A flexible tactile sensor

Abstract

The application discloses a flexible tactile sensor, which comprises a conductive elastomer, a laser-induced graphene sensitive element, a flexible substrate, a wire and a flexible packaging layer, eight laser-induced graphene sensitive elements are arranged on the upper surface of the flexible substrate in an equal-interval annular distribution, the upper side of the end of the laser-induced graphene sensitive element close to each other is provided with the conductive elastomer, and the conductive elastomer is located at the center of the flexible substrate; the wire comprises one main wire and eight branch wires; the sensor is excellent in flexibility and biocompatibility, can be used for human physiological signal measurement, can be installed on the surface of the human body everywhere, can be used for writing recognition of human fingers, and has the advantages of sensitive reaction, high recognition accuracy and the like.

Description

Technical Field

[0001] This invention relates to the field of sensors, and more particularly to a flexible tactile sensor. Background Technology

[0002] To obtain information from the outside world, humans must rely on their sensory organs. Sensors were created to enhance perception during the study of natural phenomena and laws, as well as during production activities. With the advent of the information age, the primary challenge is acquiring accurate and reliable information, and sensors are the main means and pathway for obtaining information in the natural and production fields. Sensors have long since permeated an extremely wide range of fields, including industrial production, space exploration, ocean exploration, environmental protection, resource surveys, medical diagnosis, bioengineering, and even cultural relic preservation. It is no exaggeration to say that from the vastness of space to the immensity of the ocean, and to various complex engineering systems, almost every modern project relies on various types of sensors.

[0003] Tactile sensors are used in robots to mimic tactile functions.

[0004] Flexible tactile sensors are a cutting-edge interdisciplinary research field that integrates flexible electronics, device physics, and materials science. They have great application potential in areas such as human clinical diagnosis, health assessment, health monitoring, virtual electronics, flexible touch screens, flexible electronic skin, and even industrial robots.

[0005] Touch is an important sensory function when humans come into direct contact with the external environment. Developing tactile sensors that meet the requirements of robot development is an urgent problem to be solved. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a flexible tactile sensor. The sensor is designed based on the biomimetic body structure and sensing principle of an octopus. It can detect three-dimensional force and is used for handwriting recognition by human fingers. It has the advantages of high sensitivity and high recognition accuracy.

[0007] Technical solution

[0008] A flexible tactile sensor includes a conductive elastomer, a laser-induced graphene sensing element, a flexible substrate, wires, and a flexible encapsulation layer. Eight laser-induced graphene sensing elements are embedded in the upper surface of the flexible substrate in a ring with equal spacing. A conductive elastomer is disposed on the upper side of the laser-induced graphene sensing elements at their closest ends, and the conductive elastomer is located at the center of the flexible substrate. The wires include a main wire and eight branch wires. The main wire is electrically connected to the upper surface of the conductive elastomer, and the eight branch wires are respectively electrically connected to the ends of the laser-induced graphene sensing elements that are furthest from the conductive elastomer.

[0009] Furthermore, the conductive elastomer, the laser-induced graphene sensing element, and the flexible substrate are assembled in a sandwich structure from top to bottom. After the conductive elastomer and the laser-induced graphene sensing element are determined to overlap, they are encapsulated by the flexible encapsulation layer to ensure overall electrical connection. The overall thickness after encapsulation is 15mm to 20mm.

[0010] Furthermore, the conductive elastomer is prepared by: mixing 5% to 15% Ecoflex or PDMS-doped carbon nanotubes, filling them into a cylindrical mold with a diameter of 8 to 12 mm and a height of 4 to 7 mm, and baking them in an 80°C oven for 60 minutes to obtain the final product.

[0011] Furthermore, the laser-induced graphene sensing element is prepared by laser-induced graphene transfer, and the preparation method is as follows: eight laser-induced graphene strips with a length of 17-21 mm and a width of 0.5-1.2 mm are marked on a 300-micron thick polyimide film using an infrared laser with a scanning speed of 15-22, a frequency of 80-130 kHz, and a power of 15-21%. The strips are then cast with uncured Ecoflex or PDMS and placed in a circular container with a diameter of 45-55 mm and a height of 3-7 mm. The container is then baked in an oven at 80°C for 60 minutes to obtain the laser-induced graphene sensing element and the flexible substrate.

