KR102484500B1 - Micro fluidic fuel cell and method to manufacture thereof - Google Patents

Abstract

A microfluidic fuel cell and a control method thereof for minimizing electrical noise generated when the fuel cell is driven for a long time are provided. A microfluidic fuel cell includes a main body, a photosensitive unit provided on an upper surface of the body, a microchannel formed in the photosensitive unit including a main flow path through which fluid flows, and a pair of fluid formed in the photosensitive unit spaced apart from the main flow path. It includes an inflow prevention unit and a pair of electrode parts printed on the upper surface of the photosensitive unit to connect the main flow path and the fluid inflow prevention unit.

Description

Micro fluidic fuel cell and method to manufacture the same

The present invention relates to a microfluidic fuel cell and a manufacturing method thereof, and relates to a microfluidic fuel cell and a manufacturing method thereof for minimizing electrical noise generated when the fuel cell is operated for a long time.

A microbial fuel cell is a battery that converts the chemical energy of organic substances contained in sewage or wastewater into electrical energy using microorganisms as catalysts. do. Microbial fuel cells are attracting attention as a green energy technology in that they can produce electricity while treating environmental waste containing organic matter.

Conventional microbial fuel cells have a batch type structure in which electrons are transferred to electron acceptors through a proton exchange membrane, and a buffer is injected once into a reservoir on an anode electrode in most microbial fuel cells. In addition, various types of fuel cells are being developed, such as batch-type structures using graphite electrodes and proton exchange membranes, continuous flow structures using Catbon cloth electrodes and proton exchange membranes, stackable structures using folding, and batch-type structures. There is a fuel cell with a structure in which the amount of inoculation of microorganisms is increased by using a carbon cloth electrode and a proton exchange membrane and using a 4-layer multi-anode electrode.

However, in the batch type fuel cell, the reservoir that stores fluid serves as a channel, and the anode electrode, cathode electrode, reservoir, and proton exchange membrane form a multi-layered structure of at least four layers, but bolts or There is a problem in that mass production is impossible in the process of mass production of products because fastening using tape is inevitable. In addition, the batch type fuel cell has problems such as maintenance of hydration of the proton exchange membrane, broken lines, and increase in manufacturing cost due to the use of a proton exchange membrane for electron transfer. There is a problem that electrical noise (Noise) occurs. In addition, as manual work such as manufacturing inlet extensions and absorption pads by hand and connecting them to the fuel cell body increases, the reproducibility of the fuel cell decreases, and the injection and discharge of the anode and cathode electrodes are smooth during long-term operation. There was a problem that couldn't be done.

Therefore, there is a need for a fuel cell capable of solving the above problems arising from conventional fuel cells.

Republic of Korea Patent Registration No. 10-1633526 ("Microfluid Fuel Cell and Manufacturing Method thereof", Erika Industry-Academic Cooperation Foundation, Hanyang University, 2016. 06. 20)

A technical problem to be achieved by the present invention is to solve these problems, and relates to a microfluidic fuel cell and a manufacturing method thereof for minimizing electrical noise generated during long-term operation of the fuel cell.

The microfluidic fuel cell of the present invention includes a body, a photosensitive unit provided on an upper surface of the body, and a micro channel formed in the photosensitive unit including a main flow path through which fluid flows, and the main flow path in the photosensitive unit. and a pair of fluid inflow prevention parts spaced apart from each other, and a pair of electrode parts printed on an upper surface of the photosensitive part to connect the main flow path and the fluid inflow prevention part.

The microchannel may include a plurality of inlets through which fuel and oxidizer are introduced.

The main flow path may be formed such that an interval increases along a flow direction of the fluid.

The electrode part may be formed along an edge of the main flow path based on the flow direction of the fluid, so that a distance between the electrode parts increases.

The microchannel may further include a pair of microchannels formed by a predetermined distance from the main channel toward the fluid inflow prevention unit.

It may further include a hydrophobic part provided in a protruding shape between the fluid inflow prevention part and the microchannel.

A method of manufacturing a microfluidic fuel cell of the present invention includes the step (a) of forming a body, the step of (b) providing a photosensitive unit on top of the body, and a main flow path through which fluid flows in the photosensitive unit. (c) forming a microchannel and a fluid inflow prevention part spaced apart from the main flow passage; and printing an electrode part on an upper surface of the photosensitive part to connect the fluid inflow prevention part to the main flow passage.

In the step (c), the microchannel having a plurality of inlets through which fuel and oxidizer are introduced into the photosensitive unit may be formed.

In the step (c), the main flow path may be formed such that an interval increases along the flow direction of the fluid.

The step (d) may further include forming the electrode parts by printing the electrode parts along the main flow path to increase a distance between the electrode parts.

The step (c) may further include forming a microchannel by previously removing the photosensitive unit by a preset distance from the main channel toward the fluid inflow prevention unit.

The step (c) may further include exposing the body portion from which a portion of the photosensitive portion is removed, and heating and drying the exposed body portion.

The step of heating and drying the body part may be characterized by fixing a hydrophobic part provided in a protruding shape between the microchannel and the fluid inflow prevention part.

In the step (c), a pair of micro-channels formed by a predetermined distance from the main flow path toward the fluid inlet may be formed, and the fluid inflow prevention unit may be spaced apart from the micro-channel.

After the step (c), a step of purifying and filtering a mixed solution of MWCNTs, nitric acid, and sulfuric acid to form an electrode mixture solution may be further included.

The microfluidic fuel cell and method of manufacturing the same according to the present invention prevent fluid from flowing into externally connected electrodes, thereby preventing electrical noise from occurring and driving the fuel cell for a long time.

In addition, the microfluidic fuel cell and its manufacturing method of the present invention are paper-based, so the manufacturing cost is low, and carbon dioxide is not generated during the electrical energy generation process. It has eco-friendly benefits.

In addition, the present invention is produced in a paper-based structure, but is manufactured in a structure in which the fuel cell body, the absorbing member, and the electrode are integrally formed, so that mass production is possible in the product mass production process.

In addition, the present invention reduces the internal resistance and increases the supply amount of the anode electrode (Anolyte) and the cathode electrode (Catholyte), thereby improving the duration, current density, and power density, thereby improving performance.

