CN115290223A - Flexible force-sensitive sensing test method based on RC oscillation frequency detection - Google Patents
Flexible force-sensitive sensing test method based on RC oscillation frequency detection Download PDFInfo
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- CN115290223A CN115290223A CN202111626111.XA CN202111626111A CN115290223A CN 115290223 A CN115290223 A CN 115290223A CN 202111626111 A CN202111626111 A CN 202111626111A CN 115290223 A CN115290223 A CN 115290223A
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- 230000010355 oscillation Effects 0.000 title claims abstract description 15
- 238000001514 detection method Methods 0.000 title claims abstract description 13
- 238000010998 test method Methods 0.000 title claims abstract description 9
- 239000004205 dimethyl polysiloxane Substances 0.000 claims abstract description 27
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims abstract description 27
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 26
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 6
- 235000013870 dimethyl polysiloxane Nutrition 0.000 claims abstract 7
- CXQXSVUQTKDNFP-UHFFFAOYSA-N octamethyltrisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C CXQXSVUQTKDNFP-UHFFFAOYSA-N 0.000 claims abstract 7
- 238000004987 plasma desorption mass spectroscopy Methods 0.000 claims abstract 7
- 230000008859 change Effects 0.000 claims description 25
- 230000035945 sensitivity Effects 0.000 claims description 11
- 239000011231 conductive filler Substances 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 5
- 238000005259 measurement Methods 0.000 claims description 4
- 238000004458 analytical method Methods 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 2
- 239000002114 nanocomposite Substances 0.000 abstract description 3
- 239000002071 nanotube Substances 0.000 abstract description 3
- 229920000642 polymer Polymers 0.000 abstract description 3
- 239000002131 composite material Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- -1 polydimethylsiloxane Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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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
- G01L1/005—Measuring force or stress, in general by electrical means and not provided for in G01L1/06 - G01L1/22
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses a flexible force-sensitive sensing test method based on RC oscillation frequency detection, which is characterized in that a CNT/PDMS force-sensitive structure is tested in an alternating current state, the stress applied to the nanocomposite force-sensitive structure is considered, the positions, shapes and the like of carbon nano tubes in a polymer are changed, the distances among a plurality of nano tubes are also changed, a conductive network is changed, the resistance is changed, the capacitance is also considered to be changed, and finally the whole circuit is analyzed and considered. Therefore, the flexible force-sensitive sensing method for high-precision and high-sensitivity RC oscillation frequency detection is realized.
Description
Technical Field
The invention relates to the technical field of flexible force-sensitive sensing methods, in particular to a flexible force-sensitive sensing test method based on RC oscillation frequency detection.
Background
The flexible pressure sensor can be attached to an irregular surface due to the soft characteristic, and can be used for monitoring external mechanical signals, so that the flexible pressure sensor is widely applied to the fields of wearable electronics, robots, medical monitoring, human-computer interfaces and the like. According to different signal transmission modes, the flexible pressure sensors can be divided into three types: piezoresistive sensors, capacitive sensors, piezoelectric sensors, among them, piezoresistive sensors have been widely studied due to their simplicity of manufacture, low cost, convenience of signal acquisition, high pressure measurement range and high sensitivity.
At present, the sensitivity of the flexible pressure sensor is mainly tested through the change of resistance under the action of stress, and the sensitivity of the sensor is obtained through testing the change of resistance under the action of different pressures. However, the sensitivity of the force-sensitive structure is tested through the change of the resistance, so that the problem of low testing precision exists, and the improvement of the sensitivity is further influenced.
With the development of various composite force-sensitive structures, higher sensitivity and precision are required. After stress action is applied under the condition of alternating current, the change of the impedance of the composite force-sensitive structure is divided into two parts of resistance and capacitive reactance change, and the change is more accurate compared with the change of a single resistance under the condition of direct current. Therefore, a flexible force-sensitive sensing method based on RC oscillation frequency detection can be designed.
Disclosure of Invention
The invention provides a flexible force-sensitive sensing test method based on RC oscillation frequency detection, which aims at a CNT/PDMS composite force-sensitive structure with good flexibility, and applies stress to the nano composite material force-sensitive structure under the alternating current condition, so that the positions, shapes and the like of carbon nano tubes in a polymer are changed, the distances among a plurality of nano tubes are also changed, a conductive network is changed, the resistance change rate is changed, and the capacitance is also changed besides the resistance change among conductive grids.
