CN109163653B - Preparation method of patterned graphene flexible strain sensor - Google Patents
Preparation method of patterned graphene flexible strain sensor Download PDFInfo
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- CN109163653B CN109163653B CN201811050042.0A CN201811050042A CN109163653B CN 109163653 B CN109163653 B CN 109163653B CN 201811050042 A CN201811050042 A CN 201811050042A CN 109163653 B CN109163653 B CN 109163653B
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- 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
Abstract
The invention provides a preparation method of a patterned graphene flexible strain sensor, which comprises the steps of firstly preparing a preset pattern on the surface of a hard substrate material by using a photoetching method to obtain a patterned mold, and then pouring mixed slurry of a high polymer material elastomer and a curing agent onto the surface of the patterned mold for curing to obtain a micro-channel mold; and then covering the surface of the flexible substrate with a micro-channel mold, carrying out patterning modification on the flexible substrate with dopamine, preparing a graphene sensitive layer on the surface of the modified substrate, and finally coating conductive silver paste and a bonding wire to obtain the patterned graphene flexible strain sensor. The preparation method provided by the invention does not need to carry out photoetching on the flexible substrate, does not damage the body structure of the flexible substrate, is suitable for complex curved surfaces, is suitable for large-area manufacturing, is suitable for fine pattern processing, and reduces the requirements on the material, shape and surface structure of the flexible substrate.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a preparation method of a patterned graphene flexible strain sensor.
Background
The graphene patterning film has important application value for fine processing and performance regulation of micro-nano devices, and has attracted extensive research interest. In a conventional graphene patterning method, graphene oxide is spin-coated on the surface of a substrate, and then a pattern is formed by performing processes such as photolithography, and then the patterned graphene oxide is subjected to reduction. The method needs a photoetching step, is complicated in process and high in cost, can damage the surface of the substrate to a certain extent, and has strict requirements on the material and the surface appearance of the substrate. And when the graphene oxide reagent is dripped on the rotating substrate, the interaction force between the graphene oxide and the substrate can influence the film forming, and the spin coating process can only form a film on a plane substrate with a simple shape, has a small film forming range and is not suitable for mass production.
Some other research hotspots in the art for graphene patterning currently include inkjet printing and screen printing. The ink-jet printing process has a serious coffee ring effect (which means that after a solution or suspension liquid drop is volatilized and dried on a solid surface, a ring-shaped stain is sometimes formed at the edge of the liquid drop), so that the uniformity of graphene oxide of a film is reduced when a graphene solution is formed into a film, and the pattern resolution is reduced due to the existence of the coffee ring, thereby preventing the realization of micro-nano-scale patterning processing of the graphene film. The graphene ink used in the screen printing process is generally slurry with high viscosity, and the introduction of the adhesive limits the conductivity of the graphene.
Therefore, the method for preparing the patterned graphene sensor in the prior art is complex in process, difficult to control, incapable of adapting to a complex curved surface and processing a fine pattern, and hinders the development of the flexible strain sensor.
Disclosure of Invention
In view of this, the present invention aims to provide a method for manufacturing a patterned graphene flexible strain sensor. The preparation method provided by the invention has simple steps, is easy to control, can adapt to the substrate with a complex curved surface, and is suitable for processing a refined pattern.
In order to achieve the above object, the present invention provides the following technical solutions:
a preparation method of a patterned graphene flexible strain sensor comprises the following steps:
(1) preparing a preset microstructure relief pattern on the surface of the hard substrate material by using a photoetching method to obtain a patterned mold;
(2) mixing an elastomer and a curing agent to obtain mixed slurry;
(3) coating an anti-sticking agent on the surface of the patterned mold to form an anti-sticking layer, then pouring the mixed slurry on the surface of the anti-sticking layer for curing, and stripping the cured component to obtain the micro-channel mold;
(4) covering the micro-channel mold on the surface of a flexible substrate to form a micro-channel member, dipping the micro-channel member in a dopamine solution, and then uncovering the micro-channel mold to obtain a patterned modified flexible substrate;
(5) coating the graphene-graphene oxide mixed dispersion liquid on the surface of the patterned and modified flexible substrate, and enriching the graphene-graphene oxide in a patterned and modified area to form a graphene-graphene oxide patterned thin film;
(6) reducing the graphene oxide in the graphene-graphene oxide patterned film to form a patterned graphene sensitive layer;
(7) coating conductive silver adhesive on two sides of the patterned graphene sensitive layer and bonding a lead to obtain a patterned graphene flexible strain sensor;
the step (1) and the step (2) have no time sequence limitation.
