CN108613758B - Capacitive touch sensor based on zero poisson ratio structure - Google Patents
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- 210000004027 cell Anatomy 0.000 claims abstract description 27
- 239000011347 resin Substances 0.000 claims abstract description 15
- 229920005989 resin Polymers 0.000 claims abstract description 15
- 210000002421 cell wall Anatomy 0.000 claims abstract description 10
- 238000005516 engineering process Methods 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- 229910021389 graphene Inorganic materials 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 3
- 238000010146 3D printing Methods 0.000 claims description 2
- 238000000016 photochemical curing Methods 0.000 claims description 2
- 239000000758 substrate Substances 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 239000004205 dimethyl polysiloxane Substances 0.000 description 4
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 210000003850 cellular structure Anatomy 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- -1 Polydimethylsiloxane Polymers 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 230000007547 defect Effects 0.000 description 1
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- 230000004392 development of vision Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
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- 239000004332 silver Substances 0.000 description 1
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Classifications
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- 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
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
The invention discloses a capacitive touch sensor based on a zero poisson ratio structure, which comprises an upper electrode layer, a lower electrode layer and a dielectric layer with the zero poisson ratio structure, wherein the dielectric layer is positioned between the two electrode layers; the dielectric layer with the zero poisson ratio structure is formed by a plurality of cell structures; the cell structures are arranged in an array, and the upper surface of the cell structure on the top layer is a smooth flexible photosensitive resin layer which is used for being connected with the upper electrode layer; the lower surface of the cell structure of the bottom layer is a smooth flexible photosensitive resin layer which is used for being connected with the lower electrode layer; the longitudinal section of each cell structure is a convex structure, and the lower bottom surface of the convex structure is concave; the included angle between the outer cell wall of the cell structure and the vertical direction is always alpha; when the sensor is stimulated by positive pressure, the value of alpha is unchanged all the time, so that the transverse strain perpendicular to the load direction is always zero, only the strain in the load direction is generated, and the equivalent poisson ratio is always zero.
Description
Technical Field
The invention relates to a touch sensor, in particular to a capacitive touch sensor based on a zero poisson ratio structure for measuring positive pressure.
Background
The tactile sensor is an essential medium for the robot to directly interact with the external environment. It can directly measure various property characteristics of objects and environments. Along with the progress of human life, the cooperation between the robot and the human is more and more intimate, the robot is more and more studied, and the corresponding vision and touch are endowed to the robot, so that the robot and the human are of great significance in realizing better cooperation. The development of vision is relatively mature at present, but the development of touch is continuously researched and developed. The touch sense is particularly important to realize the intelligence of the robot, and can directly reflect various information of the surrounding environment to the robot. However, the tactile skin sensors currently studied have a main function of sensing mechanical external force and lack flexibility.
The existing research shows that the mechanical properties under the touch stimulus can improve the sensitivity of the touch sensor by adding microstructures of different forms in the dielectric layer. Most of the dielectric layer materials adopted at present are Polydimethylsiloxane (PDMS), and different structure preparation is realized by utilizing the liquid-solid conversion characteristic of the PDMS material. But PDMS materials are not soft enough as a raw material for the production of electronic skin dielectric layers. The dielectric layer printed by the flexible photosensitive resin has better softness.
The document with the application number 201610644815.2 discloses a sandwich type flexible capacitive pressure sensor and a preparation method thereof, the processing and preparation method of the pressure sensor is complex, meanwhile, a multi-electrode capacitor is adopted, a very high signal to noise ratio can be generated, the influence of parasitic capacitance is large, and a silver paste binding method is adopted as a lead, so that the processing technology is high in requirement and difficult to process on a large scale.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide the capacitive touch sensor based on the zero poisson ratio structure.
