KR20190092891A - Composite film for sensing pressure, method for producing the same and pressure sensitive device having the same - Google Patents

Abstract

A composite film for sensing pressure and a pressure sensitive device including the same are disclosed. The composite film for sensing pressure includes a composite including graphene oxide and a dielectric polymer, and includes micropores of 10 nm to 100 nm. The composite film has good transparency and flexibility. So, the composite film can be applied to various devices which use pressure sensing.

Description

Composite membrane for pressure sensing, a method of manufacturing the same, and a pressure-sensitive device including the same {COMPOSITE FILM FOR SENSING PRESSURE, METHOD FOR PRODUCING THE SAME AND PRESSURE SENSITIVE DEVICE HAVING THE SAME}

The present invention relates to a composite membrane for pressure sensing, a method for manufacturing the same, and a pressure reduction device including the same.

The field of the sensor by the pressure element using pressure, such as the pressure sensor using a piezoelectric polymer material and the pressure sensor which changes a resistance by applying pressure, is developed. The change in electrical characteristics due to the decompression requires a large range of vacuum degree, and the range of the measured pressure depending on the pressure element material may be limited in the selection of the material.

 There is a pressure sensor using a polymer material among the materials of the pressure element, the piezoelectric stress constant is required, the piezoelectric stress constant can determine the way to measure the change in the electrical characteristics due to the appearance changes due to the change in the internal arrangement due to pressure. have.

Except for polymer materials, there are diaphragms, bellows, and Bourdon tubes, which measure and convert electrical properties into electrical signals by using the degree of warpage of the material. In addition, the electrical characteristics change is a capacitor for measuring electrode distance change and capacitance change, a differential transformer having a change in magnetic force and mutual ductance, a potentiometer for measuring resistance change, and an optical fiber for measuring reflection and interference of light.

In addition, there are diaphragm capsules, which measure resistance, voltage, voltage-current, delay time, and color change, which are strain gages, semiconductor strain gauges, piezoelectric elements, piezoelectric sheets, MOS transistors, Hall elements, diode transistors, surface wave elements, and reduced pressure. Used for film.

In some cases, the temperature, discharge, ions, and light are measured according to the change of the thermocouple vacuum system using thermoelectric power, which is a characteristic of the molecular density (pressure) dependence of the thermal conductivity, and the resistance change is measured in the characteristic of the molecular density (pressure) dependence of the thermal conductivity. Pirane gauge, thermistor vacuum gauge, Geissler tube for measuring voltage on the pressure dependence characteristic of discharge start voltage, ionization vacuum, magnetron type ionization vacuum system for measuring ion current change by gas ionization, ionization and magnetic field Quartz-based glass measures phase due to interference, and mode strippers measure light intensity due to microband loss. The change amount according to the decompression is different for each device material having the measurement characteristics applicable to the above-mentioned pressure device, there is a limited range, and a new pressure device that can be easily applied to various pressure ranges and applications. Material is needed.

Composite film for pressure sensing that can be applied to various devices using pressure sensing because of the sensitive characteristics of graphene whose electrical properties change depending on pressure and dielectric materials, and the transparent and flexible response. It relates to a manufacturing method thereof and a pressure-sensitive device using the same.

According to an embodiment, a composite film including graphene oxide and a dielectric polymer is provided, and includes a micropore of 10 nm to 100 nm, and a composite membrane for pressure sensing is provided.

According to an embodiment, the graphene oxide may be included in an amount of 25 to 200 parts by weight based on 100 parts by weight of the composite.

According to one embodiment, the dielectric polymer to the graphene oxide may be included in 1: 0.20 to 2 (mass ratio).

According to one embodiment, the dielectric polymer may be a fluororesin.

According to one embodiment, the composite, polymethacrylate (polymethacrylate), polyacrylate (polyacrylate), polyacrylonitrile (polyacrylonitrile), acryltrile, acrylic acid copolymer, polyvinyl alcohol, polyester at least one organic resin selected from the group consisting of polyester, polyester naphthalate, polycarbonate, polyvinylchloride (PVC), polyacetate and polynorbornene It may be to include more.

According to an embodiment, the organic resin may be included in an amount of 5 to 50 parts by weight based on 100 parts by weight of the composite.

According to an embodiment, the composite membrane for pressure sensing may have a light transmittance of 70% or more, and the composite membrane for pressure sensing may have a thickness of 5 μm to 100 μm.

