A three-electrode sensor integrating positioning and pressure detection and its manufacturing method.

Abstract

This invention relates to the field of sensor technology, and particularly to a three-electrode sensor integrating positioning and pressure detection, and its manufacturing method. The sensor comprises a resistive positioning unit, gaskets, a piezoelectric unit, and an encapsulation layer connected sequentially. The resistive positioning unit detects the location of applied force. The upper parts of the two gaskets are connected to the edges of the resistive positioning unit, and the lower parts of the two gaskets are connected to the edges of the piezoelectric unit, forming a cavity structure between the resistive positioning unit and the piezoelectric unit. The piezoelectric unit detects the magnitude of the applied force. The sensor of this invention can simultaneously acquire pressure location and pressure magnitude, and features a simple structure, independent signal, and stable performance. It has great application potential in several cutting-edge fields such as flexible sensing, medical devices, and robotic grasping.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to a three-electrode sensor integrating positioning and pressure detection and its manufacturing method. Background Technology

[0002] With the development of smart electronic devices, wearable devices, robotics, and medical health monitoring, the demand for flexible and integrated sensors is increasing.

[0003] Existing sensors can effectively detect single physical quantities. Resistive, capacitive, and piezoelectric sensors can be used to detect pressure values; photoelectric and laser sensors, capacitive, resistive, and magnetic sensors can be used to detect position information; capacitive sensors are relatively sensitive to environmental and temperature changes; photoelectric positioning sensors require very precise structures and have high measurement accuracy; resistive sensors have simple structures and high sensitivity; piezoelectric sensors exhibit excellent performance in dynamic pressure detection; and magnetic sensors are often used for non-contact measurements.

[0004] Existing composite sensing technologies mostly combine position and pressure signals into a single channel for transmission. However, this approach has several drawbacks: the two signals are not completely independent, requiring complex algorithms for decoupling, resulting in high computational costs; and the coupling during multi-signal transmission degrades the overall sensor performance.

[0005] Therefore, existing composite sensors suffer from problems such as output signal coupling, high cost, complex structure, and low sensitivity. Summary of the Invention

[0006] In view of this, the present invention proposes a three-electrode sensor integrating positioning and pressure detection and its manufacturing method to solve the above problems, including:

[0007] A three-electrode sensor integrating positioning and pressure detection includes a resistive positioning unit, pads, a piezoelectric unit, and an encapsulation layer connected in sequence; wherein, the resistive positioning unit is used to detect the position of the force; the upper parts of the two pads are respectively connected to the edge of the resistive positioning unit, and the lower parts of the two pads are respectively connected to the edge of the piezoelectric unit, so that the resistive positioning unit and the piezoelectric unit form a cavity structure; the piezoelectric unit is used to detect the magnitude of the force.

[0008] A method for manufacturing a three-electrode sensor integrating positioning and pressure detection, for manufacturing the aforementioned sensor, includes the following steps:

[0009] S1. Clean the film and cut it to obtain the insulating layer and the encapsulation layer;

[0010] S2. Clean the surface stains of the insulation and encapsulation layers;

[0011] S3. Coat the lower surface of the insulating layer with a conductive mixed sensitive material to form a resistance sensitive layer, dry it, and attach an electrode to the resistance sensitive layer to obtain a resistance positioning unit.

[0012] S4. Prepare a piezoelectric material solution, polarize the piezoelectric material solution, pour it into a mold, dry and demold to obtain a piezoelectric layer;

[0013] S5. Attach a metal electrode to each of the two surfaces of the piezoelectric layer to obtain a piezoelectric unit.

[0014] S6. Assemble the components from top to bottom in the order of resistor positioning unit, gasket, piezoelectric unit, and encapsulation layer. During the assembly process, two gaskets are used to fix the resistor positioning unit and the piezoelectric unit so that the two units do not contact each other when not in operation, and the non-contacting parts form a cavity.

