CN113787800B - Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor - Google Patents

Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor Download PDF

Info

Publication number
CN113787800B
CN113787800B CN202111112561.7A CN202111112561A CN113787800B CN 113787800 B CN113787800 B CN 113787800B CN 202111112561 A CN202111112561 A CN 202111112561A CN 113787800 B CN113787800 B CN 113787800B
Authority
CN
China
Prior art keywords
hydrogel
adhesive layer
grid electrode
strain sensor
flexible
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202111112561.7A
Other languages
Chinese (zh)
Other versions
CN113787800A (en
Inventor
周建新
胡聪
周玉成
戎家胜
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nanjing University of Aeronautics and Astronautics
Original Assignee
Nanjing University of Aeronautics and Astronautics
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nanjing University of Aeronautics and Astronautics filed Critical Nanjing University of Aeronautics and Astronautics
Priority to CN202111112561.7A priority Critical patent/CN113787800B/en
Publication of CN113787800A publication Critical patent/CN113787800A/en
Application granted granted Critical
Publication of CN113787800B publication Critical patent/CN113787800B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/40—Layered products comprising a layer of synthetic resin comprising polyurethanes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
    • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/52—Amides or imides
    • C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
    • C08F220/56—Acrylamide; Methacrylamide
    • 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
    • G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
    • G01B7/18—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge using change in resistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/54—Yield strength; Tensile strength

Landscapes

  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

The invention relates to the technical field of hydrogel, and provides a preparation method of a hydrogel flexible strain sensor with a resistance-capacitance double mode and the sensor; the sensor is formed by laminating and compounding hydrogel and flexible grid electrodes, has two working modes of a resistance type and a capacitance type according to different wiring modes, wherein the resistance type sensing is realized by the flexible grid electrodes with strain response capability, and the capacitance type sensing is realized by double electric layer capacitance at the interface of the hydrogel and the flexible grid electrodes and can be used for detecting tensile strain; the flexible device designed by the invention has good stretchability, high sensitivity and wide detection range, can realize real-time monitoring of tiny and violent human body motions, and can be applied to the fields of wearable equipment, flexible robots, electronic skins and the like.

