JP2006351248A - Micro fluidic element for power conversion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro fluidic element for power conversion capable of utilizing functional fluid as well different from that for power conversion, and improving on various problems accompanying power conversion. <P>SOLUTION: As an example, the micro fluidic element (a micro channel device 10) for power conversion is provided with a main micro channel 12 (a main flow channel) in which laminar flows of acidic aqueous solution A as one kind of the fluid for power conversion and basic aqueous solution B as the other kind as well as a laminar flow of support electrolyte solution so as to intercalate between the above two. Two first-supply micro channels 14A, 14B (first supply flow channels) and one second supply micro channel 14C (a second supply flow channel) as supply flow channels, and two first exhaust micro channels 16A, 16B and one second exhaust micro channel 16C as exhaust flow channels, at either end of the main micro channel 12, are communicated with each other, three for three, to constitute the micro fluidic element for power conversion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power conversion microfluidic device in which a power conversion unit is formed in a microchannel (flow channel) that moves a power conversion fluid.

  In recent years, microfluidic devices capable of performing basic chemical operations such as reaction, separation, extraction, and detection have been actively studied. By using this microfluidic device, it is possible to integrate and miniaturize reaction spaces for performing basic chemical operations, and application to synthesis equipment, analysis equipment, and the like is being studied.

  The component of the microfluidic device is a microchannel (flow path) having a cross-sectional dimension of several tens to several thousand microns. The microchannel is usually formed by joining two plates, that is, a substrate on which a groove to be a fine channel is formed and a flat substrate. Some microfluidic devices have been proposed in which not only two but also three or more fluid laminar flows are formed (for example, Non-Patent Document 1).

  On the other hand, there is a proposal to use a microfluidic device as a power conversion device (for example, Non-Patent Document 2). In this proposal, two types of fluids for power conversion are introduced into a microfluidic device, a laminar flow is formed in the microchannel, and energy from a chemical reaction is converted into electrical energy (electric power) in the laminar flow region. It is.

S. Takayama et al,. Adv Mat. , 13, 570 (2001) Journal of Power Sources 128 (2004) p54-60

  In addition to the proposal of Non-Patent Document 1 described above, Japanese Patent Application No. 2003-393714 proposes a microfluidic device for power conversion. However, power conversion using only two types of power conversion fluids as functional fluids is performed. Is going. Although it is disclosed that three or more fluids are used for microfluidic devices different from those for power conversion, only devices using only two types of power conversion fluids are still realized for power conversion. In order to improve various problems associated with power conversion, a microfluidic device for power conversion that can use a functional fluid different from the fluid for power conversion is desired.

  Therefore, in view of the above problems, an object of the present invention is to provide a power conversion microfluidic device that can use a functional fluid different from the power conversion fluid and can improve various problems associated with power conversion.

The above problem is solved by the following means.
That is, the microfluidic device for power conversion of the present invention is
A main flow path in which a laminar flow of fluid is formed and power conversion is performed in the laminar flow region;
At least three supply channels that communicate with one end of the main channel and supply the fluid to the main channel;
At least one discharge flow path communicating with the other end of the main flow path and discharging the fluid from the main flow path;
It is characterized by having.

  The microfluidic device for power conversion according to the present invention includes at least three supply channels so that a functional fluid different from the two fluids required for power conversion can be supplied to the main channel. Therefore, various problems (for example, generation of turbulent flow between two power conversion fluids, generation of bubbles, etc.) can be improved by this functional fluid.

  In the power conversion microfluidic device of the present invention, the supply flow path includes two first supply flow paths for supplying two power conversion liquids as the fluid to the main flow path, and a supporting electrolyte as the fluid. And a second supply channel that supplies the main channel so as to be interposed between the two power conversion liquids.

  Conventionally, in a microfluidic device using only two power conversion liquids, the laminar flow (interface) between the two power conversion liquids is disturbed in the main flow path where power conversion is performed, and the output becomes unstable. There was a problem that.

  Therefore, the supporting electrolyte is supplied to the main flow path so as to be interposed between the two power conversion liquids, and the laminar flow of the supporting electrolyte is interposed between the laminar flows of the two power conversion fluids in the main flow path. Thereby, disturbance is suppressed between the laminar flows of the two power conversion fluids, and a stable output can be obtained.

  Here, the supporting electrolyte means a liquid in which the electrolyte becomes ions to give conductivity.

