Maxell, Ltd.

Gs Yuasa International Ltd.

Naohisa Kitazawa

Tadashi Kakeya

Emi Kuromatsu

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&#x2265;0.3 (ml/g) holds true.

Electrochemical oxygen sensor

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.

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.

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Kyoto, Japan

Naohisa Kitazawa