Description

Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor
Technical Field
The invention relates to the technical field of hydrogel, in particular to a hydrogel flexible strain sensor with a resistance-capacitance dual mode.
Background
With the development of modern society intellectualization, the research on flexible intelligent wearable devices is increasing day by day, and the demand for sensors with strong stretchability and ductility is rapidly increasing. Compared with the traditional flexible strain sensor based on metal and semiconductor, the hydrogel flexible strain sensor is widely researched due to good stretchability and a simple and feasible preparation method.
Patent CN 112724339a discloses a hydrogel flexible strain sensor and a preparation method thereof, comprising the following steps: step one, mixing monomer acrylamide, calcium chloride, sodium caseinate and polydopamine solution, dissolving in deionized water, and dissolving to obtain a mixed solution; adding a chemical cross-linking agent N, N' -methylene bisacrylamide into the mixed solution, stirring, adding the single-layer graphene oxide dispersion liquid, and stirring at room temperature to obtain a pre-polymerization solution; step three, adding an initiator and a catalyst into the prepolymerization solution; step four, injecting the polymerization solution into a reaction mould to obtain hydrogel; and fifthly, cleaning and drying the hydrogel, mounting a conductive copper electrode, and packaging into the flexible strain sensor. An electronic conductive network is constructed in hydrogel by utilizing polydopamine to reduce graphene oxide, the sensing mode is a resistance type, and the electrode material is a conductive copper electrode.
Patent CN 109294133A discloses a stretchable self-healing hydrogel flexible strain sensor, which is a multifunctional flexible strain sensor obtained by preparing a self-healing hydrogel with high stretchability through a one-step sol-gel method and encapsulating the self-healing hydrogel with an adhesive tape. The multi-walled carbon nanotube is used as an active piezoelectric material to construct an electronic conductive network in hydrogel, the sensing mode is resistance type, and an electrode material is not mentioned.
Patent CN 112212779a discloses a method for preparing a hydrogel flexible strain sensor, in which a chlorinated choline base eutectic solvent is used as a raw material, a polyvinyl alcohol high-molecular polymer is combined to prepare a double-network hydrogel, and cellulose nanocrystals and graphite carbon nitride nanosheets are added to obtain the characteristics of excellent self-repairing property, frost resistance and strong tensile property. The sensing mode is still resistance type, and electrode materials are not mentioned.
The currently reported hydrogel flexible strain sensors all use rigid materials such as metal sheets and copper wires as electrodes, cannot meet the requirement of applying a large amount of complicated dynamically-changed stress, and are easy to break under the action of external force damage, so that the sensing failure is caused. When the flexible sensor is integrally stretched, the rigid material electrode cannot deform together with the hydrogel, the interface of the electrode and the hydrogel bears large stress, large fluctuation is brought to measurement of a sensing signal, and a metal electrode (such as a copper wire) can react with the hydrogel and be corroded after long-term use, so that the service life of the sensor is shortened. These problems limit their application in wearable devices. In addition, most of the forms adopted by the hydrogel flexible strain sensor reported at present are resistance-type sensing, the sensing form is single, and the requirements of capacitance/resistance dual-mode use cannot be met.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a method for preparing a hydrogel flexible strain sensor with a resistance-capacitance dual mode and a sensor, so as to meet the requirement of a flexible device on the stretchability and ductility of the sensor.
In order to achieve the purpose, the invention adopts the following technical scheme:
firstly, the application provides a preparation method of a hydrogel flexible strain sensor with a resistance-capacitance dual mode, which comprises the following steps:
1) dissolving a hydrogel monomer and salt in deionized water, stirring for 5-10 min at room temperature, adding a cross-linking agent and an initiator after complete dissolution, and stirring for 3-5 min at room temperature until the solution is uniform to obtain a hydrogel pre-polymerization solution for later use;
the hydrogel monomer is acrylamide, and the salt can be one or more of sodium chloride, lithium chloride and potassium chloride; in the obtained pre-polymerization liquid, the concentration of the hydrogel monomer is 2-3 mol.L-1The salt concentration is 1 to 3 mol.L-1；
The cross-linking agent is preferably N, N' -methylene bisacrylamide, and the initiator is preferably ammonium persulfate.
The mass ratio of the cross-linking agent, the initiator and the hydrogel monomer is preferably 0.0006:0.0017: 1;
2) placing the mold into a plasma cleaning machine, and cleaning the surface of the inner cavity of the mold for 3-5 min by using oxygen plasma; the material of the mold can be conventional materials such as acrylic, glass and quartz, and the working pressure of the oxygen plasma cleaning mold is preferably 70-90 Pa.
3) Transferring the hydrogel prepolymerization solution obtained in the step 1) into the die cleaned in the step 2), and adding a crosslinking accelerator to form a lower electric adhesive layer with the thickness of 0.5-2 mm;