In addition, the present invention forms a carbon-based electrode by printing Multi-Walled Carbon Nano-Tube (MWCNT) using a screen printing technique to form a gap between the anode electrode (Anolyte) and the cathode electrode (Catholyte). There is an advantage that a proton exchange membrane is unnecessary by forming a liquid-liquid interface.

1 is a diagram of a microfluidic fuel cell according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of FIG. 1 taken along line AA.
3 is a view in which the electrode part of the microfluidic fuel cell according to the first embodiment of the present invention is removed.
FIG. 4 is a partially enlarged perspective view illustrating a portion of FIG. 3 enlarged.
5 is a diagram of a microfluidic fuel cell according to a second embodiment of the present invention.
6 is a diagram of a microfluidic fuel cell according to a third embodiment of the present invention.
7 is a diagram of a microfluidic fuel cell according to a fourth embodiment of the present invention.
8 is a graph of current density and OCV according to structural changes of the microfluidic fuel cell of the present invention.
9 is a graph of current density and power density according to structural changes of the microfluidic fuel cell of the present invention.
10 is an EIS measurement graph according to structural changes of the microfluidic fuel cell of the present invention.
11 is a graph of duration measurement of a microfluidic fuel cell.
12 is a flow chart of a method for manufacturing a microfluidic fuel cell according to the present invention.
13 is a view for explaining a manufacturing method of the body part of the present invention.
14 is a view for explaining a method for preparing a liquid mixture of an electrode part of the present invention.
15 is a view for explaining a method of printing an electrode part on a body part of the present invention.

Advantages and features of the present invention and methods for achieving them will become clear with reference to the detailed description of the following embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments make the disclosure of the present invention complete and those skilled in the art in the art to which the present invention belongs It is provided to fully inform the person of the scope of the invention, and the invention is defined only by the claims. Like reference numerals designate like elements throughout the specification.

Hereinafter, a microfluidic fuel cell and a manufacturing method thereof according to the present invention will be described with reference to FIGS. 1 to 15 .

A microfluidic fuel cell according to a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4, and a microfluidic fuel cell according to another embodiment of the present invention will be described with reference to FIGS. 5 to 7 After a detailed description and detailed description of the performance of the microfluidic fuel cell of the present invention with reference to the graphs of FIGS. 8 to 11, the manufacturing method of the microfluidic fuel cell of the present invention shown in FIGS. 12 to 15 Please explain in detail.

1 is a diagram of a microfluidic fuel cell according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG. 1 taken along line A-A, and FIG. 3 is a microfluidic fuel cell according to a first embodiment of the present invention. It is a drawing in which the electrode part is removed, and FIG. 4 is a partially enlarged perspective view showing a part of FIG. 3 enlarged.

The microfluidic fuel cell 1 of the present invention is a power generation system that uses microorganisms as catalysts to generate electric energy by generating a potential difference while sending electrons to an acceptor through a process in which the microorganisms decompose organic matter (electron donor). The microfluidic fuel cell 1 does not emit carbon dioxide during the electrical energy production process, and has eco-friendly characteristics by decomposing organic matter present in environmental waste and producing electrical energy at the same time.

In general, microfluidic fuel cells have a problem in that electrical noise is generated due to the connection of external connection electrodes. The microfluidic fuel cell 1 of the present invention may include a structure of a fluid inflow prevention part 30 formed on the upper surface of the body part 10 in order to prevent such electrical noise from occurring. The fluid inflow prevention unit 30 may prevent an electrical noise phenomenon generated when fluid flows into the electrode unit 50 .

In addition, the microfluidic fuel cell 1 of the present invention is eco-friendly because it is made of paper and has low manufacturing cost. The microfluidic fuel cell 1 has a single-layer structure in which the main body 10, the absorption member, and the electrode 50 are integrally manufactured, so that it can be mass-produced during mass production.

In addition, the electrode part 50 of the present invention includes a carbon-based electrode part 50 formed on the upper surface of the body part 10 by a screen printing technique. The electrode unit 50 as described above has an advantage of not requiring a proton exchange membrane by forming a liquid-liquid interface between the anode electrode (anolyte) and the cathode electrode (catholyte).

Hereinafter, the structure and manufacturing method of the present invention that can exhibit the above characteristics will be described in detail.

1 and 2, the microfluidic fuel cell 1 of the present invention includes a body part 10, a micro channel 20, a fluid inflow prevention part (see 30 in FIG. 3), an electrode part ( 50) included. Specifically, the microfluidic fuel cell 1 of the present invention includes a main body 10, a photosensitive unit 60 provided on the upper surface of the body 10, and a main flow path 22 through which fluid flows. A microchannel 20 formed in the miner 60, a pair of fluid inflow prevention parts 30 formed in the photosensitive unit 60 and spaced apart from the main flow passage 22, and fluid inflow prevention between the main flow passage 22 It includes a pair of electrode parts 50 printed on the upper surface of the photosensitive part 60 to connect the parts 30 to each other.

The main body 10 forms the housing of the microfluidic fuel cell 1, and may be made of a paper material capable of absorbing fluid by capillarity. As an example, the main body 10 may be made of Whatman paper having a thickness of 180 um and a pore size of 11 um to form a substrate of the microfluidic fuel cell 1 .

The photosensitive unit 60 may be formed by coating a photosensitive agent on the upper surface of the body unit 10 . The photosensitive unit 60 is provided on the upper surface of the body unit 10 to form one layer, and may be formed by coating SU8-3035 (MicroChem, USA) on the upper surface of the body unit 10, but is limited thereto It is not, and may be formed using a known photosensitizer or a photosensitizer developed in a later technology.

A microchannel 20 may be formed by etching or removing the photosensitive portion 60 . Specifically, the inlet 21 through which the fluid flows through the etching of the photosensitive unit 60, the main flow path 22 through which the fluid flows, the micro flow path 23 through which the fluid minutely flows, A fluid inflow prevention unit 30 or the like may be formed, and a hydrophobic unit 40 or the like that prevents fluid inflow by forming the microchannel 23 and the fluid inflow prevention unit 30 may be formed.

