CN112945431B - Conductive porous pressure-sensitive metamaterial with negative Poisson ratio characteristic and preparation method and application thereof - Google Patents
Conductive porous pressure-sensitive metamaterial with negative Poisson ratio characteristic and preparation method and application thereof Download PDFInfo
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- CN112945431B CN112945431B CN202110311561.3A CN202110311561A CN112945431B CN 112945431 B CN112945431 B CN 112945431B CN 202110311561 A CN202110311561 A CN 202110311561A CN 112945431 B CN112945431 B CN 112945431B
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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
- G01L1/18—Measuring force or stress, in general using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6843—Monitoring or controlling sensor contact pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
- G01L9/06—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of piezo-resistive devices
Abstract
The invention relates to a conductive porous pressure-sensitive metamaterial with a negative Poisson ratio characteristic, a preparation method and application thereof, and belongs to the field of research of sensing materials and sensing devices. Mixing the conductive nano material with an organic cross-linking agent, and forming a uniformly dispersed aqueous solution through a hydrothermal reaction; forming a porous block material with a symmetrical concave cellular micropore structure by a directional freeze drying technology; and (3) heating and roasting to enable the nano material and the organic cross-linking agent to form a cross-linked network. When the porous metamaterial is pressed, the density and the number of conductive paths of the metamaterial are rapidly increased due to bidirectional shrinkage caused by the negative Poisson ratio, so that the pressure-sensitive characteristic, the compression elasticity, the impact resistance and other mechanical properties of the metamaterial are remarkably improved. The invention also relates to an ultrasensitive flexible pressure sensor based on the conductive porous metamaterial.
Description
Technical Field
The invention relates to a preparation method and application of a porous metamaterial and a flexible pressure sensor, in particular to a preparation method of a conductive porous pressure-sensitive metamaterial with a negative Poisson ratio characteristic and an ultrasensitive pressure sensor thereof. The material can exhibit extraordinary mechanical properties, including excellent crush resistance, high load-bearing capacity, large deformability, and superior fracture toughness. It can be used for detecting pressure signal, and in the case of compression, it can be contracted in both longitudinal and transverse directions, so that its sensitivity can be greatly raised.
Background
Physical activity in the human body can produce various pressure signals, for example, low pressure signals produced by intracranial pressure, internal jugular vein pressure, and the like, in vivo can provide valuable information about physiological health conditions. Therefore, the use of pressure sensors in human health monitoring and diagnostics is becoming increasingly important. In recent years, efforts have been made to develop wearable sensors having excellent sensing performance, particularly pressure sensors having high sensitivity and durability. Generally, a pressure sensor converts a change in external force into an electrical signal. The sensing mechanisms mainly comprise piezoelectric effect, piezoresistive effect and piezoresistive effect. The sensor element of piezoresistive pressure sensor is made of active material and can be placed on a pair of parallel digital electrodes or sandwiched between two vertically arranged electrodes, and its manufacture process is simple and extensible, signal acquisition is convenient, and piezoresistive material selection is wideHas been widely studied for its advantages. However, low pressure is achieved in the wearable pressure sensor: (<High sensitivity at 1 kPa: (>100kPa -1 ) It remains a huge challenge.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a conductive porous pressure-sensitive metamaterial with a negative Poisson ratio characteristic, a preparation method thereof and application of the metamaterial in an ultra-sensitive pressure sensor.
The technical scheme of the invention is as follows:
a conductive porous pressure-sensitive metamaterial with a negative Poisson ratio characteristic is characterized in that a symmetrical concave honeycomb-shaped micropore structure is arranged in an XY plane in the conductive porous pressure-sensitive metamaterial, and micropore walls are formed by assembling conductive nano materials and organic cross-linking agents; the conductive porous pressure-sensitive metamaterial has a negative Poisson ratio, is stressed and compressed in the Y-axis direction, generates transverse contraction in the X-axis direction, and rapidly increases the density and the number of conductive paths. The conductive porous pressure-sensitive metamaterial is stressed and compressed in the Y-axis direction, the microporous walls are inwards bent towards the center direction of the metamaterial, the density of the material is rapidly increased, a large number of pore walls are in contact with the pore walls, a large number of conductive paths are formed, the internal resistance of the material is greatly reduced, and the ultra-sensitive pressure-sensitive characteristic is generated.
