CN118089665A - Preparation method of angle sensor with anisotropic structure - Google Patents
Preparation method of angle sensor with anisotropic structure Download PDFInfo
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- CN118089665A CN118089665A CN202410495658.8A CN202410495658A CN118089665A CN 118089665 A CN118089665 A CN 118089665A CN 202410495658 A CN202410495658 A CN 202410495658A CN 118089665 A CN118089665 A CN 118089665A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- 229910001338 liquidmetal Inorganic materials 0.000 claims abstract description 108
- 238000001514 detection method Methods 0.000 claims abstract description 50
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000002245 particle Substances 0.000 claims abstract description 10
- 239000004205 dimethyl polysiloxane Substances 0.000 claims description 22
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 21
- 238000002347 injection Methods 0.000 claims description 14
- 239000007924 injection Substances 0.000 claims description 14
- 239000002861 polymer material Substances 0.000 claims description 13
- 238000004806 packaging method and process Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 10
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- 241001668545 Pascopyrum Species 0.000 claims description 5
- -1 Polydimethylsiloxane Polymers 0.000 claims description 5
- 229910001128 Sn alloy Inorganic materials 0.000 claims description 5
- 241000196324 Embryophyta Species 0.000 claims description 4
- 241001465754 Metazoa Species 0.000 claims description 4
- 229920005570 flexible polymer Polymers 0.000 claims description 4
- 241000238631 Hexapoda Species 0.000 claims description 3
- YZZNJYQZJKSEER-UHFFFAOYSA-N gallium tin Chemical compound [Ga].[Sn] YZZNJYQZJKSEER-UHFFFAOYSA-N 0.000 claims description 3
- 229910000807 Ga alloy Inorganic materials 0.000 claims 1
- RHZWSUVWRRXEJF-UHFFFAOYSA-N indium tin Chemical compound [In].[Sn] RHZWSUVWRRXEJF-UHFFFAOYSA-N 0.000 claims 1
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- 230000009471 action Effects 0.000 description 10
- 229910052733 gallium Inorganic materials 0.000 description 10
- 230000000694 effects Effects 0.000 description 8
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- 235000019752 Wheat Middilings Nutrition 0.000 description 3
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
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- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical group [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 1
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- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C9/00—Measuring inclination, e.g. by clinometers, by levels
- G01C9/18—Measuring inclination, e.g. by clinometers, by levels by using liquids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/30—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C9/00—Measuring inclination, e.g. by clinometers, by levels
- G01C9/18—Measuring inclination, e.g. by clinometers, by levels by using liquids
- G01C2009/182—Measuring inclination, e.g. by clinometers, by levels by using liquids conductive
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
The invention relates to a preparation method of an angle sensor with an anisotropic structure, which comprises the steps of forming an anisotropic capillary channel in an anisotropic cavity, injecting liquid metal into the anisotropic capillary channel, and coating conductive silver paste electrodes at two ends of the anisotropic cavity structure. By duplicating the natural anisotropic fiber structure and utilizing the anisotropic characteristic of circumferential arrangement of a plurality of cylindrical or angular columnar particle swarm structures, the anisotropic capillary tube is obtained, the liquid metal conductive fluid is filled, the specificity and microstructure of the anisotropic structure are fully utilized, the flow resistance of the liquid metal in the tube is increased, the liquid metal is in gradient distribution, the detection electrode has higher conductive efficiency, the sensitivity of signals can be greatly improved, and the high-precision inclination angle sensing function of 0.005 DEG can be realized.
Description
Technical Field
The invention relates to the field of angle sensors, in particular to an angle sensor with an anisotropic structure and a preparation method thereof.
Background
The angle sensor has wide application prospects in the industrial field, such as equipment stability, aircraft flight attitude, vehicle elevation angle, medical robots and high-precision balance work stability detection. At present, the angle sensor mainly comprises capacitive, inductive and optical angle sensors, and the devices have higher requirements on environment and higher cost. The liquid-based angle sensor has poor stability and low precision, and limits further development.
