A multifunctional underwater flexible sensor

Abstract

The application discloses a kind of underwater flexible sensor of multi-function.The sensor is mainly composed of first force conducting layer, substrate layer and second force conducting layer in turn, electrode layer and pressure sensitive material layer are placed on substrate layer respectively, first and second pressure sensitive units are located around and in the center of pressure sensitive material layer respectively, two independent pins are provided on the first and second pressure sensitive units, independent pins are connected to circuit board through electrode line in electrode layer, ring wall is provided in the center of lower surface of first force conducting layer, ring wall is in sealing contact with substrate layer, protruding structure is provided on first force conducting layer and second force conducting layer, pressure sensitive material layer is provided with pattern matched with protruding structure, resistance of pressure sensitive material layer can be changed under pressure through cooperation among the three.The sensor in the application can be directly exposed to water for use, realizing high range, low interference, full process force touch perception and water depth detection in underwater environment.

Description

Technical Field

[0001] This invention relates to a sensor in the field of underwater robot technology, and in particular to a multifunctional flexible underwater sensor. Background Technology

[0002] With the development of underwater robot technology, replacing divers with robots to perform tasks such as inspection, sensing, diagnosis, and operation is a new way to achieve efficient, low-cost, and intelligent operation and maintenance of underwater facilities. Integrating tactile sensing systems into underwater robots to build intelligent robots with force and tactile sensing capabilities and feedback is conducive to promoting human-machine collaborative, cross-domain, on-site sensing remote operation and control, which has great potential in my country's underwater operation and maintenance applications and marine resource development.

[0003] The perception requirements for underwater robots primarily lie in the acquisition of force-sensing information about the objects they grasp and in determining their depth by detecting underwater pressure. Underwater force-sensing capabilities enable robots to obtain rich information about object surfaces in complex aquatic environments, such as shape, hardness, and slippage, thus providing status displays and data feedback for grasping operations. Depth perception allows robots to take timely measures to respond to unexpected situations at different depths and is crucial for underwater exploration activities.

[0004] Flexible electronic skin technology has attracted widespread research attention due to its high flexibility, high sensitivity, and wearability, and holds promise for meeting underwater sensing needs. However, underwater flexible sensor technology is still immature compared to airborne electronic skin technology due to a series of technical failures caused by the complex underwater environment. Aquatic media, such as seawater with high ionic conductivity, can cause electrical interference, short circuits, and even electrochemical corrosion, often requiring additional waterproof sealing to protect components from water damage. However, this sealing inevitably leads to serious problems such as increased size, reduced flexibility, and decreased sensitivity. Furthermore, prolonged underwater use or water pressure can cause leakage in the enclosure, leading to sensor failure. More importantly, water pressure increases with depth, posing a significant challenge to the sealing and sealing of flexible sensors and maintaining high sensitivity. Additionally, crosscurrents and disturbances from swimming aquatic organisms in the underwater environment can affect the output signal of underwater sensors. Summary of the Invention

[0005] To address the problems existing in the background technology, the present invention provides a multifunctional underwater flexible sensor that can achieve high-range, low-interference, and full-process force and tactile sensing and water depth detection in the underwater environment.

[0006] The technical solution adopted in this invention is:

[0007] It is mainly composed of a first force-conducting layer, a base layer, and a second force-conducting layer stacked in sequence. The electrode layer and the pressure-sensitive material layer are placed on the outer and inner rings of the base layer, respectively. The pressure-sensitive material layer is connected to the circuit board via the electrode layer.

[0008] The sensor is placed underwater. The first and second force transmission layers have mutually cooperating protrusions. The pressure-sensitive material layer has a pattern that cooperates with the protrusions. Through the cooperation between the first force transmission layer, the pressure-sensitive material layer, and the second force transmission layer, the resistance of the pressure-sensitive material layer can change under pressure. The position information of the sensor underwater and the pressure information it experiences in the water can be obtained by measuring the resistance change of the pressure-sensitive material layer using the circuit board.

[0009] The pressure-sensitive material layer includes a first pressure-sensitive unit and a second pressure-sensitive unit. The second pressure-sensitive unit is located in the center of the pressure-sensitive material layer. Multiple first pressure-sensitive units are evenly spaced around the second pressure-sensitive unit along the circumferential direction of the pressure-sensitive material layer. Two flanges are provided on both sides of the first pressure-sensitive unit and both sides of the second pressure-sensitive unit, respectively serving as two independent pins of the first pressure-sensitive unit and two independent pins of the second pressure-sensitive unit.

