KR20200093121A - Paper-based micro fluidic fuel cell and method of manufacturing the same - Google Patents

Abstract

Disclosed is a paper-based microfluidic fuel cell comprising: a paper substrate including a non-channel region with hydrophobicity and a microchannel region having hydrophilicity and a first electrode and a second electrode formed thereon; and a cover member disposed on the paper substrate to cover up the microchannel region.

Description

PAPER-BASED MICRO FLUIDIC FUEL CELL AND METHOD OF MANUFACTURING THE SAME

The technical idea of the present invention relates to a paper-based microfluidic fuel cell and a method for manufacturing the same.

A fuel cell is a battery that directly converts energy generated by oxidation of fuel into electrical energy. In these fuel cells, research and development have been focused on research to reduce the burden on environmental pollution, energy to obtain energy efficiency close to twice that of a gasoline engine, and auxiliary power for automobile power or fixed power equipment. come.

Recently, as the information society is accelerating, research into micro fuel cells advantageous for miniaturization has been actively conducted in order to use fuel cells for power supplies of portable terminals and portable high-density, high-power energy storage systems.

Micro fuel cell is a term referring to a very small sized fuel cell, and is an ultra-compact fuel cell having a capacity of 100 watts (W) or less and manufactured using micro-processing technology.

Among these micro fuel cells, a micro fluid fuel cell that generates electric energy using a flow of micro fluids uses a property that fluids flowing in a micro-channel form a laminar flow and do not mix well. In other words, the fuel and oxidant fluids are respectively flowed into the microchannels to form a liquid-liquid interface of the fuel and oxidant, which replaces the role of the conventional proton exchange membrane.

As described above, as the microfluidic fuel cell has a structure that does not use a proton exchange membrane, it can solve problems such as manufacturing process complexity and manufacturing cost increase due to the proton exchange membrane, but still provides fuel and an oxidizing agent and discharges by-products. There is a limit to the miniaturization of the device by requiring an external pump.

For this reason, a paper-based microfluidic fuel cell that can omit an external pumping system by using the capillary action of paper has been proposed as an alternative.

However, the paper-based micro-fluid fuel cell presented to date has a low current and power density compared to the conventional micro-fluid fuel cell, which is difficult to use because of the characteristics of paper, which is highly toxic or has strong acidic and basic fuels. Production is difficult and there is a limit to an effective alternative.

The technical problem to be achieved by the paper-based microfluidic fuel cell and its manufacturing method according to the technical idea of the present invention is to enable precision production and mass production, and to improve the power and efficiency of the paper-based microfluidic fuel cell and its object In implementing the manufacturing method.

The technical problems to be achieved by the paper-based microfluidic fuel cell and its manufacturing method according to the technical idea of the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. Will be able to.

According to an aspect of the inventive concept, a paper substrate having first and second electrodes formed thereon has a hydrophilic micro-channel region and a hydrophobic non-channel region; And a cover member disposed on the paper substrate to cover the micro-channel region.

According to an exemplary embodiment, the non-channel region may be a region having the hydrophobicity by absorbing a negative photosensitive material.

According to an exemplary embodiment, the micro-channel region may extend perpendicular to the paper substrate to penetrate the paper substrate, and the non-channel region may contact the micro-channel region and surround the micro-channel region. have.

According to an exemplary embodiment, the first and second electrodes may be spaced apart from each other in the micro-channel region and extend along a direction parallel to the paper substrate.

According to an exemplary embodiment, the top surface of at least one of the first and second electrodes may be positioned higher than the top surface of the micro-channel region.

According to an exemplary embodiment, the first and second electrodes may include carbon.

According to an exemplary embodiment, the cover member, through the cover member, injection holes for injecting an oxidizing agent to the first electrode of the micro-channel region and fuel to the second electrode; And an outlet for penetrating the cover member and discharging a material generated as a result of the redox reaction between the oxidizing agent and the fuel and the first and second electrodes.

According to an exemplary embodiment, the oxidizing agent and the fuel may include vanadium.

According to an exemplary embodiment, the oxidizing agent and the fuel may be injected in the form of a vanadium electrolyte containing the vanadium and sulfuric acid into the injection ports, and the molar ratio of the vanadium and the sulfuric acid may be the same.