The most studied at present is that gallium-based liquid metal is injected into an isotropic structure to form an angle sensor, but due to the defects of the isotropic structure, the structure size is smaller, the flow resistance of the liquid metal is not large enough, the distance required for forming a gradient section is longer, more liquid metal in a channel is needed, the sensitivity of a sensing device is lower, and high-precision dip angle detection cannot be met. The maximum resistance change rate of the angle sensor is lower than 1% by means of the characteristic of an isotropic structure (such as a hollow cylinder) and the detection precision is about 5 degrees, so that the angle sensor still needs to further improve the detection range, precision, stability and other performances under the condition of high detection requirements or severity.
According to the invention, the angle sensor with the anisotropic structure is obtained by injecting liquid metal into the capillary channel with the anisotropic structure, and an unstable liquid metal gradient distribution section is formed in the channel by utilizing an oxide film and pressure drop of the angle sensor. When the inclination occurs, the roughness of the surface of the liquid metal is changed under the action of gravity, so that the resistance is influenced, the corresponding relation between the resistance and the inclination angle is obtained, the inclination angle detection function is realized, and the angle detection function with high precision and high sensitivity can be realized.
Disclosure of Invention
In a first aspect, the present invention provides a method for preparing an angle sensor with an anisotropic structure according to the first aspect, including the following steps:
(1) And placing the anisotropic structure sample in a flexible high polymer material, and curing to obtain the anisotropic structure cavity.
The anisotropic structure sample is selected from one of plant stems, wheat middlings, leaf ears, animal or human hair, insect legs.
The flexible polymer material is selected from PDMS, TPU, PVP or PVA.
And the curing is to replicate and fix the anisotropic structure sample under the action of the flexible high polymer material and the curing agent to obtain the anisotropic cavity structure.
In one embodiment of the present invention, the flexible polymer material is Polydimethylsiloxane (PDMS), and the curing agent is a prepolymer having vinyl side chains and a crosslinking agent.
The mass ratio of the Polydimethylsiloxane (PDMS) to the curing agent is (8-12): 1.
The curing condition is kept at 60-120 ℃ for 1-3 hours.
(2) And taking out the anisotropic structure sample to obtain the anisotropic capillary channel.
And after the solidification is finished, taking out the anisotropic structure sample to obtain the anisotropic capillary channel.
(3) And reversely injecting the liquid metal, and forming the liquid metal in gradient distribution in the anisotropic cavity.
The liquid metal is gallium-based alloy, preferably any one or more of gallium metal, gallium indium alloy, gallium tin alloy and indium gallium tin alloy.
The injection speed of the liquid metal is 1-20mL/min.
And a liquid metal oxide layer is formed between the liquid metal and the inner wall of the anisotropic cavity, and the thickness of the liquid metal oxide layer is 0.1-10nm, preferably 0.5-5nm.
The air inside the cavity structure causes the surface of the injected liquid metal to oxidize to form an oxide layer, and pressure drop is generated along with gradual injection of the liquid metal, so that the liquid metal can form gradient distribution in the microstructure more easily, and meanwhile, the oxide layer is in gradient distribution when being contacted with the inner wall of the cavity structure.
The anisotropic cavity structure comprises a front end, a middle end and a rear end; the anisotropic capillary channel thus formed is also divided into a front end, a middle end and a rear end. The anisotropic capillary channel is divided into a front end, a middle end and a rear end; the liquid metal filling ratio of the front end is more than 75%, the liquid metal filling ratio of the middle end is 25-75%, and the liquid metal filling ratio of the rear end is less than 25%.
Specifically, as liquid metal is injected into the anisotropic capillary channel, the oxide layer is in close contact with the microstructure of the inner wall of the capillary channel due to the pressure drop in the front end region of the capillary channel; as the liquid metal pressure decreases, the middle end region of the capillary channel, the oxide layer adheres to the inner wall microstructure of the local region; as the liquid metal pressure is further reduced, the oxide layer is attached only to the inner wall of the micro flow channel at the rear end region of the capillary channel.
The liquid metal injection process is shown in fig. 2, wherein P 0 is the standard atmospheric pressure, P in is the additional pressure applied during the injection of the liquid metal, the flow velocity of the liquid metal in the capillary channel is v, and the liquid metal is subjected to smaller pressure along with the increase of the distance x from the injection port due to the flow resistance in the liquid metal flow process, the radius of curvature of the liquid metal surface at the farthest end is R 2, the pipe diameter is D, and the length is L.