The thickness of the hole wall of the cellular microporous structure is 5-200nm, and the length of the hole wall is 50-1500 mu m; the XY plane comprises a symmetrical concave honeycomb microporous structure at two sides and a central rhombus amorphous microporous structure; the density of the porous metamaterial is 0.5-1000mg/cm 3 。
The preparation method of the conductive porous pressure-sensitive metamaterial provided by the invention comprises the steps of mixing a conductive nano material with an organic cross-linking agent, and forming a uniformly dispersed aqueous solution through a hydrothermal reaction; forming a porous block material with a symmetrical concave honeycomb micropore structure by a directional freeze drying technology; forming a crosslinking network by the nanometer material and the organic crosslinking agent through heating and roasting; the method comprises the following steps:
(1) conducting solution dispersion and mixing of the conducting nano material and the organic cross-linking agent, and forming a uniform dispersion solution in a solvent through a hydrothermal reaction;
(2) by controlling an environment cold source, preparing a porous block material with a symmetrical concave honeycomb micropore structure by using a double-temperature gradient directional cold drying technology;
(3) and (3) placing the porous block material under the protection of inert gas, and heating and roasting at the temperature of 100-400 ℃ for 1-5 hours to enable the conductive nano material and the organic cross-linking agent to carry out cross-linking network so as to obtain the porous pressure-sensitive metamaterial.
In the step (1), the adding amount of the organic cross-linking agent is 5-30% of the mass of the conductive nano material. The hydrothermal reaction was carried out at 80 ℃ for one hour. The solvent is water.
Further, the conductive nano material comprises one or more of a conductive one-dimensional nanowire material, a conductive two-dimensional nanosheet material and a conductive polymer material; the conductive one-dimensional nanowire material is selected from: one or more of carbon nano-tubes, silver nano-wires, copper nano-wires and zinc oxide nano-wires; the conductive two-dimensional nanosheet material is selected from: the two-dimensional planar material single-layer or few-layer graphene oxide or partially reduced graphene oxide, which is composed of single-layer graphene atoms with hexagonal lattice arrangement on the molecular framework and contains a large number of organic oxygen-containing functional groups, comprises hydroxyl, carboxyl, epoxy and carbonyl; or a two-dimensional lamellar structure similar to graphene oxide, one of two-dimensional transition metal carbide and carbon nitride (MXene) with high specific surface area, high conductivity and narrow band gap, and a composite nanosheet consisting of two or more than two nanosheets; the conductive polymer material is selected from: one or more of polypyrrole, polyaniline, poly 3, 4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS).
Furthermore, the organic cross-linking agent is siloxane, cellulose and water-soluble polymer.
Wherein:
cellulosic crosslinking agents include, but are not limited to: one of methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose;
the water-soluble polymer-based crosslinking agent includes, but is not limited to: one of chitosan, sodium alginate, starch, polyvinyl alcohol, polyethylene glycol, polyacrylamide and polyvinylpyrrolidone;
silicone based crosslinkers include, but are not limited to: 3-triethoxysilyl-1-propylamine, gamma-glycidoxypropyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N-beta- (aminoethyl) -gamma-aminopropylmethyldimethoxysilane, N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane, N-cyclohexyl-gamma-aminopropylmethyldimethoxysilane, diethylenetriaminopropylmethyldimethoxysilane, diethylenetriaminopropyltrimethoxysilane, gamma-aminopropylbis (trimethylsiloxy) methylsilane, beta-aminopropyl-methyldimethoxysilane, beta-aminopropyl-N-glycidyloxy-methyldimethoxysilane, gamma-glycidyloxy-propyltrimethoxysilane, gamma-glycidyloxy-ethylmethyldimethoxysilane, gamma-glycidyloxy-dimethyldimethoxysilane, gamma-glycidyloxy-dimethyltrimethoxysilane, gamma-ethyltrimethoxysilane, gamma-ethylmethyldimethoxysilane, gamma-ethyltrimethoxysilane, gamma-isopropyltrimethoxysilane, gamma-glycidyloxy-dimethyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-glycidyloxy-dimethyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-propyltrimethoxysilane, gamma-methyldimethoxysilane, gamma-tert-propyltrimethoxysilane, gamma-methyldimethylsilane, gamma-butyltrimethoxysilane, or-butyltrimethoxysilane, gamma-butyltrimethoxysilane, or-butylor-or-butylor-or-, N-phenyl-gamma-aminopropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, gamma-methacryloxypropyltrimethoxysilane, octyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-chloropropyltrimethoxysilane, gamma-chloropropylmethyldimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, gamma-glycidoxypropyltriethoxysilane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 1, 2-bis (triethoxysilyl) ethane, methyltrimethoxysilane, gamma-thiocyanopropyltriethoxysilane, gamma-piperazinylpropylmethyldimethoxysilane, gamma-isocyanatopropyltriethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, gamma-glycidyloxypropyltrimethoxysilane, gamma-butyltrimethoxysilane, or, One of gamma-isocyanate propyl trimethoxy silane, 3- [ (2,3) -epoxy propoxy ] propyl methyl dimethoxy silane, 3- (2, 3-epoxy propoxy) propyl trimethoxy silane and tetraethyl silicate.