The invention solves the technical problem by providing a capacitive touch sensor based on a zero poisson ratio structure, which is characterized by comprising an upper electrode layer, a lower electrode layer and a dielectric layer with the zero poisson ratio structure, wherein the dielectric layer is positioned between the two electrode layers; the dielectric layer with the zero poisson ratio structure is formed by a plurality of cell structures; the cell structures are arranged in an array, and the upper surface of the cell structure on the top layer is a smooth flexible photosensitive resin layer which is used for being connected with the upper electrode layer; the lower surface of the cell structure of the bottom layer is a smooth flexible photosensitive resin layer which is used for being connected with the lower electrode layer; the longitudinal section of each cell structure is a convex structure, and the lower bottom surface of the convex structure is concave; the included angle between the outer cell wall of the cell structure and the vertical direction is a fixed value; when the sensor is stimulated by positive pressure, the value of the included angle is unchanged all the time.
Compared with the prior art, the invention has the beneficial effects that:
1. The middle dielectric layer is formed by printing with a light-curing technology by adopting flexible photosensitive resin, has certain flexibility, realizes poisson ratio of zero through reasonable structural design, reduces transverse strain when positive pressure is detected, avoids error caused by transverse strain on analysis of stress, effectively improves the sensitivity of the sensor by mechanical characteristics, converts pressure to capacitance to the greatest extent, measures capacitance more accurately, and improves pressure detection precision.
2. The design of a zero poisson's ratio structure is determined by the poisson's ratio definition v= -epsilon iota/epsilon, where v represents poisson's ratio and is defined as the absolute value ratio of the transverse positive strain epsilon iota to the axial positive strain epsilon. Therefore, the transverse positive strain is required to be zero, and only the longitudinal strain is required, so that the detection precision and the sensitivity of the touch sensor can be improved.
3. The upper electrode layer, the lower electrode layer and the dielectric layer of the sensor are of an integral structure, and measurement errors caused by poor sealing joint between three layers of structures are reduced.
Drawings
FIG. 1 is a schematic diagram of the overall structure of one embodiment of a capacitive touch sensor based on a zero Poisson ratio structure of the present invention;
FIG. 2 is a schematic diagram of a dielectric layer structure of one embodiment of a capacitive touch sensor based on a zero Poisson ratio structure of the present invention;
FIG. 3 is a schematic diagram illustrating cell structure isometric view of a dielectric layer of one embodiment of a capacitive touch sensor based on a zero Poisson ratio structure of the present invention;
FIG. 4 is a schematic diagram of a cellular structure of a dielectric layer of one embodiment of a capacitive touch sensor based on a zero Poisson's ratio structure of the present invention;
FIG. 5 is a schematic diagram of cellular primary structure parameters of a dielectric layer of one embodiment of a capacitive touch sensor based on a zero Poisson's ratio structure of the present invention; (1, upper electrode layer; 2, dielectric layer with zero poisson ratio structure; 3, lower electrode layer);
Detailed Description
Specific examples of the present application are given below. The specific examples are provided only for further details of the present application and do not limit the scope of the claims.
The invention provides a capacitive touch sensor (see fig. 1-5, for short) based on a zero poisson ratio structure, which is used for measuring the positive pressure, and is characterized by comprising an upper electrode layer 1, a lower electrode layer 3 and a dielectric layer 2 with the zero poisson ratio structure, wherein the dielectric layer 2 is positioned between the two electrode layers; the dielectric layer 2 with the zero poisson ratio structure is formed by a plurality of cell structures 21; the cell structures 21 are arranged in an array, and the upper surface of the cell structure 21 on the top layer is a smooth flexible photosensitive resin layer which is used for being connected with the upper electrode layer 1 through a screen printing technology; the lower surface of the cell structure 21 of the bottom layer is a smooth flexible photosensitive resin layer which is used for being connected with the lower electrode layer 3 through a screen printing technology; the longitudinal section of each cell structure 21 is similar to a convex structure, and the lower bottom surface of the convex structure is concave; the included angle between the upper part of the convex-shaped structure and the vertical direction is always alpha, namely the included angle between the outer cell wall of the cell structure 21 and the vertical direction is always alpha, and the cell wall proportion coefficient is K=M/L (wherein M represents the length of the inner cell wall, L represents the length of the outer cell wall and K is a constant value); when the sensor is stimulated by positive pressure, the value of alpha is unchanged all the time, so that the strain perpendicular to the load direction is zero all the time, namely the transverse strain is zero, the load applied to the sensor only generates the strain in the load direction, namely the pressure can be completely converted into the change of capacitance, and the equivalent poisson ratio is always zero.