Thus, the pressure measured x distance from the injection port can be expressed as formula (I):
(I)
After the liquid metal is injected, the action between the formed metal oxide layer (Ga 2O3), the Liquid Metal (LM) and the flexible polymer material (such as PDMS) is shown in figure 3. LM self surface tension is very high and is difficult to wet and spread on the surface of a flexible high polymer material (such as PDMS), but an oxide layer on the surface of the LM self surface tension gives LM certain mechanical property, in addition, the main component of the LM oxide layer surface is gallium oxide, the flexible high polymer material (such as PDMS) surface contains a large number of silicon oxygen bonds, strong van der Waals force can be formed between O-O atoms, the oxide layer is promoted to adhere to the flexible high polymer material (such as PDMS) surface, and liquid metal can wet and spread on the surface of a substrate coated with the oxide layer.
(4) And (3) packaging and solidifying the silver paste to obtain the angle detector with the anisotropic structure.
The packaging means that the two ends of the anisotropic structure cavity are packaged by conductive silver paste, and the conductive silver paste is solidified at the temperature of 60-120 ℃ for 1-5 hours to obtain the angle sensor.
In a second aspect, the present invention provides an angle sensor having an anisotropic structure, comprising: and the anisotropic cavity structure is internally provided with an anisotropic capillary channel, liquid metal is injected into the anisotropic capillary channel, and two ends of the anisotropic cavity structure are coated with conductive silver paste electrodes.
The axial length of the outer wall of the anisotropic cavity structure is 0.5-30cm, and the radial width is 0.5-20mm.
The anisotropic cavity structure comprises a plurality of acute angle and obtuse angle structures outside to form a plurality of cylindrical or angular column-shaped particle swarm structures.
Further, the plurality of cylindrical or angular columnar particle swarm structures are arranged at 5-180 ° with respect to each other, e.g. 180 °, 120 °, 90 °, 60 °,45 °, 36 °, 30 °, 15 °, 10 ° or 5 °, preferably 5-60 °.
The acute angle range is 5-65 degrees; the obtuse angle generally coincides with the anisotropic structure sample angle and may range from 115 to 170 °.
The liquid metal is reversely injected into the anisotropic capillary channel, the capillary channel has a microstructure, and the liquid metal forms a gradient distribution state under the action of the microstructure.
The microstructure is in a convex shape or a concave shape.
Further, the liquid metal level exhibits a periodically raised or recessed microstructure.
In contrast to the isotropic structure which is always perpendicular to the outer wall surface structure, the present invention uses an anisotropic structure which always has a plurality of obtuse angles and acute angles with respect to the outer wall surface, when the liquid metal passes through one microstructure when being injected into the channel, the reverse injection is performed when the microstructure passes through the acute angle region first if the microstructure is convex: if the microstructure is pit-shaped, the microstructure is reversely injected when passing through the obtuse angle area. And due to the anisotropic structure, enough liquid metal flow resistance can be provided, the requirement of the gradient distribution section of the liquid metal is met, and the sensitivity and the detection precision of the angle sensor can be greatly improved.
The microstructure may also be graphene micro-nanoplatelets or spheres added to the interior of the cavity.
In general, the reverse injection can form larger flow resistance, so that the liquid metal can form gradient distribution in the microstructure more easily, the performance of the sensing device is improved more favorably, if the flow resistance is small, the distance required for forming the gradient section is longer, and the more the liquid metal in the channel is, the more adverse is the sensitivity of the sensing device.
Gallium-based liquid metals perform well not only in terms of conductivity, but also in terms of mobility. Thus, the liquid metal is enclosed in an enclosed solid space containing an air gap, the liquid metal can move inside the solid and deform in response to external vibrations and pressure changes, resulting in a change in the electrical signal.
And a liquid metal oxide layer is formed between the liquid metal and the inner wall of the cavity. The oxide layer has a thickness of 0.1-10nm, preferably 0.5-5nm.
Further, the anisotropic cavity structure comprises a front end, a middle end and a rear end; the anisotropic capillary channel thus formed is also divided into a front end, a middle end and a rear end.
The liquid metal filling ratio of the front end is more than 75%, the liquid metal filling ratio of the middle end is 25-75%, and the liquid metal filling ratio of the rear end is less than 25%.
