Flexible pressure-sensitive optical fiber element based on spring-shaped structure, preparation method of flexible pressure-sensitive optical fiber element and sensing system

Abstract

The invention provides a flexible pressure sensitive element based on a spring-shaped polymer optical fiber, a preparation method of the flexible pressure sensitive element and a sensing system. In order to further improve the detection sensitivity of the polymer optical fiber sensor and the compactness of the device, the flexible pressure-sensitive optical fiber element provided by the invention comprises an elastic material substrate and a polymer optical fiber which are wound into a spring-shaped structure and shaped in a heating manner. The element is combined with an optical fiber sensing technology to realize high-sensitivity tactile sensing. When the structure is subjected to external pressure, the bending radius of the structure changes, and then the intensity of optical signals transmitted through the optical fiber is affected. The sensor provided by the invention has the characteristics of simple and convenient preparation process, low cost, high sensitivity, compact structure and adjustability, and establishes a corresponding relation between light intensity and pressure by measuring the change of light signal intensity of the optical fiber element under the action of the pressure, thereby realizing high-precision detection of the pressure.

Description

Technical Field

[0001] The present invention relates to a tactile pressure sensing detection device in the field of flexible optical fiber sensors, in particular to a flexible pressure sensitive optical fiber element based on a spring-like structure, a preparation method thereof and a sensing system Background Art

[0002] With the rapid development of application fields such as intelligent robots, wearable devices, medical health and virtual reality, the market demand for high-performance flexible tactile sensors continues to rise. Traditional tactile sensors are mostly based on electrical principles and have problems such as sensitivity to electromagnetic interference, cumbersome wiring and signal crosstalk. Fiber optic sensors have gradually become the focus of research due to their excellent electromagnetic interference resistance, compact size, light weight, high sensitivity and adaptability to extreme environments.

[0003] Optical fiber sensors are a technology that converts the measured physical quantity into parameters such as intensity, phase, wavelength, etc. of optical signals for detection. They usually use silica optical fiber (quartz optical fiber) or polymer optical fiber (plastic optical fiber) as the medium. In the field of communications, quartz optical fiber sensors are favored for their excellent optical properties and mechanical strength; but when used as flexible sensors, quartz optical fibers have shortcomings, especially in the application fields of flexible tactile sensors, smart fabric sensors, wearable sensors, etc., where their brittle and easy-to-break mechanical properties limit their application. In contrast, polymer optical fibers have shown greater potential and advantages in these fields with their excellent flexibility and high sensitivity. In addition, since optical fiber sensors work based on optical signals, they are not affected by electromagnetic interference and do not cause electrical safety hazards such as leakage or short circuits, so they have obvious advantages in occasions with high safety requirements. Especially in the fields of pressure sensing and tactile sensing, polymer optical fiber sensors have great applicability. Their good flexibility can achieve a smaller bending radius, a higher sensor density, and a higher sensing sensitivity. Therefore, polymer optical fiber tactile sensors have received more and more attention in recent years. Although polymer optical fiber sensors have shown certain potential in tactile sensor scenarios, their manufacturing technology still needs to be further optimized and improved in terms of process simplicity, detection sensitivity, and compactness of the device. Summary of the invention

[0004] In order to solve the problems in the background technology, the purpose of the present invention is to provide a flexible pressure-sensitive optical fiber element based on a spring-like structure, a preparation method thereof, and a sensing system. The element uses the optical loss caused by bending to detect contact force or pressure, which can improve the sensing ability and accuracy of the sensor.

[0005] The present invention proposes a flexible pressure-sensitive optical fiber element based on a spring-like structure, comprising an elastic material substrate 1 and a polymer optical fiber 2; The elastic material substrate 1 is a cubic element made of elastic material, which provides support and protection for the spring-shaped polymer optical fiber 2; The main body of the polymer optical fiber 2 is in the shape of a spring wound around a cylindrical object and is covered by an elastic material substrate 1 inside. Two ends of the polymer optical fiber 2 are reserved outside the elastic material substrate 1 and are used to connect to a light source and a detection instrument respectively.

[0006] Preferably, the elastic material is selected from polydimethylsiloxane (PDMS), thermoplastic polyurethane elastomer (TPU), styrene-ethylene-butylene-styrene (SEBS) and the like.

[0007] Preferably, the core layer material of the polymer optical fiber is selected from cycloolefin polymer (COP), polymethyl methacrylate (PMMA), polystyrene (PS) and the like.