Preferably, the young's modulus of the elastomer in the step (2) is 1MPa to 1 GPa.
Preferably, the curing temperature in the step (3) is between room temperature and 100 ℃, and the curing time is between 1 and 48 hours.
Preferably, the dopamine solution in step (4) is prepared by the following steps:
mixing trihydroxymethyl aminomethane and water to obtain a trihydroxymethyl aminomethane solution, and adjusting the pH value of the trihydroxymethyl aminomethane solution to be less than or equal to 13 to obtain a buffer solution;
dissolving dopamine hydrochloride in the buffer solution to obtain a dopamine solution.
Preferably, the mass ratio of the tris to the water is 0.1-1: 100;
the concentration of the dopamine in the dopamine solution is 0.1-0.3 mol/L.
Preferably, the impregnation in the step (4) is performed under stirring conditions; the stirring speed is 300-500 rpm, and the time is 20-30 h.
Preferably, the reduction treatment in the step (6) includes the steps of:
and (3) reversely buckling the flexible substrate with the graphene-graphene oxide patterned thin film above the HI solution for heat treatment.
Preferably, the temperature of the heat treatment is 70-90 ℃, and the time is 1-2 h.
Preferably, the method further comprises the following steps after the wire is bonded: and coating an encapsulation layer on the surfaces of the patterned graphene sensitive layer and the conductive silver adhesive, and leading out a lead from the encapsulation layer.
The invention provides a preparation method of a patterned graphene flexible strain sensor, which comprises the steps of firstly preparing a preset microstructure relief pattern on the surface of a hard substrate material by using a photoetching method to obtain a patterned mold, and then pouring mixed slurry of a high polymer material elastomer and a curing agent on the surface of the patterned mold for curing to obtain a micro-channel mold; and then covering the surface of the flexible substrate with a micro-channel mold, carrying out patterning modification on the flexible substrate with dopamine, preparing a graphene sensitive layer on the surface of the modified substrate, and finally coating conductive silver paste and a bonding wire to obtain the patterned graphene flexible strain sensor. According to the preparation method provided by the invention, the micro-channel mold is used for covering the flexible substrate, so that the dopamine solution can only flow in the micro-channel in the modification process, and the substrate area which is not exposed in the dopamine solution is not modified, so that the patterning modification of the flexible substrate is realized, and the substrate modified by dopamine has an enrichment effect on graphene, so that the patterning of a graphene sensitive layer can be realized. The preparation method provided by the invention has the advantages that the flexible substrate is not required to be subjected to photoetching, the structure of the flexible substrate body is not damaged, the flexible substrate is suitable for complex curved surfaces, is suitable for large-area manufacturing and fine pattern processing, the requirements on the material, shape and surface structure of the flexible substrate are reduced, the cost is low, the process is simple, and the manufacturing and application of the flexible strain sensor are promoted.
Furthermore, the preparation method provided by the invention reduces the graphene oxide in the HI environment without high-temperature heat treatment, so that the problem that the flexible substrate is easily damaged at high temperature is avoided, and the application range of the preparation method provided by the invention is wider.
Drawings
FIG. 1 is a schematic illustration of a flexible substrate patterned for modification in an embodiment of the invention;
fig. 2 is a diagram of a patterned graphene flexible strain sensor after packaging in an embodiment of the invention;
in fig. 2, 1-flexible substrate, 2-patterned graphene sensitive layer, 3-wire, 4-encapsulation layer.
