JP2005310613A - Electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic apparatus loaded with a fuel cell using safe fuel, which operates at room temperature. <P>SOLUTION: This electronic apparatus is loaded with an enzyme cell composed of a group of oxidizing enzymes to generate an electron by dissolving fuel such as glucose or the like, a fuel electrode 1 carrying an electron mediator to give the generated electron to an electrode, an electrolyte layer 5 to transport a proton generated by oxidizing the fuel in the fuel electrode 1 to the opposite electrode side, and an air electrode 3 to generate water by oxidizing the proton carried from the fuel electrode 1 through the electrolyte layer 5 by oxygen in the air. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic device such as a mobile phone equipped with a fuel cell as a power source.

A fuel cell basically includes a fuel electrode, an oxidant electrode (air electrode), and an electrolyte, and its operation principle is the reverse operation of water electrolysis, and water (H ₂ O) is produced by hydrogen and oxygen. Generate electricity and generate electricity. That is, the fuel (hydrogen) supplied to the fuel electrode is oxidized and separated into electrons and protons (H ⁺ ), the electrons are transferred to the fuel electrode, and H ⁺ moves to the air electrode through the electrolyte. In the air electrode, this H ⁺ reacts with oxygen supplied from the outside and electrons sent from the fuel electrode through an external circuit to generate H ₂ O.

  In this way, the fuel cell is a highly efficient power generation device that directly converts the energy of the fuel into electrical energy, and the energy of fossil energy such as natural gas, oil, and coal can be used regardless of where and when it is used. Moreover, it can be extracted as electrical energy with high conversion efficiency. For this reason, research and development of fuel cells for large-scale power generation has been actively conducted. For example, there is a track record of demonstrating that a fuel cell is mounted on a space shuttle and that it can supply crew water at the same time as power, and that it is a clean power generator.

  In recent years, a fuel cell having a relatively low operating temperature range from room temperature to about 90 ° C., such as a polymer electrolyte fuel cell using an ion exchange membrane as an electrolyte, has been developed and attracting attention. For this reason, the application to not only large-scale power generation but also small systems such as a power source for driving automobiles and a portable power source for personal computers and mobile devices is being sought.

  However, although the polymer electrolyte fuel cell has the advantage of exhibiting a low temperature range as described above, many problems to be solved remain. For example, when methanol is used as the fuel and the catalyst is poisoned by CO when operated near room temperature, energy loss occurs due to crossover, an expensive noble metal catalyst such as Pt is required, and hydrogen is used as the fuel. It is difficult to handle the case.

  Accordingly, attention has been paid to the fact that biological metabolism performed in living organisms is a highly efficient energy conversion mechanism, and proposals have been made to apply this to fuel cells. The biological metabolism here includes respiration, photosynthesis and the like performed in microorganisms and cells. Biological metabolism has the characteristics that the power generation efficiency is extremely high and the reaction proceeds under mild conditions of about room temperature.

For example, in respiration, nutrients such as saccharides, fats, and proteins are taken into microorganisms or cells, and these chemical energies are passed through a glycolytic system having a number of enzymatic reaction steps and a tricarboxylic acid (hereinafter referred to as TCA) circuit. In the process of generating carbon dioxide (CO ₂ ), nicotinamide adenine dinucleotide (hereinafter referred to as NAD ⁺ ) is reduced to produce redox energy such as reduced nicotinamide adenine dinucleotide (NADH), that is, electric energy. This is a mechanism that converts the NADH electric energy directly into proton gradient electric energy and reduces oxygen to generate water in the electron transfer system. The electrical energy obtained here produces ATP from ADP via ATP synthase, and this ATP is used for reactions necessary for the growth of microorganisms and cells. Such energy conversion occurs in the cytosol and mitochondria.

Photosynthesis takes in light energy and reduces nicotinamide adenine dinucleotide phosphate (hereinafter referred to as NADP ⁺ ) via an electron transfer system to reduce nicotinamide adenine dinucleotide phosphate (NADPH). It is a mechanism that oxidizes water to produce oxygen in the process of conversion to electrical energy. This electric energy takes in CO ₂ and is used for carbon fixation reaction, and is used for carbohydrate synthesis.