[0008] Based on the above-mentioned flexible pressure-sensitive optical fiber element with a spring-like structure, the present invention further proposes a flexible optical fiber pressure sensing system, comprising the above-mentioned flexible pressure-sensitive optical fiber element with a spring-like structure 3, a halogen lamp light source 4 and a spectrometer 5; The halogen lamp light source 4 is connected to one end of the flexible pressure-sensitive optical fiber component 3 with a spring-like structure, and the spectrometer 5 is connected to the other end of the flexible pressure-sensitive optical fiber component 3 with a spring-like structure.

[0009] Preferably, one end of the flexible pressure-sensitive optical fiber element 3 with a spring-like structure is connected to the halogen lamp light source 4 via a bare fiber adapter 6 ; the other end of the flexible pressure-sensitive optical fiber element 3 with a spring-like structure is connected to the spectrometer 5 via a bare fiber adapter 6 .

[0010] Preferably, the pressure probe 7 is located above the flexible pressure-sensitive optical fiber element 3 of the spring-like structure, and can apply pressure to the flexible pressure-sensitive optical fiber element 3 of the spring-like structure.

[0011] The method for preparing the flexible pressure-sensitive optical fiber element with a spring-like structure in the present invention is as follows: 1) Preparation of spring-shaped polymer optical fiber: First, the polymer optical fiber 2 is wound several times around a cylindrical object 8 of a specified diameter to form a spring-shaped optical fiber coil; then, the spring-shaped optical fiber coil is placed on a heating table 9 to eliminate internal tension and maintain the coil structure, thereby obtaining a spring-shaped polymer optical fiber 2; 2) Encapsulated spring-shaped polymer optical fiber: The spring-shaped polymer optical fiber 2 is placed in the cubic cavity in the middle of the packaging mold 10, and the two ends of the polymer optical fiber 2 extend out from the grooves connected to the cavity; An elastic material precursor solution is poured into the cavity of the packaging mold 10; then, it is placed on a heating platform 9 to solidify the elastic material precursor solution to form a flexible pressure-sensitive optical fiber element 3 with a spring-like structure.

[0012] Based on the above-mentioned flexible optical fiber pressure sensing system, the present invention further proposes a tactile sensor array, wherein the tactile sensor array includes an element array composed of a plurality of flexible pressure-sensitive optical fiber elements 3 with spring-like structures, each element being respectively connected to a halogen lamp light source 4 and a spectrometer 5, the halogen lamp light source 4 being used to emit detection light of different wavelengths to each flexible pressure-sensitive optical fiber element 3 with a spring-like structure, and the spectrometer 5 being used to detect the detection light intensity of the wavelength corresponding to each flexible pressure-sensitive optical fiber element 3 with a spring-like structure.

[0013] The tactile sensor array is used to be integrated on the fingertips of the robot claw to measure the corresponding fingertip pressure to improve its grasping skills.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1) In the present invention, the elastic element is designed with an elastic material, and the polymer optical fiber 2 is coiled in the elastic material. This innovation in structural design enables the element to exhibit excellent mechanical properties. This design not only achieves high sensitivity and wide dynamic range for fingertip mechanical measurement, but also suggests its potential in three-dimensional force measurement, thus heralding its broad prospects in the field of application.

[0015] 2) The sensor system of the present invention has been carefully optimized in terms of mass and volume, ensuring that each functional component is small and light. In particular, the optical fiber, a core component, has excellent flexibility, which enables the sensor to be easily integrated into flexible wearable devices, achieving a compact integrated layout.

[0016] 3) The tactile sensor adopts a spring-like structure, which simplifies the manufacturing process and reduces costs. By using the same type of polymer optical fiber material and mold technology, large-scale standardized production of spring coils is achieved, thereby ensuring the repeatability and performance stability of the sensor.

[0017] 4) Considering the excellent flexibility of polymer optical fiber, the winding process becomes simple and easy to operate. At the same time, the mechanical strength of the optical fiber is maintained during the operation, reducing the risk of breakage or damage, and significantly improving the production efficiency and success rate of the sensor.

[0018] 5) The present invention adopts flexible fiber optical sensing technology, which brings advantages such as high stability, strong anti-electromagnetic interference ability, chemical corrosion resistance and good biocompatibility to flexible mechanical sensors. These characteristics not only expand its application range, but also indicate its huge development potential in multiple fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flexible pressure-sensitive optical fiber element with a spring-like structure; Figure 2 It is the main functional component of the flexible optical fiber pressure sensing system; Figure 3 It is a schematic diagram of shaping a spring-shaped polymer optical fiber; Figure 4 is a schematic diagram of packaging of a spring-shaped flexible pressure-sensitive optical fiber element; Figure 5 This is the working principle diagram of the flexible optical fiber pressure sensing system; Figure 6 is a tactile sensor array; Figure 7 It is an adaptive robot claw equipped with a sensor array; Figure 8 This is a schematic diagram of an adaptive robot gripper grabbing an iron box.

