KR102426222B1 - Composition for pH sensing ink, fabricating method of the same and pH sensor using the same - Google Patents

Abstract

Disclosed are an ink composition for pH sensing, a method for preparing the same, and a pH sensor to which the same is applied. The ink composition for pH sensing according to an embodiment of the present invention includes a slurry including a carbon material for controlling viscosity and a conductive polymer having conductivity, dispersed in the slurry, and sensing hydrogen ions. It may contain an oxidation-reduction active material.

Description

Ink composition for pH sensing, manufacturing method thereof, and pH sensor applying the same

The present invention relates to an ink composition for pH sensing, a manufacturing method thereof, and a pH sensor to which the same is applied. More specifically, by dispersing an oxidation-reduction active material capable of sensing hydrogen ions in a conductive ink, generating an ink composition for pH sensing in ink form, and manufacturing a pH sensor by a relatively easy patterning method based on this will be.

The measurement of analyte concentration, particularly hydrogen ion concentration or pH, is important in many research, industrial and manufacturing processes. For example, the measurement of pH is routinely practiced in the treatment of food and beverages, biofuels, biopharmaceuticals, as well as water and waste.

Many conventional pH sensors use a potentiometer approach that involves the use of a glass electrode to measure pH. The potentiometer approach has a number of drawbacks. One limitation of potentiometer sensors is the requirement for continuous calibration. Potentiometer pH electrodes, such as batteries, tend to wear out over time and use. As the potentiometer electrode ages, its glass membrane tends to change its resistance, which in turn will change the electrode potential. For this reason, the glass electrode regularly requires calibration. The need for continuous recalibration to provide an accurate pH output significantly hampers industrial applications, particularly where continuous in-line pH measurement is required.

Recalibration is particularly cumbersome in biotech environments where pH measurements are performed in media containing biological materials. Another significant drawback of conventional pH sensors is that the glass electrode has an internal solution, which in some cases can leak into the solution being measured. The glass electrode may also be contaminated by species in the measurement solution, such as, for example, proteins, thereby contaminating the glass electrode.

Korean Patent Laid-Open Publication No. 10-2016-0141108

The problem to be solved by the present invention relates to an ink composition for pH sensing, a method for manufacturing the same, and a pH sensor to which the same is applied. To provide an ink composition for pH sensing capable of easily forming a pH sensor, a method for preparing the same, and a pH sensor to which the same is applied.

Ink composition for pH sensing according to an embodiment of the present invention for solving the above technical problem, a slurry containing a carbon material for controlling viscosity, and a conductive polymer having conductivity, and dispersed in the slurry, It may include an oxidation-reduction active material for sensing hydrogen ions.

The carbon material is activated carbon (activated carbon), carbon black (carbon black), carbon airgel (carbon arogel), graphite (graphite), carbon fiber (carbon fiber), carbon nanotube (carbon nanotube) and graphene (graphene) ) at least one selected from the group consisting of.

The conductive polymer is, polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythi Opene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene (polyfluorene) and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least selected from the group consisting of which one

The redox active material is at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol and phenothiazinium dye.

The mixing ratio of the slurry and the redox active material is 1:0.07 to 1:0.3.

A mixing ratio of the carbon material and the conductive polymer in the slurry is 1:0.3 to 1:1.

In a method for producing an ink composition for pH sensing according to another embodiment of the present invention for solving the above technical problem, a slurry is prepared by stirring a carbon material for controlling viscosity and a conductive polymer having conductivity under a solvent. and dispersing the oxidation-reduction active material in the slurry by introducing an oxidation-reduction active material for sensing hydrogen ions into the slurry.

Agitation of the carbon material and the conductive polymer may be performed by ultrasonication (ultrasonification).

Agitation of the slurry and the redox active material may be performed by sonication.

The carbon material is activated carbon (activated carbon), carbon black (carbon black), carbon airgel (carbon arogel), graphite (graphite), carbon fiber (carbon fiber), carbon nanotube (carbon nanotube) and graphene (graphene) ) at least one selected from the group consisting of.