  As a technique for utilizing the above-described biometabolism for a fuel cell, a microbial cell has been reported in which electric energy generated in a microorganism is taken out of the microorganism through an electron mediator and an electric current is obtained by passing the electrons to an electrode. (For example, refer to Patent Document 1).

  However, since microorganisms and cells have many unnecessary functions in addition to the intended reaction such as conversion from chemical energy to electrical energy, the above-described method consumes electrical energy for unwanted reactions, resulting in sufficient energy conversion efficiency. Is not demonstrated.

JP 2000-133297 A

  By the way, a storage battery such as a lithium ion secondary battery is generally used as a power source mounted on an electronic device such as a mobile phone or a mobile phone. The installation of a fuel cell that can be used continuously is under consideration.

  However, as described above, the conventional fuel cell is not easy to handle the fuel such as hydrogen even if the operating temperature range is relatively low, and an expensive noble metal such as Pt is required as the catalyst. There were many problems. In addition, there is a problem in that it is difficult to extract sufficient electric energy because there are many functions other than the target reaction even in a microbial battery using biological metabolism.

  In view of this, the present inventors have focused on a fuel cell configured to perform only a desired reaction by taking out an enzyme or an electronic mediator involved in a conversion reaction from chemical energy to electrical energy in biological metabolism, and repeated research. As a result, nutrients such as sugars, fats and proteins, alcohols, or organic acids such as intermediate products of sugar metabolism are used as fuels, and the enzymes involved in the decomposition of each fuel are selected appropriately and used as catalysts. It has been found that a fuel cell suitable for a power source of an electronic device can be obtained in which the temperature range is approximately -20 to 80 ° C and the fuel is easy to handle and safe. An electronic device equipped with a fuel cell using such an enzyme has not been proposed yet.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an electronic device equipped with a fuel cell that is easy to handle and safe.

  That is, the electronic device of the present invention is characterized in that a fuel cell using at least one selected from alcohols, saccharides, fats, proteins and organic acids as a fuel and using an enzyme as a catalyst is mounted.

  In the present invention, the fuel of the fuel cell is selected from alcohols, saccharides, fats, proteins, and organic acids, and the catalyst includes an enzyme group suitable for each fuel, for example, a stepwise decomposition process of the fuel. The oxidase group involved in each oxidation reaction is selected. Furthermore, depending on the oxidase group to be used, a coenzyme that becomes a reductant by the oxidation reaction of fuel and a coenzyme oxidase that returns the coenzyme reductant to an oxidant and generates two electrons per molecule are selected. The Due to the presence of such a coenzyme, electrons are generated and taken out along with the oxidation reaction of the fuel.

For example, when methanol is used as fuel, alcohol dehydrogenase (ADH) that acts on methanol as a catalyst and oxidizes to formaldehyde, formaldehyde dehydrogenase (FalDH) that acts on formaldehyde and oxidizes to formic acid, and acts on formic acid Formate dehydrogenase (FateDH) that oxidizes to CO ₂ can be used. As a result, methanol is decomposed to CO _2, and a total of 6 electrons are generated by a three-stage oxidation reaction per molecule of methanol.

When ethanol is used as a fuel, alcohol dehydrogenase (ADH) that acts on ethanol to oxidize to acetaldehyde and aldehyde dehydrogenase (AlDH) that acts on acetaldehyde to oxidize to acetic acid can be used as a catalyst. As a result, ethanol is decomposed to acetic acid, and a total of 4 electrons are generated by a two-step oxidation reaction per molecule of ethanol. Incidentally, ethanol may take the method of decomposing to CO ₂ as well as methanol. In this case, acetaldehyde dehydrogenase (AalDH) is allowed to act on acetaldehyde to form acetyl CoA, which is then passed to the TCA circuit. Further electrons are generated in the TCA circuit.

  When glucose is used as fuel, glucose dehydrogenase (GDH) can be used as a catalyst. Thereby, (beta) -D-glucose is decomposed | disassembled into D-glucono-delta-lactone, and 2 electrons are produced | generated per glucose molecule. In addition, D-glucono-delta-lactone is hydrolyzed in water to D-gluconate. In addition to glucose dehydrogenase (GDH), when gluconokinase and phosphogluconate dehydrogenase (PhGDH) catalysts are used, D-gluconate converts adenosine triphosphate (ATP) to adenosine in the presence of gluconokinase. By being hydrolyzed to diphosphate (ADP) and phosphoric acid, it is phosphorylated to 6-phospho-D-gluconate, and further, by the action of phosphogluconate dehydrogenase (PhGDH), 2-keto-6-phospho- Oxidized to D-gluconate. Therefore, in this case, glucose is decomposed into 2-keto-6-phospho-D-gluconate, and a total of 4 electrons are generated by a two-step oxidation reaction per molecule of glucose.