  As the two power conversion fluids, an acidic aqueous solution containing a positive electrode active material and a basic aqueous solution containing a negative electrode active material can be used. Further, as the supporting electrolyte, a neutral electrolyte containing a neutral salt can be used. In particular, it is preferable that the neutral salt is composed of constituents of an acidic aqueous solution and a basic aqueous solution as a power conversion liquid, or the neutral salt is contained at a saturated dissolution concentration. Thereby, a high output can be obtained more stably.

  On the other hand, in the power conversion microfluidic device of the present invention, the supply flow path includes two first supply flow paths that supply two power conversion liquids as the fluid to the main flow path, and bubble absorption as the fluid. A third supply flow path that supplies a fluid (fluid for degassing bubbles) to the main flow path so as to be in contact with the two power conversion liquids can also be configured. Note that there may be one third supply channel and two third supply channels.

  Conventionally, in a microfluidic device that uses only two power conversion liquids, bubbles are generated by the reaction of the two power conversion liquids in the main flow path where power conversion is performed, and the output becomes unstable. There was a problem.

  Therefore, bubble absorbing fluid (fluid for degassing bubbles) is supplied to the main flow path so as to be in contact with the two liquids for power conversion, and in contact with the laminar flow of the two power conversion fluids in the main flow path There is a laminar flow of absorbing fluid. Thereby, bubbles generated by the reaction between the two power conversion fluids are absorbed, that is, degassed, and a stable output can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the functional fluid different from the fluid for power conversion can be used together, and the microfluidic element for power conversion which can improve the various problems accompanying power conversion can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that members having substantially the same functions are given the same reference numerals throughout the drawings, and redundant descriptions may be omitted.

(First embodiment)
FIG. 1 is a schematic plan view showing the power conversion microfluidic device according to the first embodiment. FIG. 2 is a schematic partial cross-sectional view showing the power conversion microfluidic device according to the first embodiment, and is a cross-sectional view taken along the line AA ′ of FIG. 1.

  The microfluidic element for power conversion (hereinafter referred to as microchannel device 10) according to the present embodiment includes an acidic aqueous solution A as one of the power conversion liquid and a basic aqueous solution B as the other of the power conversion liquid and supporting electrolysis. It has a main microchannel 12 (main flow path) in which a laminar flow is formed from three liquids of liquid C and a laminar flow is formed such that the supporting electrolyte C is interposed between two liquids for power conversion ing. Two first supply microchannels 14A and 14B (first supply flow path) and one second supply microchannel 14C (second supply flow path) are provided at both ends of the main microchannel 12 as supply flow paths. The two first discharge microchannels 16A and 16B and one second discharge microchannel 16C communicate with each other as three discharge channels.

  The first supply microchannel 14A is a channel that supplies the acidic aqueous solution A, and the first supply microchannel 14B is the channel that supplies the basic aqueous solution B. The second supply microchannel 14C is a channel that is disposed between the first supply microchannels 14A and 14B and supplies the supporting electrolyte C. In addition, introduction ports 20A, 20B, and 20C for introducing each fluid communicate with each supply microchannel.

  On the other hand, the first discharge microchannel 16A discharges the acidic aqueous solution A, and the first discharge microchannel 16B supplies the basic aqueous solution B. The second discharge microchannel 16C is a channel that is disposed between the first discharge microchannels 16A and 16B and discharges the supporting electrolyte C. Further, discharge ports 22A, 22B, and 22C for discharging each fluid communicate with each discharge microchannel. In the present embodiment, a mode is shown in which each fluid is discharged so that it can be collected and reused. However, if the collected fluid is discarded, one discharge channel may be provided.

  In addition, the microchannel device 10 is provided with electrodes 18 serving as a positive electrode and a negative electrode so as to be in contact with the laminar flow formed in the main microchannel 12. Among the electrodes 18, the positive electrode is disposed in contact with the acidic aqueous solution A that constitutes one of the laminar flows, and the negative electrode is in contact with the basic aqueous solution B that constitutes one of the laminar flows. (See FIG. 2).