The conductive polymer is, polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythi Opene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene (polyfluorene) and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least selected from the group consisting of which one

The redox active material is at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol and phenothiazinium dye.

The mixing ratio of the slurry and the redox active material is 1:0.07 to 1:0.3.

A mixing ratio of the carbon material and the conductive polymer in the slurry is 1:0.3 to 1:1.

A pH sensor according to another embodiment of the present invention for solving the above technical problem includes a pH sensing electrode formed of ink for pH sensing, and a reference electrode electrically insulated from and spaced apart from the pH sensing electrode, The pH sensing ink includes a slurry including a carbon material for controlling viscosity, a conductive polymer having conductivity, and an oxidation-reduction active material dispersed in the slurry and sensing hydrogen ions can do.

The carbon material is activated carbon (activated carbon), carbon black (carbon black), carbon airgel (carbon arogel), graphite (graphite), carbon fiber (carbon fiber), carbon nanotube (carbon nanotube) and graphene (graphene) ) at least one selected from the group consisting of.

The conductive polymer is, polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythi Opene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene (polyfluorene) and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least selected from the group consisting of which one

The redox active material is at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol and phenothiazinium dye.

The mixing ratio of the slurry and the redox active material is 1:0.07 to 1:0.3.

A mixing ratio of the carbon material and the conductive polymer in the slurry is 1:0.3 to 1:1.

It may further include a first extension part electrically connected to the pH sensing electrode, and a first external module connection terminal electrically connected to the first extension part.

It may further include a second extension part electrically connected to the reference electrode, and a second external module connection terminal electrically connected to the second extension part.

According to the present invention, an ink composition for pH sensing capable of forming a pH sensor relatively easily without being affected by a substrate or material by easily patterning an electrode of a pH sensor with an ink composition for pH sensing, a manufacturing method thereof, and applying the same A pH sensor is provided.

The effects of the present invention are not limited to the above-mentioned effects, and the effects of other inventions can be clearly understood from the description of the claims.

1 is a flowchart illustrating a method of manufacturing an ink composition for pH sensing according to an embodiment of the present invention.
Figure 2 shows a plan view of the pH sensor of the present invention.
3 and 4 show the experimental results of the pH sensor according to the present invention.
5 is a Scanning Electron Microscope (SEM) photograph of a pH sensing electrode formed according to an embodiment of the present invention.
6 is a SEM photograph of the surface of the formed pH sensing electrode.
7 is an enlarged SEM photograph of the surface.
8 is an SEM photograph of the electrode surface.
9 is a cross-sectional SEM photograph of an electrode;
10 is a graph showing the thickness of the electrode generated when forming the electrode per time by pen drawing on the base film.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Detailed contents for carrying out the present invention will be described in detail with reference to the accompanying drawings below. Irrespective of the drawings, like reference numbers refer to like elements, and "and/or" includes each and every combination of one or more of the recited items.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural, unless specifically stated otherwise in the phrase. As used herein, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other components in addition to the stated components.

Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless clearly defined in particular.

Hereinafter, an ink composition for pH sensing, a method of manufacturing an ink composition for pH sensing, and a pH sensor according to embodiments of the present invention will be described.

1 is a flowchart showing a method of manufacturing an ink composition for pH sensing according to an embodiment of the present invention, FIG. 2 is a plan view of the pH sensor of the present invention, and FIGS. 3 and 4 are experiments of the pH sensor of the present invention the results are shown.

First, an ink composition for pH sensing according to an embodiment of the present invention and a manufacturing method thereof will be described with reference to FIG. 1 .

The ink composition for pH sensing according to an embodiment of the present invention is a slurry containing a carbon material for controlling viscosity and a conductive polymer having conductivity, and is dispersed in the slurry and oxidized for sensing hydrogen ions - May contain reducing active substances.

The slurry can be prepared by mixing and stirring a carbon material and a conductive polymer in a solvent (S100)

The carbon material may provide viscosity to the slurry and the ink composition for pH sensing to be prepared later. Accordingly, the pH sensing electrode to be formed by the ink composition for pH sensing of this embodiment can secure mechanical strength, and it is possible to prevent the ink from flowing down when the pH sensing electrode is formed.