[0012] Furthermore, the shape of the flexible substrate is formed by stamping with a cutting tool.

[0013] Furthermore, the laser-induced graphene sensing elements are radially and uniformly distributed on the flexible substrate, the included angle between two adjacent laser-induced graphene sensing elements is 45°, and the edge of the laser-induced graphene sensing element is 2 mm away from the edge of the flexible substrate.

[0014] Furthermore, the eight branch lines are connected to the laser-induced graphene sensing element using conductive silver paste, and the main line is connected to the upper surface of the conductive elastomer using conductive silver paste.

[0015] Furthermore, the conductive elastomer, the laser-induced graphene sensing element, the overlap position of the wire and the laser-induced graphene sensing element are encapsulated with uncured Ecoflex, and a 2mm thick flexible encapsulation layer is formed.

[0016] Furthermore, during use, the main wire connected to the upper surface of the conductive elastomer is connected to the GND port of the microcontroller, and the other eight branch wires connected to the laser-induced graphene sensitive element are respectively connected to the eight I / O ports of the microcontroller. When the object is touched, the electrical signal received by the microcontroller changes, the microcontroller records the real-time resistance value and transmits it to the computer. The dynamic time warping algorithm is used in the MATLAB software of the computer to calculate the resistance value, and then the result is obtained by the neural network.

[0017] Beneficial effects

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. By incorporating biomimetic design and referencing the body structure and sensory principles of an octopus, it can detect three-dimensional forces to adapt to complex stress conditions;

[0020] 2. The sensor has excellent flexibility and biocompatibility, and can be used to measure human physiological signals. It can be installed on various parts of the human body.

[0021] 3. For handwriting recognition using human fingers, a sensor is wrapped around the fingertip. When the fingertip wearing the sensor writes on the desktop, it does not affect normal writing and the written content can be detected and displayed by a microcontroller. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a flexible tactile sensor according to the present invention;

[0023] Figure 2 This is an exploded view of the present invention;

[0024] Figure 3 The resistance variation diagram for the step positive voltage of this invention;

[0025] Figure 4 This is a finite element analysis simulation diagram of the present invention applying a three-dimensional force in the right direction;

[0026] Figure 5 This is a schematic diagram illustrating the installation and use of the present invention in handwriting recognition.

[0027] Figure Labels

[0028] 1. Conductive elastomer; 2. Laser-induced graphene sensing element; 3. Flexible substrate. Detailed Implementation

[0029] To better illustrate the content of this invention, the following description is provided in conjunction with the accompanying drawings and examples:

[0030] have Figures 1-5As shown, this invention discloses a flexible tactile sensor, comprising a conductive elastomer 1, a laser-induced graphene sensing element 2, a flexible substrate 3, wires, and a flexible encapsulation layer. Eight equally spaced, ring-shaped laser-induced graphene sensing elements 2 are embedded on the upper surface of the flexible substrate 3. A conductive elastomer 1 is disposed on the upper side of the relatively close ends of the laser-induced graphene sensing elements 2, with the conductive elastomer 1 located at the center of the flexible substrate 3. The wires include one main wire and eight branch wires. The main wire is electrically connected to the upper surface of the conductive elastomer 1, and the eight branch wires are respectively electrically connected to the ends of the laser-induced graphene sensing elements 2 furthest from the conductive elastomer 1. When deformed by an external force, the sensor measures the change in resistance of the conductive elastomer 1 to reflect the magnitude of the vertical component of the external force, and measures the change in resistance of the laser-induced graphene sensing element 2 to reflect the magnitude and direction of the axial component of the external force. The combination of these two measurements reflects the direction and magnitude of the external force in space.