According to another aspect of the inventive concept, performing a screen printing process using a carbon paste to form first and second electrodes on a paper substrate; Forming a microchannel region having hydrophilicity and a non-channel region having hydrophobicity by providing the first and second electrodes on the paper substrate by performing a photolithography process using a voice sensitizer; And coupling a cover member covering the micro channel region on the paper substrate. A method of manufacturing a paper-based micro fluid fuel cell is disclosed.

According to an exemplary embodiment, the step of forming the first and second electrodes on the paper substrate comprises: a first having openings spaced apart from each other and extending in one direction parallel to the paper substrate. Placing a mask; Applying the carbon paste on the first mask to fill the openings; Removing the first mask to form first and second preliminary electrodes; And heating the paper substrate to form the first and second electrodes from the first and second preliminary electrodes.

According to an exemplary embodiment, the step of forming the first and second electrodes may diffuse the carbons constituting the first and second preliminary electrodes into the paper substrate to form the first and second electrodes. have.

According to an exemplary embodiment, the forming of the micro-channel region and the non-channel region on the paper may include: immersing the paper substrate in a voice-sensitive agent; Taking the paper substrate out of the negative photosensitive agent and heating it; Placing a support substrate on the lower surface of the paper substrate; Placing a second mask having an opening corresponding to the micro-channel region on the upper surface of the paper substrate; Exposing the paper substrate; Separating the support substrate and the second mask from the paper substrate; Heating the paper substrate; And developing the paper substrate to form the micro-channel region from which the voice-sensitive agent is removed and the non-channel region where the voice-sensitive agent remains.

According to an exemplary embodiment, the method of manufacturing the paper-based microfluidic fuel cell may further include a step of coupling a supporting member to the lower surface of the paper substrate.

The paper-based microfluidic fuel cell and its manufacturing method according to the embodiments according to the technical spirit of the present invention are capable of mass production and precision manufacturing through a simplified process as well as miniaturization of the device, and improved power and efficiency. There is a possible effect.

Brief descriptions of each drawing are provided in order to better understand the drawings cited herein.
1 is a perspective view schematically showing a paper-based microfluidic fuel cell according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view schematically showing the paper-based microfluidic fuel cell of FIG. 1;
3 is a cross-sectional view of the paper-based microfluidic fuel cell of FIG. 1 taken along line III-III'.
4 and 5 are cross-sectional views illustrating a process of manufacturing the paper-based microfluidic fuel cell of FIG. 1 according to a process sequence.

Exemplary embodiments according to the technical spirit of the present invention are provided to more fully describe the technical spirit of the present invention to those skilled in the art, and the following embodiments are modified in various other forms. It may be, the scope of the technical spirit of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the technical spirit of the present invention to those skilled in the art.

Although the terms first, second, etc. are used herein to describe various members, regions, layers, parts and/or components, these members, parts, regions, layers, parts and/or components are used in these terms. It is obvious that it should not be limited by. These terms do not imply a specific order, top or bottom, or superiority, and are only used to distinguish one member, region, site, or component from another member, region, site, or component. Accordingly, the first member, region, part or component described below may refer to the second member, region, part or component without departing from the teachings of the technical idea of the present invention. For example, the first component may be referred to as a second component without departing from the scope of the present invention, and similarly, the second component may also be referred to as a first component.

Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those skilled in the art to which the concept of the present invention pertains, including technical terms and scientific terms. In addition, commonly used terms, as defined in the dictionary, should be interpreted as having meanings consistent with what they mean in the context of related technologies, and in excessively formal meanings unless explicitly defined herein. It should not be interpreted.

When an embodiment can be implemented differently, a specific process order may be performed differently from the described order. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order opposite to that described.

In the accompanying drawings, for example, depending on manufacturing techniques and/or tolerances, deformations of the illustrated shapes can be expected. Therefore, the embodiments according to the technical spirit of the present invention should not be interpreted as being limited to a specific shape of a region shown in the present specification, and should include, for example, a change in shape caused in the manufacturing process. The same reference numerals are used for the same components in the drawings, and duplicate descriptions are omitted.

The term'and/or' as used herein includes each and every combination of one or more of the mentioned members.