Carbon materials include activated carbon, carbon black, carbon arogel, graphite, carbon fiber, carbon nanotube, and graphene. It may be at least one selected from the group consisting of. In addition to providing viscosity to the composition, the carbon material may additionally provide conductivity to the composition.

The conductive polymer provides conductivity to the ink composition for pH sensing. Thereby, the present ink composition may have conductivity and may act as a pH sensing electrode.

Conductive polymers include polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythiophene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least one selected from the group consisting of can be

By mixing the conductive polymer and the carbon material with each other, the viscosity can be improved. For example, a case where the conductive polymer is PEDOT and the carbon material is graphene will be described as follows. Graphene may increase the conductivity and viscosity of the ink composition for pH sensing. The chain structure of PEDOT, a conductive polymer, has a stable benzoid structure, and PEDOT can absorb the energy of graphene and change from a benzoid structure to a quinoid. As the PEDOT chain structure is changed, electron migration is favored by pi pi stacking and hydrogen bonding, thereby increasing the conductivity of the ink composition for pH sensing may occur.

Also, graphene may undergo gelation. That is, when graphene oxide is mixed with PEDOT to form an ink composition, the viscosity may increase. At this time, the viscosity may be increased from, for example, 0.05 Pas to 1.20 Pas. When the pH sensor is formed with the ink composition for pH sensing as the viscosity increases, it is possible to prevent the ink composition from flowing down or spreading.

On the other hand, the slurry is formed by stirring a carbon material and a conductive polymer under a solvent, and the solvent is as follows.

The solvent may be an aqueous solvent, a hydrocarbon-based solvent, and an ether-based solvent. Specifically, the solvent is water (H2O), methanol, ethanol, isobutane, cyclopentane, cyclopentene, pentene, pentane, benzene, cyclohexane, cyclohexane, hexane, hexene, dimethylbutane, toluene, methylcyclohexane, heptene. , heptane, methylhexane, styrene, xylene, ethylbenzene, octene, octane, cumene, naphthalene, durene, aniline, indene, decane, dodecane, furan, dichloroethane, bromoethane, Dichloromethane, diethylamine, pyridine, acetal, diethyl carbonate, bromobenzene, diethyl ether, diprotyl ether, tetrahydrofuran, tetrahydropyran, dimethyl sulfoxide, dimethyl sulfide, chloroform, ethyleneimine, methyl It may be any one of amine, acetonitrile, dimethylformaldehyde, propylene carbonate, or a mixture thereof.

On the other hand, the carbon material and the conductive polymer may be stirred by ultrasonication (ultrasonification). The ultrasonication step is a step of stirring and dispersing the conductive polymer and the graphene powder in a solvent, and may be treated at 40 to 50 kHz and 100 W for 1 hour to 2 hours. In this case, when the ultrasonic treatment time is less than 40 kHz and the sonication time is less than 1 hour, the effect is weakened, the synthesis reproducibility is deteriorated, and pi-pi stacking and hydrogen bonding are not formed, so that conductivity is reduced. And, when the ultrasonic treatment time exceeds 50 kHz and exceeds 2 hours, there may be a problem of causing damage to the particles due to the strong cavitation intensity.

Meanwhile, in the slurry, a mixing ratio of the carbon material and the conductive polymer may be 1:0.3 to 1:1. When the mixing ratio is less than 1:0.3, the content of the conductive polymer compared to the carbon material is reduced, and the electrical conductivity of the ink composition for pH sensing is lowered, which may make it difficult to function as an electrode. On the other hand, when the mixing ratio exceeds 1:1, the content of the conductive polymer compared to the carbon material increases more than necessary, and the viscosity of the ink composition for pH sensing decreases, and the mechanical strength of the ink composition for pH sensing becomes weak. When the electrode is formed with the ink, it may be difficult to prevent the ink from flowing or spreading. Also, for example, when the carbon material is selected as graphene, the graphene may serve to hold an oxidation-reduction active material, which will be described later. Because the chemical structure of the oxidation-reduction active material is similar to that of graphene, it is possible to form π-π bonds with each other.