Here, the acidic aqueous solution A is an acidic aqueous solution A containing a positive electrode active material (for example, hydrogen peroxide). For example, sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, hydrochloric acid, hydrogen iodide together with the positive electrode active material. Acid, hydrobromic acid, perchloric acid, periodic acid, orthophosphoric acid, polyphosphoric acid, nitric acid, tetrafluoroboric acid, hexafluorosilicic acid, hexafluorophosphoric acid, hexafluoroarsenic acid, hexachloroplatinic acid, acetic acid, trifluoroacetic acid An aqueous solution containing one or more acids selected from the group consisting of citric acid, succinic acid, salicylic acid, tartaric acid, maleic acid, malonic acid, phthalic acid, fumaric acid, and picric acid. In this embodiment, a mixed aqueous solution of H ₂ O ₂ / H ₂ SO ₄ using hydrogen peroxide as the positive electrode active material is applied.

On the other hand, the basic aqueous solution B is a basic aqueous solution B containing a negative electrode active material (for example, hydrogen peroxide), and together with the negative electrode active material, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, water One or more bases selected from the group comprising barium oxide, magnesium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, or carbonic acid Selected from the group comprising sodium, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium borate, potassium borate, sodium silicate, potassium silicate, sodium tripolyphosphate, potassium tripolyphosphate, sodium aluminate, and potassium aluminate A weak acid It is an aqueous solution containing alkali metal salts of one or more. In this embodiment, a mixed aqueous solution of H ₂ O ₂ / NaOH using hydrogen peroxide as the negative electrode active material is applied.

  The supporting electrolyte C is a neutral electrolyte containing a neutral salt as an electrolyte. Examples of the neutral salt include neutral salts composed of the constituents of the acidic aqueous solution A and the basic aqueous solution B, and other general neutral salts (for example, sodium chloride, potassium chloride, potassium bromide, potassium iodide, Sodium fluoride, magnesium sulfate, calcium chloride, etc.). Among these, it is preferable to use a neutral salt composed of the constituent substances of the acidic aqueous solution A and the basic aqueous solution B. Thereby, a high output can be stably obtained.

In the present embodiment, a mixed aqueous solution of H ₂ O ₂ / H ₂ SO ₄ is applied as the acidic aqueous solution A, and a mixed aqueous solution of H ₂ O ₂ / NaOH is applied as the basic aqueous solution B. Therefore, as the supporting electrolyte C, A neutral electrolyte containing Na ₂ SO ₄ as a neutral salt is applied. In addition, for example, when a mixed aqueous solution of H ₂ O ₂ / HCl is used as the acidic aqueous solution A and a mixed aqueous solution of H ₂ O ₂ / KOH is applied as the basic aqueous solution B, the supporting electrolyte C may include KCl as a neutral salt. It is preferable to apply a neutral electrolyte containing.

  Further, in the neutral electrolytic solution containing a neutral salt, the neutral salt is dissolved at a saturated dissolution concentration. Thereby, high output can be obtained. The output (electric power) can also be controlled by the dissolved concentration of the neutral salt.

  The positive electrode and the negative electrode as the electrode 18 are, for example, platinum, platinum black, platinum oxide-coated platinum, silver, gold, titanium whose surface is passivated, stainless steel whose surface is passivated, and passivated surface. It can be composed of one or more materials selected from the group consisting of nickel, surface-passivated aluminum, carbon structure, amorphous carbon, and glassy carbon. In the present embodiment, platinum black is applied to both the positive electrode and the negative electrode, which has a high activity of the power conversion liquid and is likely to cause laminar disturbance of the fluid. Moreover, as such an electrode material, there is platinum other than platinum black.

  The power conversion microfluidic device according to the present embodiment has a stacked structure in which a plurality of chips (substrates) are stacked. Specifically, the microchannel chip 26 (flow path substrate) is laminated on the electrode chip 24 (electrode substrate).

  The microchannel chip 26 includes the main microchannel 12, the first supply microchannels 14A and 14B, the second supply microchannel 14C, the first discharge microchannels 16A and 16B, the second, which constitute the microchannel device 10. Discharge microchannels 16C are formed at predetermined positions, respectively.

  Electrodes 18 constituting the microchannel device 10 are formed on the electrode chips 24 at predetermined positions. Although not shown, the electrode chip 24 or the microchannel chip 26 (flow channel substrate) has through-holes serving as introduction ports 20A, 20B, 20C and discharge ports 22A, 22B, 22C so as to communicate with the respective microchannels. Is provided.

  Here, each chip is, for example, silicon, glass, silicone rubber, resin (unsaturated polyester resin (for example, manufactured by Hitachi Chemical Co., Ltd., polyset)), polyethylene terephthalate (PET), polycarbonate, polydimethylsiloxane (PDMS). Etc.). The thickness can be selected, for example, at about 0.1 to 1.3 mm. In the present embodiment, the electrode chip 24 is made of glass, and the microchannel chip 26 is made of polydimethylsiloxane (PDMS). Each chip may be made of the same material or different materials.