[0015] The beneficial effects of this invention include:

[0016] By adopting a simple three-electrode structure, the size and manufacturing process of the sensor are fundamentally simplified, overcoming the problems of complex structure and high manufacturing cost of traditional sensors, and greatly improving the miniaturization and practicality of the sensor. Through the multi-layer stacked structure design, the two modules can work independently or collaboratively without interference, simplifying the subsequent signal processing process and significantly improving the real-time response performance of the sensor. By using emerging highly conductive sensitive materials such as silver nanowires and carbon nanotubes as the main raw materials for the resistive sensitive layer of the sensor, the flexibility requirements of the sensor are guaranteed and the overall signal transmission efficiency is improved. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the sensor structure in Embodiment 1 of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the resistor positioning unit of the present invention;

[0019] Figure 3 This is a schematic diagram of the piezoelectric unit of the present invention;

[0020] Figure 4 This illustrates the relationship between the stimulation location and resistance value of the sensor in Embodiment 2 of the present invention.

[0021] Figure 5 This illustrates the relationship between the stimulation location and resistance value of the sensor in Embodiment 3 of the present invention.

[0022] Figure 6 This illustrates the relationship between the force on the piezoelectric layer of the sensor and its output voltage in Embodiment 2 of the present invention.

[0023] Figure 7 This illustrates the relationship between the force on the piezoelectric layer of the sensor and the output voltage in Embodiment 3 of the present invention.

[0024] The labels are as follows: 1 is the insulating layer, 2 is the resistance-sensitive layer, 3 is the first gasket, 4 is the middle electrode layer, 41 is the position of the lead wire from the middle electrode layer, 5 is the piezoelectric layer, 6 is the encapsulation layer, 7 is the lower electrode layer, 71 is the position of the lead wire from the lower electrode layer, 8 is the second gasket, 9 is the upper electrode, 91 is the position of the lead wire from the upper electrode, and 10 is the cavity. Detailed Implementation

[0025] To make the objectives, technical solutions, features, and advantages of the present invention clearer, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] Example 1 is a preferred embodiment of a three-electrode sensor integrating positioning and pressure detection according to the present invention, such as... Figure 1 As shown.

[0027] It includes a resistor positioning unit, gaskets, a piezoelectric unit, and an encapsulation layer connected in sequence; wherein, the resistor positioning unit is used to detect the position of the force; the upper parts of the two gaskets are respectively connected to the edge of the resistor positioning unit, and the lower parts of the two gaskets are respectively connected to the edge of the piezoelectric unit, so that the resistor positioning unit and the piezoelectric unit form a cavity structure; the piezoelectric unit is used to detect the magnitude of the force.

[0028] Furthermore, the resistive positioning unit consists of an insulating layer, a resistive sensitive layer, and an upper electrode; the resistive sensitive layer is disposed on the lower surface of the insulating layer, and the upper electrode is disposed on the lower surface of the resistive sensitive layer; the piezoelectric unit consists of a middle electrode layer, a piezoelectric layer, and a lower electrode layer connected in sequence; the upper electrode, middle electrode layer, and lower electrode layer are used to acquire the voltage signal of the sensor.

[0029] Example 2 is a preferred embodiment of a manufacturing method for a three-electrode sensor integrating positioning and pressure detection according to the present invention; it includes the following steps:

[0030] S1. Clean the film and cut it to obtain the insulating layer and the encapsulation layer.

[0031] Specifically, the film is made of PET film; PET film has extremely high electrical insulation properties, which can effectively isolate electrical signals, prevent current leakage or interference, and has a high cost-performance ratio.

[0032] Furthermore, the cut PET film is 64mm long, 9mm wide, and 0.2mm thick.

[0033] S2. Clean the surface stains of the insulation and encapsulation layers.

[0034] S3. Coat the lower surface of the insulating layer with a conductive mixed sensitive material to form a resistance sensitive layer, dry it, and attach electrodes to the resistance sensitive layer to obtain a resistance positioning unit.