The invention is realized by adopting the following technical scheme:
a flexible force-sensitive sensing test method based on RC oscillation frequency detection comprises the following steps:
(1) Preparing CNT/PDMS force sensitive structure
Weighing carbon nanotubes as conductive filler, adding alcohol into the conductive filler, and then ultrasonically oscillating the conductive filler in an ultrasonic cell crusher for one hour to uniformly disperse the carbon nanotubes in the alcohol; then adding PDMS into the mixture to be mechanically stirred, adding a curing agent after uniformly mixing, uniformly stirring, and then pouring into a mould; then putting the uniformly mixed solution into a vacuum oven, vacuumizing for 1h, and finally putting the solution on a heating table, setting the temperature to be 80 ℃, and curing for 2 hours; obtaining a CNT/PDMS force-sensitive structure, and finally cutting the CNT/PDMS force-sensitive structure into 2cm multiplied by 1cm for performance measurement;
(2) Respectively connecting two ends of the prepared CNT/PDMS force-sensitive structure with external leads, and then connecting the CNT/PDMS force-sensitive structure with a high-precision universal meter;
(3) Fixing two ends of the connected force-sensitive structure between two clamps, and realizing accurate control of the stretching of the force-sensitive structure by controlling the displacement of the clamps;
(4) Stretching the force-sensitive structure to different degrees, wherein the stretching range is 10% -100%, the stretching is increased by 10% each time, calculating the sensitivity of the force-sensitive structure, and repeating the steps;
(5) And obtaining a relation graph of the resistance change rate and the stretching of the force-sensitive structure and a relation graph of the frequency and the stretching of the force-sensitive structure through operation and analysis.
The invention adopts the alternating current circuit to test the CNT/PDMS force sensitive structure, and compared with the direct current circuit, the problem of low accuracy caused by neglecting capacitance change of the traditional direct current circuit is solved. Under the condition of alternating current, stress is applied to the CNT/PDMS force-sensitive structure, and the conductive grids have resistance change and capacitance change, namely, impedance equivalent replacement can be used.
The invention has reasonable design and good practical application value.
Drawings
Fig. 1 shows a flexible force-sensitive working system based on RC oscillation frequency detection.
Fig. 2 shows the relative rate of change of resistance of the sensor under different tensions.
Fig. 3 shows an equivalent circuit of a composite force-sensitive structure in the case of a dc/ac circuit.
FIG. 4 shows a graph of frequency versus force sensitive structure stretch.
In the figure: 1-alternating current power supply, 2-lead, 3-CNT/PDMS force sensitive structure and 4-high precision multimeter.
Detailed Description
The following detailed description of specific embodiments of the invention refers to the accompanying drawings.
A flexible force-sensitive sensing working system based on RC oscillation frequency detection comprises a Carbon Nano Tube (CNT), polydimethylsiloxane (PDMS), a clamp, an alternating current voltage source, a lead and a high-precision multimeter. The specific connection relationship is shown in fig. 1.
And an alternating current circuit is adopted, and the capacitance change in the CNT/PDMS force-sensitive structure is fully considered, so that the calculation result is more accurate, and higher sensitivity and precision are obtained.
The specific test method comprises the following steps:
(1) Preparing CNT/PDMS force sensitive structure
Weighing 0.25 g of carbon nano tube as a conductive filler, adding 1 ml of alcohol into the conductive filler, and then carrying out ultrasonic oscillation for one hour in an ultrasonic cell crusher to uniformly disperse the carbon nano tube in the alcohol; then adding PDMS into the mixture to be mechanically stirred, adding a curing agent after uniformly mixing, uniformly stirring, and then pouring into a mould; in order to remove bubbles in the sample, the uniformly mixed solution is put into a vacuum oven, vacuumized for 1h, finally placed on a heating table, set at the temperature of 80 ℃ and cured for 2 hours; the CNT/PDMS force sensitive structures were obtained and finally cut into 2cm by 1cm sizes for performance measurements.
(2) And respectively connecting two ends of the prepared CNT/PDMS force-sensitive structure with external leads, and then connecting the CNT/PDMS force-sensitive structure with a high-precision multimeter.
(3) And fixing two ends of the connected force-sensitive structure between two clamps, and realizing the accurate control of the stretching of the force-sensitive structure by controlling the displacement of the clamps.
(4) And stretching the force-sensitive structure to different degrees, wherein the stretching range is 10% -100%, the stretching is increased by 10% each time, the sensitivity of the force-sensitive structure is calculated, and the process is repeated.
(5) And obtaining a relation graph of the resistance change rate and the stretching of the force-sensitive structure and a relation graph of the frequency and the stretching of the force-sensitive structure through calculation and analysis.
As shown in FIG. 2, the relative rate of change of resistance of the sensor under different tensile conditions, where ΔRThe resistance change values of the sensor under different stretching states are obtained. It can be found that the greater the stretching, the greater the relative rate of change in resistance.
As shown in FIG. 3, the equivalent circuit of CNT/PDMS force-sensitive test is performed under DC condition ((a) (b)) and AC condition ((c) (d)). Under the condition of direct current, the capacitance change is ignored by the composite force sensitive structure, and under the condition of alternating current, the capacitance change is fully considered, so that the measurement is more accurate.
As shown in fig. 4, the force-sensitive characteristic of the force-sensitive structure under different tensile stresses is tested. The horizontal axis of the graph shows the frequency, and the maximum value of the frequency can be found to be changed by observing different stretching conditions.