  The microfluidic device according to this embodiment can be obtained by manufacturing the chips and bonding them together. Specifically, for example, the microchannel chip 26 can be obtained by forming a predetermined groove serving as each microchannel on the chip surface. Depending on the chip material, this groove may be formed by, for example, photolithography and dry etching techniques used in semiconductor processing technology to obtain a microchannel having a high aspect ratio (groove depth / width dimension ratio) of 1 or more, or A method of grooving silicon or glass using photolithography and wet etching technology, a method of transferring the structure of PMMA (polymethyl methacrylate) to metal by plating using a LIGA process used in micromachine processing technology, A thick film resist for ultraviolet rays (a negative resist based on an epoxy resin) can be formed by a molding method for transferring the structure to a silicone rubber or the like.

  The electrode tip 24 can be obtained by depositing an electrode material at a predetermined position on the surface of the tip by chemical vapor deposition or sputtering.

  Then, the obtained microchips can be obtained by stacking the obtained chips while aligning them and joining them by a known joining technique.

  In the microfluidic device according to the present embodiment having such a configuration, when each fluid is first introduced from the inlets 20A, 20B, and 20C, the acidic aqueous solution A is converted from the first supply microchannel 14A to the first supply microchannel. The basic aqueous solution B flows from 14B and the supporting electrolyte C flows from the second supply microchannel 14C into the main microchannel 12, respectively. At this time, the acidic aqueous solution A and the basic aqueous solution B flow into the main microchannel 12 through the supporting electrolyte C, respectively. In the main microchannel 12, a laminar flow of the supporting electrolyte C is formed with the laminar flow of the acidic aqueous solution A and the basic aqueous solution B, and between the acidic aqueous solution A and the basic aqueous solution B. An oxidation-reduction reaction due to the positive and negative active materials occurs through the supporting electrolyte C, and electric power resulting therefrom is taken out from the electrode 18.

  On the other hand, the acidic aqueous solution A, the basic aqueous solution B, and the supporting electrolyte C that have finished the oxidation-reduction reaction in the main microchannel 12 are the first discharge microchannel 16A, the first discharge microchannel 16B, and the second discharge. Respectively flows into the microchannel 16C and discharged from the discharge ports 22A, 22B, 22C.

  In this manner, power conversion is performed in the microfluidic device according to the present embodiment. Note that power conversion and materials used are described in Japanese Patent Application No. 2003-393714.

  As described above, in the microfluidic device according to the present embodiment described above, the supporting electrolyte C is supplied to the main microchannel 12 so as to be interposed between the acidic aqueous solution A and the basic aqueous solution B that are two power conversion liquids. A redox reaction between the acidic aqueous solution A and the basic aqueous solution B by the positive and negative active materials is caused in the channel 12 with the laminar flow of the supporting electrolyte C interposed therebetween. For this reason, disturbance of laminar flow of acidic aqueous solution A and basic aqueous solution B is suppressed, and a stable output can be obtained.

  Further, by suppressing the turbulence of the laminar flow of the acidic aqueous solution A and the basic aqueous solution B, even if the length of the main microchannel 12 that is a reaction field is increased, a redox reaction can be stably generated. High output can be achieved.

Thus, it is estimated that the reason why the laminar flow of the acidic aqueous solution A and the basic aqueous solution B is suppressed by interposing the laminar flow of the supporting electrolyte C is as follows. Bubbles disturb the interface between acidic aqueous solution A and basic aqueous solution B, and the neutralization reaction proceeds. Then, the H ⁺ concentration in the vicinity of the positive electrode and the OH ⁻ concentration in the vicinity of the negative electrode change greatly, and the output becomes unstable. However, since the direct contact between the acidic aqueous solution A and the basic aqueous solution B is avoided by passing the supporting electrolyte C (neutral solution) at the center, the neutralization reaction does not proceed and the H ⁺ and OH ^{− in} the vicinity of both electrodes Concentration change becomes gradual and stable.

(Second Embodiment)
FIG. 3 is a schematic plan view showing a microfluidic element for power conversion according to the second embodiment. FIG. 4 is a schematic partial cross-sectional view showing the power conversion microfluidic device according to the second embodiment, and is a cross-sectional view taken along line AA ′ of FIG.

