of the hollow columns is covered with an ultra-thin transparent elastic film. This film not only protects the internal structure of the hollow columns but also enhances the sealing of the waveguide layer, preventing external impurities and moisture from affecting optical performance. In addition, to further optimize the light transmission characteristics, a special treatment is performed on the inner wall surface of the hollow column, and a layer of highly reflective dielectric film 2-2 is deposited to reduce the scattering and absorption of light on the inner wall of the column and improve the light transmission efficiency.

[0097] Fabrication method of elastic optical waveguide layer

[0098] Hollow pillar fabrication: Using photolithography, a layer of photoresist is spin-coated onto the substrate surface. Through mask exposure and development processes, a pattern corresponding to the hollow pillar array is formed on the photoresist. Next, reactive ion etching (RIE) is used to etch the flexible substrate according to the photoresist pattern, forming the groove structure of the hollow pillars. Alternatively, laser etching can be used to directly etch the groove structure of the hollow pillars.

[0099] Inner wall coating: The prepared flexible substrate with hollow columnar structure is placed in a vacuum coating equipment. Electron beam evaporation coating technology is used to coat a titanium dioxide (TiO2) dielectric film with a thickness of about 50nm on the inner wall surface of the hollow column to improve the light reflectivity of the inner wall.

[0100] Internal encapsulation: Low-viscosity PDMS material is injected into the holes and left to stand in a vacuum environment for a period of time to remove internal air bubbles. Then, it is placed in a constant temperature oven and cured at 80°C for 1 hour to form a complete micron-scale hollow columnar structure array.

[0101] Surface protective layer: Another portion of PDMS prepolymer is mixed with a curing agent and a thin, transparent elastic film with a thickness of about 20 μm is formed on the surface of a flexible substrate with a hollow columnar structure by spin coating. Then, it is cured at 80°C for 1 hour to complete the preparation of the flexible optical waveguide layer.

[0102] In one embodiment, reference is still made to Figure 5The elastic optical path modulation unit 2 further includes: lens layer 2-3.

[0103] The lens layer 2-3 is positioned between the flexible optical waveguide layer and the photodetector unit, and its main function is to focus the optical signal transmitted by the flexible optical waveguide structure. This design significantly improves the transmission efficiency of the optical signal and the reception quality of the subsequent photodetector unit. Furthermore, the lens layer 2-3 consists of multiple microlenses arranged in an array. The presence of these microlenses enables the lens layer to more efficiently capture the optical signal transmitted from the flexible optical waveguide structure and precisely focus it onto the target area.

[0104] In one embodiment, both the lens layer 2-3 and the flexible optical waveguide structure 2-1 are made of a transparent and elastic material. Both the lens layer 2-3 and the flexible optical waveguide structure 2-1 can be made of polydimethylsiloxane (PDMS), an elastic polymer.

[0105] In one embodiment, the lens layer is an elastic hemispherical or aspherical lens structure.

[0106] In one embodiment, a transparent planarization layer 2-4 is also formed between the lens layers, and the flexible optical waveguide structure 2-1 is formed on the transparent planarization layer 2-4.

[0107] The following describes several methods for forming the aforementioned microlens arrays.

[0108] Photoresist reflow method: Photoresist is coated on a substrate using photolithography technology. A columnar photoresist pattern is formed by exposure and development. Then, the photoresist is heated and reflowed under the action of surface tension to form a hemispherical or aspherical lens structure.

[0109] Hot pressing molding method: First, use ultra-precision machining or photolithography to make a high-precision microlens mold. Then, place the heated and softened polymer material (such as PMMA, PC) between the mold and the substrate, apply pressure to make the polymer fill the mold cavity, and demold after cooling and solidification, thereby replicating the microlens array on the substrate.

[0110] Compression molding: Similar to hot pressing, the difference is that compression molding is performed by pressing the polymer material in a molten state. It is suitable for making microlens arrays with large size and high precision requirements, and is often used in the production of optical lenses and other fields.

[0111] Reactive ion etching: Using photoresist or other materials as a mask, reactive ion etching technology is used to etch the substrate material (such as silicon or glass) to remove unwanted parts, thereby forming a microlens structure.

[0112] Wet etching: This method uses chemical solutions to selectively etch substrate materials. By controlling the etching time and solution concentration, microlens shapes can be formed on the substrate.

