Flexible pressure sensor based on pressure sensing wire rod

Abstract

The utility model discloses a flexible pressure sensor based on a pressure sensing wire rod. The pressure-sensitive sensing layer comprises a first supporting sheet and a plurality of rows of pressure-sensitive wires; and each row of pressure-sensitive wires are respectively arranged on the surface of the first supporting sheet. The conductive layer comprises a second supporting sheet and a conductive circuit layer; the conductive circuit layer is arranged on the surface of the second supporting sheet. The pressure-sensitive wire comprises an inner conductive layer and a pressure-sensitive resistance layer sleeved on the outer surface of the inner conductive layer. The piezoresistive layer is in electrical contact with the conductive circuit layer; and the conductive circuit layer and the inner conductive layer are electrically connected with the signal acquisition module respectively. The pressure-sensitive material adopts a pressure-sensitive wire, and wiring can be directly carried out on the supporting sheet, so that the process of assembling and attaching a conductive material and a piezoresistive material is saved; the pressure-sensitive wires are in contact with the conductive circuit layer, so that pressure sensing matrix points can be formed, the pressure sensing effect is improved, and waste of materials in a non-sensing area of the sensor is avoided.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a flexible pressure sensor based on a pressure sensing wire. Background Art

[0002] Flexible pressure sensors are thin-film flexible electronic components that can sense the pressure applied to their surface. They can be used in medical equipment (such as medical beds), consumer electronic devices (such as wheeled robots), electronic musical instruments, smart gloves, industrial equipment (such as industrial robots) and automated assembly lines. Flexible pressure sensors sense pressure through pressure-sensitive materials and send the sensed signal to the signal acquisition module through conductive materials.

[0003] The conductive material and piezoresistive material of existing flexible pressure sensors are formed separately and need to be assembled and bonded together through subsequent processes, which increases the complexity of the process. In addition, the piezoresistive material needs to be attached to the conductive material in one piece, and some non-sensing areas are also attached with piezoresistive material, resulting in waste of piezoresistive material. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present application proposes a flexible pressure sensor based on pressure-sensing wire. The pressure-sensitive material of the flexible pressure sensor adopts a pressure-sensitive wire, and its inner conductive layer and the piezoresistive layer on the outer surface are combined to form a conductive wire with pressure sensitivity. The pressure-sensitive wire can be directly wired on the supporting sheet, which saves the process of assembling and bonding the conductive material and the piezoresistive material in the traditional process. The pressure-sensitive wire is in contact with the conductive circuit layer to form a pressure-sensing matrix point, which solves the problem of complicated assembly process of the existing flexible pressure sensor and waste of piezoresistive material in the non-sensing area.

[0005] In order to achieve the above purpose, the technical solution of this application is as follows:

[0006] A flexible pressure sensor based on a pressure sensing wire comprises a pressure-sensitive layer, a conductive layer and a signal acquisition module. The pressure-sensitive layer comprises a first support sheet and a plurality of rows of pressure-sensitive wires; each row of pressure-sensitive wires is arranged on the surface of the first support sheet. The conductive layer comprises a second support sheet and a conductive circuit layer; the conductive circuit layer is arranged on the surface of the second support sheet. The first support sheet and the second support sheet are arranged opposite and parallel to each other; the pressure-sensitive wire and the conductive circuit layer are respectively located between the first support sheet and the second support sheet. The pressure-sensitive wire comprises an inner conductive layer and a varistor layer sleeved on the outer surface of the inner conductive layer. The varistor layer is in electrical contact with the conductive circuit layer; the conductive circuit layer and the inner conductive layer are respectively electrically connected to the signal acquisition module.

[0007] Optionally, the varistor layer is made by curing a slurry for forming a varistor. The slurry for forming a varistor is a polymer plastic substrate mixed with conductive particles. The conductive particles include one or more of conductive carbon black, carbon nanotubes and conductive metal particles.

[0008] Optionally, each row of pressure-sensitive wires is protrudingly disposed on the surface of the first support sheet, and the conductive circuit layer is protrudingly disposed on the surface of the second support sheet.

[0009] Optionally, the first supporting sheet and the second supporting sheet are respectively made of flexible cloth material.

[0010] Optionally, the conductive circuit layer is woven from conductive metal fibers or made of a conductive coating. The conductive circuit layer is woven or bonded to the second support sheet and electrically connected to the signal acquisition module via a circuit guide sheet, one end of which is provided with a raised welding sheet.