Meanwhile, if necessary, a functional additive may be further added to the slurry.

Functional additives can increase the mechanical, thermal and chemical stability of the electrode. The functional additive may be a stabilizer, a filler, a flame retardant, a colorant, a lubricant, an antiblocking agent, and the like. Stabilizers have a function of improving durability and preventing oxidation or degradation of polymers, and include hydroxybenzophenones, Ni phenolates, hindered phenols, organic phosphites, and the like. The filler has a function of improving stiffness, and there are talc, cerite, glass fiber, piezoelectric agent, carbon black, carbon nanotube (CNT), and the like. Flame retardants have a flame retardant function and include halogenated organic compounds, Mg/Al hydroxide, and ammonium polyphosphate. Lubricants have a function of improving molding processability, and there are alkanoic acid amides, alkenoic acid amides, fatty acid esters, and the like. The anti-blocking agent has a function of preventing film adhesion and includes fine silica.

Next, an oxidation-reduction active material that is dispersed in the slurry and senses hydrogen ions is included in the ink composition. That is, an oxidation-reduction active material for sensing hydrogen ions is added to the slurry, and the oxidation-reduction active material is dispersed in the slurry (S200), thereby preparing an ink composition for pH sensing.

That is, the oxidation-reduction active material is dispersed in the slurry constituting the ink composition for pH sensing according to an embodiment of the present invention. At least one redox active functional group dispersed in the slurry is sensitive to the presence and/or level of the substance in solution.

The redox active material may be chemically or physically bound to the surface. The redox active material may be covalently attached or adsorbed to the conductive polymer and/or carbon material. This combination may be advantageous in improving the life or stability of the pH sensing electrode to be formed later.

The oxidation-reduction active material may be at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol, and phenothiazinium dye.

Meanwhile, the slurry and the oxidation-reduction active material may be stirred by ultrasonication (ultrasonification). The ultrasonic treatment is a step of dispersing the slurry and the oxidation-reduction active material by stirring, and may be treated at 40 to 50 kHz and 100 W for 1 to 2 hours. At this time, when the ultrasonic treatment time is less than 40 kHz and the sonication time is less than 1 hour, the effect is weakened, the mixing reproducibility is deteriorated, and pi-pi stacking and hydrogen bonding are not formed, so that conductivity is reduced. And, when the ultrasonic treatment time exceeds 50 kHz and exceeds 2 hours, there may be a problem of causing damage to the particles due to the strong cavitation intensity.

Meanwhile, in the ink composition for pH sensing, a mixing ratio of the slurry and the oxidation-reduction active material may be 1:0.07 to 1:0.3. If the mixing ratio is less than 1:0.07, the content of the oxidation-reduction active material compared to the slurry is reduced, and thus the pH sensing ability of the ink composition is lowered, and thus it may be difficult to function as a pH sensing electrode. On the other hand, when the mixing ratio exceeds 1:0.3, the content of the oxidation-reduction active material compared to the slurry increases more than necessary, and the viscosity or electrical conductivity of the ink composition for pH sensing is lowered, and thus the mechanical strength of the ink composition for pH sensing It may be difficult to function as an electrode due to the weakening of the electrode and the lowering of the conductivity.

Subsequently, the pH sensor according to another embodiment of the present invention will be described as follows.

Referring to FIG. 2 , the pH sensor 10 according to an embodiment of the present invention is electrically insulated from and spaced apart from the pH sensing electrode 11 and the pH sensing electrode 11 formed of ink for pH sensing. An electrode 12 may be included. Here, the pH sensing ink includes a carbon material for controlling viscosity, a slurry containing a conductive polymer having conductivity, and an oxidation-reduction active material that is dispersed in the slurry and senses hydrogen ions. may include Meanwhile, since the pH sensing ink is substantially the same as the pH sensing ink composition according to an embodiment of the present invention, a repeated description will be omitted.