the mass ratio of the crosslinking accelerator to the hydrogel monomer is preferably 0.0048:1, if the amount of the crosslinking accelerator is small, the hydrogel is slowly solidified, which is not beneficial for subsequent operation, and if the amount of the crosslinking accelerator is too large, the hydrogel is quickly solidified, but the state is slightly viscous.
4) Treat that the glue film is the adhesive of semi-setting, cover grid electrode in its surface down, lower grid electrode minor face and glue film minor face phase-match down, the long limit extends to glue film long limit both sides outside 1~ 2cm down, should extend to glue film both sides outside partial grid electrode promptly down the lead electrode down.
Secondly, injecting hydrogel pre-polymerization liquid on the surface of the lower grid electrode in the mold, and adding a crosslinking accelerator to form an intermediate adhesive layer with the thickness of 1-5 mm; the mass ratio of the crosslinking accelerator to the hydrogel monomer is preferably 0.0048: 1.
5) And when the middle adhesive layer is in a semi-solidified adhesive shape, covering the upper grid electrode on the surface of the middle adhesive layer, matching the short edge of the upper grid electrode with the middle adhesive layer, extending the long edge to the outside 1-2 cm of the two sides of the long edge of the middle adhesive layer, and taking the partial grid electrode extending to the outside of the two sides of the middle adhesive layer as an upper lead electrode.
6) Thirdly, injecting hydrogel pre-polymerization liquid into the surface of the upper grid electrode in the mould, and adding a crosslinking accelerator to form a sizing layer with the thickness of 0.5-2 mm; the mass ratio of the co-accelerator to the hydrogel monomer is preferably 0.0048: 1.
7) And sealing the mold for 2-5min to obtain an integrated lower adhesive layer, lower grid electrode, middle adhesive layer, upper grid electrode and upper adhesive layer hydrogel multilayer composite structure.
8) Except for the upper lead electrode and the lower lead electrode, the outer surface of the hydrogel multilayer composite structure is packaged by a flexible polymer film to obtain a packaging layer, and the hydrogel flexible strain sensor with the resistance-capacitance dual mode can be obtained. The packaging method in the step can achieve the purpose of packaging in the step by adopting a conventional method in the field, such as the packaging method disclosed in the Chinese patent CN 108376838A.
Further, the flexible polymer film for encapsulation described above is preferably at least one of polydimethylsiloxane, VHB4910 tape. The thickness of the packaging layer is 0.1 mm-1 mm, and the packaging layer can provide comfortable touch and prevent moisture in the hydrogel from evaporating.
Secondly, the application provides the hydrogel flexible strain sensor with the resistance-capacitance double modes, which is prepared by the method. The sensor comprises an upper adhesive layer, a middle adhesive layer and a lower adhesive layer which are in the same shape; an upper grid electrode is arranged between the upper adhesive layer and the middle adhesive layer, and a lower grid electrode is arranged between the lower adhesive layer and the middle adhesive layer; the short side of the upper grid electrode is matched with the width of the middle adhesive layer, and the long side of the upper grid electrode extends to the outside of the two sides of the long side of the middle adhesive layer; the short edges of the lower grid electrodes are matched with the width of the lower adhesive layer, and the long edges extend to the outside of the long edges at the two sides of the lower adhesive layer; (ii) a The outer surface of the sensor is provided with a flexible polymer film encapsulation layer.
The lower grid electrode and the upper grid electrode used in the application are prepared by the following method:
(1) the method comprises the step of printing flexible polymer grids by using thermoplastic polyurethane by using a conventional 3D printing method (patent CN201510979494.7), wherein the line width of each grid is not more than 500 mu m, the thickness of each grid is not more than 200 mu m, and the flexible grids are of plane telescopic structures, such as curved quadrangles, spring-like connection grids, hinge-like connection grids, negative Poisson ratio expansion grids and the like.
(2) And cleaning the flexible polymer grid by using a conventional method such as ultraviolet-ozone atmosphere or oxygen plasma.
(3) Using a vacuum coating method to firstly evaporate a 5-20 nm thick chromium layer or titanium layer on a 3D printed flexible polymer grid, and then evaporating a 25-100 nm thick gold layer; the vacuum coating method is a conventional coating method in the art, such as the method disclosed in chinese patent CN 1718845a, and can achieve the purpose of coating.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, the flexible strain sensor is prepared by compounding the flexible grid electrode printed in 3D and the hydrogel to form a sandwich structure, and the whole device completely has flexibility including an electrode part, and can be integrally stretched and deformed without influencing the contact between the electrode and the hydrogel interface and the integral sensing performance of the device. Moreover, due to the strain responsiveness of the flexible grid electrode, the strain sensor also has two sensing modes, namely a resistance mode and a capacitance mode according to different wiring modes of the lead electrode.
Drawings
FIG. 1 is a schematic representation of a hydrogel multilayer composite prepared in example 1 of the present invention;