It is also possible to take a method of decomposing glucose to CO ₂ . In this case, it is necessary to utilize sugar metabolism. The complex enzyme reaction utilizing sugar metabolism is roughly divided into glucose decomposition and pyruvic acid production by a glycolysis system, and TCA cycle. The glycolysis system and the TCA circuit are widely known reaction systems, and the description thereof is omitted. However, when this is used, more electric energy can be extracted.

  Since the above-described fuel cell using the enzyme (hereinafter referred to as an enzyme cell) utilizes biological metabolism, its operating temperature is -20 to 80 ° C, preferably 0 to 40 ° C. Power generation operation is possible in the environment.

  If the enzyme battery is mounted as a power source for an electronic device, the enzyme battery may not be able to follow the sudden large current consumption during operation of the electronic device, so a backup lithium ion secondary battery, etc. It is desirable to configure a power supply system that combines these storage batteries.

  According to the present invention, by mounting the enzyme battery on an electronic device, the electronic device can be operated continuously without requiring charging like a storage battery. In addition, the enzyme battery can use safe fuel that can be used as food except for methanol, and can generate power at room temperature and is easy to handle. Furthermore, since the enzyme battery does not require a reformer or a heating device unlike other fuel cells, the power supply system in the electronic device can be made compact.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows an embodiment of an enzyme battery according to the present invention, which is composed of a fuel electrode 1, an air electrode 3, and an electrolyte layer 5 that separates the fuel electrode 1 and the air electrode 3. Has been. In the fuel electrode 1, an enzyme and an electron mediator are supported to take out electrons from the fuel 7 such as glucose and generate protons (H ⁺ ) 9. In the air electrode 3, H ⁺ that has moved from the fuel electrode 1 through the electrolyte layer 5 reacts with oxygen (O ₂ ) in the air to generate water (H ₂ O).

The fuel electrode 1 includes, for example, an enzyme involved in fuel decomposition on a porous electrode such as carbon paper, and a coenzyme (for example, NAD ⁺ , NADP ^+, etc.) that generates a reductant in response to the oxidation reaction of the fuel. ), A coenzyme oxidase (eg, diaphorase; DI) that oxidizes a reduced form of coenzyme (eg, NADH, NADPH, etc.), and an electrode that receives electrons from the coenzyme oxidase accompanying the oxidation of the coenzyme. And an electron mediator (for example, 2-amino-3-carboxy-1,4-naphthoquinone; ACNQ, vitamin K3, etc.) to be transferred to the substrate, and immobilized by an immobilizing material (for example, a polymer, etc.).

For example, when the fuel is methanol, the enzymes involved in the decomposition of the fuel include alcohol dehydrogenase (ADH) that oxidizes methanol to formaldehyde, formaldehyde dehydrogenase (FalDH) that oxidizes formaldehyde to formic acid, and formate dehydrogenase that oxidizes formic acid to CO ₂ . (FateDH). By these oxidases, methanol is finally decomposed to CO ₂ at room temperature.

  When the fuel is ethanol, examples of enzymes involved in fuel decomposition include alcohol dehydrogenase (ADH) that oxidizes ethanol to acetaldehyde and aldehyde dehydrogenase (AlDH) that oxidizes acetaldehyde to acetic acid. By these oxidases, ethanol is oxidized to acetic acid at room temperature.

  In addition, when the fuel is glucose, an example of an enzyme involved in fuel decomposition is glucose dehydrogenase (GDH). By the action of this oxidase, β-D-glucose is oxidized to D-glucono-δ-lactone. D-glucono-δ-lactone is converted to D-gluconate by hydrolysis.