The anisotropic cavity is the epidermis of biological tissues such as plant stems, wheat middlings, leaf ears, animal or human hair, insect leg structures and the like.
In a third aspect, the present invention provides an angle sensor obtained by the preparation method according to the first aspect or an application of the angle sensor according to the second aspect in angle detection.
The liquid metal in the angle sensor with the anisotropic structure can flow freely under the action of gravity, when the inclination angle of the angle sensor changes, the liquid metal can flow along the inner wall of the anisotropic structure, the shape of the liquid metal can be changed, so that the internal resistance value of the anisotropic structure is changed, and the electric signal output proportional to the inclination angle is obtained by detecting the change of the resistance value, so that the monitoring of the real-time angle change can be realized.
The beneficial effects of the invention are as follows:
1. According to the invention, by duplicating the natural anisotropic fiber structure and utilizing the anisotropic characteristic that a plurality of cylindrical or angular column-shaped particle swarm structures are circumferentially distributed, the anisotropic capillary tube is obtained, the liquid metal conductive fluid is filled, the specificity and microstructure of the anisotropic structure are fully utilized, the flow resistance of the liquid metal in the tube is increased, the liquid metal is in gradient distribution, so that the detection electrode has higher conductive efficiency, and the sensitivity of signals can be greatly improved. When the electrode of the angle sensor with the anisotropic structure is inclined, the liquid metal generates obvious electric signal change under the action of gravity, so that the angle sensor with the anisotropic structure has a high-sensitivity angle sensing function, and the angle sensor with the anisotropic structure can realize a high-precision inclination angle sensing function of 0.005 degrees.
2. The angle sensor provided by the invention can be applied to the industrial fields of constructional engineering, geological exploration, mechanical manufacturing and the like, can also be applied to the fields of aircrafts, medical robots, high-precision level and the like with higher requirements on the accuracy of inclination angle detection for detecting angle change, forms a proper anisotropic structure by adjusting parameters such as materials, dimensions and the like, can realize accurate monitoring in different scenes, and provides support and guarantee for the work in the related fields.
3. The angle sensor provided by the invention has the advantages of ingenious structural design, simple manufacturing process, low cost, small volume, environmental friendliness and the like, is mainly made of natural biodegradable materials, can realize wider measurement range due to the fact that the liquid metal angle sensor with the anisotropic structure can be selected according to the inner wall forms of different natural organisms, can better realize the detection of the inclination angle of crops in nature, and can be widely applied to the production and research of crops.
Drawings
FIG. 1 is a schematic diagram of an anisotropic angle sensor of embodiment 1;
FIG. 2 is a schematic illustration of a process for injecting liquid metal;
FIG. 3 is a schematic illustration of the formation of a metal oxide layer and interface conditions by liquid metal injection;
FIG. 4 is a graph showing the effect of the angle sensor of example 1 on detecting tilt angle; wherein a is a detection precision signal diagram, and b is a response time signal detection diagram; c is a signal change detection diagram in a 16000s detection period; d is a signal change detection diagram in a period of 8500-8600 s; e is a signal change detection diagram in a period of 0-30 days;
Fig. 5 is a graph showing the effect of the angle sensor of example 2 on detecting the tilt angle signal. Wherein a is a detection signal diagram near 2 degrees, b is a detection precision diagram, and c is a signal amplification diagram of b;
FIG. 6 is a graph showing the effect of the angle sensor in detecting tilt signals according to embodiment 3; wherein a is a human body movement schematic diagram, b is an inclination angle detection signal diagram of an arm in a movement process, and c is an inclination angle detection signal diagram of a leg in the movement process;
FIG. 7 is a graph showing the effect of the angle sensor in detecting tilt signals according to embodiment 4;
fig. 8 is a graph showing the effect of detecting the inclination angle signal by the angle sensor according to embodiment 5. Wherein a is an analog 3D printing device structure, b is a connection signal acquisition device, c is a gear rotation process angle signal detection diagram, and D is an impact height and angle signal relation diagram;
fig. 9 is a graph showing the effect of detecting the tilt angle signal by the hollow fiber-based angle sensor of comparative example 1. Wherein a is an angle detection signal diagram, b is a fluctuation curve signal diagram, c is a rotation process signal stability effect diagram, and d is a detection precision effect diagram.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein can be arranged and designed in a wide variety of different configurations.
