An electric field-based proximity and tactile sensing flexible sensor

Abstract

The application discloses a kind of based on electric field's proximity and tactile perception flexible sensor, it is related to sensing technical field.The sensor includes: transmitting electrode, 3D structure receiving electrode array and elastic layer.Wherein, transmitting electrode is used to generate electric field;3D structure receiving electrode array is used to generate electric potential according to electric field;Elastic layer is used to encapsulate 3D structure receiving electrode array;When target object enters electric field and does not contact elastic layer, the electric potential is used to determine the proximity of target object;When target object enters electric field and applies pressure to elastic layer, make elastic layer and 3D structure receiving electrode array deformation, the electric potential is used to determine the pressure of target object.The sensor provided by the application can realize dual perception of proximity distance and tactile pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sensing technology, in particular to a flexible sensor for proximity and tactile sensing based on electric field. BACKGROUND

[0002] Human-machine interaction, especially machine-human interaction, needs to be equipped with sensors for sensing proximity distance. In order to achieve more flexible interaction, it is also necessary to detect the force exerted by the human on the machine. Although there are sensors that can detect pressure and sensors that can detect proximity distance at present. However, it is expensive, cumbersome and complex to assemble the existing pressure sensors and proximity distance sensors on the machine, and even mutual interference may occur, which reduces the operability and reliability of human-machine interaction.

[0003] Therefore, there is an urgent need for a sensor that can realize dual sensing of proximity distance and tactile pressure. SUMMARY

[0004] The purpose of the present application is to provide a flexible sensor for proximity and tactile sensing based on electric field, so as to realize dual sensing of proximity distance and tactile pressure.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] A flexible sensor for proximity and tactile sensing based on electric field, comprising:

[0007] a transmitting electrode for generating an electric field;

[0008] a 3D structure receiving electrode array for generating an electric potential according to the electric field;

[0009] an elastic layer for encapsulating the 3D structure receiving electrode array;

[0010] When a target object enters the electric field and does not contact the elastic layer, the electric potential is used to determine the proximity of the target object; when a target object enters the electric field and exerts pressure on the elastic layer, the elastic layer and the 3D structure receiving electrode array are deformed, and the electric potential is used to determine the pressure of the target object.

[0011] Optionally, the 3D structure receiving electrode array comprises: an even number of edge receiving electrodes in canting cantilever beam structure; the even number of edge receiving electrodes are symmetric two by two and are equally spaced on the edge of the lower surface of the elastic layer.

[0012] Optionally, the transmitting electrode is encapsulated in the elastic layer and located at the center of the lower surface of the elastic layer.

[0013] Optionally, the proximity and tactile perception flexible sensor further comprises:

[0014] an insulation layer, located below the elastic layer;

[0015] a shielding layer, located below the insulation layer.

[0016] Optionally, the 3D structure receiving electrode array further comprises: a center receiving electrode; the center receiving electrode is encapsulated in the elastic layer and located at the center of the lower surface of the elastic layer.

[0017] Optionally, the transmitting electrode is embedded in the insulation layer.

[0018] Optionally, the number of the edge receiving electrodes is four.

[0019] Optionally, the structure of the elastic layer is a porous structure, a groove structure or a pleated structure.

[0020] Optionally, the materials of the transmitting electrode and the 3D structure receiving electrode array are conductive TPU; the material of the elastic layer is PDMS or Ecoflex.

[0021] Optionally, the material of the insulation layer is insulating TPU; the material of the shielding layer is conductive TPU.

[0022] According to the specific embodiments of the present application, the following technical effects are provided:

[0023] The present application provides a proximity and tactile perception flexible sensor based on electric field, which is provided with a transmitting electrode for generating electric field and a receiving electrode array for generating electric potential according to the electric field, and the receiving electrode array is a 3D structure which will be deformed under force. When a target object enters the electric field and does not contact the elastic layer, it will induce a new capacitance in the electric field, thereby affecting the electric potential generated on the receiving electrode array, so that the electric potential generated on the receiving electrode array and the proximity of the target object have a first mapping relationship, so that the proximity of the target object can be determined by using the electric potential generated by the receiving electrode array; when the target object enters the electric field and exerts pressure on the elastic layer, the elastic layer and the receiving electrode array will be deformed, thereby affecting the electric potential generated on the receiving electrode array, so that the electric potential generated on the receiving electrode array and the pressure of the target object have a second mapping relationship, so that the pressure of the target object can be determined by using the electric potential generated on the receiving electrode array. Therefore, the sensor provided by the present application can realize dual perception of proximity distance and tactile pressure. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor.

