Frozen package temperature monitor, to indicate if it has thawed, uses two chemicals separated by a dividing layer which is permeable at a given temperature for the chemicals to combine with a visible reaction

摘要

The system to monitor the temperature of a deep frozen packaged product (1) has two chemical components (3) in paper towels (4), separated from each other by a dividing layer (2), which is permeable when the temperature breaches a given level. When permeable, the two chemicals combine in an optically visible reaction.