[0010] Both the first pressure-sensitive unit and the second pressure-sensitive unit are placed on the upper surface of the substrate layer, and there is a gap area between the first pressure-sensitive unit and the second pressure-sensitive unit.

[0011] The lower surface of the first force-conducting layer has an annular protrusion in the center as an annular wall. The lower surface of the annular wall is in sealed contact with the center of the upper surface of the base layer, so that a relatively closed cavity is formed between the first force-conducting layer and the base layer inside the annular wall. The second pressure-sensitive unit in the pressure-sensitive material layer is located inside the cavity.

[0012] The lower surface of the first force-conducting layer and the upper surface of the second force-conducting layer are both provided with protruding structures. The protruding structures include inner and outer rings of first circular protrusion groups and a ring of second circular protrusion groups. Each ring of first circular protrusion groups is mainly formed by several first circular protrusions evenly spaced along the circumference of the first force-conducting layer. The number and arrangement of the first circular protrusions in the second force-conducting layer are the same as those in the first force-conducting layer and are aligned. The first circular protrusion groups in the inner ring of the first force-conducting layer are located outside the annular wall. The second circular protrusion groups are mainly formed by several circular protrusion arrays evenly spaced along the circumference of the first force-conducting layer. The number and arrangement of the circular protrusion arrays in the second force-conducting layer are the same as those in the first force-conducting layer and are aligned. The first circular protrusion groups and the ring of second circular protrusion groups in the outer ring are located in the same circumferential direction, and the first circular protrusions and the circular protrusion arrays are arranged alternately along the circumference.

[0013] Each first pressure-sensitive unit has a slot in the middle. The first circular boss in the first circular boss group of the outer ring on the first force transmission layer is located at the slot of the first pressure-sensitive unit. The first circular boss in the first circular boss group of the inner ring on the first force transmission layer is located in the gap area between the first pressure-sensitive unit and the second pressure-sensitive unit. The first force transmission layer and the second force transmission layer are both connected to the base layer through the first circular boss. The circular boss array in the first force transmission layer and the circular boss array in the second force transmission layer are located on the upper and lower sides of the first pressure-sensitive unit where there is no slot, respectively.

[0014] The circular protrusion array is mainly formed by a close array of several second circular protrusions. The height of the first circular protrusion is greater than the height of the second circular protrusion. The second circular protrusions in the second force transmission layer are staggered with the second circular protrusions in the first force transmission layer in the vertical direction.

[0015] The electrode layer mainly consists of several electrode lines. One end of the electrode line is placed on the upper surface of the substrate layer, and the other end of the electrode line is evenly distributed on the outer side of the substrate layer. The end of each electrode line placed on the substrate layer is electrically connected to an independent pin on the first pressure-sensitive unit or the second pressure-sensitive unit. The end of the electrode line distributed on the outer side of the substrate layer is connected to the circuit board through the circuit board.

[0016] The pressure-sensitive material layer is mainly prepared by using uncured polydimethylsiloxane (PDMS) as the base material and mixing it with graphene nanosheets and carbon nanotube particles.

[0017] The electrode layer is mainly composed of silver nanoparticles and uncured polydimethylsiloxane (PDMS), and the surface of the electrode layer is coated with PDMS as a waterproof coating.

[0018] The first force-conducting layer, the base layer, and the second force-conducting layer are all made of polydimethylsiloxane (PDMS) as the base material.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention utilizes the piezoresistive principle to achieve underwater pressure sensing and underwater depth detection functions. It uses low surface activity and hydrophobic polydimethylsiloxane (PDMS) as the substrate of the conductive polymer to prepare flexible pressure-sensitive sensing materials and flexible electrode materials that can be directly exposed to aquatic media with strong ionic conductivity and work normally.

[0021] 2. The sensor in this invention does not need to be sealed on the outside. The pressure of water is used to balance the signal and avoid signal interference caused by the pressure of water squeezing the sensor.

[0022] 3. The present invention applies a polydimethylsiloxane (PDMS) waterproof coating to the surface of the flexible electrode to prevent water from forming a conductive path between the flexible electrode and the water, thus avoiding electrical interference or even short circuit.