wherein, 1-lower adhesive layer; 2-lower grid electrode; 3-middle glue layer; 4-grid electrode on; 5-applying an adhesive layer; 6-wiring; 7-wiring; 8-wiring; 9-wiring.
FIG. 2 is a pictorial view of a hydrogel flexible strain sensor having resistive-capacitive dual modes, made in accordance with example 1 of the present invention;
FIG. 3 is a diagram of a hydrogel co-stretched object with a grid electrode of a hydrogel flexible strain sensor having resistive-capacitive dual modes prepared in example 1 of the present invention;
FIG. 4 is a graph showing the change in resistance of the hydrogel flexible strain sensor with resistive-capacitive dual modes prepared in example 1 of the present invention under different tensile strains.
FIG. 5 is a graph showing the relative capacitance change during stretching of the hydrogel flexible strain sensor having resistive-capacitive dual modes prepared in example 1 of the present invention.
FIG. 6 is a schematic diagram of a flexible curved quadrilateral mesh electrode of a hydrogel flexible strain sensor with resistive-capacitive dual modes prepared in example 1 of the present invention;
FIG. 7 is a schematic diagram of a spring-like connected grid electrode of a hydrogel flexible strain sensor having resistive-capacitive dual modes prepared in example 2 of the present invention;
FIG. 8 is a schematic diagram of a spring-like connected grid electrode of a hydrogel flexible strain sensor having resistive-capacitive dual modes prepared in example 3 of the present invention;
FIG. 9 is a schematic diagram of a hinge-like connection grid electrode of a hydrogel flexible strain sensor having resistive-capacitive dual modes prepared in example 4 of the present invention;
FIG. 10 is a schematic view of a negative Poisson's ratio auxetic mesh electrode of the hydrogel flexible strain sensor with resistive-capacitive dual modes prepared in example 5 of the present invention;
FIG. 11 is a schematic diagram of a negative Poisson's ratio auxetic mesh electrode of the hydrogel flexible strain sensor with resistive-capacitive dual modes prepared in example 6 of the present invention.
Detailed Description
The invention will be described in further detail with reference to the following figures and specific examples, which are given by way of illustration and description only and are not intended to limit the invention thereto.
Reagents and equipment used in the examples: acrylamide monomer, methylene bisacrylamide, ammonium persulfate, tetramethylethylenediamine, polydimethylsiloxane, VHB4910 adhesive tape, a multifunctional extrusion type biological 3D printer, a plasma cleaning machine and the like.
Acrylamide monomers were purchased from Shanghai Allantin Biotechnology, Inc.
Methylene bisacrylamide was purchased from Shanghai Allantin Biotech Co., Ltd.
Ammonium persulfate was purchased from Shanghai Aladdin Biotechnology Ltd.
Tetramethylethylenediamine was purchased from Shanghai Allantin Biotech Co., Ltd.
Polydimethylsiloxane is available from dow corning ltd.
VHB4910 tape was purchased from 3M company, usa.
The multifunctional extrusion type biological 3D printer was purchased from Yongqin spring Intelligent Equipment, Inc., Suzhou, model number BP-6602.
The plasma cleaner was purchased from HarrickPlasma, USA, and the model is PDC-32G-2.
In the embodiment, the lower grid electrode and the upper grid electrode are prepared according to the following steps:
(1) by utilizing a multifunctional extrusion type biological 3D printer, a conventional 3D printing method (patent CN201510979494.7) is used for printing a flexible polymer grid by using thermoplastic polyurethane, the line width of the grid is not more than 500 mu m, the thickness of the grid is not more than 200 mu m, and the flexible grid is of a plane telescopic structure, such as a curved side quadrangle, a spring-like connection grid, a hinge-like connection grid, a negative Poisson ratio expansion grid and the like.
(2) And cleaning the flexible polymer grid by using ultraviolet-ozone atmosphere or oxygen plasma.
(3) A conventional vacuum coating method (patent CN200510014639.6) is used, a metal chromium layer or a metal titanium layer with the thickness of 5-20 nm is firstly evaporated on a flexible polymer grid printed by 3D, and then a gold layer with the thickness of 25-100 nm is evaporated.
EXAMPLE 1 hydrogel Flexible Strain sensor with resistive-capacitive Dual modes
The sensor prepared by the embodiment comprises an upper adhesive layer 5, a middle adhesive layer 3 and a lower adhesive layer 1 which are in the same shape; an upper grid electrode 4 is arranged between the upper adhesive layer 5 and the middle adhesive layer 3, and a lower grid electrode 2 is arranged between the lower adhesive layer 1 and the middle adhesive layer 3; the wide edge of the upper grid electrode 4 is matched with the width of the middle adhesive layer 3, and the long edge extends to the outer part of the long edge at two sides of the middle adhesive layer 3; the shape of the lower grid electrode 2 is the same as that of the upper grid electrode 4; the outer surface of the sensor is provided with a flexible polymer film encapsulation layer.
The preparation method of the sensor comprises the following steps:
and (1) dissolving 15.6g of acrylamide monomer and 17.5g of sodium chloride in 100mL of deionized water, stirring for 10min at room temperature until the acrylamide monomer and the sodium chloride are completely dissolved, adding 0.0094g of methylene bisacrylamide and 0.0266g of ammonium persulfate, and stirring for 5min at room temperature until the solution is uniform to obtain a hydrogel prepolymerization solution.