Detailed Description
The invention provides a preparation method of a patterned graphene flexible strain sensor, which comprises the following steps:
(1) preparing a preset microstructure relief pattern on the surface of the hard substrate material by using a photoetching method to obtain a patterned mold;
(2) mixing an elastomer and a curing agent to obtain mixed slurry;
(3) coating an anti-sticking agent on the surface of the patterned mold to form an anti-sticking layer, then pouring the mixed slurry on the surface of the anti-sticking layer for curing, and stripping the cured component to obtain the micro-channel mold;
(4) providing a flexible substrate, covering the surface of the flexible substrate with the micro-channel mold to form a micro-channel member, dipping the micro-channel member in a dopamine solution, and then uncovering the micro-channel mold to obtain a patterned modified flexible substrate;
(5) coating the graphene-graphene oxide mixed dispersion liquid on the surface of the patterned and modified flexible substrate, and enriching the graphene-graphene oxide in a patterned and modified area to form a graphene-graphene oxide patterned thin film;
(6) reducing the graphene oxide in the graphene-graphene oxide patterned film to form a patterned graphene sensitive layer;
(7) coating conductive silver adhesive on two sides of the patterned graphene sensitive layer and bonding a lead to obtain a patterned graphene flexible strain sensor;
the step (1) and the step (2) have no time sequence limitation.
The invention uses photoetching method to prepare the preset microstructure relief pattern on the surface of the hard substrate material. In the present invention, the hard base material preferably includes a silicon base; the invention has no special requirements on the specific method of the photoetching method, and the photoetching method which is well known by the technicians in the field can be applied; the invention has no special requirements along with the specific shape of the microstructure relief pattern, and can be designed according to the actual requirements.
According to the invention, the elastomer and the curing agent are mixed to obtain the mixed slurry. In the present invention, the elastomer is preferably a polymer material elastomer; the Young modulus of the high polymer material elastomer is preferably 1MPa to 1GPa, and more preferably 10MPa to 100 MPa; the high polymer material elastomer is preferably Polydimethylsiloxane (PDMS) elastomer; the mass ratio of the high polymer material elastomer to the curing agent is preferably 5-20: 1, and more preferably 10: 1; the present invention does not require any particular kind of curing agent, and those known to those skilled in the art can be used.
After the elastomer and the curing agent are mixed, the mixture is preferably subjected to ultrasonic treatment after being uniformly stirred; the power of the ultrasonic wave is preferably 20-100W, more preferably 80W, and the time of the ultrasonic wave is preferably 5-10 min, more preferably 6-8 min; the invention removes air bubbles in the mixture by ultrasound.
And after the mixed slurry is obtained, coating an anti-sticking agent on the surface of the patterned mold to form an anti-sticking layer, then pouring the mixed slurry on the surface of the anti-sticking layer for curing, and stripping the cured component to obtain the micro-channel mold. In the present invention, the anti-sticking agent is preferably 1H, 2H-perfluorooctyltriethoxysilane; the 1H,1H,2H, 2H-perfluoro octyl triethoxysilane liquid substance is preferably used for heating the 1H,1H,2H, 2H-perfluoro octyl triethoxysilane to volatilize steam, and fumigating the pattern side of the hard substrate with the microstructure relief pattern on the surface, so that the conformal coating of the surface of the hard substrate is realized, and an anti-sticking agent layer is formed; the anti-sticking agent has no special requirement on the coating thickness, and can achieve the anti-sticking effect. In the present invention, the curing temperature is preferably room temperature to 100 ℃, more preferably 60 ℃, and the curing time is preferably 1h to 48h, more preferably 1.5 h. According to the invention, the patterned mold is peeled off after curing, the obtained micro-channel mold copies the pattern on the surface of the patterned mold, and the micro-channel mold has the characteristics of softness and good elasticity.
After the micro-channel mold is obtained, the micro-channel mold is covered on the surface of the flexible substrate to form the micro-channel component. In the present invention, the material of the flexible substrate is preferably PDMS (polydimethylsiloxane), PVDF (polyvinylidene fluoride), PET (polyethylene terephthalate), or PI (polyimide); the invention has no special requirement on the source of the flexible substrate, and can be directly purchased or prepared by self. In the invention, the surface of the flexible substrate is attached to the pattern side of the microchannel mold to form the microchannel.