[0113] In one specific implementation, the flexible optical path modulation unit mentioned in this invention can be constructed in practical applications as follows:

[0114] The top waveguide layer consists of a micron-sized hollow column array based on PDMS, with diameters ranging from 50 to 100 μm and heights between 200 and 500 μm. When the structure is subjected to external pressure, these columns tilt, altering the path of light during total internal reflection and resulting in a linear change in transmittance. The pressure-to-intensity conversion factor is 0.8 V / (N / cm²).

[0115] The bottom microlens layer consists of a variable-focus lens array with focal lengths ranging from 500 μm to 2 mm. When a shear force is applied to it, the lens will undergo lateral displacement, which will cause the position of the light spot on the photodetector to shift, and its displacement-voltage sensitivity is 10 mV / μm.

[0116] This construction method enables effective modulation of the optical path to meet different application requirements.

[0117] Photoelectric detection unit

[0118] The photoelectric detection unit used in this invention is not limited to a specific structural form in its design and implementation. To better illustrate its application, a specific example structure will be provided below for detailed explanation. However, it is important to emphasize that the provided example is merely for ease of understanding and does not imply a limitation on the scope of protection of this invention. The actual application scope of this invention far exceeds the specific structural form described in the example, covering many more possible technical solutions and implementation methods.

[0119] In one embodiment, reference is made to Figure 6 The photoelectric detection unit 1 includes:

[0120] A flexible substrate 1-2 is constructed on the rigid substrate 1-1. The rigid substrate can be made of glass, a common and stable material. The flexible substrate is a flexible film material such as flexible PI (polyimide), PEN (polyethylene naphthalate), or PET (polyethylene terephthalate) film. These flexible substrates are formed on the glass substrate by lamination or coating.

[0121] The first electrode structure 1-3, also known as the Gate layer, is constructed on the already formed flexible substrate 1-2. During the fabrication of the first electrode structure, magnetron sputtering can be used to create single-layer or composite thin films of alloys such as molybdenum, aluminum, and copper, which serve as the first electrode thin film layer. This first electrode thin film layer is then patterned. The specific process involves exposure using a photomask, followed by development, and finally etching to obtain the first electrode structure with a specific pattern. The Gate layer wiring is closely related to the TFT switch and plays a crucial role in the overall structure and functional implementation.

[0122] A gate insulating layer 1-4 is deposited on the surface of the pre-fabricated first electrode structure 1-3 using plasma-enhanced chemical vapor deposition (PECVD). This gate insulating layer offers flexibility in material selection; it can be constructed using either silicon nitride (SiNx) or silicon oxide (SiOx) thin films as single materials, or a composite film formed by combining these two materials. Alternatively, it can be constructed using organic insulating materials such as polymethyl methacrylate (PMMA) through spin-coating.

[0123] Next, a photomask is needed to fabricate the via structure. Specifically, the photomask is first placed on the substrate to be processed, and then the photoresist is exposed using an exposure device, causing a chemical change in specific areas of the photoresist. Subsequently, the exposed or unexposed areas of the photoresist are removed using a developer, exposing the target area underneath. Finally, the exposed areas are etched using a wet or dry etching process to form the desired via structure, enabling subsequent circuit connections.

[0124] Active structures 1-5 are formed in the gate insulating layer 1-4. Active structures 1-5 are semiconductor dielectric layers. The active layer is formed using organic materials such as polythiophene or materials such as LTPS, amorphous silicon, and IGZO. The active structures are then obtained by exposure, development, and etching using a photomask.

[0125] Forming the second electrode structure 1-6. First, a second electrode layer thin film is formed, which can be a single layer or composite thin film of metal alloy such as molybdenum, aluminum, or copper prepared by magnetron sputtering. The second electrode layer thin film is patterned, and then exposed, developed, and etched through a mask to obtain the patterned second electrode structure 1-6, which is the source and drain metal.

[0126] The first insulating material layer 1-7 is formed by PECVD deposition. The first insulating material layer 1-7 can be a SiNx thin film, a SiOx thin film, or a composite film of both; or an organic insulating layer material such as spin-coated PMMA can be used; and the via structure is obtained by exposure, development, and etching through a photomask.

[0127] A photodiode layer 1-8 is formed on the first insulating material layer 1-7. The photodiode layer 1-8 includes a lower electrode layer, a middle PIN junction, and an upper electrode layer ITO. The lower electrode layer can be a metal such as Al, Mo, or Cu. The PIN junction can be an amorphous silicon N-layer (amorphous silicon doped with PH3), an I-layer (intrinsic amorphous silicon), or a P-layer (amorphous silicon doped with B2H6). The upper layer is a transparent ITO electrode. Each layer is processed through exposure, development, and etching to obtain a pixel structure, with a pixel size of 100μm × 100μm. The photodiode layers 1-8 constitute a PD array.