And (2) placing a rectangular acrylic mold with the length of 6cm, the width of 3cm and the height of 1cm into a plasma cleaning machine, and cleaning the surface of an inner cavity of the mold for 3min by using oxygen plasma under the working pressure of 70Pa, wherein the size of the inner cavity of the acrylic mold is 5cm in length, 2cm in width and 0.7cm in depth.
And (3) transferring 2ml of the hydrogel prepolymerization solution into the mold, and adding 20 mu L of tetramethylethylenediamine to form a lower rubber layer 1 with the thickness of 2 mm.
And (4) covering the lower grid electrode 2 on the surface of the lower grid electrode 2 when the lower adhesive layer 1 is in a semi-solidified adhesive state, wherein the short side of the lower grid electrode 2 is matched with the width of the lower adhesive layer 1, the two sides of the long side of the lower grid electrode 2 extend to the outside of the long side of the lower adhesive layer 1, the two sides of the lower grid electrode 2 exceed the long side of the lower adhesive layer by about 2cm, and the extending parts of the two sides in the lower grid electrode 2 are a lead electrode (wiring) 6 and a lead electrode (wiring) 7.
The lower grid electrode 2 used in this embodiment has a structure shown in fig. 6, which is a curved quadrilateral grid, and is made of thermoplastic polyurethane, with a line width of 500 μm and a thickness of 200 μm, and the surface-deposited metal chromium layer has a thickness of 20nm and the gold layer has a thickness of 100 nm.
Step (5), 5mL of hydrogel pre-polymerization solution is injected on the surface of the lower grid electrode 2 in the mold, and 50 muL of hydrogel pre-polymerization solution with the density of 0.775 g/mL is added-1Tetramethylethylenediamine with a purity of 96%, forming an intermediate glue layer 3 with a thickness of 5 mm.
And (6) when the middle adhesive layer 3 is in a semi-solidified adhesive shape, covering the upper grid electrode 4 on the surface of the middle adhesive layer, wherein the short side of the upper grid electrode 4 is matched with the width of the middle adhesive layer 3, the two sides of the long side of the upper grid electrode 4 extend to the outside of the long side of the middle adhesive layer 3, the two sides of the long side of the upper grid electrode 4 exceed the part by about 2cm, and the extending parts of the two sides of the upper grid electrode 4 are a lead electrode (wiring) 8 and a lead electrode (wiring) 9. The structure and the preparation method of the upper grid electrode 4 are the same as those of the lower grid electrode 2.
Step (7), 2mL of hydrogel pre-polymerization solution is injected on the surface of the upper grid electrode 4 in the mould, and 20 muL of hydrogel pre-polymerization solution with the density of 0.775 g/mL is added-1Tetramethylethylenediamine with a purity of 96%, forming a size layer 5 with a thickness of 2 mm.
And (8) sealing the mould for 5min to obtain an integrated hydrogel multilayer composite structure of the lower adhesive layer 1, the lower grid electrode 2, the middle adhesive layer 3, the upper grid electrode 4 and the upper adhesive layer 5, wherein the structural schematic diagram is shown in figure 1.
And (9) packaging the hydrogel multilayer composite structure by using a polydimethylsiloxane film with the thickness of 100 mu m, and reserving lead electrodes 6-9 at the same time, thus obtaining the hydrogel flexible strain sensor with the resistance-capacitance dual mode. The physical diagram is shown in figure 2.
The sensor (grid electrode and hydrogel) prepared in this example was stretched cooperatively, and the results are shown in fig. 3, where the tensile strain of the two electrodes can reach 100%.
The resistance-capacitance dual-mode response behavior detection of the hydrogel flexible Strain sensor with the resistive-capacitance dual modes obtained in the embodiment is shown in FIGS. 4 and 5, and FIG. 4 is a resistance change graph under different tensile strains (detection method references: He F, You X, Gong H, et al Stretchable, Biocompatible, and Multifunctional Single fiber-Based Hydrogels touch able to Strain/Pressure Sensors and Triboelectric Nanogenerators [ J ]. ApACS l Mater Interfaces 2020,12(5):6442 6450.); FIG. 5 is a graph showing the relative change in capacitance during stretching (detection method references: Shen Z, Zhu X, Majidi C, et al. Cutaneous Ionogel mechanicals for Soft Machines, Physiological Sensing, and Ampule Prostheses [ J ]. Advanced Materials,2021: e 2102069). It can be seen that when the tensile strain is 5%, 10%, 15%, respectively, the resistance change between the wirings 6 and 7 is 17.2%, 19.4%, 21.7%, and the capacitance change between the wirings 6 and 8 is 7.1%, 15.3%, 24.5%, respectively, which has significant resistance-capacitance dual-mode sensing characteristics.
Example 2
The sensor of this example was prepared in the same manner as in example 1, except that: in this embodiment, the thickness of the lower glue layer is 0.5mm, the thickness of the middle glue layer is 1mm, and the thickness of the upper glue layer is 0.5 mm. The upper grid electrode and the lower grid electrode are in spring-like connection grid structures as shown in fig. 7, the upper grid electrode and the lower grid electrode are made of thermoplastic polyurethane, the line width is 20 micrometers, the thickness is 50 micrometers, the thickness of a metal chromium layer evaporated on the surface is 5nm, and the thickness of a gold layer is 25 nm.
In this embodiment, the length of the lead electrodes 6-9 (i.e., the portions of the upper/lower grid electrodes that extend beyond the long side of the middle adhesive layer) is 1 cm.