[0023] 4. This invention introduces a multi-level circular boss microstructure, which improves the sensitivity of the multifunctional sensor while avoiding signal disturbances and detection failures caused by underwater cross currents. Ultimately, the sensor can achieve high-range, low-interference, and full-process force and tactile perception and water depth detection in the underwater environment. Attached Figure Description

[0024] Figure 1 This is an exploded view of the layered structure of the multifunctional underwater flexible sensor of the present invention;

[0025] Figure 2 This is a top view showing the location distribution of the pressure-sensitive material layer and the electrode layer;

[0026] Figure 3 This is a top view of the pressure-sensitive material layer;

[0027] Figure 4 This is a top view of the electrode layer;

[0028] Figure 5 (a) is a plan view of the first conductive layer. Figure 5 (b) is a plan view of the second force transmission layer;

[0029] Figure 6 (a) is a screen printing plate with a pattern of pressure-sensitive material layer printed on it. Figure 6 (b) is a screen printing plate with the electrode layer pattern printed on it;

[0030] Figure 7 (a) is a schematic diagram illustrating the principle of the sensor of the present invention when it is first immersed in a water environment. Figure 7 (b) is a diagram illustrating the water pressure detection principle of the sensor of the present invention when it is immersed in water at a certain depth. Figure 7 (c) is a schematic diagram illustrating the principle of the flexible sensor of the present invention when subjected to minute pressure underwater. Figure 7 (d) is a schematic diagram illustrating the principle of the flexible sensor of the present invention when subjected to large pressure underwater.

[0031] Figure 8 (a) is the initial resistance change curve of a composite pressure-sensitive material prepared by mixing carbon nanotubes (CNTs) and graphene (GR) with ordinary silicone rubber (SR) as a substrate after long-term immersion in water. Figure 8 (b) is the initial resistance change curve of a flexible pressure-sensitive material prepared by mixing carbon nanotubes (CNTs) and graphene (GR) with uncured polydimethylsiloxane (PDMS) as a substrate after long-term immersion in water.

[0032] Figure 9This is a manufacturing process diagram of the multifunctional underwater flexible sensor of the present invention;

[0033] In the diagram: 1. First force transmission layer; 2. Pressure-sensitive material layer; 3. Electrode layer; 4. Base layer; 5. Second force transmission layer; 6. First pressure-sensitive unit; 7. Second pressure-sensitive unit; 8. Annular wall; 9. First circular boss; 10. Second circular boss; 11. Water; 12. Air. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] like Figure 1 and Figure 2 As shown, the sensor is mainly composed of a first force transmission layer 1, a base layer 4, and a second force transmission layer 5 stacked in sequence. The electrode layer 3 and the pressure-sensitive material layer 2 are placed on the outer and inner rings of the base layer 4, respectively. The pressure-sensitive material layer 2 is connected to the circuit board via the electrode layer 3.

[0036] The sensor is placed underwater. The first force transmission layer 1 and the second force transmission layer 5 have mutually cooperating protrusions. The pressure-sensitive material layer 2 has a pattern that cooperates with the protrusions. Through the cooperation between the first force transmission layer 1, the pressure-sensitive material layer 2 and the second force transmission layer 5, the resistance of the pressure-sensitive material layer 2 can change under pressure. The position information of the sensor underwater and the pressure information it experiences in the water can be obtained by measuring the resistance change of the pressure-sensitive material layer 2 using the circuit board.

[0037] When the sensor is submerged in water 11 and is not subjected to external force or the external force is very small, neither the first force transmission layer 1 nor the second force transmission layer 5 is in contact with the pressure-sensitive material layer 2. When the sensor is subjected to a large external force, both the first force transmission layer 1 and the second force transmission layer 5 compress the pressure-sensitive material layer 2. The pressure-sensitive material layer 2 deforms due to compression, and its resistance changes accordingly. After the resistance of the pressure-sensitive material layer 2 changes, a pressure signal is generated in the circuit board, thereby obtaining the pressure information of the sensor.

[0038] The first force transmission layer 1, the base layer 4, and the second force transmission layer 5 serve as the structural support for the sensor.

[0039] like Figure 3 As shown, the pressure-sensitive material layer 2 includes a first pressure-sensitive unit 6 and a second pressure-sensitive unit 7. The second pressure-sensitive unit 7 is located in the center of the pressure-sensitive material layer 2. Multiple first pressure-sensitive units 6 are evenly spaced around the second pressure-sensitive unit 7 along the circumference of the pressure-sensitive material layer 2. The first pressure-sensitive unit 6 is the part of the pressure-sensitive material layer 2 that is directly exposed to water, and the second pressure-sensitive unit 7 is the part of the pressure-sensitive material layer 2 that is wrapped by air 12. Two flanges are provided on both sides of the first pressure-sensitive unit 6 and both sides of the second pressure-sensitive unit 7, which serve as two independent pins of the first pressure-sensitive unit 6 and two independent pins of the second pressure-sensitive unit 7, respectively.