Hereinafter, exemplary embodiments according to the technical spirit of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view schematically showing a paper-based microfluidic fuel cell 100 according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view schematically showing a paper-based microfluidic fuel cell 100 of FIG. 1 to be.

1 and 2, the paper-based microfluidic cell 100 according to an embodiment of the present invention may include a support member 110, a paper substrate 120 and a cover member 130.

The support member 110 may be made of, for example, a glass material. However, the present invention is not limited thereto, and any material that can prevent warping by supporting the paper substrate 120 having a thin thickness may be variously applied. Meanwhile, according to an embodiment, if the paper substrate 120 has a relatively sufficient thickness, the support member 110 may be omitted.

The paper substrate 120 is disposed on the support member 110.

The paper substrate 120 has a predetermined shape, for example, a Y-shape, but a micro-channel region CH extending in the z direction to penetrate the paper substrate 120 and a non-channel region surrounding the micro-channel region CH. (NCH).

The microchannel region (CH) may have hydrophilicity and may have a non-channel region (hydrophobic). Due to this property difference, the microchannel region in the structure in which the non-channel region (NCH) surrounds the micro-channel region (CH). (CH) functions as a flow path for fuel and oxidant.

The difference in properties between the micro-channel region (CH) and the non-channel region (NCH), while the photosensitive agent is removed from the micro-channel region (CH) in the process of performing the photolithography process described below (see FIG. 5), the non-channel region ( NCH) occurs because it remains absorbed in the base paper material.

First and second electrodes 121 and 122 each functioning as either an anode or a cathode are formed on both sides of the micro-channel region CH. Hereinafter, for convenience of description, an embodiment in which the first electrode 121 functions as an anode and the second electrode 122 functions as a cathode will be described.

The first and second electrodes 121 and 122 are spaced apart from each other at predetermined intervals along the x direction to form an interface in which a portion of the fuel and oxidant flowing through the microchannel region CH are mixed, and each along the y direction. It can be extended to form a line. Here, the line shape may have a line shape having a uniform width, but is not limited thereto.

The first and second electrodes 121 and 122 may have the same width and length, but are not limited thereto, and may have different widths and lengths from each other.

The first and second electrodes 121 and 122 may each include carbon.

The paper-based microfluidic fuel cell 100 of FIG. 1 will be described with reference to FIG. 3 further illustrating a cross-sectional view taken along III-III'.

Referring to FIG. 3 further, the first and second electrodes 121 and 122 may extend in the z direction to have a predetermined thickness in the micro channel region CH.

The first and second electrodes 121 and 122 may have the same thickness as each other. However, the present invention is not limited thereto, and the first and second electrodes 121 and 122 may have different thicknesses from each other.

In addition, the upper surfaces of the first and second electrodes 121 and 122 may be located at the same or different heights from each other based on the upper surfaces of the support members 110.

In the process of performing the screen printing process described below (see FIG. 4 ), the first and second electrodes 121 and 122 of the first and second electrodes 121 and 122 are disposed according to the degree of diffusion of carbon on the upper surface of the microchannel region CH into the microchannel region CH. This is because thickness and the like may vary.

Meanwhile, at least one upper surface of the first and second electrodes 121 and 122 may be positioned higher than the upper surface of the micro-channel region CH based on the upper surface of the support member 110. That is, at least one of the first and second electrodes 121 and 122 may protrude from the upper surface of the micro-channel region CH.

The reason that the upper surfaces of the first and second electrodes 121 and 122 and the upper surfaces of the micro-channel regions CH are different based on the upper surfaces of the support members 110 is a screen printing process performed later (see FIG. 4 ). This is because carbon on the upper surface of the microchannel region CH may partially remain without being diffused into the microchannel region CH.

However, this is only an example, and when the carbon on the micro channel region CH is entirely diffused in the screen printing process described below, or when the remaining carbon on the micro channel region CH is removed through an additional planarization treatment. In the upper surface of the first and second electrodes 121 and 122 and the upper surface of the micro-channel region CH, a coplanar surface may be formed.