Example 1
An angle sensor with an anisotropic (wheat-awn) structure is prepared by the following method:
(1) Placing the anisotropic structure sample in a flexible high polymer material, and curing to obtain the outer wall of the anisotropic structure: PDMS and a curing agent are mixed according to the mass ratio of 10:1, vacuumizing to remove internal bubbles, inserting a wheat grass plant rod into the mixture, vacuumizing to remove bubbles, and keeping the mixture at 80 ℃ for 2 hours until the PDMS is solidified. The axial length of the outer wall of the anisotropic cavity structure is about 1.5-1.8 cm, and the radial diameter is about 0.05-0.2 mm.
(2) And after solidification, taking out the wheat grass plant stems in the forward direction to obtain the anisotropic capillary channel.
(3) Injecting liquid metal, and forming gradient distribution of the liquid metal in the anisotropic cavity: the liquid metal gallium indium alloy is reversely injected at the speed of 5mL/min, and pressure drop is generated along with the gradual injection of the liquid metal, so that the oxide layer is contacted with the inner wall of the cavity structure and is in gradient distribution. The thickness of the oxide layer is 3nm.
The capillary channel has a microstructure, and the liquid metal forms a gradient distribution state under the action of the microstructure.
The anisotropic capillary channel is divided into a front end, a middle end and a rear end. The liquid metal filling ratio of the front end is more than 75%, the liquid metal filling ratio of the middle end is 25-75%, and the liquid metal filling ratio of the rear end is less than 25%.
(4) And (3) packaging and solidifying silver paste to obtain the inclination angle detector with an anisotropic structure: and packaging the two ends of the anisotropic structure cavity by using conductive silver paste, and keeping the temperature of 90 ℃ for 2 hours to solidify the conductive silver paste to obtain the angle sensor.
The anisotropic cavity structure is provided with a plurality of obtuse angles and a plurality of acute angles relative to the outer wall to form a plurality of cylindrical or angular column-shaped particle group structures, and the cylindrical or angular column-shaped particle group structures are mutually distributed at 5-40 degrees. Wherein the acute angle is in the range of 10 ° to 60 °; the obtuse angle is limited by the specific configuration of the surface of the wheat middling.
The angle sensor with the anisotropic structure is connected with the electric turntable and the Agilent 34420A, and an inclination angle signal can be obtained in the process that the angle sensor rotates along with the electric turntable as shown in figure 4. The detection result shows that the detection precision of 2 degrees can be realized in the full angle range of full +/-90 degrees, the detection precision can reach 0.05 degrees in the inclination angle range of +/-14 degrees (figure 4 a), and the response time is 110ms (figure 4b, square line); after 16000s period test, the detected inclination angle signal change graph does not have obvious fluctuation (fig. 4 c), and during the period of continuous running 8500-8600s rotation cycle, the amplified signal is shown as fig. 4d, which shows that the detection result has excellent stability; the detection result is still stable after 30 days of operation, the signal fluctuation is not obviously changed (figure 4 e), and the service life is good; the anisotropic structure angle sensor has the advantages of wide detection range, high precision, high stability and long service life.
Example 2
An angle sensor with an anisotropic (barley grass) structure is prepared by the following method:
(1) Placing the anisotropic structure sample in a flexible high polymer material, and curing to obtain the outer wall of the anisotropic structure: PDMS and a curing agent (the components are a prepolymer with vinyl side chains and a crosslinking agent, purchased from dakaning 184) were mixed in a mass ratio of 12:1, vacuumizing to remove internal bubbles, inserting a wheat grass plant rod into the mixture, vacuumizing to remove bubbles, and keeping the mixture at 80 ℃ for 2 hours until the PDMS is solidified. The axial length of the outer wall of the anisotropic cavity structure is about 5-8 cm, and the radial diameter is about 0.2-0.5 mm.
(2) And after solidification, taking out the wheat grass plant stems in the forward direction to obtain the anisotropic capillary channel.