[0035] Specifically, the resistive positioning unit consists of an insulating layer, a resistive sensitive layer, and an upper electrode. The resistive sensitive layer is disposed on the insulating layer, and the upper electrode is disposed on the resistive sensitive layer. The conductive hybrid sensitive material is composed of a conductive material and a thickener. The conductive material uses carbon nanotube dispersion (CNTs) and silver nanowires (AgNWs). The thickener is methyl cellulose (MC). The CNTs and AgNWs nanowire dispersion possess high strength and flexibility, and their conductivity is close to that of metals. If there is too little conductive material, it will be difficult to form pathways on the surface of the resistive sensitive layer and the distribution will be uneven, which will lead to a reduction in sensor sensitivity, linearity, and lifespan.

[0036] Further, 8 ml (13 wt%) of carbon nanotube dispersion, 3 ml (10 mg / ml) of silver nanowires, and 0.01 g of methylcellulose were mixed and stirred for 20 min. The resistance-sensitive layer used this material as a uniform insulating layer 1 as a base, with the above mixture uniformly coated upwards. This coating was applied once and dried in a 50°C drying oven. The upper electrode 9 used a copper foil with a thickness of 0.02 mm, a length of 1 mm, and a width of 9 mm. The effective length of the resistance-sensitive layer was 60 mm, the width was 5 mm, the thickness was 0.2 mm, and the total resistance was 198 Ω. The relationship between the output resistance and the pressing position is as follows: Figure 4 As shown.

[0037] S4. Prepare a piezoelectric material solution, polarize the piezoelectric material solution, pour it into a mold, dry and demold to obtain a piezoelectric layer.

[0038] Furthermore, the piezoelectric material solution is composed of a polymeric piezoelectric material and a solvent; in this embodiment, polyvinylidene fluoride (PVDF) is used as the piezoelectric material, and a mixed solution of acetone and N,N-dimethylformamide is selected as the solvent. PVDF has good flexibility and processing performance, and can be prepared into piezoelectric layers of varying thicknesses. The presence of fluorine atoms in its molecular chain structure contributes to its high chemical stability and fatigue resistance. When subjected to pressure or bending, electrical signals are generated on the electrode surfaces above and below the piezoelectric material, the magnitude of which is proportional to its deformation.

[0039] Specifically, 1.8g of polyvinylidene fluoride (PVDF) was added to 6ml of acetone and 9ml of a mixed solvent of N,N-dimethylformamide, along with 0.3g of PVP (K40). Using a thermal polarization method, the mixture was magnetically stirred at 70℃ for 15 minutes until it became a transparent gel. This gel was then poured into a mold and allowed to evaporate naturally to form the desired piezoelectric layer. The resulting piezoelectric layer was 60mm long, 5mm wide, and 1mm thick. The relationship between the piezoelectric layer's output voltage and the applied force is as follows: Figure 6 As shown.

[0040] S5. Attach a metal electrode to each of the two surfaces of the piezoelectric layer to obtain a piezoelectric unit.

[0041] Specifically, the piezoelectric unit is composed of a middle electrode layer 4, a piezoelectric layer 5, and a lower electrode layer 7 connected sequentially. The middle electrode layer 4 is connected to the resistance-sensitive layer through a cavity. Both the middle electrode layer 4 and the lower electrode layer 7 are made of copper foil with a thickness of 0.02 mm. The middle electrode layer 4 is laid flat on the upper surface of the piezoelectric layer 5, and the lower electrode layer 7 is pasted on the upper surface of the encapsulation layer 6. The middle electrode layer 4 and the lower electrode layer 7 are the same width as the piezoelectric layer 5, and their length is equal to the length L + 2 mm of the piezoelectric layer 5 to facilitate the connection of wires. The structure of the piezoelectric unit is as follows: Figure 3 As shown.

[0042] S6. Assemble the components from top to bottom in the order of resistor positioning unit, gasket, piezoelectric unit, and encapsulation layer. During the assembly process, two gaskets are used to fix the resistor positioning unit and the piezoelectric unit so that the two units do not contact each other when not in operation, and the non-contacting parts form a cavity.