Enzymes involved in fuel decomposition are not limited to the above-mentioned oxidases, but these are NAD ⁺ -dependent dehydrogenases. When these oxidases are used, NAD ⁺ is used as a coenzyme. NAD ⁺ -dependent dehydrogenase reduces the coenzyme NAD ⁺ by oxidizing (dehydrogenating) the fuel to produce NADH and H ⁺ . This reaction is represented by the following formula.
Fuel + NAD ⁺ → Fuel oxidant + NADH + H ⁺ (1)

The generated NADH is oxidized to NAD ⁺ by DI and generates two electrons and H ⁺ as shown in the following equation.
NADH → NAD ⁺ + H ⁺ + 2e ⁻ (2)

Therefore, two electrons and two H ⁺ are generated in one oxidation reaction per molecule of fuel. The electrons generated in the above process are transferred from DI to the electrode via the electron mediator, and H ⁺ is transported to the air electrode 3 through the electrolyte layer 5.

  The electron mediator exchanges electrons with the electrode, and the voltage of the fuel cell depends on the redox potential of the electron mediator. In other words, in order to obtain a higher voltage, it is better to select an electron mediator having a more negative potential on the fuel electrode side. However, the electron mediator's reaction affinity with the enzyme, the rate of electron exchange with the electrode, and the inhibitor (light, oxygen Etc.) must be considered. From such a viewpoint, ACNQ, vitamin K3, and the like are suitable as the electron mediator that acts on the fuel electrode 1. In addition, for example, compounds having a quinone skeleton, metal complexes such as Os, Ru, Fe and Co, viologen compounds such as benzyl viologen, compounds having a nicotinamide structure, compounds having a riboflavin structure, compounds having a nucleotide-phosphate structure Etc. can also be used as electron mediators.

  The enzyme, coenzyme, and electron mediator are adjusted to a pH optimum for the enzyme, for example, around pH 7, with a buffer solution such as Tris buffer or phosphate buffer so that the electrode reaction can be performed efficiently and constantly. It is preferably maintained. Further, the ionic strength (IS) is too large or too small to adversely affect the enzyme activity, but considering the electrochemical response, it should be an appropriate ionic strength, for example, about 0.3. Is preferred. However, pH and ionic strength have optimum values for each of the enzymes used, and are not limited to the values described above.

  The enzyme, coenzyme, and electron mediator may be used in a state dissolved in a buffer solution, but are preferably immobilized on an electrode using an immobilizing material. This makes it possible to efficiently capture the enzyme reaction phenomenon occurring in the vicinity of the electrode as an electrical signal. As such an immobilizing material, for example, glutaraldehyde and poly-L-lysine can be used in combination. Moreover, each may be individual or another polymer may be sufficient.

By configuring the fuel electrode 1 as described above, H ⁺ can be directly generated by contacting with a fuel such as glucose near room temperature.

  The air electrode 3 is composed of carbon powder on which a catalyst is supported or catalyst particles that are not held by carbon. As the catalyst, for example, platinum (Pt) fine particles, or fine particles of transition metal such as iron (Fe), nickel (Ni), cobalt (Co) or ruthenium (Ru) and platinum, or oxide fine particles are used. It is done. A structure in which a catalyst layer made of a catalyst or a carbon powder containing a catalyst and a gas diffusion layer made of a porous carbon material are laminated in order from the electrolyte layer 5 side.

The electrolyte layer 5 is a proton conductive membrane that transports H ⁺ generated in the fuel electrode 1 to the air electrode 3 and is made of a material that does not have electron conductivity and can transport H ⁺ . For example, perfluorocarbon sulfonic acid (PFS) resin film, copolymer film of trifluorostyrene derivative, polybenzimidazole film impregnated with phosphoric acid, aromatic polyether ketone sulfonic acid film, PSSA-PVA (polystyrene sulfonic acid) Polyvinyl alcohol copolymer) and PSSA-EVOH (polystyrene sulfonate ethylene vinyl alcohol copolymer). Among these, those made of an ion exchange resin having a fluorine-containing carbon sulfonic acid group are preferable, and specifically, Nafion (trade name, US DuPont) is used.

In the enzyme battery configured as described above, NADH is generated from the coenzyme NAD ⁺ when at least one type of NAD ⁺ -dependent dehydrogenase oxidizes the fuel on the fuel electrode 1 side. The generated NADH passes two electrons to the fuel electrode 1 via the electron mediator by DI, and returns to NAD ⁺ . The electrons passed to the fuel electrode 1 reach the air electrode 3 through an external circuit, thereby generating a current. Further, H ⁺ generated in the above-described process moves to the air electrode 3 through the electrolyte layer 5. In the air electrode 3, water is generated from the reached H ⁺ , the two electrons supplied from the external circuit, and oxygen.