[0020] Among them, 1-elastic material substrate, 2-polymer optical fiber, 3-flexible pressure-sensitive optical fiber element with spring-like structure, 4-halogen lamp light source, 5-spectrometer, 6-bare fiber adapter, 7-pressure probe, 8-steel needle, 9-heating table, 10-packaging mold, 11-tactile sensor array, 12-adaptive machine claw, 13-iron box. DETAILED DESCRIPTION

[0021] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0022] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] Example 1. Flexible pressure-sensitive optical fiber element with a spring-like structure The preparation method of the flexible pressure-sensitive optical fiber element with a spring-like structure in this embodiment is as follows: 1) First, if Figure 3 As shown, the polymer optical fiber 2 is coiled around a cylindrical object 8 (such as a steel needle) of a specific diameter, and then placed on a heating table 9 and heated for a period of time to eliminate the internal tension and to be able to maintain the coil structure before being taken out.

[0024] 2) If Figure 4As shown, the polymer optical fiber 2 is placed in the cubic cavity in the middle of the packaging mold 10, and the two ends of the polymer optical fiber 2 extend from the grooves connected to the cavity; then a certain amount of elastic material precursor solution is poured. Then it is placed on the heating table 9 and slowly baked at low temperature, waiting for the elastic material substrate 1 to solidify, and finally a flexible pressure-sensitive optical fiber element 3 with a spring-like structure is obtained.

[0025] The flexible pressure-sensitive optical fiber element based on the spring-like structure obtained in this embodiment is as follows: Figure 1 As shown, it includes an elastic material substrate 1 and a polymer optical fiber 2; The elastic material substrate 1 is a cubic element made of elastic material, which provides support and protection for the spring-shaped polymer optical fiber 2; The main body of the polymer optical fiber 2 is in the shape of a spring wound around a cylindrical object and is covered by an elastic material substrate 1 inside. Two ends of the polymer optical fiber 2 are reserved outside the elastic material substrate 1 and are used to connect to a light source and a detection instrument respectively.

[0026] Example 2 Flexible optical fiber pressure sensing system like Figure 2 As shown, the main functional components of the flexible optical fiber pressure sensing system in this embodiment include: a flexible pressure-sensitive optical fiber element 3 with a spring-like structure, a halogen lamp light source 4, a spectrometer 5, a bare fiber adapter 6 and a pressure probe 7.

[0027] Firstly, the two ends of the flexible pressure-sensitive optical fiber element 3 with a spring-like structure need to be connected to the halogen lamp light source 4 and the spectrometer 5 respectively through the bare fiber adapter 6 .

[0028] The halogen lamp light source 4 can emit continuous and stable light to generate an optical signal.

[0029] The spectrometer 5 can identify the light signal transmitted from the output optical fiber and accurately measure the light intensity at a specific wavelength according to different light intensities.

[0030] The pressure probe 7 is located above the flexible pressure-sensitive optical fiber element 3 of the spring-like structure, and can apply pressure to the flexible pressure-sensitive optical fiber element 3 of the spring-like structure.

[0031] The working principle diagram of the flexible optical fiber pressure sensing system is as follows: Figure 5 As shown, the polymer optical fiber 2 forms a specific three-dimensional structure in the elastic material substrate 1. The pressure probe 7 applies external pressure to the middle of the elastic material substrate 1, and the polymer optical fiber 2 undergoes a slight deformation, resulting in bending deformation, which causes the signal light to escape from the polymer optical fiber due to bending loss, thereby reducing the optical signal received by the spectrometer 5. Therefore, pressure sensing can be achieved by measuring the loss of signal light caused by pressure.

[0032] Example 3: Flexible optical fiber fingertip pressure sensor for mechanical claws The four spring-like flexible pressure-sensitive optical fiber elements 3 are pressed as follows. Figure 6 In the manner shown, a tactile sensor array 11 is made, which is composed of four flexible pressure-sensitive optical fiber elements 3 with spring-like structures. It is integrated into a fingertip of a two-finger adaptive robot gripper 12 to assist in grasping objects. Figure 7 An adaptive robotic gripper 12 is shown with an array of tactile sensors 11 mounted on individual fingertips.