According to one embodiment, a pressure reduction device including a composite membrane for pressure sensing according to the present invention is provided.

According to one embodiment, preparing a graphene oxide dispersion; Preparing a dielectric polymer solution; Mixing the graphene oxide dispersion with the dielectric polymer solution; And coating the mixed solution on a substrate. Provided is a method of manufacturing a pressure-sensitive device according to the present invention.

According to one embodiment, the porosity due to the fine pores in the composite film may be adjusted according to the content of the graphene oxide.

According to one embodiment, the sensitivity of the electrical characteristics according to the pressure change is improved by using the graphene characteristics and dielectric materials can sense a wide range of pressure, for example, the pressure-sensitive sensor that changes the electrical characteristics according to the decompression And / or a composite membrane for pressure sensing that can be applied to a pressure sensor by piezoelectricity.

According to one embodiment, excellent transparency and flexibility can provide a composite membrane for pressure sensing that can be applied to a flexible product.

According to one embodiment, it is easy to control the electrical properties according to the addition ratio of graphene and dielectric material, can provide the required electrical properties according to the application, and can operate within a variety of pressure range, It is possible to solve the problem of material selection limited to devices for pressure sensing, such as pressure-sensitive sensors and pressure sensors, and to provide electrical property changes at weak physical pressures, for example 100 g of pressure. Sensing can provide sensitive sensing ranges.

The effects obtainable through the described embodiments are not limited to the above effects, and should be understood to include all effects inferred from the specific details for carrying out the invention described below or from the configuration of the invention described in the claims. .

1 is a schematic diagram showing an example of a configuration of a transparent piezoelectric element manufactured in an embodiment of the present invention.
Figure 2 shows an SEM image of the dielectric composite film prepared in the embodiment of the present invention.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. However, various changes may be made to the embodiments so that the scope of the patent application is not limited or limited by these embodiments. It is to be understood that all changes, equivalents, and substitutes for the embodiments are included in the scope of rights.

The terminology used herein is for the purpose of description and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

In addition, in the description with reference to the accompanying drawings, the same components regardless of reference numerals will be given the same reference numerals and duplicate description thereof will be omitted. In the following description of the embodiment, when it is determined that the detailed description of the related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

According to one embodiment, there is provided a composite film for pressure sensing, the composite film, a composite comprising a graphene oxide and a dielectric polymer; It may include.

According to one embodiment, the graphene oxide is to improve the pressure sensing performance and sensitivity by using the inherent characteristics of graphene by using a relatively low graphene oxide than graphene having a high conductivity, and also, the oxidation Graphene may also serve as a dielectric. For example, it may be desirable to apply an insulator having a dielectric constant such as graphene oxide to a device for pressure sensing. That is, since the top and bottom of the dielectric in the pressure element is an electrode line, when the conductivity is high, the upper electrode and the lower electrode has an electric signal separately, and the difficulty of recognition by energization occurs to check the touched part, You can take damage to the electrodes.

The graphene oxide may be a single layer, a multilayer, or both, and preferably, a multilayer graphene having a plurality of layers of such a single layer may be used rather than a single layer in which two-dimensional carbon layers are stacked. That is, when graphene is oxidized, graphene layers are oxidized, and functional groups such as alcohol groups are attached to graphene, and graphene layers are opened.These layers change intervals according to the applied pressure, so the change in dielectric constant and electrical characteristics of graphene are different. And using it, the application to the pressure sensor may be advantageous.

The graphene oxide may be included in an amount of 25 parts by weight to 200 parts by weight based on 100 parts by weight of the composite. When included in the content range is increased sensitivity to pressure sensing by the graphene oxide, it may be easy to adjust the pressure range that can be sensed.

According to one embodiment, the dielectric polymer is a dielectric polymer having a high streamline constant to compensate for the low conductivity of the graphene oxide, for example, it may be a fluorine resin (Fluorine resin). For example, the fluororesin is tetrafluoroethylene (TFE), hexafluoropropylene (TFP), chlorotrifluoroethylene (CTFE), trifluoroethylene, hexafluoroisobutylene, perfluorobutyl Ethylene, perfluoropropyl vinyl ether (PPVE), perfluoroethyl vinyl ether (PEVE), perfluoromethyl vinyl ether (PMVE), polyfluoroalkoxy (PFA), ethylene tetrafluoroethylene (ETFE), ethylene black Letetrafluoroethylene (ECTFE), fluoroethylenepropylene (FEP), perfluoro-2,2-dimethyl-1,3-diosol (PDD) and perfluoro-2-methylene-4-methyl-1,3 -Dioxolane (PMD) may include one or more selected from the group consisting of, but is not limited thereto.