  The power conversion microfluidic device (hereinafter referred to as a microchannel device 10) according to the present embodiment includes two gas absorption microchannels as gas absorption channels at both ends of the main microchannel 12 in the first embodiment. 14D and 14E (gas absorption flow path) and two gas discharge microchannels 16D and 16E (gas discharge flow path) are further connected.

  The gas absorption microchannels 14D and 14E are channels that are arranged outside the first supply microchannels 14A and 14B (on the side opposite to the arrangement position of the second supply microchannel 14C) and do not supply liquid. . Further, the gas absorption microchannels 14D and 14E are supplied with the same pressure state as the first supply microchannels 14A and 14B (when the outlet side is sent in a reduced pressure state, the atmospheric pressure is applied and the inlet side is pressurized and sent. When flowing, gas inlets 20D and 20E of the same pressure as the first supply microchannels 14A and 14B are connected.

  On the other hand, the gas discharge microchannels 16D and 16E are arranged outside the first discharge microchannels 16A and 16B (on the side opposite to the arrangement position of the second discharge microchannel 16C), respectively, and the acidic aqueous solution A and the basic solution This is a channel for discharging gases D and E respectively absorbed from the aqueous solution B. The gas discharge microchannels 16D and 16E communicate with discharge ports 22D and 22E for discharging the gases D and E absorbed (degassed) from the acidic aqueous solution A and the basic aqueous solution B, respectively.

  Therefore, in the main microchannel 12 (main flow path), a laminar flow of the supporting electrolyte C is formed so as to be interposed between the laminar flows together with the laminar flow of the acidic aqueous solution A and the basic aqueous solution B, and further the acidic aqueous solution A And laminar flows of gases D and E that are absorbed (degassed) from the acidic aqueous solution A and the basic aqueous solution B, respectively, outside the laminar flow of the basic aqueous solution B (on the side opposite to the laminar flow position of the supporting electrolyte C) (See FIG. 4).

  Here, the gases D and E in the main microchannel 12 (main flow path) specifically absorb a gas generated as an autolysis of hydrogen peroxide or an electrochemical reaction product, for example, oxygen.

  In addition, the main microchannel 12 can also be suitably implemented by changing the depths of the flow grooves of the acidic aqueous solution A, the basic aqueous solution B, and the supporting electrolysis liquid C and the flow grooves of the gases D and E. Specifically, for example, by making the depth of the flow grooves of the gases D and E shallower than the depth of the flow grooves of the acidic aqueous solution A, the basic aqueous solution B, and the supporting electric field liquid C, the interfacial tension of the solution As a result, only the gas is collected and flowed in the flow grooves of the gases D and E, and the bubbles can be absorbed more efficiently.

  Further, it is possible to suitably perform a hydrophobic treatment on the flow path wall in contact with the gases D and E. Thereby, bubbles can be absorbed more efficiently.

  Since the configuration other than this is the same as that of the first embodiment, the description thereof is omitted.

  In the microfluidic device according to the present embodiment having such a configuration, first, when each fluid is introduced from the inlets 20A, 20B, 20C, 20D, and 20E, the acidic aqueous solution A is first supplied from the first supply microchannel 14A. The basic aqueous solution B is supplied from the supply microchannel 14B, the supporting electrolyte C is supplied from the second supply microchannel 14C, and the gases D and E are supplied from the third supply microchannels 14D and 14E to the main microchannel 12 respectively. Flow into.

  At this time, the gases D and E flow into the main microchannel 12 through the supporting electrolyte C so that the acidic aqueous solution A and the basic aqueous solution B and the outside of the acidic aqueous solution A and the basic aqueous solution B are in contact with each other. To do.

  In the main microchannel 12, the laminar flow of the acidic aqueous solution A and the basic aqueous solution B, the laminar flow of the supporting electrolyte C so as to be interposed between the laminar flows, and the layers of the acidic aqueous solution A and the basic aqueous solution B A laminar flow of gases D and E is formed outside the flow. Between the acidic aqueous solution A and the basic aqueous solution B, an oxidation-reduction reaction due to positive and negative active materials occurs via the supporting electrolyte C, and electric power resulting from this is taken out from the electrode 18.