[0025] Figure 1 The structural diagram of the proximity and tactile perception flexible sensor provided for the first embodiment of the present application is shown in the figure.

[0026] Figure 2 The top view of the elastic layer of the proximity and tactile perception flexible sensor provided for the first embodiment of the present application is shown in the figure.

[0027] Figure 3 The principle diagram of the proximity and tactile perception flexible sensor provided for the first embodiment of the present application is shown in the figure.

[0028] Figure 4 The structural diagram of the proximity and tactile perception flexible sensor provided for the second embodiment of the present application is shown in the figure.

[0029] Figure 5 The broken line graph of the average value of the signal strength of the four receiving electrodes changing with the height of the object is shown in the figure.

[0030] Figure 6 The broken line graph of the sum of the average value of the signal strength of the four receiving electrodes changing with the height of the object is shown in the figure.

[0031] Figure 7 The broken line graph of the difference between the signal strength deviation values of the north and south receiving electrodes changing with the position of the object is shown in the figure.

[0032] Figure 8 The broken line graph of the difference between the signal strength deviation values of the north and south receiving electrodes changing with the position of the object is shown in the figure.

[0033] Figure 9 The schematic diagram of the underlying principle of the present application is shown in the figure.

[0034] Symbol explanation:

[0035] Transmitting electrode - 101, 3D structure receiving electrode array - 102, elastic layer - 103, insulating layer - 104, shielding layer - 105. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] The purpose of this invention is to provide a flexible sensor based on electric field for proximity and tactile perception, so as to achieve dual sensing of proximity distance and tactile pressure.

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a structural diagram of the proximity and tactile sensing flexible sensor provided in Embodiment 1 of the present invention. Figure 2 This is a top view of the elastic layer of the flexible sensor for proximity and tactile perception provided in Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the proximity and tactile sensing flexible sensor provided in Embodiment 1 of the present invention. Figure 4 This is a structural diagram of the proximity and tactile sensing flexible sensor provided in Embodiment 2 of the present invention. Figures 1 to 4 As shown, the proximity and tactile sensing flexible sensor provided by the present invention includes: a transmitting electrode 101, a 3D structure receiving electrode array 102, and an elastic layer 103.

[0040] The transmitting electrode 101 generates an electric field; the 3D structure receiving electrode array 102 generates an electric potential based on the electric field; and the elastic layer 103 encapsulates the 3D structure receiving electrode array 102. When a target object enters the electric field but does not contact the elastic layer 103, the electric potential is used to determine the proximity of the target object; when the target object enters the electric field and applies pressure to the elastic layer 103, causing deformation of the elastic layer 103 and the 3D structure receiving electrode array 102, the electric potential is used to determine the pressure of the target object.

[0041] Furthermore, the proximity and tactile sensing flexible sensor also includes an insulating layer 104 and a shielding layer 105. The insulating layer 104 is located below the elastic layer, serving as the sensor's substrate; the shielding layer 105 is located below the insulating layer 104, serving as the sensor's ground electrode, i.e., the GND layer.

[0042] Specifically, the 3D structure receiving electrode array 102 includes: an even number of edge receiving electrodes with an upwardly curved cantilever beam structure; the even number of edge receiving electrodes are symmetrically arranged in pairs and equally spaced at the edge of the lower surface of the elastic layer 103 (i.e., above the insulating layer 104). Because the edge receiving electrodes are curved upward and have a certain height, the elastic layer 103 encapsulates them from the top of the edge receiving electrodes, so that the edge receiving electrodes are completely encapsulated within the elastic layer 103.