The electrode unit 50 may be formed by connecting the main flow path 22, the micro flow path (see 23 in FIG. 3 ), the hydrophobic unit (see 40 in FIG. 4 ), and the fluid inflow prevention unit (see 30 in FIG. 3 ). , It may be formed in the form of printing the electrode mixture solution.

The microchannel 20 forms a flow path of fluid flowing from one end on the upper surface of the main body 10, and may be formed by etching or removing the photosensitive unit 60 provided on the upper surface of the main body 10. there is.

The microchannel 20 includes a pair of inlets 21a and 21b through which fluids such as fuel and oxidant are introduced, and one main flow path 22 . At this time, one end of the plurality of inlets 21a and 21b may be formed to be spaced apart from each other, and the other ends of the plurality of inlets 21a and 21b may be formed to be connected to one end of the main flow path 22 .

The pair of inlets 21a and 21b may have inlet ends spaced apart from each other, but may be provided in a 'Y' shape so that their ends are connected to the main flow path 22 . The inlet portion 21 may be formed so that the inlet end is extended so that a pair of inlet portions are parallel and symmetrical to each other. Inlet portions 21a and 21b may be formed longer than the remaining portions in which portions formed parallel to each other are refracted and converged. For example, the inlet portion 21 may be formed so that portions extending and parallel to each other have a length of 30 mm, and the remaining portions refracted and converging may have a length of about 17 mm. In addition, the diameter of a part of the pair of converging inlets 21a and 21b may be 2.5 mm, and the length and diameter of the main flow path 22 forming one flow path therefrom may be formed to be 18 mm and 5 mm, respectively. It can be.

The microchannel 20 may be formed by etching a portion of the photosensitive unit 60, and the inlet 21 and the main flow path 22 form a 'Y' shape as shown in the drawing. Since it is formed by scratching a part of the photosensitive portion 60, it can be included in one layer.

The microchannel 20 in the first embodiment of the present invention will be described as an example in which a pair of inlets 21a and 21b through which fuel and oxidizer respectively flow are formed. However, it is not limited thereto, and the microchannel 20 may be formed to include four inlets 21 through which fuel and oxidizer are introduced. In addition, the microchannel 20 shows a diagram in which the diameter of the main flow path 22 is formed constant along the flow direction of the fluid. However, it is not limited thereto, and the main flow path 22 may be formed to increase in diameter along the flow direction of the fluid. This will be described later in detail through another embodiment.

The fluid flowing into the microchannel 20 of the present invention is absorbed by the main body 10 made of paper and is self-pumped by the capillary action of the paper to flow through the inlet 21 and the main body. There is a feature that can absorb and flow along the flow path (22). Accordingly, the microfluidic fuel cell 1 of the present invention has an advantage of not requiring a separate external pump.

At least a portion of the pair of electrode units 50 may be symmetrically printed on the upper surface of the main flow path 22 through which the fluid flows. This will be described in detail later.

A pair of micro-channels 23 may be respectively formed on both sides of the main channel 22 of the micro-channel 20 .

Referring to FIGS. 3 and 4 , the microchannel 23 is a kind of marking for confirming the exact position of the pair of electrode units 50 printed on the upper surface of the main body 10, can be extended. The microchannel 23 may extend from the main channel 22 toward the fluid inflow prevention unit 30 by a preset distance.

A pair of micro-passages 23 may be formed at an end of the main flow path 22 so as to be perpendicular to the main flow path 22 and bent toward the outside of the main flow path 22 . Accordingly, the micro-passage 23 and the main flow-path 22 may be formed in an 'B' shape. A hydrophobic portion 40 and a fluid inflow prevention portion 30 may be respectively formed on the side of the microchannel 23 .

The hydrophobic part 40 is to prevent the fluid from being transferred from the microchannel 23 to the fluid inflow prevention unit 30, and may be formed on the upper surface of the main body 10 adjacent to the microchannel 23. . Specifically, the hydrophobic portion 40 is formed by etching or removing the photosensitive portion 60, and is provided in a protruding shape between the fluid inflow prevention portion 30 and the microchannel 23, and the microchannel 23 blocks the passage of fluid through the

The size of the hydrophobic portion 40 may vary according to the length of the microchannel 23 . Specifically, when the preset length of the microchannel 23 extending from the main channel 22 toward the fluid inflow prevention unit 30 becomes longer, the size of the hydrophobic portion 40 increases, and the microchannel 23 When the preset length of ) is shortened, the size of the hydrophobic portion 40 is reduced.

In other words, the hydrophobic part 40 is formed on the upper surface of the body part 10, and the photosensitive part 60 having a hydrophobic property is applied between the microchannel 23 and the fluid inflow prevention part 30 to be formed. can

The hydrophobic part 40 is a part where the photosensitive part 60 is not etched or removed between the microchannel 23 and the fluid inflow prevention part 30, and as shown in FIG. 2, a lower part of the electrode part 50 It may protrude from the top surface of the body portion 10 toward the top. The hydrophobic portion 40 may form a part of the photosensitive portion 60, and may be made of the same SU8-3035 (MicroChem, USA) as the photosensitive portion 60.

The hydrophobic portion 40 may be formed by curing through a photo-lithography process together with the photosensitive portion 60, and PEB (PEB, which is a process of applying to the body portion 10, exposing to UV light of 20 mV for 15 seconds, and drying after exposure) Post Exposure Bake) process at 55° for 10 minutes. The hydrophobic portion 23 may be completely fixed and formed on the upper surface of the body portion 10 by curing after exposure through a PEB process, which will be described in more detail through a manufacturing method.

The hydrophobic portion 40 may be formed such that a distance between the microchannel 23 and the fluid inflow prevention portion 30 is 0.5 mm. Accordingly, the microchannel 23 and the fluid inflow prevention unit 30 may be separated from each other by 0.5 mm by the hydrophobic unit 40 . The pair of hydrophobic parts 40 may have one end in contact with the pair of microchannels 23 and the other end in contact with the fluid inflow prevention part 30 , respectively.

3 and 4, the fluid inflow prevention unit 30 forms a space spaced apart from the microchannel 23, and a pair of the main channel 22 and the microchannel ( 23) may be formed. The hydrophobic portion 40 made of a hydrophobic material may be spaced apart from the main flow path 22 and the micro flow path 23 .