At this time, the pH sensing electrode 11 may be patterned to have an exemplary circular region, and is electrically connected to the first external module connection terminal 31 and the conductive first extension part 21 electrically connected to it. has been Since the first external module connection terminal 31 and the first extension part 21 have conductivity, an electrical signal indicating a potential value can be transmitted from the pH sensing electrode 11 . The pH sensing electrode 11 may be attached to the base film 1 .

Meanwhile, as shown, the reference electrode 12 is patterned, and may be formed in a partial arc pattern as specifically illustrated. Also, similarly to the above, it is electrically connected to the second external module connection terminal 32 through the second extension part 22 . The reference electrode 12 may be attached to the base film 1 while being spaced apart from the pH sensing electrode 11 .

The pH sensing electrode 11 may be formed using an ink for pH sensing. The pH sensing electrode 11 may be formed by a pattern forming method. The pH sensing electrode 11 may be formed by a technique for forming a fine pattern, for example, patterning using light (photolithography, etc.), physical contact patterning (soft lithography, surface imprinting, embossing, etc.), magnetic -Can be formed by self-assembly (molecular imprinted polymer, etc.) and direct write (dip-pen nanolithography, inkjet printing, etc.).

On the other hand, when using the ink composition according to the embodiment of the present invention, the pH sensing electrode 11 can be formed relatively easily in a pen-draw method. For example, the pH sensing electrode 11 pattern may be formed on the base film 1 by using a spray nozzle using the pH sensing ink composition according to an embodiment of the present invention. In addition, the pH sensing electrode 11 pattern may be formed on the base film 1 by continuously discharging a small amount like a pen with a syringe needle using the pH sensing ink composition according to an embodiment of the present invention. have. In addition, screen printing, dispensing, etc. may be used.

Meanwhile, the first extension part 21 and the first external module connection terminal 31 may also be formed in substantially the same manner as the formation of the above-described pH sensing electrode 11 pattern.

After the pH sensing electrode is patterned (eg, formed by a method such as pen drawing), the formed pH sensing electrode should be physically and chemically flexible. By softening, crosslinking can be made between the particles of the material included in the ink composition. That is, the formed PH sensing electrode must be chemically oxidized using FeCl ₃ or the like, or physically oxidized by heat treatment such as UV irradiation. Thereby, the pH sensing electrode can be flexible. Meanwhile, even when the first extension part and the first external module connection terminal are formed with the ink composition of the present invention, the above-described softening process may be performed.

The reference electrode 12 may typically use an Ag/AgCl electrode, and in addition, Hg/HgO, Hg/Hg ₂ SO ₄ , and a calomel electrode may be used. In the case of a conventional Ag/AgCl electrode, it may be formed by forming a patterned silver (Ag) layer on the base film 1 and electroplating chlorine thereon. In addition, it is possible to maintain the electromotive force compared to the hydrogen electrode of Ag/AgCl by selectively storing it in a KCl buffer solution. Meanwhile, the second extension part 22 and the second external module connection terminal 32 may also be formed in substantially the same manner as the reference electrode 12 . In addition, when forming the reference electrode 12 with Ag/AgCl, the reference electrode 12 may be formed by drawing with a pen using Ag/AgCl in the form of ink.

On the other hand, the first external module connection terminal 31 and the second potentiometer for measuring the potential difference between the pH sensing electrode 11 and the reference electrode 12 are connected to the pH sensing electrode 11 and the reference electrode 12, respectively. It may be electrically connected to the external module connection terminal 32 . In addition, the potentiometer is connected to the transducer so that the value measured by the potentiometer is converted into a corresponding pH value. Optionally, the pH measurement system may further include a display unit for externally displaying the converted pH value, thereby confirming the pH value measured by the pH sensor simultaneously with the measurement.

Meanwhile, the pH sensor 10 may further include a counter electrode (not shown) in addition to the pH sensing electrode 11 and the reference electrode 12 . That is, the pH sensor 10 may use a three-electrode system. When using a three-electrode system, as the counter electrode, a conductive metal material such as, for example, a platinum electrode (platinum filament electrode, platinum ring electrode, etc.), a gold electrode, a silver electrode (or silver net electrode), or a combination thereof (platinum/ an electrode made of gold electrode); glass, quartz, plastic film, mica and aluminum plate coated with conductive particles; titanium electrode; A silver/mercury film electrode or the like can be used.