[0128] A metal light-shielding structure 1-9 is formed on the photodiode layer 1-8. The metal light-shielding structure 1-9 can be a single-layer or composite thin film of metal alloys such as molybdenum, aluminum, and copper prepared by magnetron sputtering. First, a light-shielding metal thin film is formed, then the light-shielding thin film is patterned, and then exposed, developed, and etched using a photomask to obtain the patterned metal light-shielding structure 1-9. The light-shielding metal of the metal light-shielding structure 1-9 can also simultaneously provide a bias signal to the photodiode.

[0129] A second insulating material layer 1-10 is deposited on the metal light-shielding structure 1-9 using PECVD. The second insulating material layer 1-10 can be a SiNx thin film, a SiOx thin film, or a composite film of both, or an organic insulating layer material such as spin-coated PMMA. Exposure, development, and etching are performed using a photomask to obtain the via structure.

[0130] After the preparation is completed according to the above process, the final step is to cut and peel to obtain the preset size.

[0131] This invention's photoelectric detection unit boasts high flexibility and customizability. Its area can be adjusted to meet specific needs, ranging from a minimum of 1 square centimeter to a maximum of 10 square centimeters, allowing for compatible designs to satisfy the specific requirements of various application scenarios. Structurally, the detection unit employs advanced pixel photodiode (PD) array technology, where each single pixel is precisely designed to be 100 micrometers × 100 micrometers in size. Furthermore, the detection unit's response spectrum covers the band from 400 nanometers to 700 nanometers, a range that closely matches the visual perception range of the human eye, making it highly suitable for various visible light detection tasks.

[0132] Reference Figure 7 The present invention also provides an optical tactile sensing system, comprising:

[0133] According to the aforementioned sensor;

[0134] An analog-to-digital converter, used to convert the analog signals acquired by the sensor into digital signals; and

[0135] A microcontroller is used to process the digital signals. In the description of this invention, a "microprocessor" can include hardware, software, or a combination of both. A microprocessor has data and / or signal processing capabilities. A microprocessor can be implemented in software, in hardware, or a combination of both.

[0136] In one embodiment, the detection unit is integrated with a high-performance 12-bit analog-to-digital converter (A / D converter) with a sampling rate of up to 1 kHz. This design enables the detection unit to maintain high-precision data acquisition and processing capabilities even under rapidly changing lighting conditions, thus providing a reliable foundation for subsequent analysis and applications.

[0137] In one embodiment, the microcontroller further includes an artificial intelligence model that identifies the target when it approaches or comes into contact with it.

[0138] In one embodiment, the artificial intelligence model is a support vector machine model.

[0139] Support Vector Machine (SV) models utilize the SV algorithm to recognize different objects. Before recognition, tactile signals from various objects must be collected. These signals include various aspects, such as pressure signals, reflecting the magnitude of force applied during contact; texture signals, showcasing the surface characteristics; roughness signals, describing the smoothness or roughness of the surface; and hardness signals, among others. Only by collecting as many of these signals as possible can a comprehensive data foundation be provided for subsequent recognition. Then, this collected signal data is used for large-scale training. Since large-scale training demands significant computing power and storage, ordinary equipment is insufficient; therefore, personal computers (PCs) or servers are used. After training, the resulting SV model is deployed to a microcontroller unit (MCU) to run, enabling it to recognize different objects in real-world applications.

[0140] In one embodiment, a grounding circuit is also included, wherein when the capacitive touch unit senses the approach of a target, the microcontroller connects the grounding circuit to release static electricity.

[0141] Reference Figure 8 The present invention also provides a detection method using the above system, comprising:

[0142] S1, the capacitive touch unit senses the approach or contact of a target. The upper plate of the capacitive touch unit, also known as the metal mesh layer, possesses an induced electric field capable of detecting the approach of a target object. When the target object actually contacts the metal mesh layer, the distance between the upper plate (metal mesh layer) and the lower plate (first metal reflective layer) changes. This change in distance directly leads to a corresponding change in the capacitance between the two plates. Subsequently, the capacitive touch unit transmits the collected signal to the microcontroller. The microcontroller then uses the changes in the received signal to accurately determine whether the target object is merely approaching or has already made contact.