Furthermore, the flexible pressure sensor is prepared from the conductive porous pressure-sensitive metamaterial with the negative Poisson ratio characteristic, and the flexible pressure sensor takes the conductive porous pressure-sensitive metamaterial as a piezoresistive layer material and is wrapped on the flexible electrode and the flexible substrate to form a sensor element.
The invention has the technical effects that: according to the invention, a conductive nano material and an organic cross-linking agent are compounded, and the obtained conductive porous metamaterial has a symmetrical concave honeycomb microporous structure in an XY plane, has compressible superelasticity and ultrasensitive pressure-sensitive characteristics;
when the conductive porous metamaterial is pressed, the density and the number of conductive paths of the metamaterial are rapidly increased due to bidirectional shrinkage caused by a negative Poisson ratio, and the conductive porous metamaterial has excellent mechanical properties such as compression elasticity and impact resistance;
the compression strain of the conductive porous metamaterial along the Y axis is 90%, and the original length can be recovered by more than 95% after the pressure is removed; the compressive strain of the metamaterial along the Y axis is 80%, and after 5000 times of compression cycle pressure is removed, the performances of the metamaterial such as conductivity, Young model and strength can be recovered to be more than 70% of the original values.
The conductive porous metamaterial is used for preparing the flexible pressure sensor, the prepared pressure sensor has the pressure sensing performance of ultrahigh sensitivity, the pressure range of 0.1Pa-100kPa can be detected, and the sensitivity reaches 100-1300kPa -1 The response time can reach 60ms, and the sensor can be recycled for more than 1000 times without damage.
Drawings
FIG. 1 is a schematic structural diagram of a conductive porous metamaterial according to the present invention.
FIG. 2 is a schematic diagram of the conductive porous metamaterial according to the present invention shrinking when compressed under a force in the Y-axis direction.
Detailed Description
The present invention will be further described with reference to the following specific examples, which are not intended to limit the scope of the present invention.
The materials, reagents and the like used specifically and not described in the examples are commercially available or may be obtained by a method known to those skilled in the art without specific description. The specific experimental procedures and operating conditions involved are generally in accordance with conventional process conditions and conditions as described in the manual or as recommended by the manufacturer.
Example 1:
(1) 30mg of MXene with the size of about 1-2 μm in a slice layer prepared by a chemical method (MILD method) is weighed and placed in a reagent bottle, 3mL of deionized water is added, and ultrasonic treatment (power is 700W) is carried out for 2 minutes to obtain 10mg/mL of MXene dispersion liquid.
(2) 6mg of trimethoxy silane coupling agent (KH560) was added to the MXene solution, and the mixture was shaken for 3 minutes.
(3) Pouring the mixed solution of MXene and trimethoxy silane coupling agent obtained in the step (2) into a hydrothermal reaction kettle. Putting the mixture into an oven to carry out hydrothermal reaction for one hour at the temperature of 80 ℃.
(4) And (4) cooling the solution obtained in the step (3) and then putting the cooled solution into a square reaction tube. Half the volume of liquid nitrogen was poured into the dewar and the reaction tube was placed inside the dewar above the liquid nitrogen. Wait for the solution to completely freeze.
(5) And (5) placing the solid obtained in the step (4) in a freeze dryer, and waiting for 5-7 days until the water is completely volatilized. The resulting porous material was taken out of the reaction tube.