[0040] The first pressure-sensitive unit 6 and the second pressure-sensitive unit 7 are both placed on the upper surface of the base layer 4. There is a gap between the first pressure-sensitive unit 6 and the second pressure-sensitive unit 7, that is, the first pressure-sensitive unit 6 and the second pressure-sensitive unit 7 do not contact each other.

[0041] The first pressure-sensitive unit 6 is used to detect the external force actively applied to the sensor in the water 11; the second pressure-sensitive unit 7 is used to detect the water depth of the sensor when it is not subjected to an actively applied external force.

[0042] like Figure 5 (a) and Figure 5 As shown in (b), an annular protrusion is provided in the center of the lower surface of the first force transmission layer 1 as an annular wall 8. The lower surface of the annular wall 8 is sealed and connected to the center of the upper surface of the base layer 4, so that a relatively closed cavity is formed between the first force transmission layer 1 and the base layer 4 inside the annular wall 8. The second pressure-sensitive unit 7 in the pressure-sensitive material layer 2 is located on the base layer 4 inside the cavity.

[0043] Both the lower surface of the first force-conducting layer 1 and the upper surface of the second force-conducting layer 5 are provided with protruding structures. These protruding structures include inner and outer rings of first circular protrusion groups and a ring of second circular protrusion groups. Each ring of first circular protrusion groups is mainly formed by several first circular protrusions 9 evenly spaced along the circumference of the first force-conducting layer 1. The number and arrangement of the first circular protrusions 9 in the second force-conducting layer 5 are the same as those in the first force-conducting layer 1, and their positions are aligned vertically. The first circular protrusions 9 in the inner ring of the first circular protrusion group on the first force-conducting layer 1 are located... On the outside of the annular wall 8; the second circular protrusion group is mainly formed by several circular protrusion arrays evenly spaced along the circumference of the first force transmission layer 1. The number and arrangement of the circular protrusion arrays in the second force transmission layer 5 are the same as those in the first force transmission layer 1, and the arrangement positions are aligned vertically. The first circular protrusion group in the outer ring and the second circular protrusion group in the outer ring are located in the same circumferential direction, and the first circular protrusion 9 and the circular protrusion array are arranged alternately along the circumference. At least one circular protrusion array is provided between each two adjacent first circular protrusion 9.

[0044] like Figure 2As shown, each first pressure-sensitive unit 6 has a slot in the middle. The first round boss 9 in the first round boss group of the outer ring on the first force transmission layer 1 is located at the slot of the first pressure-sensitive unit 6. The first round boss 9 in the first round boss group of the inner ring on the first force transmission layer 1 is located in the gap area between the first pressure-sensitive unit 6 and the second pressure-sensitive unit 7. That is, the first round boss 9 in the first force transmission layer 1 does not contact the first pressure-sensitive unit 6 and the second pressure-sensitive unit 7. The first force transmission layer 1 and the second force transmission layer 5 are both connected to the base layer 4 through the first round boss 9. The round boss array in the first force transmission layer 1 and the round boss array in the second force transmission layer 5 are located on the upper and lower sides of the first pressure-sensitive unit 6 where there is no slot, respectively.

[0045] The circular boss array is mainly formed by a close array of several second circular bosses 10. The size of the first circular boss 9 is larger than the size of the second circular boss 10, and the height of the first circular boss 9 is greater than the height of the second circular boss 10. This ensures that after the first circular boss 9 is connected to the base layer 4, the second circular boss 10 does not contact the pressure-sensitive material layer 2, and there is no contact between the first circular boss 9 and the second circular boss 10. The second circular bosses 10 in the second force transmission layer 5 and the second circular bosses 10 in the first force transmission layer 1 are staggered in the vertical direction. When there is no external force or the external force is very small, the second circular bosses 10 do not contact the first pressure-sensitive unit 6. When the external force is very large, the second circular bosses 10 in the first force transmission layer 1 contact the first pressure-sensitive unit 6 and are squeezed.