[0143] S2, when the capacitive touch unit senses target contact, the light source unit emits light towards the elastic optical path modulation unit. Simultaneously, when the capacitive touch unit senses the target approaching, the microcontroller connects the grounding circuit to release static electricity.

[0144] S3, the elastic optical path modulation unit deforms, causing the transmitted light to change before and after contact.

[0145] S4, the photoelectric detection unit collects the transmitted light.

[0146] S5, the analog-to-digital converter converts the analog signal acquired by the sensor into a digital signal; and

[0147] The microcontroller processes the digital signal to obtain the detection result.

[0148] The advantages and application value of this invention will be explained below in conjunction with an analysis of existing technologies.

[0149] With the development of human-computer interaction technology, tactile sensors need to meet the requirements of flexibility, multimodal sensing, and strong anti-interference capabilities. Traditional piezoresistive / capacitive sensors have the following bottlenecks:

[0150] Poor electromagnetic compatibility: In high electromagnetic environments such as medical MRI equipment and industrial motors, electrode signals are easily interfered with, leading to detection distortion.

[0151] Limited functionality: It can only perform contact pressure detection and lacks non-contact proximity warning capabilities.

[0152] Limited adaptability to curved surfaces: The combination of rigid electrodes and flexible substrates is prone to interface failure, making it difficult to fit complex curved surfaces. Although optical tactile sensors have the advantage of electrical isolation, their optical path stability is significantly affected by ambient light, and existing solutions do not address the long-term performance impact of electrostatic accumulation on elastic media. This invention innovatively integrates optical tactile detection and capacitive proximity sensing by reusing the function of a metal mesh shielding layer, while simultaneously improving electromagnetic protection capabilities and multimodal detection dimensions, providing an efficient sensing solution for intelligent equipment in complex scenarios.

[0153] Traditional optical tactile sensors use light-transmitting holes to reflect light for proximity detection. This design results in poor overall structural encapsulation, and the bottom photoelectric sensing device is easily interfered with by external light sources. Complex algorithms are required to separate interference signals.

[0154] The sensor provided by this invention is a flexible composite sensor that combines high-precision tactile sensing with anti-interference proximity sensing. This structural design can effectively solve the signal interference problem faced by traditional tactile sensors in complex optoelectronic environments, as well as the limitation of single-mode detection, providing a better solution for the application of sensors in complex environments.

[0155] Specifically, the advantages of this invention are mainly reflected in the following aspects:

[0156] 1. Functional reuse design: The capacitive touch unit not only has photoelectric and electromagnetic protection functions, but also realizes capacitive sensing functions. This design cleverly integrates multiple functions into one, successfully breaking through the limitation of traditional sensors that can only perform single-mode detection, and greatly expanding the application scenarios and functional range of the sensor.

[0157] 2. Regarding improved anti-interference performance: the electrostatic protection level has been significantly improved, with an increase of 100%. Furthermore, the electromagnetic shielding effectiveness is also excellent, reaching over 45dB. This performance allows the sensor to adapt well to strong electromagnetic environments, operating stably even under complex electromagnetic conditions, unaffected by external electromagnetic interference.

[0158] 3. Multi-dimensional sensing capabilities: This sensor can simultaneously perform contact-based tactile sensing (including pressure and shear force) and non-contact proximity sensing. Its detection range is also quite wide, covering a distance range of 0-5cm and a pressure range of 0-50N / cm², thus meeting various different detection needs.

[0159] 4. High resolution: The sensor's spatial resolution can reach below 0.5mm. Such high resolution allows it to identify the texture of objects with greater accuracy. By combining it with appropriate algorithms, it can further improve the dexterity of the hand, making the hand more precise and flexible when manipulating objects.

[0160] 5. Low power consumption: The light source system uses an OLED system, which is inherently low power, which helps reduce the overall energy consumption of the sensor, extend the service life of the device, and is more energy-efficient and environmentally friendly.

[0161] 6. High stability: The cold light source system is matched with proximity sensing to activate the light source system. This design effectively avoids overheating caused by prolonged exposure, as heat could cause the flexible optical adjustment system to malfunction, leading to decreased sensitivity.