Hereinafter, preferred examples are presented to help the understanding of the present invention, but the following examples are only provided for easier understanding of the present invention, and the present invention is not limited thereto.

Example 1- Preparation of pH sensing electrode ink composition (mixing ratio of graphene and PEDOT = 1:1)

1 g of graphene and 1 g of EDOT were introduced into a round flask, and 20 g of deionized water was introduced into the flask, and then they were stirred through sonication. Here, the sonication was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred. Thereby, a slurry containing graphene-PEDOT was formed. 1 g of the slurry and 0.2 g of quinone were added to another flask, and they were stirred through sonication. Here, the sonication was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes to agitate them.

The stirred composition was left at room temperature for 24 hours to evaporate the remaining moisture.

Example 2 Preparation of ink composition for pH sensing (mixing ratio of graphene and PEDOT = 1:0.5)

1 g of graphene and 0.5 g of EDOT were introduced into a round flask, and 20 g of deionized water was introduced into the flask, and then they were stirred through sonication. Here, the sonication was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred. Thereby, a slurry containing graphene-PEDOT was formed. 1 g of the slurry and 0.2 g of quinone were added to another flask, and they were stirred through sonication. Here, the ultrasonic treatment was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred.

The stirred composition was left at room temperature for 24 hours to evaporate the remaining moisture.

Comparative Example 1- Preparation of ink composition for pH sensing (mixing ratio of graphene and PEDOT = 1:0.1)

1 g of graphene and 0.1 g of EDOT were introduced into a round flask, and 20 g of deionized water was introduced into the flask, and then they were stirred through sonication. Here, the sonication was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred. Thereby, a slurry containing graphene-PEDOT was formed. 1 g of the slurry and 0.2 g of quinone were added to another flask, and they were stirred through ultrasonication. Here, the ultrasonic treatment was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred.

The stirred composition was left at room temperature for 24 hours to evaporate the remaining moisture.

Comparative Example 2- Preparation of ink composition for pH sensing (mixing ratio of graphene and PEDOT = 0.5:1)

0.5 g of graphene and 1 g of EDOT were introduced into a round flask, and 20 g of deionized water was introduced into the flask, and then they were stirred through sonication. Here, the ultrasonic treatment was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred. Thereby, a slurry containing graphene-PEDOT was formed. 1 g of the slurry and 0.2 g of quinone were added to another flask, and they were stirred through ultrasonication. Here, the ultrasonic treatment was performed at a frequency of 45 kHz and 100 W for 1 hour and 30 minutes, and they were stirred.

The stirred composition was left at room temperature for 24 hours to evaporate the remaining moisture.

Example 3 Preparation of a pH sensor with the ink compositions of Examples 1 and 2

A pH sensing electrode was formed using the ink composition for pH sensing prepared in Examples 1 and 2 and the dispensing pen for pattern formation. As the base film, an insulating flexible insulating plastic was used. The base film was 2 cm in width and length, respectively.

On the base film, after the ink composition was filled in a dispensing pen, a circular pH sensing electrode having a diameter of about 3 mm was formed.

Subsequently, a first extension portion was formed with a length of 6 mm to be connected to the pH sensing electrode, and a first external module connection terminal was formed at an end of the first extension portion.

A process of softening each of the formed pH sensing electrode, the first extension part, and the first external module connection terminal was performed. The softening process was performed at 40˚C for 1 hour using a UV-A irradiator (Korea UV, Korea) with a wavelength of 315 nm.

The reference electrode was formed using Ag/AgCl to have a size similar to that of the pH sensing electrode. Thereafter, the second extension part and the second external module connection terminal were formed to have sizes corresponding to the first extension part and the first external module connection terminal, respectively. At this time, each of the pH sensing electrode and the reference electrode, the first extension part and the second extension part, and the first external module connection terminal and the second external module connection terminal were formed to be insulated from each other in a dry period.