The fluid inflow prevention part 30 may be etched on the photosensitive part 60 so that one end comes into contact with the hydrophobic part 40 and a part of the electrode part 50 may be printed on the upper surface. The electrode unit 50 printed on the upper surface of the fluid inflow prevention unit 30 is connected to an external electrode. The hydrophobic part 40 blocks the fluid flowing into the fluid inflow prevention part 30 from the main flow passage 22 and the micro flow passage 23, so that the electrode part 50 printed on the upper surface of the fluid inflow prevention part 30 It is possible to prevent contact with the fluid. Thus, the fluid inflow prevention unit 30 has an effect of preventing electrical noise from occurring and exhibiting a high yield.

The microchannel 20 including the inlet portion 21 and the main flow path 22, the microchannel 23, the hydrophobic portion 40, and the fluid inflow prevention portion 30 described above are the paper-based main body portion 10 It can be manufactured integrally with mass production.

The electrode unit 50 forms an electrode of the microfluidic fuel cell 1, and may be formed by being printed on the upper surface of the photosensitive unit 60 to connect the main flow path 22 and the fluid inflow prevention unit 30. The electrode part 50 may be formed by applying a carbon-based electrode mixture liquid (MWCNT paste) to the upper surface of the body part 10 . The mixed solution of the electrode unit is purified while dispersing the mixed solution of nitric acid, sulfuric acid and multi-walled carbon nano-tubes (MWCNT) with ultrasonic waves for 30 minutes, and deionized water (De-lonized water) is added to the purified solution. ) can be prepared through a manufacturing process such as filtering WMCNT using a vacuum filter, further pouring deionized water into the filtered solution to remove remaining acid, and extracting only purified WMCNT. Regarding the manufacturing process of the electrode mixture solution for forming the electrode part 50, it will be described later in more detail with reference to FIG. 14.

Referring back to FIGS. 1 and 2, the electrode mixture is printed on the upper surface of the main body 10 so that one end and the other end connect the main flow path 22 and the fluid inflow prevention unit 30, respectively, so that a pair of The electrode unit 50 may be formed. More specifically, the electrode part 50 is placed on the upper surface of the photosensitive part 60 to connect the main flow path 22, the micro flow path 23, the hydrophobic part 40, and the fluid inflow preventing part 30. It can be formed by printing.

In particular, the electrode unit 50 may be printed at an accurate position on the upper surface of the main body unit 10 by the microchannel 23 . The electrode unit 50 may be formed such that the length and thickness of a portion in contact with the upper surface of the main flow path 22 are 15 mm and 1 mm, respectively. The electrode unit 50 prevents a phenomenon in which one end to which the external electrode is connected comes into contact with the fluid flowing through the main channel 22 and the micro channel 23 by the hydrophobic unit 40, thereby reducing electrical noise caused by reaction with the fluid. occurrence can be prevented.

The microfluidic fuel cell 1 according to the first embodiment of the present invention includes the structure of the fluid inflow prevention unit 30 to prevent fluid from flowing into the externally connected electrode, thereby generating electrical noise. It has a feature that can prevent and drive for a long time.

In addition, the present invention is formed on a paper basis, so the production cost is low, and mass production is possible in a short time due to the integral structure.

Hereinafter, a microfluidic fuel cell according to a second embodiment of the present invention will be described with reference to FIG. 5 .

5 is a front view of a microfluidic fuel cell according to a second embodiment of the present invention.

The microfluidic fuel cell 1a according to the second embodiment of the present invention excludes the microchannel 20a further including a pair of inlets 21a and 21b and another pair of inlets 21c and 21d. If so, it is substantially the same as that of the first embodiment already described. Therefore, the same reference numerals are attached to the components already described, and detailed descriptions will be omitted.

Referring to FIG. 5 , the microfluidic fuel cell 1a according to the second embodiment of the present invention includes a microchannel 20a having a plurality of inlets 21a, 21b, 21c, and 21d through which fluid flows. . As shown in the drawing, the microchannel 20a may include four inlets 21a, 21b, 21c, and 21d through which fuel and oxidizer are introduced and one main flow path 22a. Specifically, the microfluidic fuel cell (1a) includes a structure of another pair of inlets (21c, 21d) formed by spaced apart from each other by 0.5 mm to the outside on both sides of the pair of inlets (21a, 21b). do. In the microfluidic fuel cell 1a, the main flow path 22a may be formed to have a length of 18 mm. A pair of inlets 21a and 21b and the other pair of inlets 21c and 21d have one end where fuel and oxidizer can flow in, respectively, and the other end is connected to the main flow path 22a to have a multi-structure. A microchannel 20a may be formed.

Hereinafter, a microfluidic fuel cell according to a third embodiment of the present invention will be described with reference to FIG. 6 .

6A is a front view of the microfluidic fuel cell according to the third embodiment before electrodes are printed, and FIG. 6B is a front view of the microfluidic fuel cell according to the third embodiment after electrodes are printed.

The microfluidic fuel cell 1b according to the third embodiment of the present invention includes a main flow path 22b whose diameter increases along the flow direction of the fluid, and an electrode unit 501 printed to match the shape of the main flow path 22b. Except for , it is substantially the same as the previously described first embodiment. Therefore, the same reference numerals are attached to the components already described, and detailed descriptions will be omitted.

Referring to FIG. 6, the microfluidic fuel cell 1b according to the third embodiment of the present invention has a main flow path 22b formed to increase in diameter along the flow direction of the fluid, and a main flow path based on the flow direction of the fluid. It includes a pair of electrode parts 501a and 501b formed so that the distance between the pair increases along the edge of the flow path 22b.

은 3.5mm로 형성될 수 있으며, 유체가 배출되는 메인유로(22b) 타단부의 직경

는 5mm로 형성되어

이

보다 작게 형성될 수 있다.The main flow path 22b forms a path through which the fluid introduced through the inlets 11a and 11b flows. The main flow path 22b has one end connected to the other end of the pair of inlets 11a and 11b, extending from one end toward the other end in the direction in which fluid flows, and may be formed to have a length of 18 mm. there is. In particular, as shown in Figure 6a, the main flow path (22b) is formed in a structure in which the diameter increases from one end toward the other end in the flow direction of the fluid. For example, the diameter of one end of the main flow path 22b merged from the pair of inlets 11a and 11b

may be formed to be 3.5 mm, and the diameter of the other end of the main flow path 22b through which the fluid is discharged

is formed of 5 mm

this

can be made smaller.