Therefore, in the example given here, methanol is decomposed to CO ₂ through a three-stage oxidation process by ADH, FalDH, and FateDH, thereby generating three NADHs per molecule of methanol. Electrons can be taken out. Ethanol is oxidized in two stages by ADH and AlDH, so that four electrons can be taken out per molecule of ethanol. In addition, glucose is decomposed in one step by GDH, whereby two electrons can be taken out per glucose molecule.

  The fuel decomposition method is not limited to the above example. For example, glucose can be degraded to 2-keto-6-phospho-D-gluconate via a two-step oxidation process by using gluconokinase and phosphogluconate dehydrase (PhGDH) in addition to GDH. it can. That is, D-gluconate is phosphorylated by hydrolyzing adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and phosphate in the presence of gluconokinase, and 6-phospho-D-gluconate. This 6-phospho-D-gluconate is oxidized to 2-keto-6-phospho-D-gluconate by the action of PhGDH.

Further, ethanol and glucose can be finally decomposed to CO ₂ similarly to methanol. In this case, for ethanol, it is necessary to convert acetaldehyde, which is an oxidation product, to acetyl CoA by acetaldehyde dehydrogenase (AalDH) and then pass it to the TCA circuit. For glucose, it is necessary to utilize sugar metabolism. This complex enzyme reaction utilizing sugar metabolism is roughly divided into glycolysis and generation of pyruvic acid, acetyl-CoA conversion, and TCA cycle by glycolysis. These are widely known reaction systems. .

  In addition to methanol, ethanol, and glucose, the fuel for enzyme batteries includes alcohols, sugars, fats, proteins, organic acids such as intermediate products of glucose metabolism (glucose-6-phosphate, fructose-6- Phosphate, fructose-1,6-bisphosphate, triosephosphate isomerase, 1,3-bisphosphoglycerate, 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate, pyruvate, acetyl-CoA, citrate Acid, cis-aconitic acid, isocitric acid, oxalosuccinic acid, 2-oxoglutaric acid, succinyl-CoA, succinic acid, fumaric acid, L-malic acid, oxaloacetic acid, etc.), mixtures thereof, and the like can be used. Also for these fuels, electric energy can be taken out by decomposing them using enzymes.

  In this case, it is preferable to select and use the optimal enzyme according to a fuel. For example, enzymes used in the fuel electrode include glucose dehydrogenase, a series of enzymes in the electron transport system, ATP synthase, enzymes involved in sugar metabolism (for example, hexokinase, glucose phosphate isomerase, phosphofructokinase, fructose diphosphate aldolase, Triose phosphate isomerase, glyceraldehyde phosphate dehydrogenase, phosphoglyceromutase, phosphopyruvate hydratase, pyruvate kinase, L-lactate dehydrogenase, D-lactate dehydrogenase, pyruvate dehydrogenase, citrate synthase, aconitase, isocitrate dehydrogenase, 2- Oxoglutarate dehydrogenase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase, malonate dehydrogenase, etc.) Mention may be made of the enzyme.

  As described above, the enzyme battery can efficiently decompose the fuel such as alcohols and saccharides by the action of the enzyme and efficiently extract the electrons. Therefore, it is possible to generate power at room temperature without the need for such a device, and it can be mounted on an electronic device as a compact and easy-to-handle power source. Examples of such electronic devices equipped with enzyme batteries include portable devices such as mobile phones, electronic notebooks, notebook computers, mobiles, and PDAs, robots including pet molds, and biologically embedded chips such as pacemakers. .

  In the case of a biologically implantable chip, the internal battery can be used as the fuel for the enzyme battery. However, in other electronic devices, it is necessary to supply fuel from the outside to the enzyme battery. For example, a fuel supply cartridge is connected to the enzyme battery. Is done. Such a fuel supply cartridge is manufactured using a material that is not decomposed into a biochemical catalyst, and is formed in a shape such as a cylindrical shape or a rectangular tube shape, for example. Examples of the material that is not decomposed into the biochemical catalyst include hard resin, metal, and glass. Specifically, a polymer such as polyethylene can be used.