In the flexible force-sensitive sensing test method based on the RC oscillation frequency detection provided by this embodiment, an experiment is performed on the CNT/PDMS force-sensitive structure under an alternating current state, except for considering that stress is applied to the nanocomposite force-sensitive structure, the positions, shapes, and the like of the carbon nanotubes in the polymer change, and distances between the nanotubes also change, so that the conductive network changes, which causes the resistance to change, and also considering that the capacitance changes, and finally, the whole circuit is analyzed and considered, thereby realizing the flexible force-sensitive sensing method based on the RC oscillation frequency detection with high precision and high sensitivity.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the detailed description is made with reference to the embodiments of the present invention, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which shall be covered by the claims of the present invention.
Claims (1)
1. A flexible force-sensitive sensing test method based on RC oscillation frequency detection is characterized in that: the method comprises the following steps:
(1) Preparing CNT/PDMS force sensitive structure
Weighing carbon nano tubes as a conductive filler, adding alcohol into the conductive filler, and then carrying out ultrasonic oscillation for one hour in an ultrasonic cell crusher to uniformly disperse the carbon nano tubes in the alcohol; then adding PDMS into the mixture to be mechanically stirred, adding a curing agent after uniformly mixing, uniformly stirring, and then pouring into a mould; then putting the uniformly mixed solution into a vacuum oven, vacuumizing for 1h, and finally putting the solution on a heating table, setting the temperature to be 80 ℃, and curing for 2 hours; obtaining a CNT/PDMS force-sensitive structure, and finally cutting the CNT/PDMS force-sensitive structure into 2cm multiplied by 1cm for performance measurement;
(2) Respectively connecting two ends of the prepared CNT/PDMS force-sensitive structure with external leads, and then connecting the CNT/PDMS force-sensitive structure with a high-precision multimeter;
(3) Fixing two ends of the connected force-sensitive structure between two clamps, and realizing accurate control of the tension of the force-sensitive structure by controlling the displacement of the clamps;
(4) Stretching the force-sensitive structure to different degrees, wherein the stretching range is 10% -100%, the stretching is increased by 10% each time, calculating the sensitivity of the force-sensitive structure, and repeating the steps;
(5) And obtaining a relation graph of the resistance change rate and the stretching of the force-sensitive structure and a relation graph of the frequency and the stretching of the force-sensitive structure through operation and analysis.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105136375A (en) * | 2015-09-09 | 2015-12-09 | 宁波绿凯节能科技有限公司 | Preparation method of flexible pressure sensor having high sensitivity |
| CN105547138A (en) * | 2015-12-07 | 2016-05-04 | 大连理工大学 | Method for manufacturing flexible strain sensor by utilizing macroscopic net structure carbon nano coil |
| GB201812297D0 (en) * | 2018-07-27 | 2018-09-12 | Impact Tech Labs Ag | A force sensitive resistor |
| WO2018218895A1 (en) * | 2017-05-31 | 2018-12-06 | 华南理工大学 | High-tensile and high-sensitivity flexible force-sensitive sensory fiber and preparation method therefor |
| CN109115282A (en) * | 2018-10-25 | 2019-01-01 | 南京大学 | A kind of preparation method of Bionic flexible stress/strain sensor |
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- 2021-12-29 CN CN202111626111.XA patent/CN115290223A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105136375A (en) * | 2015-09-09 | 2015-12-09 | 宁波绿凯节能科技有限公司 | Preparation method of flexible pressure sensor having high sensitivity |
| CN105547138A (en) * | 2015-12-07 | 2016-05-04 | 大连理工大学 | Method for manufacturing flexible strain sensor by utilizing macroscopic net structure carbon nano coil |
| WO2018218895A1 (en) * | 2017-05-31 | 2018-12-06 | 华南理工大学 | High-tensile and high-sensitivity flexible force-sensitive sensory fiber and preparation method therefor |
| GB201812297D0 (en) * | 2018-07-27 | 2018-09-12 | Impact Tech Labs Ag | A force sensitive resistor |
| CN109115282A (en) * | 2018-10-25 | 2019-01-01 | 南京大学 | A kind of preparation method of Bionic flexible stress/strain sensor |
Non-Patent Citations (3)
| Title |
|---|
| 安萍;郭浩;陈萌;赵苗苗;杨江涛;刘俊;薛晨阳;唐军;: "碳纳米管/聚二甲基硅氧烷复合薄膜的制备及力敏特性研究", 物理学报, no. 23, 8 December 2014 (2014-12-08), pages 237306 - 1 * |
| 胡海龙 等: "循环拉伸－松弛处理对聚二甲基硅氧烷／碳纳米管／碳纤维柔性力敏材料性能影响规律", 《高分子材料科学与工程》, 31 August 2020 (2020-08-31), pages 93 - 98 * |
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