Abstract: An electrochemical oxygen sensor according to the present invention includes a positive electrode, a negative electrode, and an electrolyte solution constituted by an aqueous solution, in which the negative electrode includes a metal containing, as a main component, an element M selected from Sn and Ni, the electrolyte solution is an aqueous solution having a pH of 3 to 10, the positive electrode includes a catalyst layer containing a catalytic metal, and the catalyst layer includes, on a surface that is in contact with the electrolyte solution, a surface layer containing the element M.

Abstract: An electrochemical oxygen sensor with a long service life is provided. The electrochemical oxygen sensor according to the present invention includes a positive electrode, a negative electrode, and an electrolyte solution, and the negative electrode contains tin or a tin alloy, the electrolyte solution is an aqueous solution obtained by dissolving at least citric acids, the aqueous solution contains an alkali metal, a total content of the citric acids in the electrolyte solution is 2.1 mol/L or higher, a content of the alkali metal in the electrolyte solution is 0.1 to 1.6 times the total content of the citric acids, the electrolyte solution has a pH of 3.9 to 4.6, and when a volume of the electrolyte solution is x (ml) and a content of tin contained in the negative electrode is y (g), x/y?0.3 (ml/g) holds true.

Abstract: An electrochemical oxygen sensor with a long service life is provided. The electrochemical oxygen sensor according to the present invention includes a positive electrode, a negative electrode, and an electrolyte solution, and the electrolyte solution contains a chelating agent and ammonia, and a concentration of the ammonia in the electrolyte solution is 0.01 mol/L or higher. Citric acid is preferable as the chelating agent contained in the electrolyte solution. Also, the negative electrode preferably contains an Sn alloy.

Abstract: The first electrochemical oxygen sensor includes: a positive/negative electrode; and an electrolyte solution, the electrochemical oxygen sensor further including: a separation membrane for limiting an amount of oxygen supplied to the positive electrode, and a resistance element for connecting the positive electrode and the negative electrode. In one embodiment, a value of current flowing through the resistance element is 7 ?A or more in an atmosphere of 50% relative humidity at 25° C. and 1 atm, and a resistance value of the resistance element is set at 1050 ? or less. In another embodiment, a value of current flowing through the resistance element is 4 ?A or more in an atmosphere of 50% relative humidity at 25° C. and 1 atm, and a resistance value of the resistance element is set so that the output voltage between both ends of the resistance element falls within a range from 4 to 9.5 mV.

Abstract: An electrochemical oxygen sensor with a long service life is provided. The electrochemical oxygen sensor according to the present invention includes a positive electrode, a negative electrode, and an electrolyte solution, and the negative electrode contains tin or a tin alloy, the electrolyte solution is an aqueous solution obtained by dissolving at least citric acids, the aqueous solution contains an alkali metal, a total content of the citric acids in the electrolyte solution is 2.1 mol/L or higher, a content of the alkali metal in the electrolyte solution is 0.1 to 1.6 times the total content of the citric acids, the electrolyte solution has a pH of 3.9 to 4.6, and when a volume of the electrolyte solution is x (ml) and a content of tin contained in the negative electrode is y (g), x/y?0.3 (ml/g) holds true.

Abstract: An electrochemical oxygen sensor with a long service life is provided. The electrochemical oxygen sensor according to the present invention includes a positive electrode, a negative electrode, and an electrolyte solution, and the electrolyte solution contains a chelating agent and ammonia, and a concentration of the ammonia in the electrolyte solution is 0.01 mol/L or higher. Citric acid is preferable as the chelating agent contained in the electrolyte solution. Also, the negative electrode preferably contains an Sn alloy.

Abstract: Provided is an electrochemical oxygen sensor that attains a high response speed and also an improved service life of the oxygen sensor. The electrochemical oxygen sensor according to the present invention includes a holder 9 and a positive electrode 45, negative electrode 8, and electrolyte solution 7, which are contained in the holder 9. The electrolyte solution 7 contains a chelating agent, and the molar concentration of the chelating agent is 1.4 mol/L or higher.

Abstract: Provided is a galvanic cell type oxygen sensor including a positive electrode, a negative electrode, an electrolyte solution, and a first oxygen permeable membrane, wherein the concentration of oxygen detected before ordinary use of the sensor is controlled into the range of 0.1 to 4.0% by volume both inclusive, or the output voltage of the sensor before ordinary use of the sensor is controlled into the range of 2.5 to 20% both inclusive of the output voltage thereof at the time of the ordinary use.

Abstract: A sensor includes a holder; and an electrode and an electrolyte solution that are placed in the holder, wherein the electrode contains a Pb—Sb alloy.

Abstract: Provided is a galvanic cell type oxygen sensor including a positive electrode, a negative electrode, an electrolyte solution, and a first oxygen permeable membrane, wherein the concentration of oxygen detected before ordinary use of the sensor is controlled into the range of 0.1 to 4.0% by volume both inclusive, or the output voltage of the sensor before ordinary use of the sensor is controlled into the range of 2.5 to 20% both inclusive of the output voltage thereof at the time of the ordinary use.

Abstract: The invention provides an electrochemical oxygen sensor including a cathode, an anode, and an electrolyte solution, wherein the electrolyte solution contains a chelating agent. Since the electrolyte solution in the electrochemical oxygen sensor of the invention contains the chelating agent, the speed of response can be increased. In the invention, the provision of an anode of tin is preferred from the viewpoints of low cost, a low environmental load, and a low susceptibility to liquid leakage. In the invention, the concentration of the chelating agent in the electrolyte solution is preferably not less than 0.005 mol/liter because response speed characteristics are less likely to lower.