[0031] Furthermore, the conductive elastomer 1, the laser-induced graphene sensing element 2, and the flexible substrate 3 are assembled in a sandwich structure from top to bottom. After the conductive elastomer 1 and the laser-induced graphene sensing element 2 are determined to overlap, they are encapsulated by the flexible encapsulation layer to ensure overall electrical connection. The overall thickness after encapsulation is 15mm to 20mm.

[0032] Furthermore, the conductive elastomer 1 is prepared by: mixing carbon nanotubes with a mass fraction of 5% to 15% doped with Ecoflex or PDMS, filling them into a cylindrical mold with a diameter of 8 to 12 mm and a height of 4 to 7 mm, and baking them in an oven at 80°C for 60 minutes to obtain the final product.

[0033] Furthermore, the laser-induced graphene sensing element 2 is prepared by laser-induced graphene transfer printing, and the preparation method is as follows: eight laser-induced graphene strips with a length of 17-21 mm and a width of 0.5-1.2 mm are marked on a 300-micron thick polyimide film using an infrared laser with a scanning speed of 15-22, a frequency of 80-130 kHz, and a power of 15-21%. The strips are then cast with uncured Ecoflex or PDMS and placed in a circular container with a diameter of 45-55 mm and a height of 3-7 mm. The container is then baked in an oven at 80°C for 60 minutes to obtain the laser-induced graphene sensing element 2 and the flexible substrate 3.

[0034] Furthermore, the shape of the flexible substrate 3 is formed by stamping with a cutting tool.

[0035] Furthermore, the laser-induced graphene sensing elements 2 are radially and uniformly distributed on the flexible substrate 3, the included angle between two adjacent laser-induced graphene sensing elements 2 is 45°, and the edge of the laser-induced graphene sensing element 2 is 2 mm away from the edge of the flexible substrate 3.

[0036] Furthermore, the eight branch lines are connected to the laser-induced graphene sensing element 2 using conductive silver paste, and the main line is connected to the upper surface of the conductive elastomer 1 using conductive silver paste.

[0037] Furthermore, the conductive elastomer 1, the laser-induced graphene sensing element 2, and the overlap position of the wire and the laser-induced graphene sensing element 2 are encapsulated with uncured Ecoflex, and a flexible encapsulation layer with a thickness of 2 mm is formed.

[0038] Furthermore, during use, the main wire connected to the upper surface of the conductive elastomer 1 is connected to the GND port of the microcontroller, and the other eight branch wires connected to the laser-induced graphene sensitive element 2 are respectively connected to the eight I / O ports of the microcontroller. When the object is touched, the electrical signal received by the microcontroller changes, the microcontroller records the real-time resistance value and transmits it to the computer, performs dynamic time warping algorithm calculation in the MATLAB software of the computer, and then submits it to the neural network for judgment to finally obtain the result.

[0039] Specifically, a sensor is wrapped around the tip of the index finger. Eight laser-induced graphene sensitive elements are partially wrapped around the surface of the index finger and fixed at the ends. In use, the main line is connected to the GND port of the microcontroller, and the other eight branch lines are connected to the eight I / O ports of the microcontroller. When writing on paper, the electrical signal received by the microcontroller changes, and the microcontroller records the real-time resistance value and transmits it to the computer. The dynamic time warping algorithm is used in the MATLAB software on the computer to calculate the value. Multiple tests and calculations are performed on different strokes to establish a database. The database is then used by a CNN neural network to make judgments and finally obtain the results. It has the advantages of high recognition accuracy and real-time monitoring, and provides another portable solution for three-dimensional force-sensitive handwriting recognition in wearable electronic devices.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the technical solutions of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A flexible tactile sensor, characterized by: The application relates to a laser-induced graphene sensitive element, which comprises an electrically-conductive elastic body (1), laser-induced graphene sensitive elements (2), a flexible substrate (3), wires and a flexible packaging layer, eight laser-induced graphene sensitive elements (2) are evenly arranged on the upper surface of the flexible substrate (3) in a ring shape, the upper side of the end of the laser-induced graphene sensitive elements (2) close to each other is provided with the electrically-conductive elastic body (1), the electrically-conductive elastic body (1) is located at the center of the flexible substrate (3), the wires comprise one main wire and eight branch wires, the main wire is electrically connected with the upper surface of the electrically-conductive elastic body (1), and the eight branch wires are respectively electrically connected with the ends of the laser-induced graphene sensitive elements (2) away from the electrically-conductive elastic body (1). The laser-induced graphene sensitive elements (2) are evenly distributed on the flexible substrate (3) in a radial manner, the included angle between two adjacent laser-induced graphene sensitive elements (2) is 45 degrees, and the edge of the laser-induced graphene sensitive element (2) is 2mm away from the edge of the flexible substrate (3).