이 직경

보다 작게 형성될 수 있다. 전극부(501)를 따라 흐르는 전류는 메인유로(22b)를 따라 흐르는 유체의 유동방향과 반대방향으로 흐르게 된다. 이에, 전극부(501)는 유체의 유동방향을 기준으로 한 쌍의 이격된 거리가 증가하도록 형성된다고 표현할 수 있으며, 전류가 흐르는 방향을 기준으로 한 쌍의 이격된 거리가 감소하는 형태인 수렴형 형태로 형성된다고 표현할 수 있다.The electrode unit 501 may be formed so that the distance between the pair varies according to the shape of the main flow path 22b. Referring to FIG. 6B , at least a portion of the electrode unit 501 may be printed on the upper surface of the main flow path 22b along the edge of the main flow path 22b. The electrode unit 501 may be formed such that the length of a portion printed on the upper surface of the main flow path 22b has a length of 15 mm, and the distance between the pair is changed according to the shape of the main flow path 22b. can The electrode part 501 has a diameter

this diameter

can be made smaller. The current flowing along the electrode part 501 flows in a direction opposite to the flow direction of the fluid flowing along the main flow path 22b. Therefore, the electrode unit 501 can be expressed as being formed so that the distance between the pair increases based on the flow direction of the fluid, and the convergence type in which the distance between the pair decreases based on the direction in which current flows. It can be expressed as being formed by

As described above, a portion of the pair of electrode parts 501 in contact with the main flow path 22b is formed in a convergent form based on the direction in which current flows, thereby filling the gap between the anode electrode (anolyte) and the cathode electrode (catholyte). can reduce the internal resistance. In addition, the performance of the fuel cell is improved by increasing the supply amount of the anode electrode and the cathode electrode to improve the duration, current density, and power density of the microfluidic fuel cell 1b.

Hereinafter, a microfluidic fuel cell according to a fourth embodiment of the present invention will be described with reference to FIG. 7 .

7A is a front view of the microfluid according to the fourth embodiment before electrode parts are printed, and FIG. 7B is a front view of the microfluid according to the fourth embodiment after electrode parts are printed.

The microfluidic fuel cell 1c according to the fourth embodiment of the present invention includes the inlets 11a, 11b, 11c, and 11d of the second embodiment, the main flow path 22b and the electrode part 501 of the third embodiment. It consists of a combined structure. The microfluidic fuel cell (1c) according to the fourth embodiment includes a plurality of inlets (11a, 11b, 11c, 11d) into which fuel and oxidizer are introduced, one main flow path (22b) having a variable diameter, and a main flow path. Except for the electrode part 501 printed according to the shape of (22b), it is substantially the same as the previously described first embodiment. Therefore, the same reference numerals are attached to the components already described, and detailed descriptions will be omitted.

이 유체가 배출되는 타단부의 직경

보다 작게 형성될 수 있다.Referring to FIG. 7A , the microfluidic fuel cell 1c includes a micro channel 20a having a plurality of inlets 21a, 21b, 21c, and 21d through which a plurality of fuels and oxidizers flow, and four inlets. The other ends of (21a, 21b, 21c, 21d) may be connected to one main flow path (22b) to form a micro channel (20c). As in the third embodiment described above, the main flow path 22b is formed in a structure in which a diameter increases from one end toward the other end in the flow direction of the fluid. Accordingly, the main flow path 22b has a diameter of one end

Diameter of the other end through which this fluid is discharged

can be made smaller.

이

보다 작게 형성될 수 있다. 또한, 전극부(501)는 전류가 흐르는 방향을 기준으로 수렴형 형태로 형성될 수 있다. Referring to FIG. 7B , the electrode unit 501 may be formed such that the distance between the pair is increased based on the flow direction of the fluid according to the shape of the main flow path 22b. At least a portion of the electrode part 501 may be printed on the upper surface of the main passage 22b along the edge of the main passage 22b. Accordingly, the electrode part 501 is formed so that the distance between the pair is increased according to the shape of the main flow path 22b in a portion printed on the upper surface of the main flow path 22b.

this

can be made smaller. In addition, the electrode unit 501 may be formed in a convergent shape based on the direction in which current flows.

In the pair of electrode parts 501, a part contacting the main flow path 22b is formed in a convergent form based on the direction in which the current flows, thereby reducing the gap between the anode electrode and the cathode electrode to reduce internal resistance. In addition, the performance of the fuel cell is improved by increasing the supply amount of the anode electrode (Anolyte) and the cathode electrode (Catholyte) to improve the duration, current density, and power density of the microfluidic fuel cell (1b).

As described above, the microfluidic fuel cell of the present invention can be formed in various structures including different inlets 21, main flow channels 22, and electrode units 50, and the fluid diffusion length and , performance and duration show slightly different results.

Hereinafter, with reference to FIGS. 8 to 10 , the resulting values according to each structure will be described in more detail.

8 is a graph of current density and OCV according to structural changes of the microfluidic fuel cell of the present invention, and FIG. 9 is a graph of current density and power density according to structural changes of the microfluidic fuel cell of the present invention. 10 is an EIS measurement graph according to structural changes of the microfluidic fuel cell of the present invention, and FIG. 11 is a duration measurement graph of the microfluidic fuel cell.

8 to 10, Couple.Y refers to the first embodiment, Couple.Convergence refers to the second embodiment, Multi.Y refers to the third embodiment, and Multi.Convergence refers to the micro fuel fluid cell of the fourth embodiment. do.