The poisson's ratio formula v= -epsilon iota/epsilon is converted into an equivalent poisson's ratio formula containing only alpha and K as follows: wherein cos alpha >1/2K; when K is less than or equal to 0.5, 0< alpha < arcsinK; arccos (1/2K) < α < arcsinK when K > 0.5; under the precondition, let k=0.5, μ=0 be brought into the equivalent poisson's ratio formula, resulting in α=27° (α takes 0-30 °); so under this condition, when α=27°, the equivalent poisson ratio of the cellular structure is 0;
The upper electrode layer 1 and the lower electrode layer 3 are respectively made of flexible resin, and a layer of graphene conductive film is coated on the flexible substrate to form a conductive graphene electrode;
The dielectric layer 2 with the zero poisson ratio structure takes flexible photosensitive resin as a raw material, and a microstructure with the equivalent poisson ratio of zero is obtained by 3D printing through a photo-curing technology.
The thickness of the sensor is 5mm plus or minus 1mm.
The working principle and the working flow of the capacitive touch sensor based on the zero poisson ratio structure are as follows:
When the sensor is stimulated by positive pressure, the strain generated by compression is continuously increased, the upper electrode layer 1 is deformed, the dielectric layer 2 with the zero poisson ratio structure is deformed, but the cell structure 21 is structurally special, so that the cell structure is neither transversely expanded nor transversely contracted, only longitudinal compression is generated, the equivalent poisson ratio of the dielectric layer 2 with the zero poisson ratio structure is zero, the distance between the upper electrode layer 1 and the lower electrode layer 3 is changed, and the elastic modulus of the dielectric layer 2 with the zero poisson ratio structure is constant due to the adoption of flexible resin, so that the generated deformation is in direct proportion to the pressure. The principle of the capacitive touch sensor is that the distance between the parallel polar plates influences the change of the capacitance, so that the pressure change can be converted into the change of the capacitance, and the pressure is determined by measuring the change of the capacitance. When the external detection circuit collects a capacitance signal, the capacitance changes due to the change in the distance between the upper electrode layer 1 and the lower electrode layer 3, and thus a change in pressure is detected.
During experiments, a weight of 20g is placed on the sensor, an electrode is led out through a lead, the sensor is connected to a wiring terminal of a data acquisition card of an industrial personal computer of an NI company, program control is carried out in a Labview environment, and acquisition of capacitance signals is realized through the data acquisition card. And applying positive pressure to the sensor by using a digital display pull pressure tester, and calibrating the acquired capacitance and pressure, thereby realizing the detection of the pressure. The size of the sensor is 100 x 5mm, the model of the data acquisition card is NI PXI-6251, the model of the industrial personal computer is NI PXIe-1065, and the model of the digital display pull pressure tester is ZQ-21B-1.
The invention is applicable to the prior art where it is not described.
Claims (5)
1. The capacitive touch sensor based on the zero poisson ratio structure is characterized by comprising an upper electrode layer, a lower electrode layer and a dielectric layer with the zero poisson ratio structure, wherein the dielectric layer is positioned between the two electrode layers; the dielectric layer with the zero poisson ratio structure is formed by a plurality of cell structures; the cell structures are arranged in an array, and the upper surface of the cell structure on the top layer is a smooth flexible photosensitive resin layer which is used for being connected with the upper electrode layer; the lower surface of the cell structure of the bottom layer is a smooth flexible photosensitive resin layer which is used for being connected with the lower electrode layer; the longitudinal section of each cell structure is a convex structure, and the lower bottom surface of the convex structure is concave; the included angle between the outer cell wall of the cell structure and the vertical direction is always alpha, the cell wall proportion coefficient is K=M/L, and the Poisson's ratio formula v= -epsilon iota/epsilon is converted into an equivalent Poisson's ratio formula only containing alpha and K, which is as follows: Where v represents poisson's ratio, defined as the absolute value ratio of the transverse positive strain ε iota to the axial positive strain ε; m represents the inner cell wall length, L represents the outer cell wall length, K is a fixed value, and cos alpha is more than 1/2K; when the sensor is stimulated by positive pressure, the value of alpha is unchanged all the time, so that the strain perpendicular to the load direction is always zero, the load applied to the sensor only generates the strain in the load direction, the pressure is completely converted into the change of capacitance, and the equivalent poisson ratio is always zero.