[0011] Optionally, the conductive trace layer is made of copper fibers or carbon coating.

[0012] Optionally, each row of pressure-sensitive wires on the surface of the first support sheet is parallel to each other. The conductive circuit layer includes multiple rows of conductive wires; each row of conductive wires is arranged on the surface of the second support sheet in parallel to each other.

[0013] Optionally, each row of pressure-sensitive wires on the first support sheet surface and each row of conductive wires on the second support sheet surface cross each other.

[0014] Optionally, each row of pressure-sensitive wires on the first support sheet surface and each row of conductive wires on the second support sheet surface are perpendicular to each other.

[0015] Optionally, one end of each row of conductive wires is electrically connected to the signal acquisition module along the line guide sheet. A protruding welding sheet is provided at one end of the line guide sheet.

[0016] Optionally, the varistor layer is in a linear shape and is hollow inside.

[0017] Optionally, the inner conductive layer is a metal wire.

[0018] Optionally, the inner conductive layer is a copper wire, an aluminum wire or an alloy wire.

[0019] Beneficial effects of this application:

[0020] The pressure-sensitive material of the flexible pressure sensor adopts a pressure-sensitive wire, and its inner conductive layer and the pressure-sensitive resistor layer on the outer surface form a conductive wire with pressure sensitivity. The pressure-sensitive wire can be directly wired on the supporting sheet, which saves the process of assembling and bonding the conductive material and the piezoresistive material in the traditional process, reduces the complexity of the assembly process, saves manpower, and eliminates high-energy consumption and high-pollution processes such as silk-screen printing and baking, which is more energy-saving and environmentally friendly; in addition, the pressure-sensitive wire contacts the conductive circuit layer to form a pressure-sensing matrix point, improves the pressure sensing effect, and avoids wasting piezoresistive materials in the non-sensing area of ​​the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a schematic diagram of the cross-sectional structure of a flexible pressure sensor based on a pressure sensing wire in this application.

[0022] Figure 2 This is a schematic diagram of the assembly structure of the flexible pressure sensor based on the pressure sensing wire in this application.

[0023] Figure 3 It is a schematic diagram of the cross-sectional structure of the voltage-sensitive wire 10 in the present application.

[0024] Figure 4 It is a schematic cross-sectional structure diagram of the voltage-sensitive wire 10 and the conductive circuit layer 22 in the present application.

[0025] Figure 5 Schematic diagram of the pressure sensitive sensing circuit principle of the pressure sensitive wire 10 in the present application.

[0026] Figure 6 It is a schematic diagram of the processing process of the voltage-sensitive wire 10 in this application.

[0027] in, Figures 1 to 6 The reference numerals are: conductive layer 2, signal acquisition module 4; varistor wire 10; inner conductive layer 101, varistor layer 102; first support sheet 30, second support sheet 21, conductive circuit layer 22; circuit guide sheet 23, welding sheet 231. DETAILED DESCRIPTION

[0028] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1 to Figure 2 As shown, the present application discloses a flexible pressure sensor based on a pressure sensing wire, and the flexible pressure sensor includes a pressure sensitive layer, a conductive layer 2 and a signal acquisition module 4.

[0030] The pressure-sensitive layer is arranged opposite to and parallel to the conductive layer 2. The pressure-sensitive layer and the conductive layer 2 are electrically connected to the signal acquisition module 4 respectively to form a conductive loop. The pressure-sensitive layer is used for pressure sensing; the conductive layer 2 is used for transmitting pressure sensing signals; and the signal acquisition module 4 is used for collecting pressure sensing signals.

[0031] like Figure 1 or Figure 2 As shown, the pressure-sensitive layer includes a first support sheet 30 and a plurality of rows of pressure-sensitive wires 10. Each row of pressure-sensitive wires 10 is arranged on the surface of the first support sheet 30.

[0032] like Figure 1 or Figure 2 As shown, the conductive layer 2 includes a second supporting sheet 21 and a conductive circuit layer 22. The conductive circuit layer 22 is arranged on the surface of the second supporting sheet 21.

[0033] The second support sheet 21 is disposed opposite to and parallel to the first support sheet 30. The pressure-sensitive wire 10 and the conductive circuit layer 22 are respectively located between the second support sheet 21 and the first support sheet 30. The pressure-sensitive wire 10 and the conductive circuit layer 22 are in electrical contact.