Meanwhile, the upper surfaces of the first and second electrodes 121 and 122 may be positioned lower than the upper surfaces of the micro-channel region CH based on the upper surfaces of the support members 110. That is, the first and second electrodes 121 and 122 may be buried inside the micro channel region CH without being exposed through the upper surface of the micro channel region CH.

Referring back to FIGS. 1 and 2, on the paper substrate 120, first and second electrode pads 123 and 124 extending in opposite directions from one end of each of the first and second electrodes 122 are provided. Is formed.

The first and second electrode pads 123 and 124 serve as an extended electrode part and a connection part for electrical connection of first and second electrodes 121 and 122 to a power supply target element and the like, and supply of fuel and oxidant Accordingly, power can be generated from the current between the first and second electrodes 121 and 122.

Meanwhile, FIGS. 1 and 2 illustrate that the first and second electrode pads 123 and 124 each have a line shape having a uniform width, but are not limited thereto. For example, the widths of the first and second electrode pads 123 and 124 may be continuously or intermittently varied in a direction away from the first and second electrodes 121 and 122, respectively.

In addition, although FIGS. 1 and 2 illustrate that the first and second electrode pads 123 and 124 have the same shape, the first and second electrode pads 123 and 124 are not limited to each other. It goes without saying that it can have different shapes.

A cover member 130 covering the micro channel region CH and the non-channel region NCH is disposed on the paper substrate 120.

The cover member 130 serves to block the contact of the fuel and the oxidizing agent and oxygen flowing into the micro channel region CH, and according to the embodiment, unlike the structures illustrated in FIGS. 1 and 2, the micro channel region ( It may have a shape that covers only CH).

The cover member 130 may be made of, for example, glass. Alternatively, the cover member 130 may be made of an organic material having low oxygen permeability. Alternatively, the cover member 130 is made of a first organic material, for example, polydimethylsiloxane (PDMS), but has a structure in which a second organic material having a relatively low oxygen transmittance on at least one surface is coated with, for example, Parylene C. Can have

The cover member 130 may include a first injection hole 131 for injecting an oxidizing agent into the first electrode 121 and a second injection hole 132 for injecting fuel into the second electrode 122. . The cover member 130 may further include an outlet 133 for discharging by-products generated by oxidation and reduction reactions between the first and second electrodes 121 and 122 and the fuel and the oxidizing agent.

1 and 2, as shown in Figures 1 and 2, through the cover member 130 so as to be positioned at the starting point of one of the forks of the micro-channel region (CH) provided in a Y-shape It is formed, it is possible to inject an oxidizing agent to the first electrode 121.

The second injection hole 132 is formed through the cover member 130 so as to be positioned at the starting point of the other fork of the fork of the micro-channel region CH, and fuel can be injected into the second electrode 122.

When the oxidizing agent and fuel are injected through the first and second injection holes 131 and 133, the injected oxidizing agent and fuel are supplied to the first and second electrodes 121 and 122, respectively, and the injected oxidizing agent and fuel and the first And the redox reaction between the second electrodes 121 and 122 to generate electrical energy having a predetermined power density.

In some embodiments, the fuel and the oxidizing agent may be injected into the micro channel region CH in the form of a vanadium electrolyte solution in which vanadium and a supporting electrolyte, sulfuric acid, are mixed at a predetermined ratio. It has been experimentally verified that the vanadium and the sulfuric acid of the vanadium electrolyte may have the same molar ratio, and when these molar ratios are the same, optimum current and power density can be obtained. Preferably, the vanadium and the sulfuric acid may be included in the vanadium electrolyte at a concentration of 2M, respectively.

Meanwhile, the outlet 133 is a portion where hydrogen and oxygen bubbles generated during the redox reaction are discharged, and may be formed through the cover member 130 to be located at the end of the micro-channel region CH.

As described above, the paper-based microfluidic fuel cell 100 according to an embodiment of the present invention allows electrodes to react with vanadium-based fuel and oxidant in a microchannel region (CH) made of paper, while simultaneously contacting oxygen and vanadium. By effectively blocking the, power density and efficiency can be greatly improved compared to a conventional paper-based microfluidic fuel cell using formic acid-based fuel and an oxidizing agent.

4 and 5 are cross-sectional views illustrating a process of manufacturing the paper-based microfluidic fuel cell 100 of FIG. 1 according to a process sequence.