[0043] Specifically, the gaskets are rectangular PTFE sheets; gasket 1 (3) is 2mm long, 9mm wide, and 2mm thick; gasket 2 (8) is 2mm long, 9mm wide, and 1.78mm thick. For example... Figure 2 As shown.

[0044] Furthermore, in this embodiment, the sensor is 64mm long, 9mm wide, and 3.44mm thick. The insulating layer 1 of the sensor deforms under stress, causing the resistance-sensitive layer 2 to contact the middle electrode layer 4. A pathway is formed between the upper electrode 9, the resistance-sensitive layer 2, and the middle electrode layer 4, allowing the detection of the resistance value of the resistance-sensitive layer 2 and thus determining the location of the force point. The upper electrode 9 and the middle electrode layer 4 collect resistance signals, while the middle electrode layer 4 and the lower electrode layer 7 collect voltage signals. The middle electrode layer 4 serves as the common working electrode for both the resistance positioning unit and the piezoelectric unit. The upper electrode 9 and the lower electrode layer 7 are independently connected to the two units, thereby enabling the separate detection of the spatial location and pressure information of external stimuli.

[0045] Furthermore, conductive silver paste is used to connect wires to the upper electrode 9, the middle electrode layer 4, and the lower electrode layer 7, respectively. The wires of the upper electrode 9 and the middle electrode layer 4 are led out from points 91 and 41, respectively, and the wires of the lower electrode layer 7 are led out from point 71.

[0046] Example 3 is another preferred embodiment of a method for manufacturing a three-electrode sensor that integrates positioning and pressure detection.

[0047] The difference between Example 3 and Example 2 is as follows:

[0048] With varying proportions of conductive mixed sensitive materials, mixing 8 ml (13 wt%) of carbon nanotube dispersion, 1 ml (10 mg / ml) of silver nanowires, and 0.01 g of methylcellulose, and stirring for 20 min, resulted in a total resistance of 245 Ω for the resistive layer. The relationship between output resistance and pressing position is as follows: Figure 5 As shown.

[0049] Polyvinylidene fluoride (PVDF) was selected as the polymeric piezoelectric material, and a mixed solution of acetone and N,N-dimethylformamide was used as the solvent. Specifically, 1.7g of PVDF was added to 6ml of acetone and 9ml of the mixed solvent of PVDF and N,N-dimethylformamide, along with 0.8g of PVP (K40). The mixture was magnetically stirred at 70℃ for 20 minutes until it became a transparent gel. This gel was then poured into a mold and allowed to evaporate naturally to form the piezoelectric layer, which was 60mm long, 5mm wide, and 1mm thick. The relationship between the piezoelectric layer's output voltage and the applied force is as follows: Figure 7 As shown.

[0050] Finally, it should be noted that the above description only depicts some embodiments of the present invention. For those skilled in the art, various changes, modifications, substitutions, and variations can be conceived of these embodiments without departing from the principles and spirit of the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents, and all the above-mentioned behaviors should be covered within the scope of protection of the present invention.

Claims

1. A three-electrode sensor integrating positioning and pressure detection, characterized in that, It includes a resistor positioning unit, gaskets, a piezoelectric unit, and an encapsulation layer connected in sequence; wherein, the resistor positioning unit is used to detect the position of the force; the upper parts of the two gaskets are respectively connected to the edge of the resistor positioning unit, and the lower parts of the two gaskets are respectively connected to the edge of the piezoelectric unit, so that the resistor positioning unit and the piezoelectric unit form a cavity structure; the piezoelectric unit is used to detect the magnitude of the force. The resistive positioning unit consists of an insulating layer, a resistive sensitive layer, and an upper electrode. The resistive sensitive layer is located on the lower surface of the insulating layer, and the upper electrode is located on the lower surface of the resistive sensitive layer. The piezoelectric unit consists of a middle electrode layer, a piezoelectric layer, and a lower electrode layer connected in sequence. When the insulating layer of the sensor is subjected to force, it deforms, causing the resistive sensitive layer to come into contact with the middle electrode layer. A path is formed between the upper electrode, the resistive sensitive layer, and the middle electrode layer, allowing the resistance value of the resistive sensitive layer to be detected, thereby determining the location information of the force point. The upper electrode and the middle electrode layer collect resistance signals, while the middle electrode layer and the lower electrode layer collect voltage signals. The middle electrode layer is the common working electrode for both the resistive positioning unit and the piezoelectric unit. The upper electrode layer and the lower electrode layer are independently connected to the two units, thereby enabling the separate detection of the spatial location and pressure information of external stimuli.