[0034] In one embodiment, Figure 3 As shown, the varistor wire 10 includes an inner conductive layer 101 and a varistor layer 102 which is sleeved on the outer surface of the inner conductive layer 101 .

[0035] The piezoresistive layer 102 is used to sense the magnitude of pressure and protect the inner conductive layer 101. The inner conductive layer 101 is used to transmit the pressure sensing signal generated by the piezoresistive layer 102.

[0036] The inner conductive layer 101 is electrically connected to the signal acquisition module 4 . The varistor layer 102 is electrically connected to the conductive circuit layer 22 .

[0037] In one embodiment, the varistor layer 102 is made by curing a slurry for forming a varistor.

[0038] The varistor layer 102 is made of a slurry for forming a varistor and is soft and bendable, so as to facilitate the wiring of the varistor wire 10 during use.

[0039] Optionally, the slurry for forming the varistor is a polymer plastic base material mixed with conductive particles. The conductive particles account for 5%-50% of the mass of the slurry for forming the varistor, and the remaining components are the polymer plastic base material.

[0040] The conductive particles are single or a mixture of conductive carbon black, carbon nanotubes or conductive metal particles.

[0041] The polymer plastic substrates include polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC) or polypropylene (PP).

[0042] like Figure 6 As shown, the inner conductive layer 101 passes through the extrusion port 50 and moves along the A direction. The polymer plastic substrate and the conductive particles are mixed in a certain proportion, melted and extruded from the extrusion port 50 through an extrusion process, and coated on the outer circle of the inner conductive layer 101, and moves along the A direction together with the inner conductive layer 101. After cooling, the polymer plastic substrate forms a varistor layer 102.

[0043] In one embodiment, the varistor layer 102 is in a linear shape and is hollow inside.

[0044] In one embodiment, the inner conductive layer 101 is a metal wire with good conductivity.

[0045] In one embodiment, the inner conductive layer 101 is a metal wire made of copper, aluminum or alloy, etc. Since the inner conductive layer 101 and the varistor layer 102 are integrally formed and in close contact, the inner conductive layer 101 can reduce resistance without relying on precious metal materials such as silver, and has good conductivity.

[0046] In one embodiment, the cross section of the inner conductive layer 101 is circular or square.

[0047] In one embodiment, the rows of pressure-sensitive wires 10 on the surface of the first support sheet 30 are parallel to each other.

[0048] In one embodiment, the conductive circuit layer 22 includes multiple rows of conductive wires. Each row of conductive wires is arranged parallel to each other on the surface of the second support sheet 21. One end of each row of conductive wires is electrically connected to the signal acquisition module 4 along the circuit guide sheet 23. The circuit guide sheet 23 is installed on the second support sheet 21. A protruding welding sheet 231 is provided at one end of the circuit guide sheet 23 to facilitate welding with the signal acquisition module 4.

[0049] In one embodiment, the rows of pressure-sensitive wires 10 on the surface of the first support sheet 30 and the rows of conductive wires on the surface of the second support sheet 21 intersect with each other.

[0050] The rows of pressure-sensitive wires 10 of the first support sheet 30 and the conductive circuit layer 22 of the second support sheet 21 intersect with each other to form a matrix, and the intersection areas of the matrix are pressure sensing points.

[0051] In one embodiment, the rows of pressure-sensitive wires 10 on the surface of the first support sheet 30 and the rows of conductive wires on the surface of the second support sheet 21 are perpendicular to each other.

[0052] like Figure 4 The figure shows a schematic diagram of the cross-sectional structure of the varistor wire 10 and the conductive circuit layer 22. The varistor wire 10 and the conductive circuit layer 22 cross-contact each other, and the area of ​​the intersection is the pressure sensing point. Among them, one end of the inner conductive layer 101 of the varistor wire 10 is connected to the positive electrode of the signal acquisition module 4, and one end of the conductive circuit layer 22 is connected to the negative electrode of the signal acquisition module 4. When the varistor layer 102 is subjected to an external force F, the varistor layer 102 undergoes elastic deformation, and the distance between the conductive particles inside it decreases, which is manifested macroscopically as a decrease in the resistance of the loop. The greater the pressure, the greater the extrusion deformation, the smaller the distance between the conductive particles, and the smaller the resistance. The resistance of the varistor wire 10 changes, thereby playing a role in pressure sensing, and the pressure sensing signal generated by the varistor layer 102 is transmitted to the signal acquisition module 4 through the inner conductive layer 101. See Figure 5 As shown, the pressure-sensitive wire 10 is Figure 4The sampling circuit schematic diagram in FIG. 1 shows a fixed resistor on the inner conductive layer 101, R0 is the resistor at the pressure sensing point, VCC is a DC voltage source, and the pressure sensing voltage , the greater the pressure, the smaller R0 and the greater Vout.