The dielectric polymer may include 30 to 90 parts by weight based on 100 parts by weight of the composite; Or it may be included in 33 parts by weight to 80 parts by weight. When included in the content range, while providing transparency and flexibility of the composite film, it may be combined with graphene oxide to increase sensitivity to changes in dielectric constant due to pressure.

According to one embodiment, the dielectric polymer to the graphene oxide is 1: 0.20 to 2 (mass ratio); When included, and within the above range, it is excellent in the sensitivity of the change in electrical properties according to the pressure, can exhibit transparency and flexibility.

According to one embodiment, the composite, polymethacrylate (polymethacrylate), polyacrylate (polyacrylate), polyacrylonitrile (polyacrylonitrile), acryltrile, acrylic acid copolymer, polyvinyl alcohol, polyester at least one organic resin selected from the group consisting of polyester, polyester naphthalate, polycarbonate, polyvinylchloride (PVC), polyacetate and polynorbornene Further comprising, the organic resin may further comprise a hydrophilic group. The organic resin may be added to the dielectric polymer and the composite of the graphene oxide to help widen the layer of graphene oxide, thereby increasing the width of the electrical characteristics, thereby providing an advantage in evaluating the electrical characteristics according to the pressure. Preferably polyvinylidene fluoride (PVDF), the polyvinylidene fluoride (PVDF) is a high piezoelectric polymer, is advantageous for application to the device for pressure sensing using piezoelectric properties while providing transparency and flexibility, pressure It is possible to improve the sensitivity to the measurement of the change in electrical characteristics.

The organic resin may be included in 5 to 50 parts by weight based on 100 parts by weight of the composite. If included in the content range it can increase the sensitivity by the pressure of the composite membrane.

According to one embodiment, the composite membrane, may include micropores of 5 ㎛ to 100 ㎛, which can be adjusted according to the mixing ratio, content, etc. of graphene oxide, sensitivity by pressure sensing by the control of the fine pores The sensing range can be easily adjusted. In addition, the composite film, 20% or more; More than 30%; Or 30% to 70% porosity.

According to one embodiment, the composite membrane for pressure sensing, 70% or more; It may have transparency and flexibility having a light transmittance of 80% or more (eg, visible light region), and may be applied to a device using pressure sensing in a flexible device, a touch screen, a transparent display, and the like.

According to an embodiment, the composite membrane for pressure sensing may have a thickness of 5 μm to 100 μm, preferably 30 μm to 100 μm. When included in the thickness range it is easy to control the required thickness change according to the pressure element, it may be advantageous that the thickness is high to increase the sensitivity.

According to an embodiment, the composite membrane for pressure sensing may be applied to various pressure devices using characteristics such as pressure, pressure reduction, and piezoelectricity by adjusting thickness, porosity, graphene oxide, and the like, for example, It can be applied to the pressure-sensitive device that can sense the pressure by using the electrical characteristics that change with the pressure. The decompression element is applied as a decompression sensor, and the configuration of the decompression element may be applied without limitation as long as it is applied in the technical field of the present invention.

According to one embodiment, there is provided a method of manufacturing a pressure-sensitive device, preparing a graphene oxide dispersion; Preparing a dielectric polymer solution; Mixing the graphene oxide dispersion with the dielectric polymer solution; And coating the mixed solution on a substrate.

According to one embodiment, preparing the graphene oxide dispersion and preparing the dielectric polymer solution may include the same or different organic solvents, such as dispersible and dielectric polymer of the graphene oxide Any amount can be applied without limitation so long as it is easy to use and / or disperse the additive components. For example, the organic solvent is dimethylformamide (DMF), dimethylacetoamide, dimethylsulfoxide, N-methyl pyrrolidone, isophorone (Isophorone), methyl ethyl ketone (MEK), acetone, tetrahydrofuran, Methyl isobutyl ketone, butyl acetate, cyclohexane source, diacetone alcohol, diisobutyl ketone, ethyl acetoacetate, butyrolactone, propylene carbonate, glyceryl triacetate and dimethyl phthalate Can be.