The micro-channel component is soaked in dopamine solution, and then the micro-channel mould is uncovered, so that the patterned modified flexible substrate is obtained. In the present invention, the dopamine solution is preferably prepared by the following steps:
mixing the trihydroxymethyl aminomethane with water to obtain a trihydroxymethyl aminomethane solution, adjusting the pH value of the trihydroxymethyl aminomethane solution to be less than or equal to 13 to obtain a buffer solution;
dissolving dopamine hydrochloride in a buffer solution to obtain a dopamine solution.
In the invention, the mass ratio of the tris to water is preferably 0.1-1: 100, more preferably 0.248: 100; the water is preferably deionized water; the pH value of the tris solution is adjusted to be less than or equal to 13, and is more preferably adjusted to be 8.5; the pH value of the tris solution is preferably adjusted by using dilute hydrochloric acid, and the method has no special requirement on the mass concentration of the dilute hydrochloric acid and can adjust the pH value of the tris solution to the required pH value. According to the invention, the pH value of the buffer solution is adjusted to be within the range, so that good conditions are provided for the growth of dopamine.
In the invention, the concentration of the dopamine in the dopamine solution is preferably 0.1-0.3 mol/L, and more preferably 0.2 mol/L.
In the present invention, the temperature of the impregnation is preferably room temperature, and the impregnation is preferably performed under stirring conditions; the rotating speed of the stirring is preferably 300-500 rpm, and more preferably 400 rpm; the stirring time is preferably 20-30 h, and more preferably 24 h. In the invention, the dopamine solution flows in the micro-channel, and the region which is not exposed in the dopamine solution does not flow, so that the patterning modification of the flexible substrate is realized. The dopamine forms a polydopamine layer on the surface of the flexible substrate, the polydopamine contains catechol functional groups and has super-strong adhesion and chemical activity, and the polydopamine layer, the flexible substrate and the graphene are all easy to generate strong interface interaction, so that the interface combination of the polydopamine layer and the flexible substrate is improved.
After dipping, the present invention preferably removes the micro flow channel member from the dopamine solution, removes the micro flow channel mold, and then washes the patterned modified flexible substrate. In the invention, the washing is preferably water washing, and the invention has no special requirement on the specific method of the washing and can clean the polydopamine agglomerates attached to the surface of the flexible substrate.
After the patterned and modified flexible substrate is obtained, the graphene-graphene oxide mixed dispersion liquid is coated on the surface of the patterned and modified flexible substrate to form the graphene-graphene oxide patterned film. In the present invention, the mass fraction of the oxygen-containing functional group in the graphene-graphene oxide mixed dispersion liquid is preferably 20 to 60%, and more preferably 30 to 50% (the content of the oxygen-containing functional group is obtained by XPS spectroscopy, and the content of the oxygen-containing functional group can be obtained from the peak area by measuring XPS peak); the sheet diameter of graphene in the mixed dispersion liquid is preferably less than or equal to 20nm, and more preferably 5-15 nm; the sheet diameter of the graphene oxide in the mixed dispersion liquid is preferably less than or equal to 500nm, and more preferably 300-400 nm. According to the invention, the small-diameter graphene is used for filling gaps of the large-diameter graphene oxide, so that the film formation is more uniform; according to the invention, the interface combination of the graphene and the flexible substrate can be adjusted by adjusting the mass ratio of the graphene to the graphene oxide and adjusting the oxygen-containing functional group ratio, so that the sensitivity, the response time and the range are adjusted.
In the present invention, the dispersion solution of the mixed dispersion is preferably N-methylpyrrolidone.
In a specific embodiment of the present invention, preferably, the graphene dispersion liquid and the graphene oxide dispersion liquid are prepared first, and then the two are mixed to obtain a graphene-graphene oxide mixed dispersion liquid; according to the method, the graphene solution and the graphene oxide solution are preferably uniformly mixed by ultrasound; the power of the ultrasonic is preferably 30% of the rated power of the ultrasonic cleaning machine, and the time of the ultrasonic is preferably 5 min; according to the invention, the ratio of graphene to graphene oxide in the mixed dispersion liquid is controlled by controlling the mixing ratio of the graphene dispersion liquid and the graphene oxide dispersion liquid, so that the number of oxygen-containing functional groups in the mixed dispersion liquid is controlled, and the purposes of regulating and controlling the sensitivity, response time and measuring range of the sensor are achieved.