[0053] It can be understood that the varistor layer 102 of the varistor wire 10 is similar to the outer insulating layer of a traditional wire in that both can protect the internal conductive wire; the difference between the two is that the insulating skin of a traditional wire is insulating, while the varistor layer 102 of the varistor wire 10 is conductive.

[0054] In the present application, since the surface of the inner conductive layer 101 is wrapped by the varistor layer 102 to synthesize a conductive wire with pressure sensitivity, the varistor wire 10 can be directly wired on the first supporting sheet 30, which saves the process of assembling and bonding the conductive material and the piezoresistive material in the traditional process, reduces the complexity of the assembly process, saves manpower, and eliminates high-energy consumption and high-pollution processes such as silk-screen printing and baking, which is more energy-saving and environmentally friendly; in addition, the varistor wire 10 is in electrical contact with the conductive circuit layer 22, and can form a pressure sensing matrix point, which improves the pressure sensing effect and avoids wasting piezoresistive materials in the non-sensing area of ​​the sensor; the varistor layer 102 can prevent water, dust or oxygen and other substances from corroding the inner conductive layer 101, thereby providing a good protective effect on the inner conductive layer 101.

[0055] In one embodiment, each row of piezoresistive wires 10 is protruding from the surface of the first supporting sheet 30 , and the conductive circuit layer 22 is protruding from the surface of the second supporting sheet 21 , so as to improve the sensitivity of the piezoresistive resistor layer 102 to pressure sensing.

[0056] In one embodiment, the first support sheet 30 and the second support sheet 21 are respectively made of flexible cloth materials, such as non-woven fabrics, warp and weft fabrics, or cotton fabrics.

[0057] Optionally, the pressure-sensitive wire 10 and the conductive circuit layer 22 are fixed to the fabric by weaving or silk-screening, which can play a fixing role and prevent the pressure-sensitive wire 10 from loosening and causing cross-contact and mutual conduction. Among them, weaving includes flat embroidery, quilting or coil embroidery.

[0058] In one embodiment, the first support sheet 30 and the second support sheet 21 are respectively made of a flexible plastic material, such as polyethylene terephthalate (PET), polycarbonate (PC), or polypropylene (PP).

[0059] Optionally, the varistor wire 10 and the conductive circuit layer 22 are fixed to the plastic material by bonding or silk-screen printing.

[0060] In one embodiment, the second support sheet 21 is made of metal material. Optionally, the second support sheet 21 is a copper sheet, an aluminum sheet, or a stainless steel sheet.

[0061] Optionally, the conductive circuit layer 22 is arranged on the metal material by riveting, electroplating or silk-screen printing.

[0062] In one embodiment, the conductive circuit layer 22 is woven from conductive metal fibers or conductive fabrics. The conductive metal fibers include stainless steel fibers or copper fibers. The conductive circuit layer 22 is arranged on the second support sheet 21 by weaving, silk-screening, bonding or riveting. The conductive metal fibers or conductive fabrics are electrically connected to the signal acquisition module 4 through the circuit guide sheet 23. A raised welding sheet 231 is provided at one end of the circuit guide sheet 23 to facilitate welding with the signal acquisition module 4. Optionally, the circuit guide sheet 23 is a flexible PCB board.

[0063] In one embodiment, the conductive circuit layer 22 is made of a conductive coating material. The conductive coating includes a carbon coating, a coating of pure metal or a metal mixture such as gold or silver. The conductive coating is coated on the second support sheet 21 to form the conductive circuit layer 22. The conductive coating is electrically connected to the signal acquisition module 4 through the circuit guide sheet 23, and a raised welding sheet 231 is provided at one end of the circuit guide sheet 23 to facilitate welding with the signal acquisition module 4. Optionally, the circuit guide sheet 23 is a flexible PCB board.