In FIGS. 4 and 5, cross-sectional views of the paper-based microfluidic fuel cell 100 cut along III-III' as shown in FIG. 3 are illustrated according to each process sequence. In describing FIGS. 4 and 5, the same reference numerals as in FIGS. 1 to 3 denote the same members, and duplicate description is omitted below for the sake of simplicity.

First, with reference to FIG. 4, screen printing process steps for forming the first and second electrodes 121 and 122 will be described.

Referring to FIG. 4, openings for forming the first and second electrodes 121 and 122 (see FIGS. 1 to 3) on the paper substrate 120, that is, spaced apart from each other along the x direction but in the y direction The first mask M1 having the line-shaped openings extending is disposed (Fig. 4(a)). On the other hand, although not shown, the first mask M1 has one end of each of openings for forming the first and second electrode pads 123, 124 (see FIGS. 1 to 3), that is, line-shaped openings. It may further have openings extending along the x direction.

Subsequently, after placing the carbon paste on one side of the first mask M1, and spreading the carbon paste through an applicator (not shown) to fill the openings (FIG. 4(b)), the first mask M1 is The first and second preliminary electrodes p121 and p122 are formed by removing them (Fig. 4(c)).

Subsequently, the paper substrate 120 is heated to diffuse the carbons constituting the first and second preliminary electrodes p121 and p122 inside the paper substrate 120, that is, by extending in the z-direction to the inside of the paper substrate 120. To form the first and second electrodes 121 and 122 (FIG. 4(d)). Here, the heat treatment may be performed at a temperature of approximately 120° C. for approximately 60 minutes.

Next, with reference to FIG. 5, each step of the photolithography process for forming the microchannel region CH and the non-channel region NCH having different properties on the paper substrate 120 will be described.

Referring to FIG. 5, the paper substrate 120 on which the first and second electrodes 121 and 122 are formed is immersed in a negative photosensitive agent, for example, SU-8 for approximately 5 minutes, so that the negative photosensitive material is applied to the paper substrate ( 120) (Fig. 5 (a))

Subsequently, after removing some of the negative photoresist absorbed by the paper substrate 120, the paper substrate 120 is heated (FIG. 5(b)). Here, the heat treatment may be performed at a temperature of approximately 85° C. for approximately 5 minutes.

Next, the support substrate CS is disposed on the lower surface of the paper substrate 120 (FIG. 5(c)). Here, the support substrate CS is made of a paper material such as the paper substrate 120, may have a thickness greater than the paper substrate 120, the paper substrate by the viscosity of the negative photosensitive agent remaining on the paper substrate 120 It may be adhered to the lower surface of (120).

Subsequently, a second mask M2 having an opening (for example, a Y-shaped opening) for defining the micro-channel region CH is disposed on the upper surface of the paper substrate 120 and exposed using ultraviolet rays (FIG. 5). (D)). According to this exposure process, the negative photoresist may be modified in a region corresponding to the opening. Meanwhile, exposure uses 20 mW of ultraviolet light and can be performed for approximately 10 seconds.

Subsequently, the support substrate CS and the second mask M2 are separated from the paper substrate 120, and then the paper substrate 120 is heated (FIG. 5(e)). Here, the heat treatment may be performed at a temperature of approximately 85° C. for approximately 5 minutes.

Subsequently, the paper substrate 120 is developed with a dedicated developer (ie, a developer dedicated to SU-8) for approximately 10 minutes and acetone for 2 minutes, rinsed with deionized water, and a negative photosensitive agent is applied to the paper substrate 120. The removed micro-channel region CH and the non-channel region NCH where the voice sensitizer remains are formed (Fig. 5(f)).

Subsequently, the cover member 130 is coupled to cover the micro channel region CH on the top surface of the paper substrate 120, and the support member 110 is coupled to the bottom surface of the paper substrate 120 (FIG. )).

As described above, in manufacturing the paper-based microfluidic fuel cell 100, the first and second electrodes 121 and 122 are formed through a screen printing process, and the microchannel region in the paper substrate 120 is formed through a photolithography process. By forming (CH), it is possible to precisely manufacture electrodes, microchannels, etc., thereby improving the efficiency of the battery, and mass production may be possible through a simplified process.