[0046] like Figure 7 (a) and Figure 7 As shown in (b), the annular wall 8 is sealed to the base layer 4, and the space between the annular wall 8 and the base layer 4 is not in contact with the water 11. That is, the second pressure-sensitive unit 7 is placed in the air 12. When the sensor is not subjected to an actively applied external force, the pressure in the water 11 compresses the air 12, causing the second pressure-sensitive unit 7 to deform. The underwater depth of the sensor is detected by the change in resistance of the second pressure-sensitive unit 7 after deformation.

[0047] like Figure 7 (c) and Figure 7 As shown in (d), when the first circular protrusion 9 is subjected to a small underwater disturbance on the surface of the first force transmission layer 1, such as during an underwater cross current, the first force transmission layer 1 deforms due to the force, and the sensor surface becomes concave. However, since the force is small, the second circular protrusion 10 does not directly contact the first pressure-sensitive unit 6, so there is no pressure signal output. When a large pressure is applied to the surface of the first force transmission layer 1, the second circular protrusion 10 squeezes the first pressure-sensitive unit 6. After the first pressure-sensitive unit 6 is deformed, its resistance increases, and the change in resistance generates a pressure signal in the circuit board.

[0048] like Figure 4As shown, the electrode layer 3 is mainly composed of several electrode lines. One end of the electrode line is placed on the upper surface of the base layer 4, and the other end of the electrode line is evenly distributed on the outside of the base layer 4. The end of each electrode line placed on the base layer 4 is electrically connected to an independent pin on the first pressure-sensitive unit 6 or the second pressure-sensitive unit 7. The end of the electrode line distributed on the outside of the base layer 4 is connected to the circuit board through the circuit board. The circuit board has a built-in switch controller, which is used to control the conduction between two independent pins in the same pressure-sensitive unit 6 or 7.

[0049] By using a row and column scanning method, the resistance change signal of the pressure-sensitive material layer 2 is collected by the electrode layer 3. The resistance change signal is converted into a pressure signal by the circuit board. The pressure signal is used to realize the underwater pressure sensing and underwater depth detection functions of the sensor.

[0050] The pressure-sensitive material layer 2 is mainly made of uncured polydimethylsiloxane (PDMS) as the base material, mixed with graphene nanosheets and carbon nanotube particles. Due to the low surface activity and hydrophobic properties of polydimethylsiloxane (PDMS), the pressure-sensitive material layer 2 can be directly exposed in water 11 and work normally. When the pressure-sensitive material layer 2 is squeezed, it is stretched, and the output resistance changes due to the stretching deformation of the pressure-sensitive material layer 2.

[0051] Electrode layer 3 is mainly composed of silver nano-conductive particles and uncured polydimethylsiloxane (PDMS). A thin layer of polydimethylsiloxane (PDMS) is coated on the surface of electrode layer 3 as a waterproof coating. The polydimethylsiloxane (PDMS) waterproof coating is used to prevent the formation of a conductive channel between the electrode wire and water 11, and to prevent electrical interference or even short circuit caused by conductive particles in water 11.

[0052] The first force-conducting layer 1, the base layer 4, and the second force-conducting layer 5 are all made of polydimethylsiloxane (PDMS) as the base material.

[0053] Except for the annular wall in the first force transmission layer 1, which needs to be sealed to the base layer 4, all other parts of the sensor do not require sealing and can be directly exposed to water 11. The lack of sealing in the sensor means that both the pressure-sensitive material layer 2 and the electrode layer 3 can be directly exposed to water 11 without affecting the sensor's detection performance. Water 11 includes highly conductive aquatic media such as seawater. Figure 8 (a) and Figure 8 As shown in (b), compared with the pressure-sensitive material layer 2 prepared with ordinary silicone rubber (SR) as the substrate, the pressure-sensitive material layer 2 with polydimethylsiloxane (PDMS) as the substrate has no significant change in resistance value when placed in a water environment for a long time, and the initial resistance of the pressure-sensitive material layer 2 is small and the fluctuation range is small.

[0054] Materials prepared using polydimethylsiloxane (PDMS) as a conductive substrate exhibit superior underwater detection performance. This is because the main molecular formula of both PDMS and ordinary silicone rubber consists of silicon-oxygen bonds (Si-O). Since silicon atoms are tetravalent, each silicon atom in both PDMS and ordinary silicone rubber has two side chains. The side chains of PDMS are all hydrophobic methyl groups (-CH3), which have lower surface activity and form a hydrophobic layer on the surface to prevent water molecules from entering the interior. The side chains of ordinary silicone rubber are methyl or vinyl groups (-CH=CH2), and vinyl groups are susceptible to oxidation by water, thereby damaging the hydrophobic film on their surface.