[0033] like Figure 8 As shown, the adaptive robot gripper 12 equipped with the integrated sensor array 11 is controlled to grasp an iron box 13, the gripper gradually closes, fixes the iron box 13 for a period of time, and then opens and releases. The real-time optical intensity output of the four sensor units is obtained through a linear CCD array. The intensity fluctuation of the peak value of each tactile sensing unit is recorded during the process of grasping and releasing the iron box 13. All four tactile sensors record the contact force when the adaptive robot gripper 12 grasps the iron box 13. After the above signals are received and integrated by the CCD, through subsequent data processing, the corresponding fingertip pressure physical quantity to be measured can be fully reflected. Thus, a complete fingertip force measurement is completed.

[0034] In addition, it should be noted that: The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0035] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0036] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A flexible pressure-sensitive optical fiber element based on a spring-like structure, characterized in that: The element comprises an elastic material substrate (1) and a polymer optical fiber (2); The elastic material substrate (1) is a cubic element made of elastic material, which provides support and protection for the spring-shaped polymer optical fiber (2); The main body of the polymer optical fiber (2) is in the shape of a spring formed by winding around a cylindrical object, and is coated inside by an elastic material base (1), and its two ends are reserved outside the elastic material base (1) and are respectively used to connect to a light source and a detection instrument.

2. The flexible pressure-sensitive optical fiber element based on a spring-like structure according to claim 1, characterized in that: The elastic material is selected from one or more combinations of polydimethylsiloxane, thermoplastic polyurethane elastomer, and styrene-ethylene-butylene-styrene.

3. The flexible pressure-sensitive optical fiber element based on a spring-like structure according to claim 1, characterized in that: The core material of the polymer optical fiber (2) is selected from one of cycloolefin polymer, polymethyl methacrylate and polystyrene.

4. A pressure sensing system based on a flexible pressure sensitive optical fiber element with a spring-like structure according to claim 1, characterized in that: The system comprises the flexible pressure-sensitive optical fiber element (3) of the spring-like structure, a halogen lamp light source (4) and a spectrometer (5); The halogen lamp light source (4) is connected to one end of the flexible pressure-sensitive optical fiber element (3) with a spring-like structure, and the spectrometer (5) is connected to the other end of the flexible pressure-sensitive optical fiber element (3) with a spring-like structure.

5. The pressure sensing system according to claim 4, characterized in that: One end of the flexible pressure-sensitive optical fiber element (3) with a spring-like structure is connected to a halogen lamp light source (4) via a bare fiber adapter (6); and the other end of the flexible pressure-sensitive optical fiber element (3) with a spring-like structure is connected to a spectrometer (5) via a bare fiber adapter (6).

6. The pressure sensing system according to claim 4, characterized in that: The pressure probe (7) is located above the flexible pressure-sensitive optical fiber element (3) with a spring-like structure, and can apply pressure to the flexible pressure-sensitive optical fiber element (3) with a spring-like structure.

7. The method for preparing a flexible pressure-sensitive optical fiber element based on a spring-like structure according to claim 1, characterized in that: The steps of this method are: 1) Preparation of spring-shaped polymer optical fiber: First, a polymer optical fiber (2) is wound several times around a cylindrical object (8) of a specified diameter to form a spring-shaped optical fiber coil; then, the spring-shaped optical fiber coil is placed on a heating table (9) to eliminate internal tension and maintain the coil structure, thereby obtaining a spring-shaped polymer optical fiber (2); 2) Encapsulated spring-shaped polymer optical fiber: Placing the spring-shaped polymer optical fiber (2) in a cubic cavity in the middle of a packaging mold (10), with two ends of the polymer optical fiber (2) extending from grooves connected to the cavity; An elastic material precursor solution is poured into the cavity of the packaging mold (10); then, the mold is placed on a heating platform (9) to solidify the elastic material precursor solution, thereby forming a flexible pressure-sensitive optical fiber element (3) with a spring-like structure.

8. A tactile sensor array based on the pressure sensing system according to claim 4, characterized in that: The tactile sensor array comprises an element array composed of a plurality of flexible pressure-sensitive optical fiber elements (3) with spring-like structures, each element being respectively connected to a halogen lamp light source (4) and a spectrometer (5), the halogen lamp light source (4) being used to emit detection light of different wavelengths to each flexible pressure-sensitive optical fiber element (3) with a spring-like structure, and the spectrometer (5) being used to detect the intensity of the detection light of the wavelength corresponding to each flexible pressure-sensitive optical fiber element (3) with a spring-like structure.

9. The tactile sensor array as described in claim 8 is used to be integrated on the fingertips of a robot gripper to measure the corresponding fingertip pressure.

Images