When the hydrogel flexible strain sensor with the resistance-capacitance dual mode obtained in the embodiment is tested by referring to the method of the embodiment 1, when the tensile strain is respectively 5%, 10% and 15%, the resistance change between the wires 6 and 7 is respectively 17.5%, 19.2% and 21.6%, and the capacitance change between the wires 6 and 8 is respectively 7.4%, 15.1% and 24.7%, so that the hydrogel flexible strain sensor with the resistance-capacitance dual mode has remarkable resistance-capacitance sensing characteristics.
Example 3
The sensor of this example was prepared in the same manner as in example 1, except that: the upper grid electrode and the lower grid electrode in this embodiment are spring-like connected grid structures as shown in fig. 8, and are made of thermoplastic polyurethane, the line width is 500 μm, the thickness is 200 μm, the thickness of the metal titanium layer evaporated on the surface is 20nm, and the thickness of the gold layer is 100 nm.
When the hydrogel flexible strain sensor with the resistance-capacitance double modes obtained in the embodiment is tested by referring to the method in the embodiment 1, when the tensile strain is respectively 5%, 10% and 15%, the resistance change between the connecting wires 6 and 7 is respectively 17.2%, 19.4% and 21.6%, and the capacitance change between the connecting wires 6 and 8 is respectively 7.5%, 15.3% and 24.6%, so that the hydrogel flexible strain sensor with the resistance-capacitance double modes has remarkable resistance-capacitance double-mode sensing characteristics.
Example 4
The sensor of this example was prepared in the same manner as in example 1, except that: the upper grid electrode and the lower grid electrode in this embodiment are of hinge-like connection grid structure as shown in fig. 9, and are made of thermoplastic polyurethane, the line width is 500 μm, the thickness is 200 μm, the thickness of the metal titanium layer evaporated on the surface is 5nm, and the thickness of the gold layer is 25 nm.
When the hydrogel flexible strain sensor with the resistance-capacitance dual mode obtained in the embodiment is tested by referring to the method of the embodiment 1, when the tensile strain is respectively 5%, 10% and 15%, the resistance change between the wires 6 and 7 is respectively 17.2%, 19.4% and 21.4%, and the capacitance change between the wires 6 and 8 is respectively 7.2%, 15.0% and 24.6%, so that the hydrogel flexible strain sensor with the resistance-capacitance dual mode has remarkable resistance-capacitance sensing characteristics.
Example 5
The sensor of this example was prepared in the same manner as in example 1, except that: the structure of the upper grid electrode 2 and the lower grid electrode 4 in this embodiment is a negative poisson ratio auxetic grid as shown in fig. 10, the material of the negative poisson ratio auxetic grid is thermoplastic polyurethane, the line width is 500 μm, the thickness is 200 μm, the thickness of the chromium layer evaporated on the surface is 20nm, and the thickness of the gold layer is 25 nm.
When the hydrogel flexible strain sensor with the resistance-capacitance dual mode obtained in the embodiment is tested by referring to the method of the embodiment 1, when the tensile strain is respectively 5%, 10% and 15%, the resistance change between the wires 6 and 7 is respectively 17.3%, 19.5% and 21.6%, and the capacitance change between the wires 6 and 8 is respectively 7.1%, 15.5% and 24.7%, so that the hydrogel flexible strain sensor with the resistance-capacitance dual mode has remarkable resistance-capacitance sensing characteristics.
Example 6
The sensor of this example was prepared in the same manner as in example 1, except that: the upper grid electrode and the lower grid electrode in this embodiment have a negative poisson ratio auxetic grid structure as shown in fig. 11, and are made of thermoplastic polyurethane, the line width is 500 μm, the thickness is 200 μm, the thickness of the chromium layer evaporated on the surface is 5nm, and the thickness of the gold layer is 100 nm.
When the hydrogel flexible strain sensor with the resistance-capacitance dual mode obtained in the embodiment is tested by referring to the method in embodiment 1, when the tensile strain is respectively 5%, 10% and 15%, the resistance change between the wires 6 and 7 is respectively 17.4%, 19.5% and 21.5%, and the capacitance change between the wires 6 and 8 is respectively 7.3%, 15.2% and 24.5%, so that the hydrogel flexible strain sensor with the resistance-capacitance dual mode has remarkable resistance-capacitance sensing characteristics.
Example 7
The sensor of this example was prepared in the same manner as in example 1, except that: the structure of the grid electrode in this embodiment is shown in fig. 6, and is a curved quadrilateral grid, which is made of thermoplastic polyurethane, and has a line width of 500 μm and a thickness of 200 μm, a chromium layer deposited on the surface of 20nm in thickness, and a gold layer of 100nm in thickness; the lower grid electrode 4 is a spring-like connection grid as shown in fig. 7, and is made of thermoplastic polyurethane, the line width is 20 μm, the thickness is 50 μm, the thickness of the chromium layer evaporated on the surface is 20nm, and the thickness of the gold layer is 200 nm.
When the hydrogel flexible strain sensor with the resistance-capacitance dual mode obtained in the embodiment is tested by referring to the method of the embodiment 1, when the tensile strain is respectively 5%, 10% and 15%, the resistance change between the wires 6 and 7 is respectively 17.4%, 19.3% and 21.4%, and the capacitance change between the wires 6 and 8 is respectively 7.3%, 15.4% and 24.6%, so that the hydrogel flexible strain sensor with the resistance-capacitance dual mode has remarkable resistance-capacitance sensing characteristics.