After the graphene-graphene oxide mixed dispersion liquid is obtained, the mixed dispersion liquid is coated on the surface of the patterned and modified flexible substrate. In the present invention, the coating is preferably spray coating, and the present invention preferably charges the mixed dispersion into a spray gun, and then flatly attaches the patterned modified flexible substrate to the center of a petri dish, and then preheats the petri dish, and then sprays the spray gun nozzle directly against the center of the patterned modified flexible substrate. In the present invention, the size of the culture dish is preferably 100mm × 100 mm; the preheating temperature is preferably 40-60 ℃, and more preferably 50 ℃; the vertical distance between the spray gun nozzle and the patterned modified substrate is preferably 12-16 cm, and more preferably 15 cm. According to the invention, the graphene-graphene oxide dispersion liquid is uniformly sprayed on the surface of the patterned modified substrate, the modified part of the substrate has strong surface activity and is adhered with a polydopamine layer, and the polydopamine layer has good adhesion, so that the sprayed graphene and graphene oxide are selectively enriched on the patterned modified part of the flexible substrate.
After the spraying is finished, preferably drying the graphene-graphene oxide wet film; the drying is preferably room-temperature air drying, and the air drying time is preferably 24 hours; in the specific embodiment of the invention, the drying can be carried out in an air pressure booster, and the drying pressure is preferably 0.01 to 1MPa, more preferably 0.1 to 0.5 MPa; the adhesion effect between the graphene and graphene oxide and the substrate can be further enhanced by the pressurized drying.
After the graphene-graphene oxide patterned thin film is formed, the graphene oxide in the graphene-graphene oxide patterned thin film is subjected to reduction treatment to form a patterned graphene sensitive layer. In the present invention, the reduction treatment preferably includes the steps of:
and (3) reversely buckling the flexible substrate with the graphene-graphene oxide patterned thin film above the HI solution for heat treatment.
Preferably, the HI solution is placed in a crystallization dish, then a flexible substrate with a graphene-graphene oxide patterned film is fixed on the inner side of a glass culture dish, and then the glass culture dish attached with the flexible substrate is reversely buckled on the crystallization dish; and then carrying out heat treatment on the crystallizing dish to volatilize HI in the HI solution, completely exposing the graphene-graphene oxide patterned film in an HI environment, and reducing the graphene oxide into graphene under the action of HI. In the invention, the heat treatment temperature is preferably 70-90 ℃, more preferably 80 ℃, and the heat treatment time is preferably 1-2 h, more preferably 1 h.
After the heat treatment is completed, the flexible substrate on which the patterned graphene sensitive layer is formed is preferably washed and dried in sequence. In the invention, the washing is preferably water washing, and the water for water washing is preferably deionized water; according to the invention, the redundant HI on the surface of the graphene sensitive layer is removed by washing. In the present invention, the drying is preferably air-drying at room temperature; the air drying time is preferably 24 h.
After the graphene sensitive layer is formed, coating conductive silver adhesive on two sides of the patterned graphene sensitive layer and bonding a lead to obtain the patterned graphene flexible strain sensor. The invention has no special requirements on the brushing position and the shape of the conductive silver adhesive, and can realize the connection between the graphene sensitive layer and the lead. In the present invention, the wire is preferably a silver wire, and the diameter of the silver wire is preferably 0.1 mm.
After bonding the wires, the present invention preferably further comprises: and coating an encapsulation layer on the surfaces of the patterned sensitive layer and the conductive silver adhesive, and leading out the wires from the encapsulation layer. In the present invention, the encapsulation layer is preferably polydimethylsiloxane; the invention has no special requirements on the specific method and thickness of the coating, and can realize the packaging effect.
The invention leads the lead to extend out of the packaging layer, and leads the lead to be connected with the anode and the cathode of the electrical test workstation when in application.