[0055] The sensor avoids signal interference caused by the pressure in the water 11 squeezing the sensor by utilizing the pressure self-balancing mechanism of the water 11. Specifically, the sensor directly exposed to the water is subjected to the same pressure from the water, and the pressures cancel each other out. In addition, the sensor is thin and there are no air bubbles inside the material layers, so it will not be compressed.

[0056] The size of the first circular protrusion 9 can be adjusted according to the magnitude of underwater disturbance in the application scenario. The larger the size of the first circular protrusion 9, the larger the range of underwater disturbance shielding. The smaller the size of the first circular protrusion 9, the smaller the minimum force that the sensor can detect.

[0057] A method for fabricating a multifunctional underwater flexible sensor, such as Figure 9 As shown, it includes the following steps:

[0058] Step 1: Using 3D printing technology, print 3D printed molds that match the first force transmission layer 1 and the second force transmission layer 5 respectively. Clean the printed 3D printed molds with anhydrous ethanol for 30 minutes to remove dirt from the surface of the 3D printed molds. Then, remove the 3D printed molds and dry them in a vacuum drying oven to allow the anhydrous ethanol to evaporate completely. Then, spray a release agent evenly into the groove of the 3D printed molds to facilitate the peeling of various parts from the 3D printed molds without damaging the external shape of the parts.

[0059] Prepare screen printing molds in advance that match the electrode layer 3 and the pressure-sensitive material layer 2 respectively, such as... Figure 6 (a) and Figure 6 As shown in (b), the screen printing die is a manufacturing die with a patterned slit between the electrode layer 3 and the pressure-sensitive material layer 2; Figure 6 (a) and Figure 6 In (b), the black area is the shape of the screen printing plate, and the white area is used to make the product. It is the area in the screen printing plate where the material is filled in, and it is a cutout structure.

[0060] Step 2: Mix polydimethylsiloxane (PDMS) liquid and curing agent at a mass ratio of 10:1 to prepare a polydimethylsiloxane (PDMS) base material. Fill the polydimethylsiloxane (PDMS) base material into the 3D printing mold prepared in Step 1. Degas the 3D printing mold in a vacuum drying oven for 30 minutes to make the internal material of the first force conducting layer 1 and the second force conducting layer 5 uniform and dense. Then heat the 3D printing mold at 80°C for 2 hours to completely cure the polydimethylsiloxane (PDMS) base material. After demolding, cut off the excess edges to obtain the complete first force conducting layer 1 and the second force conducting layer 5.

[0061] A polyimide film is applied to a spin coater, and uncured polydimethylsiloxane (PDMS) substrate material is dropped onto the polyimide film. The spin coater is turned on to prepare a polydimethylsiloxane (PDMS) film. Then, a laser cutter is used to cut out the designed shape of the substrate layer 4 to form the substrate layer 4.

[0062] Graphene, carbon nanotubes, polyphenylmethylsiloxane, tetrahydrofuran, and polydimethylsiloxane (PDMS) substrate materials were mixed in a mass ratio of 4:2:6:100:100, and then mixed in a planetary stirrer at 2000 rpm for 3 minutes to obtain a flexible pressure-sensitive material. The prepared substrate layer 4 was placed horizontally on a glass plate, and a screen printing plate matching the pressure-sensitive material layer 2 was placed parallel to the upper surface of the substrate layer 4. The prepared flexible pressure-sensitive material was filled into the gaps of the screen printing plate. After completion, the screen printing plate was removed, and the flexible pressure-sensitive material was cured by heating at 80°C for 2 hours.

[0063] Silver nanosheets, polydimethylsiloxane (PDMS) substrate material, and polyvinylpyrrolidone were mixed at a mass ratio of 250:100:2.5 and stirred in a planetary mixer for 3 minutes to obtain a flexible electrode material. A screen printing plate matching the electrode layer 3 was placed parallel to the upper surface of the substrate layer 4 with the existing pressure-sensitive material layer 2. The prepared flexible electrode material was filled into the gaps of the screen printing plate. After completion, the screen printing plate was removed and heated at 80°C for 2 hours to cure, so that the electrode layer 3 and the pressure-sensitive material layer 2 were fixedly connected.