(6) And (4) placing the porous material obtained in the step (5) into a tube furnace, and roasting at 200 ℃ for two hours. And cooling and taking out to obtain the final porous metamaterial.
Example 2:
in the embodiment, a porous block material with a symmetrical concave honeycomb micropore structure is formed by adopting a conductive nano material and an organic cross-linking agent which are different from those in the embodiment 1 through a directional freeze drying technology; and heating and roasting to obtain the final conductive porous pressure-sensitive metamaterial product.
(1) 40mg of chemically prepared (modified Hummers method) graphene oxide with a size of about 1-2 μm in a sheet is weighed and placed in a reagent bottle, 2mL of deionized water is added, and ultrasonic processing (power of 700W) is performed for 60 minutes to obtain 20mg/mL graphene oxide dispersion.
(2) 2mg of Carbon Nanofibers (CNF) were added to the graphene oxide dispersion, and the mixture was shaken for 3 minutes.
(3) Pouring the mixed solution of MXene and carbon nanofiber obtained in the step (2) into a hydrothermal reaction kettle. Putting the mixture into an oven to carry out hydrothermal reaction for three hours at the temperature of 100 ℃.
(4) And (4) cooling the solution obtained in the step (3) and then putting the cooled solution into a square reaction tube. Half the volume of liquid nitrogen was poured into the dewar and the reaction tube was placed inside the dewar above the liquid nitrogen. Wait for the solution to completely freeze.
(5) And (5) placing the solid obtained in the step (4) in a freeze dryer, and waiting for 5-7 days until the water is completely volatilized. The resulting porous material was taken out of the reaction tube.
(6) And (4) placing the porous material obtained in the step (5) into a tube furnace, and roasting at 400 ℃ for four hours. And cooling and taking out to obtain the final porous metamaterial.
Example 3:
in the embodiment, a porous block material with a symmetrical concave honeycomb microporous structure is formed by adopting a conductive nano material and an organic cross-linking agent which are different from those in the embodiments 1 and 2 through a directional freeze drying technology; and heating and roasting to obtain the final conductive porous pressure-sensitive metamaterial product.
(1) 6mL of silver nanowire dispersion (10mg/mL) is weighed into a reagent bottle, diluted to 5mg/mL by adding water and shaken uniformly.
(2) 2mg of polyvinyl alcohol (PVA, molecular weight 120000) was added to the silver nanowire dispersion, and the mixture was shaken for 30 minutes and then sonicated for 30 seconds.
(3) And (3) putting the solution obtained in the step (2) into a square reaction tube. Half the volume of liquid nitrogen was poured into the dewar and the reaction tube was placed inside the dewar above the liquid nitrogen. Wait for the solution to completely freeze.
(4) And (4) placing the solid obtained in the step (3) in a freeze dryer, and waiting for 5-7 days until the water is completely volatilized. And taking out the reaction tube to obtain the final porous material.
Referring to attached drawings 1 and 2, the conductive porous pressure-sensitive metamaterial has a symmetrical concave honeycomb-shaped micropore structure in an XY plane, and micropore walls are formed by assembling conductive nano materials and organic cross-linking agents; the conductive porous pressure-sensitive metamaterial has a negative Poisson ratio, is stressed and compressed in the Y-axis direction, and generates transverse contraction in the X-axis direction, so that the density of the metamaterial and the number of conductive paths are rapidly increased. The cellular microporous structure has the pore wall thickness of 5-200nm and the pore wall length of 50-1500 μm; the XY plane comprises a symmetrical concave honeycomb microporous structure at two sides and a central rhombus amorphous microporous structure; the density of the porous metamaterial is 0.5-1000mg/cm 3 。
The conductive porous pressure-sensitive metamaterial has compressible superelasticity and impact resistance, is stressed and compressed in the Y-axis direction, and the microporous walls are concavely bent towards the center direction of the metamaterial, so that the density of the material is rapidly increased, a large number of pore walls are generated to be in contact with the pore walls, a large number of conductive paths are formed, the internal resistance of the material is greatly reduced, and the ultrasensitive pressure-sensitive characteristic is generated. The compressive strain of the metamaterial along the Y axis is 90%, and the original length can be recovered by more than 95% after the pressure is removed; particularly, the compressive strain of the metamaterial along the Y axis is 80%, and after 5000 times of compression cycle pressure is removed, the performances of the metamaterial such as conductivity, Young model and strength can be recovered to be more than 70% of the original values. The flexible pressure sensor prepared from the conductive porous pressure-sensitive metamaterial has an ultrasensitive performance. The probe is used for detecting pressure signals, and can contract in the longitudinal direction and the transverse direction under the condition of compression, so that the sensitivity is greatly improved.