The following describes in detail a method for manufacturing a patterned graphene flexible strain sensor according to the present invention with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
(1) Manufacturing a patterned mold: the method comprises the steps of manufacturing a microstructure relief pattern on a silicon substrate by a photoetching method, coating a layer of anti-sticking agent on the surface of the pattern, wherein the anti-sticking agent is 1H,1H,2H, 2H-perfluorooctyl triethoxysilane, heating the 1H,1H,2H, 2H-perfluorooctyl triethoxysilane at 100 ℃, volatilizing steam to fumigate the pattern side of the silicon substrate, and successfully coating the pattern side of the mold in a conformal manner for 6 hours to form an adhesive layer.
(2) Preparing a micro-channel mold: mixing the PDMS basic component and a curing agent (the mixing mass ratio is 10: 1), stirring uniformly by a stirrer, carrying out ultrasonic treatment in an ultrasonic cleaning machine for 5-10 minutes until bubbles completely disappear, pouring the mixture on the surface of an anti-sticking agent layer of a patterned mold, placing the mixture in a 60 ℃ oven for 1 hour for curing, and easily stripping the cured PDMS from the surface of the patterned mold to obtain the micro-channel mold.
(3) Modifying the patterned area of the PDMS substrate: weighing 0.248g of Tris drug by using a precision balance, transferring the Tris drug into a beaker, adding 100g of deionized water, placing the beaker on a magnetic stirrer, stirring (the rotating speed is 400r/min) to prepare a buffer solution, dropwise adding dilute hydrochloric acid to adjust the pH value of the buffer solution to 8.5 so as to provide a weak alkaline environment for the growth of dopamine, weighing 0.2476g of dopamine hydrochloride drug, and pouring the dopamine hydrochloride drug into the buffer solution to obtain a dopamine solution.
Adding a Polydimethylsiloxane (PDMS) basic component and a curing agent in a 250ml beaker according to a mass ratio of 10:1, uniformly stirring for 2min by a 130w stirrer, then putting the mixture into an ultrasonic cleaning machine, and carrying out ultrasonic treatment for 10min under the condition that the ultrasonic power is 100% until bubbles completely disappear, and taking out the mixture. And 5.5g of the ultrasonically mixed slurry is poured into a culture dish with the diameter of 125mm, and the culture dish is horizontally placed on a laboratory bench and cured for 24 hours at normal temperature to obtain the PDMS substrate. Cutting the cured PDMS substrate into a size of about 2cm multiplied by 1cm, and flatly attaching the PDMS substrate to the surface of the glass slide.
Covering the surface of PDMS to form a micro-flow channel member, completely soaking the micro-flow channel member in dopamine solution, and stirring for 24 hours with a magnetic stirrer (stirring speed of 400r/min) to modify the surface of the substrate exposed in the flow channel, wherein the unexposed area is not treated. And taking out the micro-channel component from the dopamine solution after the modification is finished, uncovering the micro-channel mold, washing off polydopamine aggregates attached to the surface of the flexible substrate by using a large amount of deionized water to obtain the patterned modified flexible substrate, and soaking the patterned modified flexible substrate in the deionized water for later use. A schematic diagram of a patterned modified flexible substrate is shown in fig. 1.
(4) Preparing a graphene-graphene oxide patterned film: 0.08ml of graphene N-methylpyrrolidone (NMP) dispersion liquid (2mg/ml, the graphene sheet diameter is 20nm) is measured by using a dropper and transferred into a glass bottle, then 0.02ml of graphene oxide NMP dispersion liquid (2mg/ml, the graphene oxide sheet diameter is 500nm) is added dropwise, and the content of oxygen-containing functional groups in the mixed liquid is 12-18% by using XPS spectrum testing. And immediately putting the mixed solution into an ultrasonic cleaning machine (with the power of 30%) for 5min to uniformly mix the two solutions to obtain a graphene-graphene oxide mixed dispersion liquid (the oxygen-containing functional group in the mixed dispersion liquid accounts for 20%), and transferring the mixed dispersion liquid into a spray gun for later use. And taking out the patterned modified flexible substrate in the deionized water, and completely drying by a nitrogen gun. The flexible substrate is flatly attached to the center of a square culture dish (100mm x 100mm), the culture dish is horizontally placed on a hot plate in a fume hood for preheating at 50 ℃, a spray gun is placed at a position 15cm away from the substrate, a nozzle is aligned to the center of the substrate, the substrate is slowly sprayed at a constant speed, and graphene oxide are enriched in a modified area. And horizontally placing the culture dish in a fume hood, and air-drying at normal temperature for 24 hours to obtain the graphene-graphene oxide patterned film. The resistance of the graphene oxide was measured and found to be infinite.
