Patent ID: 8701587

Claim:
A precise critical temperature indicator comprising: a temperature sensor including an upper portion made of a transparent material, in which the upper portion includes a container sealed by a seal member to receive a development material therein, a support portion supporting the container, first and second cylindrical portions formed in layers of concentric circle having diameters different from each other, the first cylindrical portion including a circular plate formed away in a certain gap from the circumference thereof, the second cylindrical portion receiving the container therein and a lower portion including a development medium member for arranging the support portion on a seat portion under the lower surface of the upper portion and sealing the lower surface thereof adjacent to the development medium member and applying an adhesive agent thereto to be attached to freezing and refrigerating products; an indication portion made of an opaque material and including at least one indication window formed on the cylindrical portion of the upper portion; and a cap portion made of an opaque material and sealing the lower surface thereof, in which an activation button is fitted into the center hole thereof and the temperature sensor is received therein.