[0043] Figure 3This is a schematic diagram of the proximity and tactile sensing flexible sensor provided in Embodiment 1 of the present invention, wherein, Figure 3 Part (a) in the diagram is a schematic diagram of the target object before it enters the electric field. Figure 3 Part (b) is a schematic diagram of the target object entering the electric field but not touching the sensor. Figure 3 Part (c) in the diagram illustrates the situation when the target object enters the electric field and applies pressure to the sensor. For example... Figure 3 As shown, due to the electric field generated by the emitting electrode 101 (see... Figure 3 (The lines with arrows in the image) The 3D structure receiving electrode array 102 generates an electric potential in an electric field, and this potential has a first mapping relationship with the proximity of the target object. When the elastic layer 103 and the 3D structure receiving electrode array 102 are subjected to force, the mapping relationship changes, meaning that the potential at this point has a second mapping relationship with the pressure of the target object. Therefore, this invention also achieves proximity and tactile perception solely based on the electric field by establishing two different mapping models.

[0044] Specifically, the proximity and pressure sensing capabilities of the sensors can be calibrated using a test object. For example, when calibrating proximity sensing, potential data is collected by placing the test object 1 cm away from the sensor surface (i.e., elastic layer 103). The collected data is then averaged and linearly interpolated to obtain the relationship between proximity and potential, i.e., the first mapping relationship. Similarly, when calibrating pressure sensing, potential data is collected by placing the test object 10 Pa away from the sensor surface. The collected data is then averaged and linearly interpolated to obtain the relationship between pressure and potential, i.e., the second mapping relationship.

[0045] In one specific implementation, four edge receiving electrodes are located in the four cardinal directions (north, south, east, and west) to form a differential structure. This structure outputs potential data in the form of differential signals, enabling ultra-high resolution object location identification. Therefore, this invention can achieve super-resolution proximity and tactile perception using a finite 3D structure receiving electrode array 102.

[0046] The elastic layer 103 has a porous, grooved, or wrinkled structure. The emitting electrode 101 and the 3D receiving electrode array 102 are both made of conductive TPU (Thermoplastic polyurethanes); the elastic layer 103 is made of PDMS (Polydimethylsiloxane) or Ecoflex (Aliphatic aromatic random copolyester). The insulating layer 104 is made of insulating TPU; the shielding layer 105 is made of conductive TPU.

[0047] The sensor is prepared from the material, is flexible, is attached to the surface of the machine without dead angle, can detect the distance and surface pressure of the human to the machine, is soft, thin and high integrated compared with the prior sensor, and combines the approaching distance and the touch perception.

[0048] Further, the application provides two different packaging combinations of the transmitting electrode 101 and the 3D structure receiving electrode array 102, see embodiment one and embodiment two.

[0049] Embodiment one

[0050] Figure 1 The structure diagram of the approaching and touch perception flexible sensor provided in the embodiment, Figure 2 The top view of the elastic layer of the approaching and touch perception flexible sensor provided in the embodiment. Figure 1 And Figure 2 As shown in the embodiment, the 3D structure receiving electrode array only includes four edge receiving electrodes, the four edge receiving electrodes are in mouth shape, are symmetrically distributed in the southeast and northwest four edges of the lower surface of the elastic layer 103, and the top view of each edge receiving electrode is specifically in isosceles trapezoidal shape; the transmitting electrode 101 is packaged in the elastic layer 103, and is located at the center of the lower surface of the elastic layer 103, that is, at the center position of the four edge receiving electrodes. Specifically, the bottom surface shape of the transmitting electrode 101 is square, and the height of the transmitting electrode 101 is less than the height of the edge receiving electrode.

[0051] Embodiment two

[0052] Figure 4 The structure diagram of the approaching and touch perception flexible sensor provided in the embodiment two. As shown in the embodiment, Figure 4 In the embodiment, the 3D structure receiving electrode array 102 also includes a center receiving electrode; the center receiving electrode is packaged in the elastic layer 103, and is located at the center of the lower surface of the elastic layer 103. The transmitting electrode 101 is embedded in the insulating layer 104. That is, the center receiving electrode is located at the position of the transmitting electrode 101 in the embodiment one, and the transmitting electrode 101 is moved to the lower side of the receiving electrode and the upper side of the ground electrode (that is, the shielding layer 105).