As described above, the technical idea of the present invention has been described in detail with reference to preferred embodiments, but the technical idea of the present invention is not limited to the above embodiments and has ordinary knowledge in the art within the scope of the technical idea of the present invention. Various modifications and changes are possible by the ruler.

100: paper based micro fluid fuel cell
110: support member
120: paper board
121, 122: first electrode, second electrode
123, 124: first electrode pad, second electrode pad
CH: micro channel area
NCH: non-channel region
130: cover member
131, 133: first inlet, second inlet
133: outlet

Claims (14)

A paper substrate on which first and second electrodes are formed and having a hydrophilic micro-channel region and a hydrophobic non-channel region; And
A cover member disposed on the paper substrate to cover the micro channel region;
Including, paper-based paper-based microfluidic fuel cell.
According to claim 1,
The non-channel region is a paper-based microfluidic fuel cell, wherein the negative photosensitizer material is absorbed and has the hydrophobicity.
According to claim 1,
The micro-channel region extends perpendicular to the paper substrate to penetrate the paper substrate,
The non-channel region, in contact with the micro-channel region, surrounds the micro-channel region, paper-based micro-fluid fuel cell.
According to claim 1,
The first and second electrodes are spaced apart from each other in the micro-channel region and extend along a direction parallel to the paper substrate, the paper-based micro-fluid fuel cell.
According to claim 1,
A paper-based microfluidic fuel cell, wherein an upper surface of at least one of the first and second electrodes is positioned higher than an upper surface of the microchannel region.
According to claim 1,
The first and second electrodes comprise carbon, a paper-based microfluidic fuel cell.
According to claim 1,
The cover member,
Injection holes for penetrating the cover member, injecting an oxidizing agent into the first electrode in the micro-channel region and injecting fuel into the second electrode; And
A paper-based micro-fluid fuel cell comprising: a discharge port for passing through the cover member and discharging a material generated as a result of the redox reaction between the oxidizing agent and the fuel and the first and second electrodes.
The method of claim 7,
The oxidizing agent and the fuel include vanadium, a paper-based micro fluid fuel cell.
The method of claim 8,
The oxidizing agent and the fuel are injected into the injection holes in the form of a vanadium electrolyte containing the vanadium and sulfuric acid,
The vanadium and sulfuric acid molar ratios are the same as each other, a paper-based micro-fluid fuel cell.
Performing a screen printing process using a carbon paste to form first and second electrodes on a paper substrate;
Forming a microchannel region having hydrophilicity and a non-channel region having hydrophobicity by providing the first and second electrodes on the paper substrate by performing a photolithography process using a voice sensitizer; And
Combining a cover member covering the micro channel region on the paper substrate;
A method of manufacturing a paper-based microfluidic fuel cell comprising a.
The method of claim 10,
The forming of the first and second electrodes on the paper substrate may include:
Placing a first mask on the paper substrate, the first mask having openings spaced apart from each other and extending along a direction parallel to the paper substrate;
Applying the carbon paste on the first mask to fill the openings;
Removing the first mask to form first and second preliminary electrodes; And
And heating the paper substrate to form the first and second electrodes from the first and second preliminary electrodes.
The method of claim 11,
The forming of the first and second electrodes may include:
A method of manufacturing a paper-based microfluidic fuel cell, wherein carbon forming the first and second preliminary electrodes is diffused into the paper substrate to form the first and second electrodes.
The method of claim 10,
Forming the micro-channel region and the non-channel region on the paper,
Immersing the paper substrate in a negative photosensitive agent;
Taking the paper substrate out of the negative photosensitive agent and heating it;
Placing a support substrate on the lower surface of the paper substrate;
Placing a second mask having an opening corresponding to the micro-channel region on the upper surface of the paper substrate;
Exposing the paper substrate;
Separating the support substrate and the second mask from the paper substrate;
Heating the paper substrate; And
And developing the paper substrate to form the non-channel region in which the negative photosensitive agent is removed and the microchannel region from which the negative photosensitive agent is removed.
The method of claim 10,
A method of manufacturing a paper-based microfluidic fuel cell further comprising; bonding a support member to the lower surface of the paper substrate.

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