The preparing of the dielectric polymer solution may further include additional additives as necessary. The coating of the mixed solution on a substrate may include spin coating and dip coating the mixed solution on a substrate. (dip coating), spray coating, Dr. blade coating, roll coating, bar coating, ink jet coating, gravy coating And one or more selected from the group consisting of slot-die coating.

The substrate may be appropriately selected depending on the application, and for example, indium-tin oxide (ITO), fluorine-tin oxide (FTO), aluminum-zinc oxide (AZO), or gallium-zinc oxide (GZO) ), Ag, Au, Pd, Al, Pt, Cu, Zn, Cd, In, Si, Zr, Mo, Ni, Cr, Mg, Mn, Co and a transparent electrode containing a semiconductor, Sapphire, silicon, wafer, glass, and the like.

Production Example

Oxidation Graphene  Produce

Graphene oxide manufacturing method was carried out by the application of the Hemmer method. In a Erlenmeyer flask, 2-4 g of graphite and 100 mL of sulfuric acid were stirred. At this time, graphite was used as synthetic graphite, and sulfuric acid was concentrated sulfuric acid, and its concentration was 90% to 99%. This process is to oxidize the dispersed graphite and oxidize. After 30 minutes of sufficient dispersion, the flask is immersed in an ice bath to adjust the temperature of the solution to 0 ° C., potassium permanganate 3-12 g was further oxidized. It is a process that weakens the van der Waals forces between carbons by attaching several functional groups between the carbon layers so that the layers are separated from each other. Potassium permanganate is reduced to form manganese sulfide salts. Next, the centrifuge was centrifuged and washed several times to neutralize the pH. When the pH is neutral, the solution is sonicated to disperse the aggregated oxidized graphene and centrifugation once more to separate the remaining unoxidized graphite and graphene oxide. Graphene obtained repeatedly was confirmed to be oxidized by checking the peak of the C = C, C-O, -OH group using FT-IR.

Example

(1) Preparation of Composite Dielectric Composition

GO in Isophorone was placed in a 2: 1 ratio beaker and stirred at a hot plate of 100 ° C. at 250 RPM for 3 hours to evaporate water and disperse GO in Isophorone. Next, GO dispersion was further performed using Sonication to prepare a GO dispersion.

Fluorine resin, which is a fluorine resin, was mixed in a beaker with a solvent of Isophorone in a 1: 3 so as to be liquefied, and a resin mixture was prepared by stirring a hot plate at 130 ° C. and 250 RPM for 5 hours.

The GO-F mixture was prepared by mixing the GO dispersion and the resin mixture by varying the GO addition amount of the GO dispersion to form a ratio of the liquefied fluorinated resin and the GO according to Table 1 below.

(2) Preparation of Device Film

Each spin-coating of GO-F mixtures of F: GO (1: 0), (1: 0.5), (1: 1) and (1: 2) was performed on ITO Glass for 500 RPM for 5 seconds according to Table 1. After the spin coating, the coating was dried for 20 minutes in an oven at 100 ° C., and Ag was deposited by sputtering by forming a pattern of 1 × 1 cm on the top surface of the fabricated 5 μm thick film. The above electrode was formed at 4 minutes at 0.3 A and 10 sccm of Ar to form a transparent piezoelectric element shown in FIG. 1.

SEM images of the films before Ag deposition were measured and shown in FIG. 2. In Figure 1 it can be seen that as the content of GO increases the fine pores on the surface of the membrane.

The change in dielectric constant due to the reduced pressure of the transparent piezoelectric element and the change in current due to the reduced pressure according to the applied voltage were measured. RLC meter was used to see the change of permittivity according to the decompression, and the measurement was performed with reference to F (that is, F: GO = 1: 0) without GO to see the change of permittivity according to the amount of GO added. The results are shown in Table 1.

In addition, the current signal delay time according to the applied voltage was measured. As a result of measuring the current response speed of each F-GO (1: n) by pressure based on the applied voltage of 100V, it was confirmed that the larger the dielectric constant value, the larger the delay time.