  On the other hand, the acidic aqueous solution A, the basic aqueous solution B, the supporting electrolyte C, and the gases D and E that have finished the oxidation-reduction reaction in the main microchannel 12 are the first discharge microchannel 16A and the first discharge microchannel 16B. , Flows into the second discharge microchannel 16C, the third discharge microchannel 16D, and the third discharge microchannel 16E, and is discharged from the discharge ports 22A, 22B, 22C, 22D, and 22E, respectively.

  As described above, in the microfluidic device according to the present embodiment described above, the gases D and E are supplied to the main microchannel 12 so as to come into contact with the acidic aqueous solution A and the basic aqueous solution B that are the two power conversion liquids. In a state where the laminar flows of the gases D and E are in contact with each other in the channel 12, a redox reaction between the acidic aqueous solution A and the basic aqueous solution B is caused by the positive and negative active materials. For this reason, the gas D and E absorb, that is, deaerate the bubbles generated during the oxidation-reduction reaction of the acidic aqueous solution A and the basic aqueous solution B, so that an efficient oxidation-reduction reaction can be generated and stable output can be achieved. Can be obtained.

  Further, by removing bubbles generated in the acidic aqueous solution A and the basic aqueous solution B, even if the length of the main microchannel 12 which is a reaction field is increased, the oxidation-reduction reaction can be stably generated. Can also be achieved.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

Example 1
Using the microfluidic device (microchannel device 10: see FIG. 1 and FIG. 2) according to the first embodiment, an output (power generation) experiment was performed as follows, and current / voltage characteristics were tested.

  First, an aqueous hydrogen peroxide solution (special grade 35%, Kanto Chemical Co., Inc.), sulfuric acid (special grade 96%, Kanto Chemical Co., Ltd.) and distilled water were mixed to prepare an acidic aqueous solution A. Here, the hydrogen peroxide and sulfuric acid concentrations were 0.33 mol / l and 0.33 mol / l, respectively.

  Also, a basic aqueous solution B was prepared by mixing an aqueous hydrogen peroxide solution (special grade 35%, Kanto Chemical Co., Inc.), sodium hydroxide (special grade 97%, Kanto Chemical Co., Ltd.) and distilled water. Here, the hydrogen peroxide and sodium hydroxide concentrations were 0.33 mol / l and 0.67 mol / l.

  Moreover, neutral salt is mixed with distilled water, sodium sulfate concentration of 1.87 mol / l (saturated dissolution concentration), 1.33 mol / l, 0.67 mol / l, 0 mol / l (distilled water only) An aqueous solution and an aqueous potassium chloride solution having a potassium chloride concentration of 4.5 mol / l (saturated dissolution concentration) were prepared, and these were used as the supporting electrolyte C.

The acidic aqueous solution A is introduced from the inlet 20A, the supporting electrolyte C is introduced from the inlet 20C, and the basic aqueous solution B is injected from the inlet 20B by an external pump, and supplied to the main microchannel through each supply microchannel. A laminar flow of each fluid was formed. The average flow rate of each fluid was 15 ml / mn (Reynolds number Re: about 2000) at room temperature. The main micro-in channel in contact with the acidic aqueous solution A electrodes 18 (platinum black, area: 0.025 cm ²⁾ is the function of the positive electrode, the electrode 18 in contact with the basic aqueous solution B (platinum black, area: 0.025 cm ² ) Acted as a negative electrode to form a so-called battery, and an electromotive force was generated.

  An external resistor was connected to the battery (electrode 18), and the current / voltage characteristics when the resistance value was changed in the range from 0Ω to 1MΩ were measured with a digital multimeter (2000 manufactured by KEITHLEY). This measurement was performed for each species by changing the supporting electrolyte C species. The result is shown in FIG. In FIG. 5, the current value is expressed by normalizing the maximum current value for each experiment as 1.

  For comparison, the current / voltage characteristics were also measured in the same manner for a microfluidic device (an element that forms a laminar flow of only the acidic aqueous solution A and the basic aqueous solution B) with no supporting electrolyte C interposed. This result is also shown in FIG.

  From the results shown in FIG. 5, in the microfluidic device according to the first embodiment, the redox reaction of the acidic aqueous solution A and the basic aqueous solution B is caused in the main microchannel 12 via the supporting electrolyte C, It can be seen that the turbulence of the laminar flow between the aqueous solutions is suppressed and a stable output can be obtained.