Claims (9)

1. A preparation method of a hydrogel flexible strain sensor with a resistance-capacitance dual mode is characterized by comprising the following specific steps:
1) dissolving a hydrogel monomer and salt in deionized water, and adding a cross-linking agent and an initiator to obtain a hydrogel pre-polymerization solution for later use;
the hydrogel monomer is acrylamide; the salt comprises one or more of sodium chloride, lithium chloride and potassium chloride;
2) transferring the hydrogel prepolymerization solution into a mold, and adding a crosslinking accelerator to form a lower rubber layer;
3) when the lower adhesive layer is in a semi-solidified adhesive shape, covering the lower grid electrode on the surface of the lower adhesive layer, wherein the short edge of the lower grid electrode is matched with the short edge of the lower adhesive layer, the long edge extends to the outside of two sides of the long edge of the lower adhesive layer by 1-2 cm, and the part of two sides of the long edge of the lower grid electrode, which extends out of the lower adhesive layer, is the lower lead electrode;
4) adding hydrogel pre-polymerization liquid and a crosslinking accelerator on the surface of the lower grid electrode in the mold to form an intermediate adhesive layer;
5) when the middle adhesive layer is in a semi-solidified adhesive shape, covering the upper grid electrode on the surface of the middle adhesive layer, wherein the short edge of the upper grid electrode is matched with the middle adhesive layer, and the long edge extends to the outside of two sides of the long edge of the middle adhesive layer by 1-2 cm; the part of the two sides of the long side of the upper grid electrode, which extends out of the middle adhesive layer, is the upper lead electrode;
6) injecting hydrogel pre-polymerization liquid and a crosslinking accelerator into the surface of the upper grid electrode in the mold to form an upper glue layer;
7) closing the mold to obtain a hydrogel multilayer composite structure;
8) except the upper lead electrode and the lower lead electrode, a flexible polymer film is packaged on the outer surface of the hydrogel multilayer composite structure to obtain the hydrogel flexible strain sensor with the resistance-capacitance dual mode;
the lower grid electrode and the upper grid electrode are prepared by the following method: firstly evaporating a metal chromium layer or a metal titanium layer with the thickness of 5-20 nm on the flexible polymer grid, and then evaporating a gold layer with the thickness of 25-100 nm; the flexible polymer grid is obtained by 3D printing of thermoplastic polyurethane, the line width of the grid is not more than 500 mu m, and the thickness of the grid is not more than 200 mu m.
2. The method of claim 1, wherein the flexible polymer film comprises at least one of polydimethylsiloxane, VHB4910 tape.
3. The method for preparing the hydrogel flexible strain sensor with the resistive-capacitive dual mode according to claim 1, wherein the mass ratio of the crosslinking accelerator to the hydrogel monomer in the upper rubber layer, the middle rubber layer and the lower rubber layer is 0.0048: 1.
4. The method for preparing the hydrogel flexible strain sensor with the resistive-capacitive dual mode as claimed in claim 1, wherein the mass ratio of the crosslinking agent, the initiator and the hydrogel monomer is 0.0006:0.0017:1 in sequence.
5. The method for preparing the hydrogel flexible strain sensor with the resistive-capacitive dual mode according to claim 1, wherein in the hydrogel pre-polymerization liquid in the step 1), the concentration of the hydrogel monomer is 2-3 mol/L, and the concentration of the salt is 1-3 mol/L.
6. The method for preparing the hydrogel flexible strain sensor with the resistive-capacitive dual mode according to claim 1, wherein the crosslinking agent is N, N' -methylenebisacrylamide, and the initiator is ammonium persulfate.
7. The method for preparing the hydrogel flexible strain sensor with the resistance-capacitance dual mode is characterized in that the thickness of the upper adhesive layer is 0.5-2 mm, the thickness of the lower adhesive layer is 0.5-2 mm, and the thickness of the middle adhesive layer is 1-5 mm.
8. The method for preparing the hydrogel flexible strain sensor with the resistive-capacitive dual mode according to claim 1, wherein in the step 8), the thickness of the packaging layer obtained after the flexible polymer film is packaged on the outer surface of the hydrogel multilayer composite structure is 0.1 mm-1 mm.
9. Hydrogel flexible strain sensor having resistive-capacitive bimodal modes, obtainable by the method according to any one of claims 1 to 8.
CN202111112561.7A 2021-09-18 2021-09-18 Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor Active CN113787800B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111112561.7A CN113787800B (en) 2021-09-18 2021-09-18 Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111112561.7A CN113787800B (en) 2021-09-18 2021-09-18 Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor

Publications (2)

Publication Number Publication Date
CN113787800A CN113787800A (en) 2021-12-14
CN113787800B true CN113787800B (en) 2022-06-10

Family

ID=78879103

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111112561.7A Active CN113787800B (en) 2021-09-18 2021-09-18 Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor

Country Status (1)

Country Link
CN (1) CN113787800B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114124622B (en) * 2022-01-27 2022-05-17 天津大学 Data identification processing system for silent communication
CN116026372B (en) * 2022-12-06 2024-07-09 西安交通大学 Broadband flexible dynamic sensor based on preloaded design and preparation method thereof

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007125762A (en) * 2005-11-02 2007-05-24 Kawamura Inst Of Chem Res Polymer gel laminate and its manufacturing method
CN108063001B (en) * 2017-12-07 2020-12-01 南京邮电大学 Thin film electrode and manufacturing method and application thereof
CN109294133B (en) * 2018-09-25 2021-02-09 南京工业大学 Stretchable self-healing hydrogel flexible strain sensor and preparation method thereof
CN112212779B (en) * 2020-09-04 2022-05-17 厦门大学 Preparation method of hydrogel flexible strain sensor
CN112341573B (en) * 2020-12-18 2022-11-01 郑州大学 Preparation method and application of multifunctional composite hydrogel
CN113203504B (en) * 2021-04-01 2022-05-06 上海交通大学 Flexible wearable pressure sensor with ultrahigh capacitance and pressure sensor array

Also Published As

Publication number Publication date
CN113787800A (en) 2021-12-14

Similar Documents

Publication Publication Date Title
Ding et al. Recent advances in flexible and wearable pressure sensors based on piezoresistive 3D monolithic conductive sponges
CN113787800B (en) Preparation method of hydrogel flexible strain sensor with resistance-capacitance dual modes and sensor
CN106908176B (en) Multi-phase dielectric layer capacitive pressure sensor with micro-structure and manufacturing method thereof
Qin et al. Preparation of high-performance MXene/PVA-based flexible pressure sensors with adjustable sensitivity and sensing range
CN108822548A (en) A kind of 3D printing graphene-based flexible sensor and preparation method thereof of the stretchable high sensitivity of height
CN112964283B (en) Flexible interdigital capacitive sensor structure and preparation method thereof
CN113340484A (en) Wide-range flexible resistance type pressure sensor and preparation method thereof
CN110207866A (en) A kind of highly sensitive pliable pressure sensor and preparation method thereof based on modified paper base
Lu et al. Highly sensitive interlocked piezoresistive sensors based on ultrathin ordered nanocone array films and their sensitivity simulation
CN113358247B (en) Flexible sensor for simultaneously detecting pressure-strain bimodal signals and preparation method
CN113218296B (en) Elastic strain sensor and preparation method thereof
Yang et al. Ultra-sensitive, stretchable, and bidirectional wearable strain sensor for human motion detection
Yao et al. Poly (vinyl alcohol)/phosphoric acid gel electrolyte@ polydimethylsiloxane sponge for piezoresistive pressure sensors
CN113208582A (en) Wireless wearable graphene angle sensor
CN116499351A (en) Electrochemical self-powered static/dynamic tensile strain sensor and preparation method thereof
Liu et al. Wearable electromechanical sensors and its applications
Hosseini et al. A sensitive and flexible interdigitated capacitive strain gauge based on carbon nanofiber/PANI/silicone rubber nanocomposite for body motion monitoring
Alkabes et al. A wirelessly multi stimuli-responsive ultra-sensitive and self-healable wearable strain sensor based on silver quantum dots of 3D organo-hydrogel nanocomposites
Yang et al. Stress-deconcentrated ultrasensitive strain sensor with hydrogen-bonding-tuned fracture resilience for robust biomechanical monitoring
Xu et al. Skin-friendly corrugated multilayer microspherical sensor fabricated with silk fibroin, poly (lactic-co-glycolic acid), polyaniline, and kappa-carrageenan for wide range pressure detection
Chen et al. Microstructured flexible pressure sensor based on nanofibrous films for human motions and physiological detection
Ma et al. Stretchable porous conductive hydrogel films prepared by emulsion template method as flexible sensors
Lin et al. A flexible pressure sensor based on bimaterial conductivity-conversion mechanism
CN116172583A (en) Flexible electrode for collecting dual-mode signals and preparation method and application thereof
Fan et al. Recent Progress in Mechanically Robust and Conductive‐Hydrogel‐Based Sensors

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant