Abstract: Provided is a fuel cell that is high in performance capabilities of initial power generation and in volume power density, and produces a stable power. Between fixing plates, first and second cell portions are provided. The first cell portion includes an anode, a cathode, and a proton conductor, and the second cell portion includes an anode, a cathode, and a proton conductor. To a space formed by gas-liquid separation and permeable films, cathode spacers, and an anode spacer, a fuel solution is filled. The gas-liquid separation and permeable films are disposed between the fixing plate and the cathode, and between the fixing plate and the cathode. The cathode spacers are provided around the cathodes, respectively, and the anode spacer is provided between the anodes.

Abstract: Provided are an enzyme immobilizing method, a fuel cell and an electrode for the fuel cell which employ the enzyme immobilizing method, and a method for manufacturing the fuel cell and the electrode. The enzyme immobilizing method prevents reduction in enzyme activity when the enzyme is immobilized on the electrode, so as to make it possible to obtain a high catalyst current value. In the method for immobilizing an enzyme on the electrode used in the fuel cell, an enzyme variant with at least one amino acid residue being deleted, substituted, added, or inserted in a wild-type amino acid sequences is used as the enzyme, and the enzyme variant increases in activity through heat treatment. The immobilization is performed within a temperature range which makes it possible to increase the activity of the enzyme variant.

Abstract: A fuel cell with which in the case where an enzyme is immobilized to at least one of a cathode and an anode, sufficient buffer ability is able to be obtained even at the time of high output operation, ability inherent in the enzyme is able to be sufficiently demonstrated, and which has superior performance is provided. In a bio-fuel cell which has a structure in which a cathode and an anode are opposed to each other with an electrolyte layer containing a buffer substance in between, and in which an enzyme is immobilized to at least one of the cathode and the anode, a compound containing an imidazole ring is contained in the electrolyte layer as a buffer substance, and one or more acids selected from the group consisting of acetic acid, phosphoric acid, and sulfuric acid are further added.

Abstract: Provided is a fuel cell having a structure in which a cathode and an anode face each other with a proton conductor therebetween. In this fuel cell, an oxygen reductase or the like is immobilized on at least the cathode, and the cathode is composed of a material having pores therein such as porous carbon. In this fuel cell, the volume of water contained in the cathode is controlled to be 70% or less of the volume of the pores of the cathode, whereby a high current value can be stably obtained through optimization of the amount of moisture contained in the cathode when an enzyme is immobilized on at least the cathode. Also provided is a method for operating the fuel cell.

Abstract: A fuel cell is provided having a structure in which a cathode and an anode face each other with an electrolyte layer therebetween. The cathode includes an electrode on which an oxygen reductase and the like are immobilized, and the electrode has pores therein, water repellency is imparted to at least part of the surface of the electrode. Water repellency is imparted by forming a water-repellent agent on the surface of the electrode. The water-repellent agent includes a water-repellent material such as carbon powder and an organic solvent such as methyl isobutyl ketone that causes phase separation with water. When the electrode has pores therein, there are provided a fuel cell that stably provides a high current value and a method for manufacturing the fuel cell.

Abstract: A fuel cell is provided. The fuel cell includes at least one of a plant essential oil and a plant essential oil ingredient in an effective amount so as to function as a biological repellent.

Abstract: Disclosed herein is a system for inquiring about fitness of a beverage as battery fuel, including a search request receiving section configured to receive an input of beverage information regarding a beverage as a search request, a storage section having stored therein a reference database in which search requests and performance data of fuel cells are associated with each other, a search section configured to automatically search the reference database for performance data which coincides with the search request, and a search answer outputting section configured to output a search answer.

Abstract: The present invention provides a fuel reformer which enables power generation to be actually performed even in the case of using very-safe familiar things such as food and drink and food scraps as a fuel of a biofuel cell. The fuel reformer is used for a fuel cell which generates power as an oxidation reduction reaction progresses using enzyme as a catalyst, and has: a primary fuel introduction unit for introducing a primary fuel; a fuel reforming unit communicating with the primary fuel introduction unit and reforming the primary fuel to a secondary fuel from which electrons can be emitted by an oxidation reduction reaction using enzyme as a catalyst; and a secondary fuel supplying unit communicating with the fuel reforming unit and supplying the secondary fuel to the fuel cell.

Abstract: Provided is an enzyme electrode in which oxidation-reduction reactions proceed with an enzyme acting as a catalyst, and the enzyme is modified to increase affinity and/or reaction rate with a reaction substrate or an electron transfer mediator by adding or inserting at least one codon encoding a particular amino acid residue to or into a base sequence encoding the enzyme, and is immobilized. Since the oxidation-reduction reactions on the electrode proceed highly efficiently, the enzyme electrode can cause to increase the obtained output of electric energy and thus can be suitably used in all types of fuel cells, biosensors, and electronic apparatuses.

Abstract: A fuel cell having excellent properties is provided in which, when an enzyme is immobilized in at least one of a positive electrode and a negative electrode, a sufficient buffering capability can be provided even in a high power output operation and the inherent capability of the enzyme can be sufficiently exerted. In a biofuel cell including a structure in which a positive electrode 2 and a negative electrode 1 face each other with an electrolyte layer 3 therebetween, the electrolyte layer 3 containing a buffer material, and the biofuel cell including an enzyme immobilized in at least one of the positive electrode 2 and the negative electrode 1, the electrolyte layer 3 contains a compound including an imidazole ring as a buffer material and at least one acid selected from the group consisting of acetic acid, phosphoric acid, and sulfuric acid is further added to the electrolyte layer 3.

Abstract: In the case in which a fuel cell has a structure in which a cathode (2) and an anode (1) are opposed with the intermediary of an electrolyte layer (3) and the cathode (2) is formed of an electrode to which an oxygen reductase and so on is immobilized and this electrode has pores inside, at least part of the surface of this electrode is rendered water repellent. For example, the surface of the electrode is rendered water repellent by forming a water-repellent agent on the surface of this electrode. Thereby, in the case in which the cathode is formed of an electrode to which an enzyme is immobilized and this electrode has pores inside, a fuel cell that can stably achieve a high current value by optimization of the amount of water contained in the cathode and a manufacturing method thereof are provided.

Abstract: A mutant protein having diaphorase activity is provided. A mutant protein includes an amino acid sequence obtained by deletion, replacement, addition, or insertion of at least one amino acid residue of a native-form amino acid sequence of SEQ. ID. No. 1, wherein the mutant protein has diaphorase activity with an enzyme activity of 245 or more.

Abstract: A heat-resistant bilirubin oxidase mutant is disclosed. The bilirubin oxidase mutant is obtained by deletion, replacement, addition or insertion of at least one amino acid residue of a wild type amino sequence of SEQ. ID. No. 1 of a bilirubin oxidase derived from an imperfect filamentous fungus, Myrothecium verrucaria. A biocathode including a thermo stable bilirubin oxidase mutant immobilized thereon, and its use in a biofuel cell is disclosed.

Abstract: A mutant protein having diaphorase activity is provided. A mutant protein includes an amino acid sequence obtained by deletion, replacement, addition, or insertion of at least one amino acid residue of a native-form amino acid sequence of SEQ. ID. No. 1, wherein the mutant protein has diaphorase activity with an enzyme activity of 245 or more.

Abstract: A heat-resistant bilirubin oxidase mutant is disclosed. The bilirubin oxidase is obtained by deletion, replacement, addition or insertion of at least one amino acid residue of a wild type amino sequence of SEQ. ID. No. 1 of a bilirubin oxidase derived from an imperfect filamentous fungus, Myrothecium verrucaria.

Abstract: A mutant protein having diaphorase activity is provided. A mutant protein includes an amino acid sequence obtained by deletion, replacement, addition, or insertion of at least one amino acid residue of a native-form amino acid sequence of SEQ. ID. No. 1, wherein the mutant protein has diaphorase activity with an enzyme activity of 245 or more.