CN110987031B - Flexible touch sensor - Google Patents

Flexible touch sensor Download PDF

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CN110987031B
CN110987031B CN201911299727.3A CN201911299727A CN110987031B CN 110987031 B CN110987031 B CN 110987031B CN 201911299727 A CN201911299727 A CN 201911299727A CN 110987031 B CN110987031 B CN 110987031B
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electrode
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electrode layer
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CN110987031A (en
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赵海文
王曼菲
刘吉晓
郭士杰
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Hebei University of Technology
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Hebei University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
    • G01D5/241—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes
    • G01D5/2412—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by relative movement of capacitor electrodes by varying overlap
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors

Abstract

The invention relates to a flexible touch sensor, which comprises an upper electrode layer, a middle electrode layer, a lower electrode layer, a flexible insulating layer, a piezoelectric film and two insulated flexible medium layers with elasticity; a flexible dielectric layer is positioned between the upper electrode layer and the middle electrode layer, and the upper surface and the lower surface of the flexible dielectric layer are respectively tightly attached to the lower surface of the upper electrode layer and the upper surface of the middle electrode layer; the other flexible medium layer is positioned between the middle electrode layer and the lower electrode layer, and the upper surface and the lower surface of the flexible medium layer are respectively clung to the lower surface of the middle electrode layer and the upper surface of the lower electrode layer; the flexible insulating layer is tightly attached to the lower surface of the lower electrode layer, and the piezoelectric film is tightly attached to the lower surface of the flexible insulating layer. The touch sensor can measure the size and direction of the shearing force and the positive pressure at the same time, overcomes the defect that most touch sensors in the prior art can only measure the positive pressure, and enables the robot to be more intelligent and to act more accurately and quickly.

Description

Flexible touch sensor
Technical Field
The invention relates to the technical field of robot touch sensors, in particular to a flexible touch sensor.
Background
With the progress of human life, the touch sensor has wide application in many aspects, especially in the fields of wearable equipment, bionic robots, medical care and the like. With the development of artificial intelligence technology, the requirements for human-computer interaction are higher and higher, the robot is required to accurately sense the action intention of a human, and the touch sensor is a medium for the robot to sense the action of the human body and is mainly used for sensing the external force applied to the robot. Most of the current touch sensors can measure positive pressure, and the touch sensors really receive forces in any spatial direction, so the measured forces cannot truly reflect the forces received by the robot.
The patent with application publication number CN 103852088A discloses a touch sensor, a unit capacitor of the touch sensor is composed of 4 capacitor areas, each capacitor area comprises four first electrodes and a corresponding second electrode, so as to distinguish the direction of a shearing force applied to the touch sensor; in addition, the direction of the shearing force needs to be judged through the capacitance change of the two capacitors positioned on the same side, and the sensor can only qualitatively analyze the change of the capacitance so as to judge the direction of the shearing force and cannot quantitatively analyze the size of the shearing force; the sensor cannot measure the received positive pressure, so that the sensor cannot measure the external force in any direction.
Disclosure of Invention
In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a flexible tactile sensor.
The technical scheme adopted by the invention for solving the technical problems is to provide a flexible touch sensor which is characterized by comprising an upper electrode layer, a middle electrode layer, a lower electrode layer, a flexible insulating layer, a piezoelectric film and two insulating flexible dielectric layers with elasticity; a flexible dielectric layer is positioned between the upper electrode layer and the middle electrode layer, and the upper surface and the lower surface of the flexible dielectric layer are respectively tightly attached to the lower surface of the upper electrode layer and the upper surface of the middle electrode layer; the other flexible medium layer is positioned between the middle electrode layer and the lower electrode layer, and the upper surface and the lower surface of the flexible medium layer are respectively clung to the lower surface of the middle electrode layer and the upper surface of the lower electrode layer; the flexible insulating layer is tightly attached to the lower surface of the lower electrode layer, and the piezoelectric film is tightly attached to the lower surface of the flexible insulating layer; the upper surface and the lower surface of the piezoelectric film are respectively led out with a lead which is respectively connected with the charge amplifier;
the upper electrode layer comprises a first electrode, a second electrode and a third electrode which are transverse, the first electrode and the third electrode are respectively positioned at the upper end and the lower end of the second electrode, and the first electrode and the third electrode are parallel to and do not contact with the second electrode; a lead is respectively led out of the first electrode, the second electrode and the third electrode on the upper electrode layer;
the lower electrode layer comprises a vertical fourth electrode, a vertical fifth electrode and a vertical sixth electrode, the fourth electrode and the vertical sixth electrode are respectively positioned on two sides of the vertical fifth electrode, and the fourth electrode and the vertical sixth electrode are parallel to the vertical fifth electrode and are not in contact with the vertical fifth electrode; the length of the fifth electrode is equal to the shortest distance between the first electrode and the third electrode; the shortest distance between the fourth electrode and the sixth electrode is equal to the length of the second electrode; a lead is respectively led out of the fourth electrode, the fifth electrode and the sixth electrode on the lower electrode layer;