이고, 제3 실시예(Multi.Convergence)에 따른 마이크로 유체 연료전지(1b)는

로 나타난다. 연료 전지 성능은 메인유로(22)의 직경의 변화가 있는 구조를 포함하는 제3 실시예(Multi.Convergence)의 마이크로 유체 연료전지(1b)에서 제1 실시예(Couple.Y)의 구조 대비 5.0%가 향상된 것으로 나타났다. 제2 실시예(Couple.Convergence)에 따른 마이크로 유체 연료전지(1a)는 최대전력밀도가

로, 유입부(21)의 개수가 늘어나게 되면서 제1 실시예(Couple.Y)의 구조 대비 21.9%의 연료전지 성능 향상된 것으로 나타났다. Referring to FIGS. 8 and 9 , linear sweep measurement graphs according to structural changes of the microfluidic fuel cells of the first to fourth embodiments of the present invention and graphs according to current density and power density are shown. The present invention shows a slight difference in performance of the fuel cell according to the structural changes of the first to fourth embodiments. As a result of comparing the computational fluid analysis results, the maximum power density according to the structure of the microfluidic fuel cell 1 according to the first embodiment (Couple.Y) is

And, the microfluidic fuel cell 1b according to the third embodiment (Multi.Convergence)

appears as The fuel cell performance was 5.0 compared to the structure of the first embodiment (Couple.Y) in the microfluidic fuel cell 1b of the third embodiment (Multi.Convergence) including the structure in which the diameter of the main flow path 22 was changed. % was found to be improved. The microfluidic fuel cell 1a according to the second embodiment (Couple.Convergence) has a maximum power density

As the number of inlets 21 increased, fuel cell performance was improved by 21.9% compared to the structure of the first embodiment (Couple.Y).

로, 제1 실시예(Couple.Y)의 구조 대비 28.6%의 연료전지 성능 향상이 있는 것으로 나타났다.In addition, the microfluidic fuel cell 1c of the fourth embodiment (Multi.Convergence) has a structural change including the structure of the four inlets 21 and the main flow path 22b with a change in diameter, thereby maximizing power density

, it was found that there was a 28.6% improvement in fuel cell performance compared to the structure of the first embodiment (Couple.Y).

The present invention is a structure of a main flow path (22b) in which the gap increases along the flow path of the fluid, and a structure of a pair of electrode parts 510 that reduces the gap between the anode electrode and the cathode electrode at the front end of the main flow path (22b). Through this, the effect of reducing the internal resistance can be shown. In addition, the present invention can increase the supply of the anode electrode and the cathode electrode through the multi-inlet structure including a plurality of inlets 21, and the fuel cell performance is greatly improved as the diffusion area is reduced through computational fluid analysis results. you can look into

Referring to FIG. 10, EIS graphs according to structural changes of the microfluidic fuel cells of the first to fourth embodiments of the present invention are shown. The microfluidic fuel cell 1b of the third embodiment (Multi.Y) has ohmic resistance ( Ohmic resistance) by 6.8% and anode resistance by 28.5%.

The microfluidic fuel cell 1a of the second embodiment (Couple. Convergence) increases the number of inlets 21 to increase the supply amount of the anode electrode and the cathode electrode and reduces the diffusion area, thereby reducing the diffusion area. Compared to the structure of Y), the Ohmic resistance is reduced by 16.7% and the anode resistance is reduced by 65.8%. In addition, the microfluidic fuel cell 1c of the fourth embodiment (Multi.Convergence) has an ohmic resistance of 24.4% and an anode resistance of the first embodiment (Couple.Y) compared to the structure of the first embodiment (Couple.Y). A decrease of 71.4% can be observed.

Referring to FIG. 11 , the microfluidic fuel cells 1 and 1c can observe the change in OCV over time and the duration through the chronopotentiometry method of applying a constant current and seeing the voltage over time.

FIG. 11A shows a graph of performance measured and compared according to structural changes of a fuel cell under a continuous flow condition. Referring to FIG. 11A, the duration of the microfluidic fuel cell 1c according to the fourth embodiment (Multi.Convergence) in the continuous flow condition was 8 hours and 26 minutes, and the first embodiment (Couple.Y) The duration of the microfluidic fuel cell 1 according to was 3 hours and 43 minutes. The duration of the fuel cell according to the fourth embodiment (Multi.Convergence) and the first embodiment (Couple.Y) shows a difference of 2.2 times or more. The microfluidic fuel cell (1c) of the fourth embodiment (Multi.Convergence) absorbs wetness faster than the structure of the microfluidic fuel cell (1) of the first embodiment (Couple.Y). The area of the pad may appear high. In addition, pores of the microfluidic fuel cell are blocked due to causes such as crystallization of potassium ferricyanide due to catholyte drying and anolyte contamination by external bacteria in the air. At this time, since the structure of the fourth embodiment (Multi.Convergence) resolves pore clogging to some extent at a faster supply speed than the structure of the first embodiment (Couple.Y), it can show a result of more than two times improvement in duration. .

11B shows a graph of performance measured and compared according to a change in fuel cell structure under a stop flow condition. Referring to FIG. 11B, in the Stop Flow condition, the duration of the structure of the fourth embodiment (Multi.Convergence) is 46 minutes and the duration of the first embodiment (Couple.Y) is 36.7 minutes, and the fourth embodiment (Multi.Convergence) shows a duration of 36.7 minutes. You can see that the structure of (Multi.Convergence) shows a longer duration with a difference of about 9 minutes. Since the positive and negative electrodes are not continuously supplied under the Stop Flow condition, and the supply speed drops significantly, it can be seen that both the duration and voltage are significantly different between the Continuous Flow and Stop Flow conditions.

Hereinafter, with reference to FIGS. 12 to 15, a method of manufacturing a microfluidic fuel cell according to the present invention will be described in detail.

12 is a flow chart of a method for manufacturing a microfluidic fuel cell according to the present invention, FIG. 13 is a view for explaining a method for manufacturing a main body part according to the present invention, and FIG. 14 explains a method for manufacturing a mixture solution for an electrode part according to the present invention. 15 is a view for explaining a method of printing an electrode part on the body part of the present invention.

Referring to FIG. 12, the manufacturing method of the microfluidic fuel cell 1 of the present invention includes steps (a) of forming the main body 10 (S200) and (b) steps of providing the photosensitive unit 60 ( S210), (c) forming the microchannel 20 and the fluid inflow prevention unit 30 (S220), and printing the electrode unit 50 (S230).