Finally, a pH sensor including a pH sensing electrode formed of the ink composition of Example 1 on a base film and a pH sensor including a pH sensing electrode formed of the ink composition of Example 2 were prepared.

Referring to FIGS. 5 to 10 , the formed pH sensing electrodes are as follows. Referring to FIG. 5 , it is a Scanning Electron Microscope (SEM) photograph of a patterned pH sensing electrode formed of graphene-PEDOT on a base film. Referring to FIG. 5 , it can be seen that the pH sensing electrode was successfully fabricated.

6 is an SEM photograph of the surface of the formed pH sensing electrode, and it can be seen that a porous electrode is formed. 7 is an enlarged SEM photograph of the surface. 8 is a SEM photograph of the electrode surface, it was confirmed that the PEDOT polymer component was formed in a round shape along the electrode surface. 9 is a cross-sectional SEM photograph of the electrode. Looking at the small photograph of FIG. 9 , it can be seen that the circular shape is PEDOT, and the PEDOT is evenly dispersed on the electrode surface and inside the electrode.

10 shows the thickness of the electrode generated when forming the electrode per time by pen drawing on the base film. It was found that the thickness of the electrode increased by approximately 10 μm per cycle.

Comparative Example 4- Ink composition of Comparative Examples 1 and 2

A pH sensor was prepared in substantially the same manner as in Example 3, except that the ink compositions of Comparative Examples 1 to 3 were used.

Experimental example

1) Physical property test of pH sensor

pH sensing electrode composition Surface resistance (ohm) Residual rate of electrode after tape attachment (%) pH sensor Example 1 1.3×10 ⁴ 91 Example 2 3.1×10 ⁴ 85 Comparative Example 1 1.6×10 ⁵ 84 Comparative Example 2 2.6×10 ⁴ 63

As a result of measuring the surface resistance of the pH sensing electrode formed on each sensor, it was found that as the content of the conductive polymer PEDOT increased, the surface resistance decreased and the electrical conductivity increased. Meanwhile, in order to confirm the mechanical strength of the formed pH sensing electrode, after attaching and detaching a scotch tape to the pH sensing electrode, the size of the pH sensing electrode remaining on the base film was compared with that of the electrode before the tape was attached. As a result, it was found that when the mixing ratio of graphene (carbon material) and PEDOT (conductive polymer) was less than 1, the mechanical strength of the electrode was weakened.

2) pH measurement test of pH sensor

The pH measurement property of the pH sensor prepared with the ink composition of Example 1 was tested.

Referring to FIG. 3 , it was found that the oxidation peak voltage increased as the pH of the measurement solution increased. Also, referring to FIG. 4 , it can be seen that the degree of measurement of pH is differentiated based on pH 7.2. In the case of the present invention, it was found that the pH sensitivity was excellent in a smoke-neutral solution rather than an acidic solution. As a result, it was found that the pH sensor according to the embodiments of the present invention can be easily manufactured by pen drawing and has a function of sufficiently sensing the pH.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present invention pertains will appreciate the technical spirit of the present invention. However, it will be understood that the invention may be embodied in other specific forms without changing essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: pH sensor 11: pH sensing electrode
21: first extension 31: first external module connection terminal
12: reference electrode 22: second extension
32: second external module connection terminal

Claims (22)