(5) And (3) reducing graphene oxide: attaching the completely dried sample to the inner side of a glass culture dish (150ml), putting a Hydrogen Iodide (HI) solution into a crystallization dish (with an inner diameter of 125mm), reversely buckling the culture dish attached with the sample on the crystallization dish, completely exposing the graphene-graphene oxide film side of the sample in an HI environment, placing the whole crystallization dish on a hot plate, heating at the constant temperature of 80 ℃ for 1h, then taking down the flexible substrate, removing the redundant hydrogen iodide solution on the patterned film by using deionized water, air-drying at the normal temperature in a ventilation cabinet for 24h to obtain a patterned graphene sensitive layer, and measuring the patterned graphene resistance on the sample to obtain the patterned graphene sensitive layer with the result of about 10k omega-1M omega.
(6) Assembling a sensor device: and brushing conductive silver adhesive on the edges of two sides of the graphene sensitive layer, bonding a silver wire (the diameter is 100 micrometers), and then coating a PDMS packaging layer to obtain the patterned graphene flexible strain sensor. The schematic structure of the packaged sensor is shown in fig. 2.
Example 2
The other steps were the same as in example 1 except that the volume of the N-methylpyrrolidone dispersion liquid of graphene in step (4) was changed to 0.06mL, and the volume of the N-methylpyrrolidone dispersion liquid of graphene oxide was changed to 0.04 mL. The content of the oxygen-containing functional groups in the mixed solution is 25-35% by using XPS spectrum for testing.
Example 3
The other steps were the same as in example 1 except that the volume of the N-methylpyrrolidone dispersion liquid of graphene in step (4) was changed to 0.04mL, and the volume of the N-methylpyrrolidone dispersion liquid of graphene oxide was changed to 0.06 mL. The content of the oxygen-containing functional groups in the mixed solution is 37-50% by using XPS spectrum for testing.
The electrical properties of the patterned graphene flexible strain sensor prepared in examples 1 to 3 were tested, and the test results are shown in table 1.
Table 1 electrical properties of patterned graphene flexible strain sensors obtained in examples 1 to 3
As can be seen from Table 1, the sensors prepared in examples 1-3 all have excellent electrical properties, and the sensitivity, minimum detection limit and response time of the sensors can be adjusted by the content of the oxygen-containing functional group in the sensitive layer.
According to the embodiments, the preparation method provided by the invention does not need to carry out photoetching on the flexible substrate, does not damage the body structure of the flexible substrate, is suitable for complex curved surfaces, is suitable for large-area manufacturing, is suitable for fine pattern processing, reduces the requirements on the material, shape and surface structure of the flexible substrate, has low cost and simple process, and promotes the manufacturing and application of the flexible strain sensor.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A preparation method of a patterned graphene flexible strain sensor comprises the following steps:
(1) preparing a preset microstructure relief pattern on the surface of the hard substrate material by using a photoetching method to obtain a patterned mold;
(2) mixing an elastomer and a curing agent to obtain mixed slurry;
(3) coating an anti-sticking agent on the surface of the patterned mold to form an anti-sticking layer, then pouring the mixed slurry on the surface of the anti-sticking layer for curing, and stripping the cured component to obtain the micro-channel mold;
(4) covering the micro-channel mold on the surface of a flexible substrate to form a micro-channel member, dipping the micro-channel member in a dopamine solution, and then uncovering the micro-channel mold to obtain a patterned modified flexible substrate;
(5) coating the graphene-graphene oxide mixed dispersion liquid on the surface of the patterned and modified flexible substrate, and enriching the graphene-graphene oxide in a patterned and modified area to form a graphene-graphene oxide patterned thin film;
(6) reducing the graphene oxide in the graphene-graphene oxide patterned film to form a patterned graphene sensitive layer;
(7) coating conductive silver adhesive on two sides of the patterned graphene sensitive layer and bonding a lead to obtain a patterned graphene flexible strain sensor;
the step (1) and the step (2) have no time sequence limitation.