the length and the width of the middle electrode layer are respectively equal to the length of the second electrode and the length of the fifth electrode, so that the second electrode and the fifth electrode are exactly overlapped with the middle electrode layer in space; thus, the middle electrode layer and the first electrode, the second electrode, the third electrode, the fourth electrode, the fifth electrode and the sixth electrode respectively form capacitance units, namely the sensor consists of six capacitance units; a lead is led out of the middle electrode layer and is connected with a GND end of an external measuring circuit; the leads of the first electrode, the second electrode, the third electrode, the fourth electrode, the fifth electrode and the sixth electrode are respectively connected into a capacitance-resistance voltage division circuit of an external measuring circuit, and the electrodes are mutually connected in parallel;
the length and the width of the flexible medium layer are respectively equal to the maximum distance between the first electrode and the third electrode and the maximum distance between the fourth electrode and the sixth electrode.
Compared with the prior art, the invention has the beneficial effects that:
1. the sensor can simultaneously measure the size and direction of the shearing force and the positive pressure, and overcomes the defect that most of touch sensors in the prior art can only measure the positive pressure; the sensor is arranged on the arm of the robot, the sensor senses the force and generates deformation, the direction of the shearing force is judged through the capacitance change between the electrodes, the intention of the robot can be accurately judged, namely, whether the robot wants the arm of the robot to rotate or not and to which direction the robot wants to rotate, man-machine interaction is better realized, the robot is more intelligent, the action of the robot is more accurate and faster, and the process of operating a switch button and inputting a program by a person is omitted.
2. The flexibility is better, and thickness is thinner. All electrode layers and flexible dielectric layers of the sensor are made of high-flexibility materials, the whole structure has high flexibility, deformation such as stretching, curling and pressing can be achieved, and the application range is wider.
3. The capacitance value that needs accurate measurement only has the capacitance value between second electrode and the middle electrode layer, and the measurement degree of difficulty is little, receives the interference little, and the design is more reasonable.
4. The size of each electrode can be adjusted according to actual demand by the sensor, and only need judge whether there is the capacitance value between first electrode, third electrode, fourth electrode, sixth electrode and the middle electrode layer, need not measure accurate size, so the area of first electrode, third electrode, fourth electrode, sixth electrode can be less, reduce cost.
5. The electrode material adopts the conductive adhesive tape or the conductive copper foil tape, so that the resistance is low, the cost is low, the laminating mode is direct laminating, and the process is simple.
Drawings
FIG. 1 is a longitudinal cross-sectional view of the present invention;
FIG. 2 is a diagram of the position relationship of the upper electrode layer and the flexible dielectric layer according to the present invention;
FIG. 3 is a diagram of the position relationship of the intermediate electrode layer and the flexible dielectric layer according to the present invention;
FIG. 4 is a diagram of the position relationship of the lower electrode layer and the flexible dielectric layer according to the present invention;
FIG. 5 is a diagram of the positional relationship of the upper electrode layer and the middle electrode layer according to the present invention;
FIG. 6 is a diagram of the positional relationship of the middle electrode layer and the lower electrode layer of the present invention;
FIG. 7 is a deformation diagram of the overall structure of the present invention when subjected to shear forces;
FIG. 8 is a diagram showing the relative positions of the upper electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the positive direction of the x-axis;
FIG. 9 is a diagram showing the relative positions of the lower electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the positive direction of the x-axis;
FIG. 10 is a diagram showing the relative positions of the upper electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the negative x-axis direction;
FIG. 11 is a diagram showing the relative positions of the lower electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the negative x-axis direction;
FIG. 12 is a diagram showing the relative positions of the upper electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the positive direction of the y-axis;
FIG. 13 is a diagram showing the relative positions of the lower electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the positive y-axis direction;
FIG. 14 is a diagram showing the relative positions of the upper electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the negative y-axis direction;
FIG. 15 is a diagram showing the relative positions of the lower electrode layer and the middle electrode layer when the present invention is subjected to a shear force in the negative y-axis direction;
FIG. 16 is a diagram showing the relative positions of the upper electrode layer and the middle electrode layer when a shear force is applied obliquely upward and rightward according to the present invention;
FIG. 17 is a diagram showing the relative positions of the lower electrode layer and the middle electrode layer when a shear force is applied obliquely upward and rightward according to the present invention;
in the figure: 1-an upper electrode layer; 2-a flexible dielectric layer; 3-an intermediate electrode layer; 4-a lower electrode layer; 5-a flexible insulating layer; 6-piezoelectric film; 7-a first electrode; 8-a second electrode; 9-a third electrode; 10-a fourth electrode; 11-a fifth electrode; 12-sixth electrode.
Detailed Description
The invention is further illustrated with reference to the following figures and specific examples, which are not intended to limit the invention in any way.
The invention provides a flexible touch sensor (for short, see fig. 1-17), which comprises an upper electrode layer 1, a middle electrode layer 3, a lower electrode layer 4, a flexible insulating layer 5, a piezoelectric film 6 and two insulating flexible medium layers 2 with elasticity; a flexible dielectric layer 2 is positioned between the upper electrode layer 1 and the middle electrode layer 3, and the upper surface and the lower surface of the flexible dielectric layer 2 are respectively clung to the lower surface of the upper electrode layer 1 and the upper surface of the middle electrode layer 3; the other flexible medium layer 2 is positioned between the middle electrode layer 3 and the lower electrode layer 4, and the upper surface and the lower surface of the flexible medium layer 2 are respectively clung to the lower surface of the middle electrode layer 3 and the upper surface of the lower electrode layer 4; the flexible insulating layer 5 is tightly attached to the lower surface of the lower electrode layer 4, the piezoelectric film 6 is tightly attached to the lower surface of the flexible insulating layer 5, and the flexible insulating layer 5 completely covers the upper surface of the piezoelectric film 6, so that the piezoelectric film 6 is prevented from being conductive with the lower electrode layer 4; the upper surface and the lower surface of the piezoelectric film 6 are respectively led out with a lead which is respectively connected with a charge amplifier and used for measuring the positive pressure;
the upper electrode layer 1 (see fig. 2) comprises a first electrode 7, a second electrode 8 and a third electrode 9 which are transverse, wherein the first electrode 7 and the third electrode 9 are respectively positioned at the upper end and the lower end of the second electrode 8, and are parallel to and not in contact with the second electrode 8; a lead is respectively led out from the first electrode 7, the second electrode 8 and the third electrode 9 on the upper electrode layer 1 and is connected with an external measuring circuit;
the lower electrode layer 4 (see fig. 4) comprises a fourth electrode 10, a fifth electrode 11 and a sixth electrode 12 which are vertical, the fourth electrode 10 and the sixth electrode 12 are respectively positioned at two sides of the fifth electrode 11, and are parallel to and not in contact with the fifth electrode 11; the length of the fifth electrode 11 is equal to the shortest distance between the first electrode 7 and the third electrode 9; the shortest distance between the fourth electrode 10 and the sixth electrode 12 is equal to the length of the second electrode 8; a lead is respectively led out from the fourth electrode 10, the fifth electrode 11 and the sixth electrode 12 on the lower electrode layer 4 and is connected with an external measuring circuit; the length and the width of the flexible medium layer 2 are respectively equal to the maximum distance between the first electrode 7 and the third electrode 9 and the maximum distance between the fourth electrode 10 and the sixth electrode 12;
the middle electrode layer 3 (see fig. 3) is a whole electrode, the length and width of the electrode are respectively equal to the length of the second electrode 8 and the length of the fifth electrode 11, so that the second electrode 8 and the fifth electrode 11 are exactly overlapped with the middle electrode layer 3 in space; the intermediate electrode layer 3 thus forms capacitive units with the first electrode 7, the second electrode 8, the third electrode 9, the fourth electrode 10, the fifth electrode 11 and the sixth electrode 12, respectively, i.e. the sensor is formed by six capacitive units; a lead is led out of the middle electrode layer 3 and is connected to a GND end of an external measuring circuit to serve as a common measuring end; the external measuring circuit is provided with six capacitance-resistance voltage division circuits, and leads of the first electrode 7, the second electrode 8, the third electrode 9, the fourth electrode 10, the fifth electrode 11 and the sixth electrode 12 are respectively connected into the six capacitance-resistance voltage division circuits of the external measuring circuit; and judging the direction and the magnitude of the shearing force according to the change values of the six capacitors.
The flexible medium layer 2 is made of an insulating elastomer which can automatically recover to an initial state after being stressed, and the thickness of the flexible medium layer is 1-5 mm; the composite material can be prepared by mixing and stirring Polydimethylsiloxane (PDMS) prepolymer and plasticizer according to the proportion of 100:9, and then cooling; or can be made of polyurethane thermoplastic elastomer or silica gel elastomer; the piezoelectric film 6 is made of polyvinylidene fluoride (PVDF);
the upper electrode layer 1 and the lower electrode layer 4 are both made of conductive adhesive tapes or conductive copper foil tapes, the middle electrode layer 3 is made of double-sided carbon conductive tapes or double-sided copper conductive tapes, and the thicknesses of the upper electrode layer 1, the lower electrode layer 4 and the middle electrode layer 3 are all 0.01-0.05 mm;
the flexible insulating layer 5 is made of polyethylene terephthalate (PET) film or polyimide resin (PI) film, and the thickness of the flexible insulating layer is about 0.025 mm.
The working principle and the working process of the invention are as follows:
when the sensor is in an initial position (the sensor is not subjected to external force), the relative positions among the upper electrode layer 1, the middle electrode layer 3 and the lower electrode layer 4 are not changed, the second electrode 8 and the fifth electrode 11 are respectively completely superposed with the middle electrode layer 3, and the second electrode 8 and the fifth electrode 11 respectively obtain initial capacitance values with the middle electrode layer 3; the first electrode 7, the third electrode 9, the fourth electrode 10 and the sixth electrode 12 do not have overlapping regions with the middle electrode layer 3, so that the capacitance values of the four capacitors are 0;
when the sensor is subjected to an external force, the flexible tactile sensor is deformed as a whole as shown in fig. 7; the upper electrode layer 1, the middle electrode layer 3 and the lower electrode layer 4 are staggered, the relative area between the two electrodes forming the capacitor is changed, the capacitance value of each capacitor is changed, and the force can be calculated according to the change of the capacitor.
When the sensor is subjected to a shear force in the positive direction of the x-axis, the positional relationship between the upper electrode layer 1 and the middle electrode layer 3 and the positional relationship between the middle electrode layer 3 and the lower electrode layer 4 are shown in fig. 8 and 9; the sensor inclines to the positive direction of the x axis, and the upper electrode layer 1 and the middle electrode layer 3 respectively deviate to the positive direction of the x axis; the first electrode 7, the third electrode 9 and the fourth electrode 10 do not overlap with the middle electrode layer 3, and the capacitance is still 0; the area of the second electrode 8 coinciding with the intermediate electrode layer 3 is reduced, resulting in a reduced capacitance; the sixth electrode 12 is partially overlapped with the middle electrode layer 3, so that the capacitance is increased; the overlapping area of the fifth electrode 11 and the middle electrode layer 3 is unchanged, so that the capacitance is unchanged;
when the sensor is subjected to a shearing force in the x-axis negative direction, the positional relationship between the upper electrode layer 1 and the middle electrode layer 3 and the positional relationship between the middle electrode layer 3 and the lower electrode layer 4 are shown in fig. 10 and 11; the sensor inclines to the negative direction of the x axis, and the upper electrode layer 1 and the middle electrode layer 3 respectively deviate to the negative direction of the x axis; no overlapping area exists between the first electrode 7, the third electrode 9 and the sixth electrode 12 and the middle electrode layer 3, and the capacitance is still 0; the area of the second electrode 8 coinciding with the intermediate electrode layer 3 is reduced, resulting in a reduced capacitance; the fourth electrode 10 is partially overlapped with the middle electrode layer 3, so that the capacitance is increased; the overlapping area of the fifth electrode 11 and the middle electrode layer 3 is unchanged, so that the capacitance is unchanged;
when the sensor is subjected to a shear force in the positive y-axis direction, the positional relationship between the upper electrode layer 1 and the middle electrode layer 3 and the positional relationship between the middle electrode layer 3 and the lower electrode layer 4 are shown in fig. 12 and 13; the sensor inclines to the positive direction of the y axis, and the upper electrode layer 1 and the middle electrode layer 3 respectively deviate to the positive direction of the y axis; the first electrode 7, the fourth electrode 10 and the sixth electrode 12 do not overlap with the intermediate electrode layer 3, and the capacitance remains 0; the overlapping area of the second electrode 8 and the middle electrode layer 3 is unchanged, so that the capacitance is unchanged; the third electrode 9 is partially overlapped with the middle electrode layer 3, so that the capacitance is increased; the overlapping area of the fifth electrode 11 and the middle electrode layer 3 is reduced, and the capacitance is reduced;
when the sensor is subjected to a shear force in the y-axis negative direction, the positional relationship between the upper electrode layer 1 and the middle electrode layer 3 and the positional relationship between the middle electrode layer 3 and the lower electrode layer 4 are shown in fig. 14 and 15; the sensor inclines to the negative direction of the y axis, and the upper electrode layer 1 and the middle electrode layer 3 respectively deviate to the negative direction of the y axis; no overlapping area exists between the third electrode 9, the fourth electrode 10 and the sixth electrode 12 and the middle electrode layer 3, and the capacitance is still 0; the overlapping area of the second electrode 8 and the middle electrode layer 3 is unchanged, so that the capacitance is unchanged; the first electrode 7 is partially overlapped with the middle electrode layer 3, so that the capacitance is increased; the overlapping area of the fifth electrode 11 and the middle electrode layer 3 is reduced, and the capacitance is reduced;
when the sensor is subjected to a shear force which is inclined to the upper right, the force can be decomposed into a component force in the positive direction of the x axis and a component force in the positive direction of the y axis, and the positional relationship between the upper electrode layer 1 and the middle electrode layer 3 and the positional relationship between the middle electrode layer 3 and the lower electrode layer 4 are shown in fig. 16 and 17; the first electrode 7 and the fourth electrode 10 do not overlap with the intermediate electrode layer 3, and the capacitance remains 0; the areas of the second electrode 8 and the fifth electrode 11 which are respectively overlapped with the middle electrode layer 3 are reduced, and the corresponding capacitances are respectively reduced; the third electrode 9 and the sixth electrode 12 are respectively overlapped with the middle electrode layer 3, and the corresponding capacitance is respectively increased; when the sensor is subjected to the shearing force in other oblique directions, the transformation can be carried out in the same way;
in summary, by measuring the capacitance change between each electrode and the middle electrode layer 3, the direction of the shearing force and the qualitative change of the analysis capacitance can be determined.
The following illustrates how to quantitatively determine the positive pressure and the shearing force applied to the sensor; because the thicknesses of the upper electrode layer 1, the middle electrode layer 3, the lower electrode layer 4, the flexible insulating layer 5 and the piezoelectric film 6 are different from the thicknesses of the flexible dielectric layers, the force acting on the upper electrode layer 1, the middle electrode layer 3, the lower electrode layer 4, the flexible insulating layer 5 and the piezoelectric film 6 can be ignored, and the force mainly acts on the two flexible dielectric layers;
when the sensor is only subjected to positive pressure in the vertical direction, the piezoelectric film 6 is deformed under the positive pressure to generate a piezoelectric effect, the charge quantity on the surface of the piezoelectric film can be measured by using the charge amplifier, and then the magnitude of the positive pressure F is obtained1Meets the requirements;
F1＝Q/d11， (1)
in the formula (1), Q is the amount of charge on the surface of the piezoelectric film, d11Is the piezoelectric constant of the piezoelectric film;
positive pressure F of the sensor1And also satisfies;
F1＝E*(Δd/2d0) (2)
in formula (2), E is the Young's modulus of the flexible dielectric layer, d0The initial height of a single flexible medium layer is shown, and delta d is the integral height variation of the sensor under the action of positive pressure;
obtaining delta d from the formulas (1) and (2);
when the sensor is subjected to a force in any direction in space, the force in any direction can be decomposed into a positive pressure in the vertical direction and a shearing force in the horizontal direction; the sensor is inclined under the action of shearing force, and each electrode layer is dislocated, so that the corresponding capacitance is changed, and the shearing force of the sensor in the x-axis direction is taken as an example for explanation;
initial capacitance C of the second electrode and the intermediate electrode layer0Comprises the following steps:
Figure GDA0003050824710000051
wherein epsilon is the dielectric constant of the second electrode and the medium of the intermediate electrode layer; s0The effective area between the second electrode and the middle electrode layer, namely the area of the second electrode;
capacitance C of the second electrode and the middle electrode layer after pressure is applied1Comprises the following steps:
Figure GDA0003050824710000061
wherein, the relative area change between the second electrode and the middle electrode layer is Delta S;
the capacitance change between the second electrode and the intermediate electrode layer after the application of the pressure is:
Figure GDA0003050824710000062
wherein, ε and d0And S0Is a known value, C1For the measurement, Δ S can be calculated by substituting formula (5);
the offset b of the sensor in the horizontal direction is:
b＝2*ΔS/n (6)
wherein n is the width of the second electrode;
the inclination angle of the sensor is alpha, and the tangent of the inclination angle is shear strain gamma;
γ＝tanα＝b/(2d0-Δd) (7)
in the formula (7), b is the offset of each layer in the horizontal direction;
the shear stress τ of the sensor is:
τ＝G*γ (8)
in the formula (8), G is the shear modulus of the flexible medium layer;
shear force F of the sensor2Comprises the following steps:
F2＝τ*(m*(2d0-Δd)) (9)
wherein m is the maximum distance between the first electrode 7 and the third electrode 9, i.e. the width of the flexible dielectric layer;
the sensor is subjected to shear forces in other directions, as can be obtained.