[0053] Specifically, the insulating layer 104 includes: an upper insulating layer and a lower insulating layer; the upper surface of the upper insulating layer is in contact with the lower surface of the elastic layer; the lower surface of the lower insulating layer is in contact with the upper surface of the shielding layer; and the transmitting electrode 101 is located between the upper insulating layer and the lower insulating layer.

[0054] The specific parameters and working principles of the proximity and tactile perception flexible sensor provided by the present application are described in detail below with Example Three.

[0055] Example Three

[0056] The specific parameters of the proximity and tactile perception flexible sensor provided by the present application are shown in Table 1, wherein the sensor is a cuboid structure with a square bottom surface, and the length of the side of the bottom surface is 22.5 cm, and the overall thickness is 2.5 mm. The number of edge receiving electrodes (i.e. RX) is four, and they are respectively located at the east, west, south and north edges in the elastic layer, and the top view shape is isosceles trapezoid, and the length of the lower base of the trapezoid is 19.5 cm, and the height of the trapezoid (i.e. the width of the receiving electrode) is 0.5 cm. The bottom surface shape of the transmitting electrode (i.e. TX) is square, and the length of the side of the bottom surface is 19 cm. The insulating layer material is TPU with a relative dielectric constant of about 4, the elastic layer material is Ecoflex with a relative dielectric constant of about 2.7, the thickness is 200 mm, and it is packaged in the uppermost layer for measuring the size of the pressure.

[0057] Table 1 Sensor Parameter Table

[0058] Parameter name Value Sensor area 22.5 cm x 22.5 cm = 506.25 cm 2 ]] RX_East South West North Long 19.5 cm, wide 0.5 cm TX 19 cm * 19 cm Insulation layer material TPU (relative permittivity ≈ 4) Elastic layer material Ecoflex (relative permittivity ≈ 2.7) Sensor overall thickness 2.5 mm

[0059] In the specific design, the lines do not cross and are connected to the corresponding pins in the shortest path. Because the lines are sensitive to target objects and environmental noise. It is recommended that the signal line be on the GND layer to reduce the interference received by the signal line, and the signal line width is 0.254 mm.

[0060] The object to be measured is a metal cylinder with a diameter of 10 mm, and at the center position of the sensor, the signal strength average values received by the east (East), west (West), south (South) and north (North) four receiving electrodes are measured in the vertical direction at intervals of 1.5 cm from 0-15 cm, and the broken line graph of the signal strength average values with the change of the object height is shown in Figure 5 , wherein the Z-axis position shown by the abscissa is the height of the object to be measured from the surface of the sensor.

[0061] As can be seen from Figure 5 , with the increase of the height, the signal strength average values received by the four receiving electrodes sensors decrease, and the sum of the signal strength average values received by the east, west, south and north receiving electrodes is made f(z) = SUM (east electrode signal strength average value, west electrode signal strength average value, south electrode signal strength average value, north electrode signal strength average value), and the broken line graph of the sum of the signal strength average values received by the east, west, south and north receiving electrodes with the change of the object height is shown in Figure 6 .

[0062] As can be seen from Figure 6As can be seen from the figure, the sum of the average signal strength of the east, west, south and north receiving electrodes decreases with the increase of the height, and thus the vertical direction detection distance can reach 0-150mm, and the resolution is better than 15mm.

[0063] Since the electrodes are symmetrically formed in pairs to form a differential structure, taking the south and north electrodes as an example, the closer the object to be measured is to the receiving electrode, the greater the potential value is, when the object moves from north to south, the potential of the south electrode increases, the potential of the north electrode decreases, and the deviation value of the signal strength received by the two electrodes changes with the position of the object, as shown in the broken line graph of Figure 7 , wherein the abscissa represents the Z-axis position, that is, the horizontal position of the object to be measured in the north-south direction at a certain height from the surface of the distance sensor. A monotonic curve of potential and position is obtained by subtracting the data of the north electrode from the data of the south electrode, as shown in Figure 8 , so that the position of the object in the north-south direction can be identified. The east-west direction is the same.

[0064] The underlying principle of the present application will be briefly described below taking one transmitting electrode and one receiving electrode as an example.