2. A method for manufacturing a three-electrode sensor integrating positioning and pressure detection, the method being used to manufacture the three-electrode sensor integrating positioning and pressure detection state recognition as described in claim 1, characterized in that, Including the following steps: S1. Clean the film and cut it to obtain the insulating layer and the encapsulation layer; S2. Clean the surface stains of the insulation and encapsulation layers; S3. Coat the lower surface of the insulating layer with a conductive mixed sensitive material to form a resistance sensitive layer, dry it, and attach an electrode to the resistance sensitive layer to obtain a resistance positioning unit. S4. Prepare a piezoelectric material solution, polarize the piezoelectric material solution, pour it into a mold, dry and demold to obtain a piezoelectric layer; S5. Attach a metal electrode to each of the two surfaces of the piezoelectric layer to obtain a piezoelectric unit. S6. Assemble the components from top to bottom in the order of resistor positioning unit, gasket, piezoelectric unit, and encapsulation layer. During the assembly process, two gaskets are used to fix the resistor positioning unit and the piezoelectric unit so that the two units do not contact each other when not in operation, and the non-contacting parts form a cavity.

3. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 2, characterized in that, The film is an insulating film with a thickness of 0.2mm, and the size of both the insulating layer and the encapsulation layer is 64mm*9mm.

4. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 2, characterized in that, The methods used for polarizing piezoelectric materials in solution include one or more of the following: thermal polarization, electric field polarization, mechanical stress polarization, piezoelectric thin film material polarization, and optical polarization.

5. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 2, characterized in that, The thickness of the conductive composite sensitive material coating is 0.2 mm to 1 mm, and the conductivity ranges from 0.8 × 10⁻⁶. 2 S / m~3.0×10 2 S / m.

6. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 5, characterized in that, The thickness of the piezoelectric layer is 0.5mm to 2mm, and the ratio of the thickness of the gasket to the thickness of the piezoelectric material after demolding is 0.5 to 2.

7. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 5, characterized in that, The drying temperature is 50℃~60℃, and the heating temperature of the piezoelectric material solution is 70℃.

8. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 5, characterized in that, The conductive mixed sensitive material is composed of a conductive material and a thickener, while the piezoelectric material solution is composed of a polymeric piezoelectric material and a solvent, with the volume fraction of the polymeric piezoelectric material in the piezoelectric material solution being 6% to 8%.

9. The manufacturing method of the three-electrode sensor integrating positioning and pressure detection according to claim 8, characterized in that, The film is one of polyimide, epoxy resin, polytetrafluoroethylene, polyvinyl chloride, polyethylene terephthalate, and silicon dioxide; The gasket is made of one of the following rubber materials: chloroprene rubber, nitrile rubber, silicone; or one of the following plastic and polymer materials: polytetrafluoroethylene, polyethylene; the conductive material is one or more of the following: carbon nanotubes, metal nanowires, MXene, graphene; the thickener is one or more of the following: methylcellulose, hydroxyethylcellulose, sodium alginate, sodium polyacrylate; the polymeric piezoelectric material is one or more of the following: polyvinylidene fluoride, polyvinyl fluoride, polylactic acid; and the solvent is one or more of the following: N,N-dimethylformamide, acetone, N,N-dimethylacetamide, cyclohexanone.

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