Specifically, the (a) step of forming the main body 10 (S200), the (b) step of providing the photosensitive unit 60 on the main body 10 (S210), and the main flow path through which the fluid flows (c) step S220 of forming the microchannel 20 including (22) and the fluid inflow prevention unit 30 spaced apart from the main flow path 22, and the main flow path 22 and the fluid inflow prevention unit (d) step (S230) of printing the electrode unit 50 on the upper surface of the photosensitive unit 60 so as to connect the electrode unit 30;

The manufacturing method of the microfluidic fuel cell 1 of the present invention describes the process of forming the main body 10, the process of preparing the photosensitive unit, and the process of forming the microchannel and the fluid inflow prevention unit with reference to FIG. 13. After explaining the process of forming the mixed solution of the electrode unit 50 with reference to FIG. 14, the process of printing the electrode unit 50 on the upper surface of the photosensitive unit 60 will be described in detail with reference to FIG. let it do

Referring to FIG. 13 , the main body 10 is formed by preparing a Whatmanji (S200). At this time, the body portion 10 may be manufactured using Whatmanji having a thickness of 180um and a size of 11um in the air gap.

A photosensitive agent having a hydrophobic property may be wetted on the upper part of the body part 10 made of Whatman paper and then cured to prepare the photosensitive part 60 (S210). A photosensitive agent having a hydrophobic property may be applied to the outer surface of the body portion 10 and maintained in a wet state for 10 minutes to form the photosensitive portion 60 on the upper surface of the body portion 10 .

A microchannel 20 including a main flow path 22 through which fluid flows and a fluid inflow prevention unit 30 spaced apart from the main flow path 22 are formed in the photosensitive unit 60 (S230). The microchannel 20 and the fluid inflow prevention unit 30 are formed by removing a portion of the photosensitive unit 60 that is predetermined and corresponds to a position where the microchannel 20 and the fluid inflow prevention unit 30 are formed. can do.

The microchannel 20 and the fluid inflow prevention unit 30 are formed by etching or removing a portion of the photosensitive unit 60, and may form the same layer as the photosensitive unit 60. In particular, in the process of forming the microchannel 20 and the fluid inflow prevention part 30 by etching or removing the photoresist 60, the inlet 21 into which a plurality of fuels and oxidizers flow, and the inlet 21 A microchannel 20 including one main flow path 22 through which fluid flows may be formed.

In addition, another portion of the predetermined photoresist 60 is etched to form a microchannel 23 extending in both directions perpendicular to the main flow path 22, and a fluid inflow prevention unit 30 formed spaced apart from the microchannel 23. ) can be formed. In this process, the hydrophobic portion 40 that is not etched between the microchannel 23 and the fluid inflow prevention unit 30 is formed to protrude from the main body 10 to separate the microchannel 23 and the fluid inflow prevention unit 30. ) can be formed. In the step of removing the photosensitizer, the main flow path 22 may be formed to increase in diameter along the flow direction of the fluid, and the microchannel 20 according to various embodiments, such as forming four inlets, may be formed in the body portion 10. can be formed on the upper surface of

It is coated on the upper surface and a predetermined portion of the photosensitive portion 60 is scraped off, and the Whatman paper formed with the microchannel 20, the microchannel 23, and the fluid inflow prevention portion 30 is soft-baked at 85° C. for 10 minutes, and dried. The body part 10 integrated with the photosensitive part 60 may be formed. In this case, the non-dried photoresist can be absorbed by disposing separate Whatman papers on the upper and lower surfaces of the Whatman paper, and then, the separate photoresist disposed on the upper and lower surfaces of the Whatman paper is removed.

A part of the photosensitive part 60 is removed and the dried body part 10 is exposed to light at 20 mV for 15 seconds using UV light, and the exposed body part 10 is PEB (Post Exposure Bake) at 55 ° C. for 10 minutes go through the process The manufacturing method of the microfluidic fuel cell 1 of the present invention is to expose the main body from which a part of the photosensitive unit 60 is removed, and to heat and dry the exposed main body, which is a PEB process, in the main body 10. After exposure, the cured photosensitive portion 60 can be completely fixed.

Specifically, through the PEB process, the hydrophobic portion 40 coated with the photoresist can be completely fixed to divide the microchannel 23 and the fluid inflow prevention portion 30 . The body part 10 that has gone through the PEB process proceeds with the Develop process. The development process is a process of removing photo resist from a certain area to form an image by separating necessary and unnecessary parts using a developer after alignment and exposure. The body part 10 was immersed in SU8-Developer for 15 minutes, IPA (Icosapentaenoic Acid) solution for 5 minutes, and deionized water (DI Water) for 10 minutes in the development process, and then in an oven at 40 ° C. After drying, the paper-based main body 10 having the microchannel, the microchannel 23, the hydrophobic portion 40, and the fluid inflow prevention portion 30 may be formed. The electrode unit 50 may be printed on the upper surface of the body unit 10 formed through the above process to form the microfluidic fuel cell 1 .

Meanwhile, photoresist (PR) includes positive PR and negative PR. The photosensitive part 60 is provided with negative PR on the upper surface of the body part 10, and the hydrophobic part 40, which is a part that receives light, is firmly hardened and the negative PR is removed. Microchannel 20, The microchannel 23 and the fluid inflow prevention unit 30 are characterized in that they can be easily dissolved by a developing solution.

Referring to FIG. 14 , a process of forming an electrode mixture solution to be printed on the main body 10 is illustrated. The mixed solution of the electrode unit may be formed by purifying and filtering a solution in which nitric acid and sulfuric acid are mixed. Specifically, the mixed solution of the electrode part is mixed with 10 mg of MWCNT, 10 mg of nitric acid (HNO ₃ , 70 wt%), and 20 mL of sulfuric acid (H ₂ SO ₄ , 95 to 98 wt%), and purified while dispersing with ultrasonic waves for 30 minutes. A total of 100 mL of the solution formed by mixing 70 mL of DI water with the purified 30 mL solution was filtered through MWCNTs using a vacuum filter. The acid remaining in MWCNTs can be removed by further pouring DI water into the filtered solution, leaving only purified MWCNTs.

Subsequently, Cellulose-ionic liquids solution can be prepared by mixing cellulose (Cellulose, 5wt%) and EMIM (1-Ethyl-3-methylimidazolium acetate, 95wt%) and applying ultrasonic waves at 60° C. for 1 hour. After mixing the prepared Cellulose-ionic liquids solution (95% mass) and MWCNT (5wt%) in a mass ratio, grinding may be performed for 15 minutes to form an electrode mixture solution. The electrode unit 50 may be formed by printing the mixed liquid of the electrode unit formed through the above process on the upper surface of the photosensitive unit 60 .