(3) Injecting liquid metal, and forming gradient distribution of the liquid metal in the anisotropic cavity: the liquid metal gallium indium alloy is reversely injected at the speed of 10mL/min, and pressure drop is generated along with the gradual injection of the liquid metal, so that the oxide layer is contacted with the inner wall of the cavity structure and is in gradient distribution. The thickness of the oxide layer is 4nm.
The capillary channel has a microstructure, and the liquid metal forms a gradient distribution state under the action of the microstructure.
The anisotropic capillary channel is divided into a front end, a middle end and a rear end. The liquid metal filling ratio of the front end is more than 75%, the liquid metal filling ratio of the middle end is 25-75%, and the liquid metal filling ratio of the rear end is less than 25%.
(4) And (3) packaging and solidifying the silver paste to obtain the angle detector with an anisotropic structure: and packaging the two ends of the cavity of the anisotropic structure by using conductive silver paste, and keeping the temperature of 100 ℃ for 2 hours to solidify the conductive silver paste to obtain the angle sensor.
The angle sensor with the anisotropic structure is connected with the electric turntable and the Agilent 34420A, and an inclination angle signal can be obtained in the process that the angle sensor rotates along with the electric turntable as shown in figure 5. The detection result shows that an average and stable detection signal (figure 5 a) can be obtained near 2 degrees, further, the detection precision of the inclination angle can reach 0.005 degrees (figures 5b and 5 c), the anisotropic structure angle sensor can obtain a more accurate detection angle, the detection precision can be as low as 0.005 degrees, and the detection precision of the angle sensor can be further and greatly improved by optimizing the size parameter of the anisotropic structure through design in the later stage.
Example 3
An angle sensor with an anisotropic (horsetail) structure is prepared by the following method:
(1) Polydimethylsiloxane PDMS and a curing agent (the components are a prepolymer with vinyl side chains and a crosslinking agent, which are purchased from Dow Corning 184) are mixed in a mass ratio of 10:1, and vacuum pumping is performed to remove internal bubbles. Then, horsetail hair (hair on horsetail) was inserted therein, and vacuum was applied to remove air bubbles. The reaction was maintained at 100deg.C for 1 hour and the PDMS was cured.
(2) And after the solidification is finished, taking out horsetail hair in the forward direction to obtain the anisotropic capillary channel.
(3) The liquid metal gallium indium alloy is reversely injected at the speed of 1mL/min, and pressure drop is generated along with the gradual injection of the liquid metal, so that the oxide layer is contacted with the inner wall of the cavity structure and is in gradient distribution.
(4) And packaging the two ends of the anisotropic structure cavity by using conductive silver paste, and keeping the temperature of 90 ℃ for 3 hours to solidify the conductive silver paste to obtain the angle sensor.
The angle sensor with anisotropic structure is fixed to the limbs of the human body and connected to Agilent 34420A, and the electrical signal output by the angle sensor during the movement of the human body (FIG. 6 a) is shown in FIG. 6. It can be seen that the detection signal has a larger variation range, the maximum electrical signal variation rate can reach 14%, and the sensor can be fixed to different parts of the human body, such as arms, legs and the like, and the corresponding inclination angle signals can be generated when the sensor moves at the parts: the detection signal changes of the forearm and the rear arm of the arm are shown in fig. 6b, the detection signal changes of the shank and thigh positions of the leg are shown in fig. 6c, the signal change range of the forearm is large, and the detection range can reach 14%; the change range of the leg detection signal is 4%, the signal range of the lower leg part is larger, the signal range of the thigh part is smaller, and each part of the body has stable signal output in the detection time range.
The inclination angle information of different body parts can be analyzed to accurately judge the motion gesture of the current human body, so that stable repeatability is shown when running actions are repeated for a plurality of times, and the wearable equipment is distinguished under different actions, thereby providing technical support for dynamic real-time monitoring of the wearable equipment.
Example 4
An angle sensor with an anisotropic (pig hair) structure is prepared by the following method:
(1) Placing the anisotropic structure sample in a flexible high polymer material, and curing to obtain the outer wall of the anisotropic structure: the human body silica gel and the curing agent are mixed according to the mass ratio of 8:1, vacuumizing to remove internal bubbles, inserting pig hair into the mixture, vacuumizing to remove bubbles, and maintaining the mixture at 100 ℃ for 1 hour until the human body silica gel is solidified. The axial length of the outer wall of the anisotropic cavity structure is about 10cm, and the radial maximum inner diameter is about 1mm.