[0064] Working principle of this flexible pressure sensor:

[0065] The pressure-sensitive layer and the conductive layer 2 are conductive. When subjected to vertical pressure, the piezoresistive layer 102 on the piezoresistive wire 10 undergoes elastic deformation. Since the thickness in the vertical direction is reduced after being compressed, the length and width in the horizontal direction remain unchanged, so that the resistance of the piezoresistive layer 102 in the vertical direction is also reduced. The pressure-sensitive layer and the conductive layer 2 are respectively connected to the positive and negative electrodes of the signal acquisition module 4. Pressing the second support sheet 21 or the first support sheet 30, the pressure-sensitive layer, the conductive layer 2 and the signal acquisition module 4 form a passage, and the force resistance of the piezoresistive layer 102 changes accordingly. The signal acquisition module 4 measures the resistance change of the piezoresistive layer 102 and finally obtains the corresponding pressure value. The piezoresistive wire 10 can be arranged into sensing lines of various patterns on the first support sheet 30, and can be bent and deformed with the first support sheet 30. The inner conductive layer 101 is electrically connected to the signal acquisition module 4, which can transmit pressure sensing signals on the one hand, and can achieve structural fixation of the piezoresistive wire 10 on the other hand.

[0066] The above are only optional implementations of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the basic concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A flexible pressure sensor based on a pressure sensing wire, characterized in that: It comprises a pressure-sensitive layer, a conductive layer (2) and a signal acquisition module (4); The pressure-sensitive layer comprises a first supporting sheet (30) and a plurality of rows of pressure-sensitive wires (10); each row of pressure-sensitive wires (10) is arranged on the surface of the first supporting sheet (30); The conductive layer (2) comprises a second supporting sheet (21) and a conductive circuit layer (22); the conductive circuit layer (22) is arranged on the surface of the second supporting sheet (21); The first support sheet (30) and the second support sheet (21) are arranged opposite to and in parallel; the pressure-sensitive wire (10) and the conductive circuit layer (22) are respectively located between the first support sheet (30) and the second support sheet (21); The varistor wire (10) comprises an inner conductive layer (101) and a varistor layer (102) sleeved on the outer surface of the inner conductive layer (101); The varistor layer (102) is in electrical contact with the conductive circuit layer (22); the conductive circuit layer (22) and the inner conductive layer (101) are respectively electrically connected to the signal acquisition module (4).

2. The flexible pressure sensor based on pressure sensing wire according to claim 1, characterized in that: The varistor layer (102) is formed by solidifying a polymer plastic substrate mixed with conductive particles; The conductive particles include one or more of conductive carbon black, carbon nanotubes and conductive metal particles.

3. The flexible pressure sensor based on pressure sensing wire according to claim 1, characterized in that: Each row of pressure-sensitive wires (10) is protrudingly arranged on the surface of the first supporting sheet (30); The conductive circuit layer (22) is arranged protrudingly on the surface of the second supporting sheet (21).

4. The flexible pressure sensor based on pressure sensing wire according to claim 1, characterized in that: The first supporting sheet (30) and the second supporting sheet (21) are respectively made of flexible cloth material.

5. The flexible pressure sensor based on pressure sensing wire according to claim 4, characterized in that: The conductive circuit layer (22) is woven from conductive metal fibers or made from a conductive coating; The conductive circuit layer (22) is woven or bonded to the second support sheet (21), and is electrically connected to the signal acquisition module (4) via a circuit guide sheet (23), wherein a protruding welding sheet (231) is provided at one end of the circuit guide sheet (23).

6. The flexible pressure sensor based on pressure sensing wire according to claim 5, characterized in that: The conductive circuit layer (22) is made of copper fiber or carbon coating.

7. The flexible pressure sensor based on pressure sensing wire according to claim 1, characterized in that: The rows of pressure-sensitive wires (10) on the surface of the first support sheet (30) are parallel to each other; The conductive circuit layer (22) comprises a plurality of rows of conductive wires; each row of conductive wires is arranged parallel to each other on the surface of the second supporting sheet (21).

8. The flexible pressure sensor based on pressure sensing wire according to claim 7, characterized in that: Each row of pressure-sensitive wires (10) on the surface of the first support sheet (30) and each row of conductive wires on the surface of the second support sheet (21) intersect with each other.

9. The flexible pressure sensor based on pressure sensing wire according to claim 8, characterized in that: The rows of pressure-sensitive wires (10) on the surface of the first support sheet (30) and the rows of conductive wires on the surface of the second support sheet (21) are perpendicular to each other.

10. The flexible pressure sensor based on pressure sensing wire according to claim 7, characterized in that: One end of each row of conductive wires is electrically connected to the signal acquisition module (4) along a line guide sheet (23); One end of the line guide piece (23) is provided with a protruding welding piece (231).

Images