Referring to FIG. 15 , a view of manufacturing the microfluidic fuel cell 1 having the electrode part 50 by printing the mixed solution of the electrode part on the upper surface of the photosensitive part 60 is shown. A body in which a micro channel 20, a micro channel 23, a hydrophobic part 40, a fluid inflow prevention part 30, and a photosensitive part 60 are formed by forming an OHP film (Overhead Projector Film) processed to form a carbon electrode. After fixing on the upper surface of the part 10, the electrode part mixture is applied to the upper surface of the OHP film. If the mixed solution of the electrode part applied on the upper surface of the OHP film is pushed evenly using a film applicator made of a metal bar with a smooth surface, the mixed solution of the electrode part can be printed in the form of an electrode on the paper substrate through the hole of the OHP film. there is. When the mixed solution of the electrode part is printed on the upper surface of the body part 10, the OHP film is removed.

The main body 10 from which the OHP film has been removed is heated in an oven at 40° C. for 60 minutes. At this time, when the temperature of the oven of the main body exceeds 45 ° C, the [EMIM] [AC] contained in the mixture of the electrode part is completely cured on the upper surface, causing a problem that the anode and cathode electrodes do not flow into the channel. Let it heat up in the oven. The heated main body part 10 is immersed in DI water for 20 minutes to remove [EMIM][AC] contained in the mixed solution of the electrode part.

Thereafter, the body portion 10 may be heated again in an oven at 50° C. for 20 minutes to completely print the electrode portion 50 on the upper surface of the body portion 10 . As such, the method for manufacturing a microfluidic fuel cell forms a carbon-based electrode part 50 by printing MWCNTs using a screen printing technique to form a liquid-liquid interface between an anode electrode (Anolyte) and a cathode electrode (Catholyte). By forming a proton exchange membrane, there is an unnecessary advantage.

The microfluidic fuel cell of the present invention can form microfluidic fuel cells 1, 1a, 1b, and 1c through the above process. The microfluidic fuel cell 1 of the present invention can prevent the occurrence of electrical noise by preventing fluid from flowing into the externally connected electrode, and thus has a feature of being able to operate for a long time.

In addition, the present invention is paper-based, so the production cost is low, and carbon dioxide is not generated during the electrical energy generation process, and organic matter present in wastewater is decomposed and electrical energy is generated at the same time, so there is an eco-friendly advantage. In addition, the present invention has a structure including a plurality of inlets 21 as in the second to fourth embodiments, and the diameters of the main flow path 22 and the electrode unit 50 are along the flow direction of the fluid. Including a structure that is formed to increase, there is a feature that can improve the duration, current density and power density by reducing the internal resistance and increasing the supply amount of the anode electrode (anolyte) and cathode electrode (catholyte). Accordingly, the present invention can improve fuel cell performance.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art to which the present invention pertains know that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. You will understand. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

1, 1a, 1b, 1c: Microfluidic Fuel Cell
10: body part
20, 20a, 20b, 20c: microchannel
21, 21a, 21b, 21c, 21d: inlet
22, 22a, 22b: main flow
23, 23a, 23b: micro flow path
30, 30a, 30b: fluid inflow prevention unit
40, 40b: hydrophobic part
50, 50a, 50b: electrode part
60: photosensitive unit

Claims (15)

body part;
a photosensitive unit provided on an upper surface of the body unit;
a micro channel formed in the photosensitive part including a main flow path through which fluid flows;
a pair of fluid inflow prevention units formed in the photosensitive unit to be spaced apart from the main flow path;
a pair of micro-passages formed by a predetermined distance from the main flow passage toward the fluid inflow prevention unit;
a hydrophobic part provided in a protruding shape between the fluid inflow prevention part and the microchannel; and
A microfluidic fuel cell comprising a pair of electrode parts printed on an upper surface of the photosensitive part to connect the main flow path and the fluid inflow prevention part. According to claim 1,
The microchannel,
A microfluidic fuel cell including a plurality of inlets through which fuel and oxidant are introduced. According to claim 1,
The main flow path is a microfluidic fuel cell formed such that an interval increases along the flow direction of the fluid. According to claim 3,
The electrode part is formed along the edge of the main flow path based on the flow direction of the fluid, so that the distance between the electrode parts increases. delete delete (a) forming a main body;
(b) providing a photosensitive part on top of the body part;
Forming a microchannel including a main flow path through which fluid flows in the photosensitive unit, and a fluid inflow prevention unit spaced apart from the main flow path;
forming a microchannel by removing the photosensitive unit by a preset distance from the main channel in the direction of the fluid inflow prevention unit;
Exposing the body portion from which a portion of the photosensitive portion is removed; and heating and drying the exposed body portion,
The step of heating and drying the body part is (c) step, characterized in that fixing a hydrophobic part provided in a protruding shape between the microchannel and the fluid inflow prevention part; and
(d) printing an electrode part on an upper surface of the photosensitive part to connect the main flow path and the fluid inflow prevention part;
Method of manufacturing a microfluidic fuel cell comprising a. According to claim 7,
In step (c),
A method of manufacturing a microfluidic fuel cell comprising forming the microchannel in which a plurality of inlets through which fuel and oxidizer are introduced into the photosensitive unit are formed. According to claim 7,
In step (c),
A method for manufacturing a microfluidic fuel cell in which the main flow path is formed such that the interval increases along the flow direction of the fluid. According to claim 9,
In step (d),
The method of manufacturing a microfluidic fuel cell further comprising: printing the electrode parts along the main passage to form the electrode parts so that a distance between the electrode parts increases. delete delete delete According to claim 7,
In step (c),
A microfluidic fuel cell manufacturing method comprising: forming a pair of micro-passages formed by a predetermined distance from the main flow passage in the direction of the fluid inflow prevention part, and separating the fluid inflow prevention part from the micro-passage. According to claim 7,
After step (c),
A method for manufacturing a microfluidic fuel cell, further comprising purifying and filtering a mixed solution of MWCNTs and nitric acid and sulfuric acid to form a mixed solution of the electrode part.

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