2. The capacitive touch sensor based on the zero poisson's ratio structure of claim 1, wherein 0< a < arcsinK when K is less than or equal to 0.5; arccos (1/2K) < α < arcsinK when K > 0.5; under the precondition, let k=0.5, μ=0 be brought into the equivalent poisson's ratio formula, yielding α=27°; so under this condition, when α=27°, the equivalent poisson's ratio is 0.
3. The capacitive touch sensor based on the poisson ratio structure according to claim 1 is characterized in that the upper electrode layer and the lower electrode layer are both made of flexible resin, and a layer of graphene conductive film is coated on the flexible substrate to form a conductive graphene electrode.
4. The capacitive touch sensor based on the zero poisson ratio structure according to claim 1 is characterized in that the dielectric layer of the zero poisson ratio structure takes flexible photosensitive resin as a raw material, and a microstructure with the equivalent poisson ratio of zero is obtained by 3D printing through a photo-curing technology.
5. The capacitive touch sensor based on a zero poisson's ratio structure according to claim 1, wherein the thickness of the sensor is 5mm ± 1mm.
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| CN110649307B (en) * | 2019-08-28 | 2022-08-05 | 南京航空航天大学 | Hydrogen-oxygen fuel cell box based on mixed Poisson's ratio material |
| CN111855029B (en) * | 2020-07-24 | 2022-10-04 | 京东方科技集团股份有限公司 | Flexible pressure sensor, preparation method thereof and electronic device |
| KR102357704B1 (en) * | 2021-03-30 | 2022-02-08 | 성균관대학교산학협력단 | A zero Poisson's ratio structure and a planar structure of zero Poisson's ratio in which the structure is matrixed in a plane |
| CN113358018B (en) * | 2021-06-30 | 2022-05-20 | 华中科技大学 | A tapered rod diamond lattice structure, strain sensor and measurement system |
| CN116183066A (en) * | 2022-12-08 | 2023-05-30 | 石家庄铁道大学 | Capacitive pressure sensor and preparation method thereof |
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| CN107276450A (en) * | 2017-06-07 | 2017-10-20 | 南京航空航天大学 | Indent waveform negative poisson's ratio structure based on dielectric type electroactive polymer |
| CN108032912A (en) * | 2017-12-05 | 2018-05-15 | 吉林大学 | A kind of new automobile hood with special infinitesimal born of the same parents filled layer |
| CN208998966U (en) * | 2018-06-07 | 2019-06-18 | 河北工业大学 | A capacitive tactile sensor based on zero Poisson's ratio structure |
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| GB612833A (en) * | 1945-01-20 | 1948-11-18 | Cox & Stevens Aircraft Corp | Improvements in or relating to strain gages |
| KR100201870B1 (en) * | 1997-03-27 | 1999-06-15 | 이서봉 | Cell structural body |
| JP2005233924A (en) * | 2004-01-22 | 2005-09-02 | Japan Science & Technology Agency | Apparent Poisson Ratio Control Structure, Apparent Poisson Ratio Control Method, and Sensor or Device Using the Same |
| DE202009001463U1 (en) * | 2009-02-06 | 2009-04-30 | Momes Llp | Device for measuring and determining the force, the moments and the power at a (pedal) crank |
| CN107276449B (en) * | 2017-06-07 | 2019-04-19 | 南京航空航天大学 | Chiral Negative Poisson's Ratio Structure Based on Dielectric Electroactive Polymers |
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| CN107276450A (en) * | 2017-06-07 | 2017-10-20 | 南京航空航天大学 | Indent waveform negative poisson's ratio structure based on dielectric type electroactive polymer |
| CN108032912A (en) * | 2017-12-05 | 2018-05-15 | 吉林大学 | A kind of new automobile hood with special infinitesimal born of the same parents filled layer |
| CN208998966U (en) * | 2018-06-07 | 2019-06-18 | 河北工业大学 | A capacitive tactile sensor based on zero Poisson's ratio structure |
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