  It can also be seen that high output can be achieved by applying a neutral electrolyte containing a neutral salt composed of constituents of the acidic aqueous solution A and the basic aqueous solution B as the supporting electrolyte. In particular, it can be seen that high output can be achieved by setting the neutral salt to a saturated dissolution concentration. It can also be seen that the output can be controlled by the neutral salt concentration.

(Example 2)
First, an aqueous hydrogen peroxide solution (special grade 35%, Kanto Chemical Co., Inc.), hydrochloric acid (special grade 96%, Kanto Chemical Co., Ltd.) and distilled water were mixed to prepare an acidic aqueous solution A. Here, the hydrogen peroxide and hydrochloric acid concentrations were 0.33 mol / l and 0.67 mol / l, respectively.

  Also, a basic aqueous solution B was prepared by mixing an aqueous hydrogen peroxide solution (special grade 35%, Kanto Chemical Co., Inc.), potassium hydroxide (special grade 97%, Kanto Chemical Co., Ltd.) and distilled water. Here, the hydrogen peroxide and sodium hydroxide concentrations were 0.33 mol / l and 0.67 mol / l.

  Moreover, neutral salt is mixed with distilled water, potassium chloride concentration is 4.5 mol / l (saturated dissolution concentration), 2.0 mol / l, 1.0 mol / l potassium chloride aqueous solution, and sodium sulfate. Sodium sulfate aqueous solutions having a concentration of 1.7 mol / l (saturated dissolution concentration) were prepared, and these were used as the supporting electrolyte C.

  Then, using these fluids, the current / voltage characteristics were measured by changing the supporting electrolyte C type in the same manner as in Example 1. The results are shown in FIG.

  From the results shown in FIG. 6, it can be seen that the same results as in Example 1 can be obtained even if the types of the acidic aqueous solution A, the basic aqueous solution B, and the supporting electrolyte C are changed.

1 is a schematic plan view showing a microfluidic device according to a first embodiment. It is a typical fragmentary sectional view showing the microfluidic device concerning a 1st embodiment, and is an A-A 'sectional view of Drawing 1. It is a typical top view which shows the microfluidic device which concerns on 2nd Embodiment. It is a typical fragmentary sectional view which shows the microfluidic device which concerns on 2nd Embodiment, and is A-A 'sectional drawing of FIG. FIG. 4 is a diagram showing current / voltage characteristics measured in Example 1. It is a figure which shows the electric current and voltage characteristic measured in Example 2. FIG.

Explanation of symbols

10 Microchannel device (microfluidic device)
12 main microchannels 14A, 14B first supply microchannel (first supply flow path)
14C Second supply microchannel (second supply flow path)
14D, 14E Third supply microchannel (third supply flow path)
14B discharge microchannels 22A, 22B, 22C, 22D, 22E discharge ports 16A, 16B first discharge microchannels 16C second discharge microchannels 16D, 16E third discharge microchannels 18 electrodes 20A, 20B, 20C, 20D, 20E Inlet 22A, 22B, 22C, 22D, 22E Outlet 24 Electrode chip 26 Microchannel chip A Acidic aqueous solution B Basic aqueous solution C Supporting electrolyte D, E Gas

Claims (5)

A main flow path in which a laminar flow of fluid is formed and power conversion is performed in the laminar flow region;
At least three supply channels that communicate with one end of the main channel and supply the fluid to the main channel;
At least one discharge flow path communicating with the other end of the main flow path and discharging the fluid from the main flow path;
A microfluidic device for power conversion, comprising:   The supply flow path is configured so that two power conversion liquids are supplied as the fluid to the main flow path, and a supporting electrolyte is interposed between the two power conversion liquids as the fluid. The microfluidic device for power conversion according to claim 1, comprising: a second supply channel that supplies the main channel. The two power conversion liquids are an acidic aqueous solution containing a positive electrode active material and a basic aqueous solution containing a negative electrode active material,
The supporting electrolytic solution is a neutral electrolytic solution containing a neutral salt.
The microfluidic device for power conversion according to claim 2. The two power conversion liquids are an acidic aqueous solution containing a positive electrode active material and a basic aqueous solution containing a negative electrode active material,
The supporting electrolytic solution is a neutral electrolytic solution containing a neutral salt composed of constituents of the acidic aqueous solution and the basic aqueous solution.
The microfluidic device for power conversion according to claim 2.   5. The microfluidic device for power conversion according to claim 3, wherein the supporting electrolytic solution is a neutral electrolytic solution containing the neutral salt at a saturated dissolution concentration.

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