Nothing in this specification is said to apply to the prior art.

Claims (4)

1. A flexible touch sensor is characterized by comprising an upper electrode layer, a middle electrode layer, a lower electrode layer, a flexible insulating layer, a piezoelectric film and two insulating flexible medium layers with elasticity; a flexible dielectric layer is positioned between the upper electrode layer and the middle electrode layer, and the upper surface and the lower surface of the flexible dielectric layer are respectively tightly attached to the lower surface of the upper electrode layer and the upper surface of the middle electrode layer; the other flexible medium layer is positioned between the middle electrode layer and the lower electrode layer, and the upper surface and the lower surface of the flexible medium layer are respectively clung to the lower surface of the middle electrode layer and the upper surface of the lower electrode layer; the flexible insulating layer is tightly attached to the lower surface of the lower electrode layer, and the piezoelectric film is tightly attached to the lower surface of the flexible insulating layer; the upper surface and the lower surface of the piezoelectric film are respectively led out with a lead which is respectively connected with the charge amplifier;
the upper electrode layer comprises a first electrode, a second electrode and a third electrode which are transverse, the first electrode and the third electrode are respectively positioned at the upper end and the lower end of the second electrode, and the first electrode and the third electrode are parallel to and do not contact with the second electrode; a lead is respectively led out of the first electrode, the second electrode and the third electrode on the upper electrode layer;
the lower electrode layer comprises a vertical fourth electrode, a vertical fifth electrode and a vertical sixth electrode, the fourth electrode and the vertical sixth electrode are respectively positioned on two sides of the vertical fifth electrode, and the fourth electrode and the vertical sixth electrode are parallel to the vertical fifth electrode and are not in contact with the vertical fifth electrode; the length of the fifth electrode is equal to the shortest distance between the first electrode and the third electrode; the shortest distance between the fourth electrode and the sixth electrode is equal to the length of the second electrode; a lead is respectively led out of the fourth electrode, the fifth electrode and the sixth electrode on the lower electrode layer;
the length and the width of the middle electrode layer are respectively equal to the length of the second electrode and the length of the fifth electrode, so that the second electrode and the fifth electrode are exactly overlapped with the middle electrode layer in space; thus, the middle electrode layer and the first electrode, the second electrode, the third electrode, the fourth electrode, the fifth electrode and the sixth electrode respectively form capacitance units, namely the sensor consists of six capacitance units; a lead is led out of the middle electrode layer and is connected with a GND end of an external measuring circuit; the leads of the first electrode, the second electrode, the third electrode, the fourth electrode, the fifth electrode and the sixth electrode are respectively connected into a capacitance-resistance voltage division circuit of an external measuring circuit, and the electrodes are mutually connected in parallel;
the length and the width of the flexible medium layer are respectively equal to the maximum distance between the first electrode and the third electrode and the maximum distance between the fourth electrode and the sixth electrode.
2. The flexible tactile sensor of claim 1, wherein the flexible dielectric layer is an insulating elastomer and has a thickness of 1-5 mm.
3. The flexible tactile sensor according to claim 1, wherein the upper electrode layer and the lower electrode layer are made of conductive tape or conductive copper foil tape, the middle electrode layer is made of double-sided carbon conductive tape or double-sided copper conductive tape, and the upper electrode layer, the lower electrode layer and the middle electrode layer are all 0.01-0.05mm thick.
4. The flexible tactile sensor according to claim 1, wherein the flexible insulating layer is made of a polyethylene terephthalate film or a polyimide resin film and has a thickness of 0.025 mm.
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