By way of further illustration, the present invention is not limited to the above embodiments, and the embodiments are only used for making the technical solution of the present invention understood by those skilled in the art, wherein, the conductive nanomaterial and the organic cross-linking agent are not limited to those described in the embodiments, and the conductive nanomaterial may be one or more of a conductive one-dimensional nanowire material, a conductive two-dimensional nanosheet material, or a conductive polymer material; wherein: the conductive one-dimensional nanowire material is selected from: one or more of carbon nano-tube, silver nano-wire, copper nano-wire and zinc oxide nano-wire; the conductive two-dimensional nanosheet material is selected from: the molecular framework is composed of single-layer graphene atoms arranged in a hexagonal lattice, contains a large number of organic oxygen-containing functional groups, and comprises two-dimensional planar material single-layer or few-layer graphene oxide of hydroxyl, carboxyl, epoxy and carbonyl, or partially reduced graphene oxide; or a two-dimensional lamellar structure similar to graphene oxide, one of two-dimensional transition metal carbide and carbon nitride (MXene) with high specific surface area, high conductivity and narrow band gap, and a composite nanosheet consisting of two or more than two nanosheets; the conductive polymer material is selected from: one or more of polypyrrole, polyaniline, poly 3, 4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS).
The organic cross-linking agent can be selected from siloxane, cellulose or water-soluble polymers, wherein: cellulosic crosslinkers include, but are not limited to: one of methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose; the water-soluble polymer-based crosslinking agent includes, but is not limited to: one of chitosan, sodium alginate, starch, polyvinyl alcohol, polyethylene glycol, polyacrylamide and polyvinylpyrrolidone; siloxane-based crosslinkers include, but are not limited to: 3-triethoxysilyl-1-propylamine, gamma-glycidoxypropyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N-beta- (aminoethyl) -gamma-aminopropylmethyldimethoxysilane, N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane, N-cyclohexyl-gamma-aminopropylmethyldimethoxysilane, divinyltriaminopropylmethyldimethoxysilane, divinyltriaminopropyltrimethoxysilane, gamma-aminopropylbis (trimethylsiloxy) methylsilane, di-N-isopropylaminoethyltrimethoxysilane, di-N-propylmethyldimethoxysilane, di-N-beta-aminopropyl-methyldimethoxysilane, di-N-cyclohexyl-gamma-aminopropyl-methyldimethoxysilane, di-N-glycidyloxypropyl-trimethoxysilane, di-N-methyl-methylsilane, di-t-butyl-ethyl-methyl-propyl-trimethoxysilane, di-N-aminopropyl-methyl-methoxysilane, di-t-butyl-ethyl-methyl-propyl-trimethoxysilane, di-butyl-ethyl-propyl-methyl-ethyl-propyl-trimethoxysilane, ethyl-methyl-propyl-trimethoxysilane, di-propyl-ethyl-propyl-methyl-propyl-ethyl-propyl-trimethoxysilane, ethyl-propyl-methyl-propyl-methyl-ethyl-propyl-silane, ethyl-propyl-ethyl-propyl-methyl-propyl-ethyl-propyl-ethyl-methyl-ethyl-methyl-ethyl-, N-phenyl-gamma-aminopropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, gamma-methacryloxypropyltrimethoxysilane, octyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-chloropropyltrimethoxysilane, gamma-chloropropylmethyldimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, gamma-glycidoxypropyltriethoxysilane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 1, 2-bis (triethoxysilyl) ethane, methyltrimethoxysilane, gamma-thiocyanopropyltriethoxysilane, gamma-piperazinylpropylmethyldimethoxysilane, gamma-isocyanatopropyltriethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, gamma-glycidyloxypropyltrimethoxysilane, gamma-butyltrimethoxysilane, or, One of gamma-isocyanate propyl trimethoxy silane, 3- [ (2,3) -epoxy propoxy ] propyl methyl dimethoxy silane, 3- (2, 3-epoxy propoxy) propyl trimethoxy silane and tetraethyl silicate.