[0065] Figure 9 The underlying principle of the present application is shown in Figure 9 . As shown in part (a) of TxRx , when the target object does not enter the electric field, an electric field is generated between the transmitting electrode and the receiving electrode, C Figure 9 is the capacitance of the sensor itself, and the capacitances of the transmitting electrode and the receiving electrode are read; as shown in part (b) of Figure 9 , when the target object enters the electric field and approaches the electrode, a new capacitance is induced in parallel with the initial capacitance, and since C=εS / d, wherein ε is the dielectric constant of the medium between the electrodes, S is the area of the electrodes, and d is the distance between the electrodes, it can be seen that the closer the object is, the greater the newly generated capacitance is; as shown in part (c) of , when the target object presses the surface electrode of the sensor, C HandTx and C HandRx are greater, and at the same time, the capacitance C TxRx of the sensor also changes. Since the greater the pressure of the pressing part is, the closer the distance between the target object and the electrode is, and at the same time, the closer the receiving electrode and the transmitting electrode are, and the size structure of the receiving electrode and the Young's modulus structure of the elastic layer also change, the capacitance at this time is greater than the maximum value when the object approaches but does not contact.

[0066] Compared with the prior art, the sensor provided by the present application can realize dual perception of proximity distance and tactile pressure. At the same time, since the sensor is flexible, it can be attached to the surface of the machine without dead angles, so that the sensor can detect the distance and surface pressure of the human to the machine at the same time, and is soft, light and thin, has high integration, and well integrates the proximity distance and tactile perception, thereby improving the operability and reliability of human-machine interaction.

[0067] The various embodiments described in this specification are presented for the purpose of illustrating the principles of the present application and its best mode of operation. Each of the embodiments described in this specification are presented for the purpose of illustrating the various aspects of the present application, and the embodiments are not intended to limit the scope of the application.

[0068] The principles and operation of the present application are explained so as to enable any person skilled in the art to make and use the present application. While this specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present application, it is anticipated that the application can be practiced with variations within the scope of the claims.

Claims

1. A flexible sensor for proximity and tactile perception based on an electric field, characterized in that, The proximity and tactile sensing flexible sensor includes: Emitter electrode, used to generate an electric field; A 3D structure receiving electrode array is used to generate an electric potential according to the electric field; An elastic layer is used to encapsulate the 3D structure receiving electrode array; The 3D structure receiving electrode array includes: an even number of edge receiving electrodes with an upwardly curved cantilever beam structure; the even number of edge receiving electrodes are symmetrically distributed in pairs and at equal intervals on the edge of the lower surface of the elastic layer; When a target object enters the electric field but does not contact the elastic layer, the potential is used to determine the proximity of the target object; when the target object enters the electric field and applies pressure to the elastic layer, causing deformation of the elastic layer and the 3D structure receiving electrode array, the potential is used to determine the pressure of the target object.

2. The flexible proximity and tactile sensing sensor based on an electric field according to claim 1, characterized in that, The transmitting electrode is encapsulated within the elastic layer and is located at the center of the lower surface of the elastic layer.

3. The flexible proximity and tactile sensing sensor based on an electric field according to claim 1, characterized in that, The proximity and tactile sensing flexible sensor also includes: An insulating layer is located below the elastic layer; A shielding layer is located below the insulating layer.

4. The electric field-based proximity and tactile sensing flexible sensor according to claim 3, characterized in that, The 3D structure receiving electrode array further includes a central receiving electrode; the central receiving electrode is encapsulated within the elastic layer and is located at the center of the lower surface of the elastic layer.

5. The electric field-based proximity and tactile sensing flexible sensor according to claim 4, characterized in that, The emitting electrode is embedded in the insulating layer.

6. The flexible proximity and tactile sensing sensor based on an electric field according to claim 1, characterized in that, The number of edge receiving electrodes is four.

7. The flexible proximity and tactile sensing sensor based on an electric field according to claim 1, characterized in that, The elastic layer has a porous structure, a grooved structure, or a folded structure.

8. The electric field-based proximity and tactile sensing flexible sensor according to claim 1, characterized in that, The material of the transmitting electrode and the 3D structure receiving electrode array is conductive TPU; the material of the elastic layer is PDMS or Ecoflex.

9. The electric field-based proximity and tactile sensing flexible sensor according to claim 3, characterized in that, The insulating layer is made of insulating TPU; the shielding layer is made of conductive TPU.

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