2. The production method according to claim 1, wherein the young's modulus of the elastomer in the step (2) is 1MPa to 1 GPa.
3. The preparation method according to claim 1, wherein the curing in the step (3) is carried out at a temperature of room temperature to 100 ℃ for 1 to 48 hours.
4. The preparation method according to claim 1, wherein the dopamine solution in the step (4) is prepared by the following steps: mixing trihydroxymethyl aminomethane and water to obtain a trihydroxymethyl aminomethane solution, and adjusting the pH value of the trihydroxymethyl aminomethane solution to be less than or equal to 13 to obtain a buffer solution; dissolving dopamine hydrochloride in the buffer solution to obtain a dopamine solution.
5. The preparation method according to claim 4, wherein the mass ratio of the tris (hydroxymethyl) aminomethane to the water is (0.1-1): 100; the concentration of the dopamine in the dopamine solution is 0.1-0.3 mol/L.
6. The production method according to claim 1, wherein the impregnation in the step (4) is performed under stirring conditions; the stirring speed is 300-500 rpm, and the time is 20-30 h.
7. The production method according to claim 1, wherein the reduction treatment in the step (6) includes the steps of: and (3) reversely buckling the flexible substrate with the graphene-graphene oxide patterned thin film above the HI solution for heat treatment.
8. The method according to claim 7, wherein the heat treatment is carried out at a temperature of 70 to 90 ℃ for 1 to 2 hours.
9. The method of claim 1, further comprising, after bonding the wire: and coating an encapsulation layer on the surfaces of the patterned graphene sensitive layer and the conductive silver adhesive, and leading out a lead from the encapsulation layer.
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| CN110085018A (en) * | 2019-06-06 | 2019-08-02 | 吉林大学 | A kind of vibration signal wireless acquisition device and wireless acquisition system |
| CN110243276A (en) * | 2019-06-28 | 2019-09-17 | 江苏大学 | A kind of stretchable stress strain gauge and preparation method applied to articulations digitorum manus |
| CN110953982B (en) * | 2019-12-20 | 2024-02-06 | 浙江清华柔性电子技术研究院 | Thin film device and preparation method thereof, flexible strain sensor and preparation method thereof |
| CN111721192B (en) * | 2020-06-30 | 2020-12-29 | 暨南大学 | Strain sensor based on graphical induced cracks and preparation method thereof |
| CN111998765B (en) * | 2020-07-10 | 2021-08-24 | 清华大学 | Integrated flexible stretching sensor and preparation method thereof |
| CN112146796A (en) * | 2020-09-17 | 2020-12-29 | 有研工程技术研究院有限公司 | Flexible stress sensor and preparation method thereof |
| CN113029404B (en) * | 2021-03-10 | 2022-05-24 | 电子科技大学 | Preparation method of dual-channel flexible polymorphic stress sensor based on graphene |
| CN113074846B (en) * | 2021-03-12 | 2022-07-29 | 电子科技大学 | Micro-channel stress sensor based on structural metamaterial and preparation method thereof |
| CN113503914B (en) * | 2021-06-29 | 2023-11-17 | 西北工业大学 | Preparation method of flexible sensor |
| CN113532261B (en) * | 2021-08-16 | 2022-09-20 | 河北工业大学 | Strain monitoring system and method |
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| CN102653454A (en) * | 2011-08-12 | 2012-09-05 | 京东方科技集团股份有限公司 | Preparation method for patterned graphene membrane |
| CN103205006B (en) * | 2013-04-02 | 2015-04-22 | 天津工业大学 | Surface patterning high-strength and high-toughness hybrid hydrogel membrane and preparation method thereof |
| JP6280070B2 (en) * | 2015-03-12 | 2018-02-14 | 日本電信電話株式会社 | Strain sensor and strain detection method |
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| CN106057644A (en) * | 2016-06-07 | 2016-10-26 | 中国船舶重工集团公司第七二五研究所 | Method for directly writing graphene pattern on nonmetal surface by laser |
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