In the ink composition for pH sensing for forming a pH sensing electrode included in the pH sensor,
a slurry comprising a carbon material for controlling viscosity and a conductive polymer having conductivity in order to prevent spillage or spreading when the pH sensing electrode is formed; and
An ink composition for pH sensing, which is dispersed in the slurry and includes an oxidation-reduction active material for sensing hydrogen ions. The method of claim 1,
The carbon material is activated carbon (activated carbon), carbon black (carbon black), carbon airgel (carbon arogel), graphite (graphite), carbon fiber (carbon fiber), carbon nanotube (carbon nanotube) and graphene (graphene) ), which is at least one selected from the group consisting of an ink composition for pH sensing. The method of claim 1,
The conductive polymer is, polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythi Opene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene (polyfluorene) and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least selected from the group consisting of Any one of the ink composition for pH sensing. The method of claim 1,
The oxidation-reduction active material is at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol, and phenothiazinium dye, an ink composition for pH sensing. The method of claim 1,
The mass ratio of the slurry and the oxidation-reduction active material is 1:0.07 to 1:0.3 pH sensing ink composition. The method of claim 1,
A mass ratio of the carbon material and the conductive polymer in the slurry is 1:0.3 to 1:1. In the manufacturing method of the ink composition for pH sensing for forming the pH sensing electrode included in the pH sensor,
preparing a slurry by stirring a carbon material for controlling viscosity and a conductive polymer having conductivity in a solvent to prevent spillage or spreading when the pH sensing electrode is formed; and
dispersing the oxidation-reduction active material in the slurry by introducing an oxidation-reduction active material for sensing hydrogen ions into the slurry; A method for producing an ink composition for pH sensing comprising 8. The method of claim 7,
A method of producing an ink composition for pH sensing wherein the stirring of the carbon material and the conductive polymer is performed by ultrasonication (ultrasonification). 9. The method of claim 8,
A method of producing an ink composition for pH sensing wherein the slurry and the stirring of the oxidation-reduction active material is performed by ultrasonication. 8. The method of claim 7,
The carbon material is activated carbon (activated carbon), carbon black (carbon black), carbon airgel (carbon arogel), graphite (graphite), carbon fiber (carbon fiber), carbon nanotube (carbon nanotube) and graphene (graphene) ), which is at least one selected from the group consisting of a method for producing an ink composition for pH sensing. 8. The method of claim 7,
The conductive polymer is, polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythi Opene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene (polyfluorene) and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least selected from the group consisting of Any one method for producing an ink composition for sensing pH. 8. The method of claim 7,
The oxidation-reduction active material is at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol and phenothiazinium dye of the ink composition for pH sensing. manufacturing method. 8. The method of claim 7,
A mass ratio of the slurry and the oxidation-reduction active material is 1:0.07 to 1:0.3. 8. The method of claim 7,
A mass ratio of the carbon material and the conductive polymer in the slurry is 1:0.3 to 1:1. pH sensing electrode formed of ink for pH sensing; and
Including a reference electrode that is electrically insulated from the pH sensing electrode and is located spaced apart,
The pH sensing ink,
A slurry comprising a carbon material for controlling viscosity and a conductive polymer having conductivity in order to prevent flow down or spreading when the pH sensing electrode is formed;
A pH sensor comprising an oxidation-reduction active material dispersed in the slurry and sensing hydrogen ions. 16. The method of claim 15,
The carbon material is activated carbon (activated carbon), carbon black (carbon black), carbon airgel (carbon arogel), graphite (graphite), carbon fiber (carbon fiber), carbon nanotube (carbon nanotube) and graphene (graphene) ) at least one pH sensor selected from the group consisting of. 16. The method of claim 15,
The conductive polymer is, polythiophene, polypyrrole, polyaniline, poly(p-phenylene vinylene), poly(3,4-ethylenedioxythi Opene) (Poly (3,4-ethylenedioxythiophene), PEDOT), polyacetylene (polyacetylene), polyfluorene (polyfluorene) and poly (para-phenylene sulfide) (Poly (p-phenylene sulfide)) at least selected from the group consisting of Any one of the pH sensors. 16. The method of claim 15,
The oxidation-reduction active material is at least one selected from the group consisting of anthracene, quinone, hydroquinone, anthroquinone, phenanthroquinone, phenylene diamine, catechol and phenothiazinium dye. 16. The method of claim 15,
The mass ratio of the slurry and the oxidation-reduction active material is 1:0.07 to 1:0.3 pH sensor. 16. The method of claim 15,
A mass ratio of the carbon material and the conductive polymer in the slurry is 1:0.3 to 1:1. 16. The method of claim 15,
A pH sensor further comprising: a first extension part electrically connected to the pH sensing electrode; and a first external module connection terminal electrically connected to the first extension part. 16. The method of claim 15,
A pH sensor further comprising: a second extension part electrically connected to the reference electrode; and a second external module connection terminal electrically connected to the second extension part.

Images