(2) And after solidification, taking out the pig hair in the forward direction to obtain the anisotropic capillary channel.
(3) Injecting liquid metal gallium indium alloy, and forming gradient distributed liquid metal in the anisotropic cavity: and reversely injecting the liquid metal at the speed of 12mL/min, and gradually injecting the liquid metal to generate pressure drop so that the oxide layer contacts with the inner wall of the cavity structure and is in gradient distribution. The oxide layer thickness is about 1nm.
The anisotropic capillary channel is divided into a front end, a middle end and a rear end. The liquid metal filling ratio of the front end is more than 75%, the liquid metal filling ratio of the middle end is 25-75%, and the liquid metal filling ratio of the rear end is less than 25%
(4) And (3) packaging and solidifying the silver paste to obtain the angle detector with an anisotropic structure: and packaging the two ends of the anisotropic structure cavity by using conductive silver paste, and keeping the temperature of 70 ℃ for 2 hours to solidify the conductive silver paste to obtain the angle sensor.
The anisotropic cavity structure is provided with a plurality of obtuse angles and a plurality of acute angles relative to the outer wall to form a plurality of cylindrical or angular column-shaped particle group structures, and the cylindrical or angular column-shaped particle group structures are mutually distributed at 5-40 degrees.
Wherein the acute angle is in the range of 5 ° to 40 °; the obtuse angle is limited by the specific structure of the surface of the pig hair.
The angle sensor with the anisotropic structure is connected with a sample to be detected, and in the process of tilting the sample to be detected, the rotation state changes by 1-2-3-4, so that an inclination angle signal can be obtained, as shown in figure 7, and the detection process can be seen, and a larger signal detection range can be displayed, which can reach up to 18%; the raw materials of the angle sensor can be derived from plants and various animals, and the universality of the angle sensor with the anisotropic structure is shown.
Example 5
An angle sensor with an anisotropic (human hair) structure is prepared by the following method:
(1) Polydimethylsiloxane PDMS and a curing agent (the components are a prepolymer with vinyl side chains and a crosslinking agent, which are purchased from Dow Corning 184) are mixed in a mass ratio of 10:1, and vacuum pumping is performed to remove internal bubbles. Then human hair is inserted into the air bag, and the air bag is evacuated. The reaction was maintained at 100deg.C for 1 hour and the PDMS was cured. The length of the outer wall of the anisotropic cavity structure is about 2cm, and the radial diameter is about 0.1mm.
(2) And after curing is finished, taking out human hair in the forward direction to obtain the anisotropic capillary channel.
(3) The liquid metal gallium indium alloy is reversely injected at the speed of 1mL/min, and pressure drop is generated along with the gradual injection of the liquid metal, so that the oxide layer is contacted with the inner wall of the cavity structure and is in gradient distribution. The oxide layer thickness is about 3nm.
(4) And packaging the two ends of the anisotropic structure cavity by using conductive silver paste, and keeping the temperature of 90 ℃ for 3 hours to solidify the conductive silver paste to obtain the angle sensor.
The angle sensor with the anisotropic structure is fixed on a 3D mobile platform modified by a 3D printing structure and is connected with a signal acquisition device (figures 8 a-b). The angle sensor may be rotated by a gear in the form of a striker striking surface at the bottom of the platform, and an associated electrical tilt signal may be obtained (fig. 8 c). And simultaneously by analyzing the correspondence of the impact height and the inclination signal (fig. 8 d). The method is used for analyzing the morphology of the impact surface of the firing pin and is applied to a surface morphology scanning system.
Comparative example 1
(1) A hollow fiber shell with an inner diameter of 5mm is selected, and is cut into small cylinders with a length of 20cm after air drying.
(2) The gallium-indium alloy liquid metal is used as a filler in the sensor, the liquid metal is slowly injected from one end of the fiber at 2mL/min through the injector, the air in the fiber can cause the surface of the injected liquid metal to oxidize, and the oxide layer is contacted with the inner wall of the fiber and forms a gradient.