  Since the fuel supply cartridge uses a liquid typified by methanol, ethanol, and an aqueous glucose solution as the fuel, it is preferable that the fuel supply cartridge has a structure that can stably supply the liquid fuel to the fuel electrode 1 of the enzyme cell. FIG. 2 shows an example of the fuel supply cartridge 11, which has a structure in which a movable wall 17 facing the supply port 15 of the fuel chamber 13 filled with fuel is pressed by a spring 19.

  As for the robot, the fuel of the enzyme battery can be taken from the mouth so as to eat food.

  In these electronic devices, the enzyme battery is unlikely to be able to follow a rapid load fluctuation like a general fuel cell. It is preferable to use a power supply system that combines various storage batteries. That is, in this power supply system, the steady state current consumption is covered by the output of the enzyme battery, and in the case of a sudden large current consumption, the battery is discharged until the output current of the enzyme battery reaches the consumed current, and then The storage battery is charged using a part of the output current of the enzyme battery. By using such a power supply system, it is possible to operate the enzyme battery stably by suppressing rapid current fluctuations in the enzyme battery in electronic equipment, and to quickly respond to sudden large current consumption. Can be secured.

Hereinafter, the present invention will be further described with reference to examples of enzyme cells using glucose as a fuel.
On 4 cm ² of carbon paper, 70 μl of glucose dehydrogenase (GDH: Amano Enzyme) phosphate buffer solution (47 μM), 70 μl of diaphorase (DI: Amano Enzyme) phosphate buffer solution (47 μM), NAD ⁺ phosphate buffer solution ( (200 mM) 30 μl, ACNQ ethanol solution (10 mM) 95 μl, glutaraldehyde aqueous solution (0.125%) 100 μl, poly-L-lysine aqueous solution (1%) 100 μl mixed solution, and air-dried at room temperature Thereafter, it was washed with distilled water to obtain a GDH-DI / ACNQ fixed electrode.

Using this GDH-DI / ACNQ fixed electrode as a fuel electrode, an enzyme battery as shown in FIG. 1 was constructed, and as a result of introducing a 400 mM glucose aqueous solution into the fuel electrode side, an output of 10 mW / cm ² was confirmed at 25 ° C. However, no decrease in output was observed after 30 minutes.

  When this enzyme battery is installed in, for example, a mobile phone, the required battery output can be obtained by stacking five 3 cm long x 3 cm wide x 4 mm thick cells, and the battery size should be 3 cm x 3 cm x 2 cm. Can do.

It is a schematic diagram which shows one Embodiment of the enzyme battery concerning this invention. It is the schematic which shows an example of a fuel supply cartridge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel electrode, 3 ... Air electrode, 5 ... Electrolyte layer, 7 ... Fuel, 9 ... Proton, 11 ... Fuel supply cartridge, 15 ... Supply port, 19 ... Spring

Claims (9)

  An electronic device comprising a fuel cell using at least one selected from alcohols, sugars, fats, proteins and organic acids as fuel and using an enzyme as a catalyst.   The electronic device according to claim 1, wherein the fuel of the fuel cell is at least one selected from methanol, ethanol, and glucose.   The electronic device according to claim 1, wherein the enzyme of the fuel cell includes an oxidase that decomposes the fuel and generates an oxidant of the fuel.   4. The electronic device according to claim 3, wherein the enzyme of the fuel cell includes a coenzyme oxidase that returns the coenzyme that has been reduced by the oxidation reaction of the fuel to the oxidant and generates electrons.   The electronic device according to claim 1, wherein an operating temperature of the fuel cell is −20 to 80 ° C.   2. The electronic device according to claim 1, wherein the fuel cell uses alcohol dehydrogenase (ADH), formaldehyde dehydrogenase (FalDH), and formate dehydrogenase (FateDH) that stepwise decompose methanol using methanol as a fuel. .   2. The electronic device according to claim 1, wherein the fuel cell uses alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AlDH) that decompose ethanol in stages using ethanol as a fuel.   The electronic device according to claim 1, wherein the fuel cell uses glucose dehydrogenase (GDH) that uses glucose as a fuel and decomposes glucose as an enzyme. 2. The electronic apparatus according to claim 1, further comprising a power supply system in which a backup storage battery is combined with the fuel cell.

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