F: GO (mass ratio) Permittivity change Delay Time
(At 500g pressurization) Pressure (100g) Pressure (300g) Pressure (500g) 1: 0 0.15 nF 35 nF 50 nF 50us 1: 0.5 40 nF 50 nF 90 nF 22us 1: 1 47 nF 63nF 110 nF 36us 1: 2 60 nF 75 nF 170 nF 68us

In Table 1, when the weight of 500g is applied to the weight of 100g, the change in permittivity is F: GO (1: 0.5), (1: 1), and (1: 2) including GO rather than F: GO (1: 0). It can be seen that the larger the dielectric constant change with the addition amount of GO. In addition, F: GO (1: 2) confirmed the change in permittivity of 40nF when 100g is applied, and 90nF when 300g is applied, and 50nF when 500g is applied. It was confirmed that this can be expected that the increase of micropores on the surface of the membrane according to the addition amount of GO affects the electrical property change.

Based on this result, the current signal delay time was measured according to the applied voltage. In Table 1, as a result of measuring the current response speed for each pressure of F-GO (1: n), the delay time was also increased as the dielectric constant value was increased.

That is, it was confirmed that it can be used as a pressure sensor using a pressure-sensitive device using a change in electrical properties according to the pressure that can measure various ranges using one material by adjusting the dielectric constant according to the GO addition ratio.

According to Table 2, set the F-GO (1: 0) and the F-GO (1: 0.5) GO-F mixture solution at 500 RPM on the ITO Glass for 5 seconds by spin coating, respectively, and then distribute the mixture evenly. The desired constant thickness was adjusted for 30 seconds. A film of 5-6 μm was formed in one spin coating, and the film forming conditions were spin coated 1 to 5 times to fabricate a device film according to thickness. After spin coating, the substrate was dried in an oven at 100 ° C. for 20 minutes, and Ag was deposited by sputtering by forming a pattern of 1 × 1 cm on the top of the fabricated film. The deposition conditions were 0.3 A and 4 minutes at an Ar 10 sccm quantum to form an upper electrode to prepare a transparent piezoelectric element. Table 2 shows the change in dielectric constant according to the decompression of each transparent piezoelectric element and the change in current due to the decompression according to the applied voltage. The change in permittivity was shown when the decompression was applied from 100 to 500 g.

Thickness (㎛) F: GO (1: 0) F: GO (1: 0.5) Permittivity change 5 μm 0.15 nF 45 nF 15 μm 0.33 nF 40 nF 30 μm 0.35 nF 25 nF

In the results of Table 2, the F: GO (1: 0) shows that the change of permittivity increases as the film thickness increases as the film thickness increases.In the case of F: GO (1: 0.5), the dielectric constant gradually increases as the film thickness increases. It can be seen that there is interference due to the effect of GO as the film thickness increases.

The present invention is a pressure including a graphene oxide and a fluorine-based resin capable of sensing a wide range of pressure by using the mechanical properties of the graphene, the conductivity varies depending on the pressure applied, and the dielectric constant change characteristics according to the ratio of addition to the dielectric material. A composite membrane for sensing can be provided. In addition, it can be utilized as various pressure elements by incorporating pressure, pressure reduction, and piezoelectric fields.

Although the embodiments have been described with reference to the accompanying drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the following claims.

Claims (6)

A composite comprising graphene oxide and a dielectric polymer;
Including micropores that are 10 nm to 100 nm,
Composite membrane for pressure sensing.
The method of claim 1,
The dielectric polymer to the graphene oxide include 1: 0.20 to 2 (mass ratio),
The dielectric polymer is a fluorine resin, composite film for pressure sensing.
The method of claim 1,
The composite is polymethacrylate (polymethacrylate), polyacrylate (polyacrylate), polyacrylonitrile (polyacrylonitrile), acryltrile, acrylic acid copolymer, polyvinyl alcohol, polyester (polyester), polyester Further comprising at least one organic resin selected from the group consisting of naphthalate (polyester naphthalate), polycarbonate, polyvinyl chloride (PVC: polyvinylchloride), polyacetate (polyacetate) and polynorbornene (polynorbornene) , Composite membrane for pressure sensing.
The method of claim 1,
The composite membrane for pressure sensing has a light transmittance of 80% or more,
The composite membrane for pressure sensing is a composite membrane for pressure sensing, having a thickness of 5 ㎛ to 100 ㎛.
The composite membrane for pressure sensing of claim 1;
Including,
Decompression element.
Preparing a graphene oxide dispersion;
Preparing a dielectric polymer solution;
Mixing the graphene oxide dispersion with the dielectric polymer solution; And
Coating the mixed solution onto a substrate; Including,
The porosity due to the fine pores of the composite membrane is controlled according to the content of the graphene oxide, a method for producing a composite membrane for pressure sensing.

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