(3) And packaging the two ends of the fiber by using conductive silver paste, ensuring that liquid metal cannot flow out, then placing the fiber on a heating table for heating, controlling the temperature to be 90 ℃, and keeping the temperature for 2 hours, wherein the conductive silver paste is solidified, so as to obtain the angle sensor.
The angle sensor is connected with the electric turntable and Agilent 34420A, and the inclination angle signal is obtained in the process that the angle sensor rotates along with the electric turntable as shown in figure 9. It can be seen that the maximum resistance change rate of the angle sensor of comparative example 1 based on hollow fiber was only 0.7% (fig. 9 a), which is far lower than that of the angle sensors of examples 1 to 5; a sinusoidal signal with significant fluctuations during rotation (fig. 9 b), significant fluctuations during cyclic testing, poor stability (fig. 9 c); moreover, the angle sensor can only perform the function of angle sensing within the range of-15 degrees to 15 degrees, can only detect the change of the inclination angle of more than 5 degrees, and has lower detection precision (figure 9 d) than the detection precision of the angle sensor in the embodiment 1-5.
According to the embodiment and the comparative example, the design of the angle sensor with the anisotropic structure has the tilt angle sensing function with higher sensitivity, can meet the use requirement of the related field with higher requirements on the tilt angle detection precision, and the preparation method is accurate, simple and efficient, greatly reduces the production cost and is beneficial to industrialized popularization.
The above examples are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention, but it should be understood by those skilled in the art that the present invention is not limited thereto, and that the present invention is described in detail with reference to the foregoing examples: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The preparation method of the angle sensor with the anisotropic structure is characterized by comprising the following steps of:
(1) Placing an anisotropic structure sample in a flexible high polymer material, and curing to obtain an anisotropic structure outer wall;
(2) Taking out the anisotropic structure sample to obtain an anisotropic cavity structure and a capillary channel;
(3) Reversely injecting liquid metal into the capillary channel, and forming gradient distributed liquid metal in the anisotropic cavity structure;
(4) Packaging to obtain the angle detector with anisotropic structure.
2. The method of manufacturing an angle sensor according to claim 1, wherein the anisotropic structure sample in step (1) is selected from one of a plant stem, a wheat grass, a leaf spike, animal or human hair, and an insect leg;
The flexible polymer material is selected from one or more of PDMS, TPU, PVP or PVA.
3. The method of claim 2, wherein in step (1), the mass ratio of Polydimethylsiloxane (PDMS) to curing agent (8-12): 1, a step of; the curing condition is that the temperature is kept between 60 and 120 ℃ for 1 to 3 hours.
4. The method of manufacturing an angle sensor according to claim 1, wherein the liquid metal in step (3) is selected from one or more of indium-gallium alloy, indium-tin alloy, gallium-tin alloy and indium-gallium-tin alloy;
The injection speed of the liquid metal is 1-20mL/min.
5. The method of manufacturing an angle sensor according to claim 4, wherein the anisotropic capillary channel is divided into a front end, a middle end and a rear end; the liquid metal filling ratio of the front end is more than 75%, the liquid metal filling ratio of the middle end is 25-75%, and the liquid metal filling ratio of the rear end is less than 25%.
6. The method for manufacturing an angle sensor according to claim 4, wherein a liquid metal oxide layer is formed between the liquid metal and the inner wall of the anisotropic cavity, and the thickness of the liquid metal oxide layer is 0.5-5nm.
7. The method of manufacturing an angle sensor according to claim 1, wherein both ends of the anisotropic structure cavity are encapsulated with conductive silver paste in step (4), and the conductive silver paste is solidified at a temperature of 60-120 ℃ for 1-5 hours, thereby obtaining the angle sensor.
8. The angle sensor according to any one of claims 1 to 7, wherein the outer wall of the anisotropic cavity structure of the angle sensor comprises a plurality of acute and obtuse angle structures, forming a plurality of cylindrical or angular column-like particle swarm structures.
9. The angle sensor of claim 8, wherein the plurality of cylindrical or angular particle swarm structures are arranged at 5-180 ° relative to each other.
10. Use of an angle sensor obtained by the production method according to any one of claims 1 to 7 or an angle sensor according to any one of claims 8 to 9 for angle detection.
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