[0162] In summary, the hardware system of the sensor of this invention consists of a photoelectric detection unit, an elastic optical path modulation unit, a light source unit, and a capacitive touch unit. The innovatively designed capacitive touch unit has dual functions: first, it isolates electromagnetic interference through a nano-silver wire mesh structure, ensuring the stability of the optical signal and achieving an electrostatic protection level of ±8kV; second, it forms a surface capacitance with the underlying electrode, enabling non-contact proximity detection within 0-5cm. The elastic optical path modulation unit uses a PDMS-based micron-sized hollow column array, achieving decoupled detection of normal pressure (sensitivity 0.1mN / mm²) and tangential stress (resolution 5%FS) through total internal reflection angle shift when under pressure. The overall thickness of the sensor of this invention is ≤1.2mm, allowing it to conform to curved surfaces with a radius of curvature ≥5mm. It is suitable for applications such as intelligent robots, wearable devices, and medical instruments, overcoming the limitations of traditional tactile sensors in signal interference and single-modal detection under complex electromagnetic environments.

[0163] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effects of the present invention, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of the present invention.

[0164] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A sensor, characterized in that, include: The photoelectric detection unit, the flexible optical path modulation unit, the light source unit, and the capacitive touch unit are stacked sequentially; among them... The capacitive touch unit is used to sense when a target approaches or comes into contact with it; The light source unit is used to emit light toward the elastic optical path modulation unit when the target touches the capacitive touch unit; The elastic optical path modulation unit is used to generate deformation when the target contacts the capacitive touch unit, thereby causing the transmitted light to change before and after contact. The photoelectric detection unit is used to collect the transmitted light.

2. The sensor according to claim 1, characterized in that, The capacitive touch unit includes a metal mesh layer, a first metal reflective layer, and an insulating layer located between the two, wherein the first metal reflective layer is disposed closer to the light source unit than the metal mesh layer.

3. The sensor according to claim 2, characterized in that, The capacitive touch unit also includes an encapsulation layer disposed on the surface of the metal mesh layer away from the light source unit.

4. The sensor according to claim 2 or 3, characterized in that, The light source unit includes: The light source and the second metal reflective layer, wherein The light source is located between the first metal reflective layer and the second metal reflective layer; The second metal reflective layer is closer to the elastic optical path modulation unit than the light source, and the second metal emitting layer is provided with a plurality of light-transmitting holes spaced apart, so that the light can enter the elastic optical path modulation unit.

5. The sensor according to claim 1, characterized in that: The elastic optical path modulation unit includes: an elastic optical waveguide layer; wherein The elastic optical waveguide layer includes several flexible optical waveguide structures, which are columnar structures arranged vertically between the light source unit and the photoelectric detection unit, with gaps between adjacent flexible optical waveguide structures.

6. The sensor according to claim 5, characterized in that: The inner wall of the flexible optical waveguide structure is provided with a dielectric film.

7. The sensor according to claim 6, characterized in that: The flexible optical path modulation unit further includes: A lens layer is located between the elastic optical waveguide layer and the photoelectric detection unit; The lens layer is used to focus the light transmitted through the flexible optical waveguide structure.

8. The sensor according to claim 7, characterized in that: The lens layer is an elastic hemispherical or aspherical lens structure.

9. The sensor according to claim 6, characterized in that: The elastic optical path modulation unit further includes a transparent elastic film for encapsulation, located between the elastic optical waveguide layer and the light source unit.

10. An optical tactile sensing system, characterized in that, include: The sensor according to any one of claims 1-9; An analog-to-digital converter is used to convert the analog signals collected by the sensor into digital signals; and A microcontroller is used to process the digital signals.

11. The system according to claim 10, characterized in that, The microcontroller also includes an artificial intelligence model that identifies the target when it approaches or comes into contact with it.

12. The system according to claim 11, characterized in that, The artificial intelligence model is a support vector machine model.

13. The system according to any one of claims 10-12, characterized in that, It also includes a grounding circuit, wherein when the capacitive touch unit senses the approach of a target, the microcontroller connects the grounding circuit to release static electricity.

14. A detection method, employing the system described in any one of claims 10-13, characterized in that, include: The capacitive touch unit senses when the target approaches or comes into contact with it; When the capacitive touch unit senses a target contact, the light source unit emits light toward the elastic optical path modulation unit; The elastic optical path modulation unit deforms, causing the transmitted light to change before and after contact. The photoelectric detection unit collects the transmitted light; The analog-to-digital converter converts the analog signals acquired by the sensor into digital signals; and The microcontroller processes the digital signal to obtain the detection result.

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