All the above raw material selections can achieve the purpose of the present invention and achieve the technical effects of the present invention, and the process conditions are not limited to the embodiments, and the modifications and changes should fall within the protection scope of the present invention as long as they belong to the technical idea of the present invention and are obvious.
Claims (9)
1. A conductive porous pressure-sensitive metamaterial with a negative Poisson ratio characteristic is characterized in that a symmetrical concave honeycomb-shaped microporous structure is arranged in an XY plane in the conductive porous pressure-sensitive metamaterial, and a microporous wall is formed by assembling a conductive nano material and an organic cross-linking agent; the conductive porous pressure-sensitive metamaterial has a negative Poisson ratio, is stressed and compressed in the Y-axis direction, and generates transverse contraction in the X-axis direction, so that the density and the number of conductive paths of the conductive porous pressure-sensitive metamaterial are rapidly increased;
the thickness of the hole wall of the cellular microporous structure is 5-200nm, and the length of the hole wall is 50-1500 mu m; the XY plane comprises a bilateral symmetrical concave honeycomb microporous structure and a central rhombus amorphous microporous structure; the density of the porous metamaterial is 0.5-1000mg/cm 3 。
2. The conductive porous pressure-sensitive metamaterial with the negative Poisson's ratio characteristic as claimed in claim 1, wherein the conductive porous pressure-sensitive metamaterial is stressed and compressed in the Y-axis direction, the microporous wall is concavely bent towards the center direction of the metamaterial, the material density is rapidly increased, a large number of pore walls are generated to be in contact with the pore walls, a large number of conductive paths are formed, the internal resistance of the material is greatly reduced, and the ultrasensitive pressure-sensitive characteristic is generated.
3. The preparation method of the conductive porous pressure-sensitive metamaterial with negative Poisson's ratio property as claimed in claim 1 or 2, characterized in that a conductive nano material is mixed with an organic cross-linking agent, and a uniform dispersion aqueous solution is formed through hydrothermal reaction; forming a porous block material with a symmetrical concave cellular micropore structure by a directional freeze drying technology; through heating and roasting, the nano material and the organic cross-linking agent form a cross-linked network; the method comprises the following steps:
(1) conducting solution dispersion and mixing of the conducting nano material and the organic cross-linking agent, and forming a uniform dispersion solution in a solvent through hydrothermal reaction;
(2) by controlling an environment cold source, preparing a porous block material with a symmetrical concave honeycomb micropore structure by using a double-temperature gradient directional cold drying technology;
(3) placing the porous block material under the protection of inert gas, and heating and roasting at 100-400 ℃ for 1-5 hours to enable the conductive nano material and the organic cross-linking agent to carry out cross-linking network to obtain the porous pressure-sensitive metamaterial;
in the step (1), the adding amount of the organic cross-linking agent is 5-30% of the mass of the conductive nano material.
4. The preparation method of the conductive porous pressure-sensitive metamaterial with negative Poisson's ratio characteristic as claimed in claim 3, wherein the hydrothermal reaction is carried out at 80 ℃ for one hour.
5. The method for preparing the conductive porous pressure-sensitive metamaterial with negative Poisson's ratio characteristics as claimed in claim 3, wherein the solvent is water.
6. The preparation method of the conductive porous pressure-sensitive metamaterial with the negative Poisson's ratio characteristic as claimed in claim 3, wherein the step (2) is that the dispersed solution obtained in the step (1) is placed into a square reaction tube after being cooled, half of the volume of liquid nitrogen is poured into a Dewar flask, and the reaction tube is placed above the liquid nitrogen and inside the Dewar flask to wait for the solution to be completely frozen; and (3) placing the solid obtained in the step (3) in a freeze dryer, waiting for 5-7 days until the water is completely volatilized, and taking out the solid from the reaction tube to obtain the porous block material.