2. The flexible tactile sensor of claim 1, wherein: The electrically-conductive elastic body (1), the laser-induced graphene sensitive element (2) and the flexible substrate (3) are assembled in a sandwich structure from top to bottom, the electrically-conductive elastic body (1) and the laser-induced graphene sensitive element (2) are overlapped and then packaged by the flexible packaging layer to ensure overall electrical connection, and the overall thickness after packaging is 15mm-20mm.

3. The flexible tactile sensor of claim 2, wherein: The electrically-conductive elastic body (1) is prepared by mixing Ecoflex or PDMS with 5%-15% of carbon nanotubes in mass fraction, stirring uniformly, filling into a cylindrical mold with a diameter of 8-12mm and a height of 4-7mm, and placing in an 80 DEG C oven for baking for 60 minutes.

4. The flexible tactile sensor of claim 3, wherein: The laser-induced graphene sensitive element (2) is prepared by laser-induced graphene transfer printing, and the preparation method is as follows: eight laser-induced graphene strips with a length of 17-21mm and a width of 0.5-1.2mm are marked on a polyimide film with a thickness of 300 microns by using an infrared laser with a scanning speed of 15-22, a frequency of 80-130KHZ and a power of 15-21%, the laser-induced graphene strips are poured with unsolidified Ecoflex or PDMS, and placed in a circular container with a diameter of 45-55mm and a height of 3-7mm, and then baked in an 80 DEG C oven for 60 minutes to obtain the laser-induced graphene sensitive element (2) and the flexible substrate (3).

5. The flexible tactile sensor of claim 4, wherein: The eight branch wires are connected with the laser-induced graphene sensitive elements (2) by using conductive silver paste, and the main wire is connected with the upper surface of the electrically-conductive elastic body (1) by using conductive silver paste.

6. The flexible tactile sensor of claim 5, wherein: The electrically-conductive elastic body (1), the laser-induced graphene sensitive element (2), the wires and the overlapping position of the laser-induced graphene sensitive element (2) are packaged by using unsolidified Ecoflex, and the flexible packaging layer is formed by coating the unsolidified Ecoflex with a thickness of 2mm.

7. The flexible tactile sensor of claim 6, wherein: In use, the main wire connected with the upper surface of the conductive elastomer (1) is connected to the GND port of the single-chip microcomputer, and the other eight branch wires connected with the laser-induced graphene sensitive elements (2) are respectively connected to the eight I / O ports of the single-chip microcomputer. When the object is touched, the electrical signal received by the single-chip microcomputer changes, the single-chip microcomputer records the real-time resistance value and transmits it to the computer, the dynamic time warping algorithm is calculated in the MATLAB software of the computer, and the neural network is used for discrimination, and finally the result is obtained.

8. The flexible tactile sensor of claim 7, wherein: The shape of the flexible substrate (3) is obtained by punch pressing of a tool.

9. The flexible tactile sensor of claim 8, wherein: In use, the wire is connected to the single-chip microcomputer, the conductive elastomer (1) is subjected to external force, the conductive elastomer (1) is compressed, and eight laser-induced graphene sensitive elements (2) are deformed respectively, eight electrical signals are obtained, and the comprehensive analysis of the eight electrical signals can detect the size, direction and duration of the external force.

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