[0064] Step 3: Apply uncured polydimethylsiloxane (PDMS) as a waterproof coating evenly to the surface of electrode layer 3. The polydimethylsiloxane (PDMS) completely covers electrode layer 3. Heat at 80°C for 2 hours to fix the polydimethylsiloxane (PDMS) waterproof coating to the base layer 4 to block the formation of a conductive channel between the electrode wire and water, and avoid the sensor from being subjected to electrical interference or even short circuit.

[0065] Uncured polydimethylsiloxane (PDMS) substrate material is dotted onto the first circular boss 9, so that the first circular boss 9 in the first force transmission layer 1 and the second force transmission layer 5 are bonded to the substrate layer 4 with the top and bottom facing each other. After heating and curing, the sensor manufacturing is completed.

[0066] The sensor parameters in the embodiments of the present invention are as follows:

[0067] The film thickness of the first force conducting layer 1, the pressure-sensitive material layer 2, the electrode layer 3, the substrate layer 4, and the second force conducting layer 5 is 0.1 mm. Both the first force conducting layer 1 and the second force conducting layer 5 are circles with a diameter of 20 mm.

[0068] Each first pressure-sensitive unit 6, which is directly exposed to water, has an inner diameter of 10 mm and an outer diameter of 16 mm. The center of the first pressure-sensitive unit 6 has a notch at a 20° angle to the center line. The second pressure-sensitive unit 7, which is air-enclosed, is located inside a circle with a diameter of 5 mm. The independent pin width of the first pressure-sensitive unit 6 and the second pressure-sensitive unit 7 is 0.3 mm.

[0069] The electrode line width of electrode layer 3 is 0.3 mm, and the center-to-center spacing of the electrode lines at the end that does not contact the substrate layer 4 is 0.6 mm.

[0070] The outer diameter of the annular wall 8 is 5mm, the wall thickness is 0.25mm, and the height is 0.75mm;

[0071] The first circular boss 9 is a circular boss with a diameter of 1.5mm. The first circular boss 9 of the outer ring is evenly distributed on a concentric circle with a diameter of 14mm, and the first circular boss 9 of the inner ring is evenly distributed on a concentric circle with a diameter of 8mm.

[0072] The second circular protrusion 10 has two rings on the first force transmission layer 1. The diameter of the second circular protrusion 10 on the outer ring is 0.65 mm, and the diameter of the second circular protrusion 10 on the inner ring is 0.60 mm. The second circular protrusion 10 on the outer ring is evenly distributed on a concentric circle with a diameter of 13.5 mm. Four second circular protrusions 10 that are in contact with each other form a group, and the four second circular protrusions 10 in a group are tangent to each other in pairs.

[0073] The second circular protrusion 10 has three rings in the second force transmission layer 5. The outermost ring of the second circular protrusion 10 has a diameter of 0.69 mm, the middle ring of the second circular protrusion 10 has a diameter of 0.63 mm, and the innermost ring of the second circular protrusion 10 has a diameter of 0.57 mm. The outermost ring of the second circular protrusion 10 is evenly distributed on a concentric circle with a diameter of 14.2 mm. Nine second circular protrusions 10 that are in contact with each other form a group. The second circular protrusions 10 in the middle ring are tangent to the second circular protrusions 10 in the outer ring and the second circular protrusions 10 in the inner ring, respectively.