7. The preparation method of the conductive porous pressure-sensitive metamaterial with the negative Poisson's ratio property as claimed in claim 3, wherein the conductive nano material is one or more of a conductive one-dimensional nanowire material, a conductive two-dimensional nanosheet material or a conductive polymer material; wherein:
the conductive one-dimensional nanowire material is selected from: one or more of carbon nano-tubes, silver nano-wires, copper nano-wires and zinc oxide nano-wires;
the conductive two-dimensional nanosheet material is selected from: the two-dimensional planar material single-layer or few-layer graphene oxide or partially reduced graphene oxide, which is composed of single-layer graphene atoms with hexagonal lattice arrangement on the molecular framework and contains a large number of organic oxygen-containing functional groups, comprises hydroxyl, carboxyl, epoxy and carbonyl; or a two-dimensional lamellar structure similar to graphene oxide, one of two-dimensional transition metal carbide and carbon nitride (MXene) with high specific surface area, high conductivity and narrow band gap, and a composite nanosheet consisting of two or more than two nanosheets;
the conductive polymer material is selected from: one or more of polypyrrole, polyaniline, poly 3, 4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT: PSS).
8. The preparation method of the conductive porous pressure-sensitive metamaterial with the negative Poisson's ratio characteristic as claimed in claim 3, wherein the organic cross-linking agent is siloxane, cellulose or water-soluble polymer, wherein:
cellulosic crosslinkers include, but are not limited to: one of methylcellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, and carboxymethyl cellulose;
the water-soluble polymer-based crosslinking agent includes, but is not limited to: one of chitosan, sodium alginate, starch, polyvinyl alcohol, polyethylene glycol, polyacrylamide and polyvinylpyrrolidone;
silicone based crosslinkers include, but are not limited to: 3-triethoxysilyl-1-propylamine, gamma-glycidoxypropyltrimethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane, N-beta- (aminoethyl) -gamma-aminopropylmethyldimethoxysilane, N-beta- (aminoethyl) -gamma-aminopropyltrimethoxysilane, N-cyclohexyl-gamma-aminopropylmethyldimethoxysilane, divinyltriaminopropylmethyldimethoxysilane, divinyltriaminopropyltrimethoxysilane, gamma-aminopropylbis (trimethylsiloxy) methylsilane, di-N-isopropylaminoethyltrimethoxysilane, di-N-propylmethyldimethoxysilane, di-N-beta-aminopropyl-methyldimethoxysilane, di-N-cyclohexyl-gamma-aminopropyl-methyldimethoxysilane, di-N-glycidyloxypropyl-trimethoxysilane, di-N-methyl-methylsilane, di-t-butyl-ethyl-methyl-propyl-trimethoxysilane, di-N-aminopropyl-methyl-methoxysilane, di-t-butyl-ethyl-methyl-propyl-trimethoxysilane, di-butyl-ethyl-propyl-methyl-ethyl-propyl-trimethoxysilane, ethyl-methyl-propyl-trimethoxysilane, di-propyl-ethyl-propyl-methyl-propyl-ethyl-propyl-trimethoxysilane, ethyl-propyl-methyl-propyl-methyl-ethyl-propyl-silane, ethyl-propyl-ethyl-propyl-methyl-propyl-ethyl-propyl-ethyl-methyl-ethyl-methyl-ethyl-, N-phenyl-gamma-aminopropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, gamma-methacryloxypropyltrimethoxysilane, octyltrimethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-chloropropyltrimethoxysilane, gamma-chloropropylmethyldimethoxysilane, gamma-glycidyloxypropylmethyldiethoxysilane, gamma-glycidyloxypropyltriethoxysilane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 1, 2-bis (triethoxysilyl) ethane, methyltrimethoxysilane, gamma-thiocyanopropyltriethoxysilane, gamma-piperazinylpropylmethyldimethoxysilane, gamma-isocyanatopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, gamma-tris (2-methoxyethoxy) silane, gamma-glycidyloxypropyltrimethoxysilane, vinylmethyldiethoxysilane, octylsilane, octyltrimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltrimethoxysilane, or a, vinyltrimethoxysilane, and the like, One of gamma-isocyanate propyl trimethoxy silane, 3- [ (2,3) -epoxy propoxy ] propyl methyl dimethoxy silane, 3- (2, 3-epoxy propoxy) propyl trimethoxy silane and tetraethyl silicate.
9. The application of the conductive porous pressure-sensitive metamaterial with the negative Poisson's ratio characteristic is characterized in that the conductive porous pressure-sensitive metamaterial obtained by the method of any one of claims 3 to 8 is used as a piezoresistive layer material to be wrapped on a flexible electrode and a flexible substrate to form a sensor element.
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