[0074] The above-described specific embodiments are used to explain and illustrate the present invention, and are not intended to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A multifunctional underwater flexible sensor, characterized in that: It is mainly composed of a first force conduction layer (1), a base layer (4), and a second force conduction layer (5) stacked in sequence. The electrode layer (3) and the pressure-sensitive material layer (2) are placed on the outer and inner rings of the base layer (4), respectively. The pressure-sensitive material layer (2) is connected to the circuit board through the electrode layer (3). The sensor is placed underwater. The first force transmission layer (1) and the second force transmission layer (5) are provided with mutually cooperating protrusions. The pressure-sensitive material layer (2) is provided with a pattern that cooperates with the protrusions. Through the cooperation between the first force transmission layer (1), the pressure-sensitive material layer (2) and the second force transmission layer (5), the resistance of the pressure-sensitive material layer (2) can change under pressure. The position information of the sensor underwater and the pressure information in the water can be obtained by measuring the resistance change of the pressure-sensitive material layer (2) using the circuit board. The lower surface of the first force transmission layer (1) has an annular protrusion in the center as an annular wall (8). The lower surface of the annular wall (8) is sealed and connected to the center of the upper surface of the base layer (4), so that a relatively closed cavity is formed between the first force transmission layer (1) and the base layer (4) inside the annular wall (8). The second pressure-sensitive unit (7) in the pressure-sensitive material layer (2) is located inside the cavity. The lower surface of the first force transmission layer (1) and the upper surface of the second force transmission layer (5) are both provided with protruding structures. The protruding structures include two inner and outer rings of first circular protrusion groups and one ring of second circular protrusion groups. Each ring of first circular protrusion groups is mainly formed by several first circular protrusions (9) evenly spaced along the circumference of the first force transmission layer (1). The number and arrangement of the first circular protrusions (9) in the second force transmission layer (5) are the same as those in the first force transmission layer (1) and are aligned. (1) The first round boss group of the upper inner ring is located outside the annular wall (8); the second round boss group is mainly formed by several round boss arrays evenly spaced along the circumference of the first force transmission layer (1). The number and arrangement of the round boss array in the second force transmission layer (5) are the same as those in the first force transmission layer (1) and are aligned. The first round boss group of the outer ring and the second round boss group are located in the same circumferential direction, and the first round boss (9) and the round boss array are arranged alternately along the circumference. Each first pressure-sensitive unit (6) has a slot in the middle. The first round boss (9) in the first round boss group of the outer ring of the first force transmission layer (1) is located at the slot of the first pressure-sensitive unit (6). The first round boss (9) in the first round boss group of the inner ring of the first force transmission layer (1) is located in the gap area between the first pressure-sensitive unit (6) and the second pressure-sensitive unit (7). The first force transmission layer (1) and the second force transmission layer (5) are both connected to the base layer (4) through the first round boss (9). The round boss array in the first force transmission layer (1) and the round boss array in the second force transmission layer (5) are located on the upper and lower sides of the first pressure-sensitive unit (6) where there is no slot, respectively. The circular boss array is mainly formed by a tight array of several second circular bosses (10). The height of the first circular boss (9) is greater than the height of the second circular boss (10). The second circular bosses (10) in the second force transmission layer (5) and the second circular bosses (10) in the first force transmission layer (1) are staggered in the vertical direction.

2. The multifunctional underwater flexible sensor according to claim 1, characterized in that: The pressure-sensitive material layer (2) includes a first pressure-sensitive unit (6) and a second pressure-sensitive unit (7). The second pressure-sensitive unit (7) is located in the center of the pressure-sensitive material layer (2). Multiple first pressure-sensitive units (6) are evenly spaced around the second pressure-sensitive unit (7) along the circumference of the pressure-sensitive material layer (2). Two flanges are provided on both sides of the first pressure-sensitive unit (6) and both sides of the second pressure-sensitive unit (7) as two independent pins of the first pressure-sensitive unit (6) and two independent pins of the second pressure-sensitive unit (7), respectively. The first pressure-sensitive unit (6) and the second pressure-sensitive unit (7) are both placed on the upper surface of the base layer (4), and there is a gap area between the first pressure-sensitive unit (6) and the second pressure-sensitive unit (7).

3. The multifunctional underwater flexible sensor according to claim 1, characterized in that: The electrode layer (3) is mainly composed of several electrode lines. One end of the electrode line is placed on the upper surface of the base layer (4), and the other end of the electrode line is evenly arranged on the outside of the base layer (4). The end of each electrode line placed on the base layer (4) is electrically connected to an independent pin on the first pressure-sensitive unit (6) or the second pressure-sensitive unit (7). The end of the electrode line arranged on the outside of the base layer (4) is connected to the circuit board through the circuit board.

4. A multifunctional underwater flexible sensor according to claim 1, characterized in that: The pressure-sensitive material layer (2) is mainly made of uncured polydimethylsiloxane as the base material, mixed with graphene nanosheets and carbon nanotube particles.

5. A multifunctional underwater flexible sensor according to claim 1, characterized in that: The electrode layer (3) is mainly prepared by silver nano-conductive particles and uncured polydimethylsiloxane. The surface of the electrode layer (3) is coated with polydimethylsiloxane as a waterproof coating.

6. A multifunctional underwater flexible sensor according to claim 1, characterized in that: The first force-conducting layer (1), the base layer (4), and the second force-conducting layer (5) are all made of polydimethylsiloxane as the base material.

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