SENSORS AND METHODS FOR DETERMINING WHETHER AN ITEM HAS BEEN EXPOSED TO AN ENVIRONMENTAL CONDITION

摘要

A method for determining whether an item has been exposed to anenvironmental condition during a monitoring period. The method includesplacing asensor at least in proximity to the item at the beginning of the monitoringperiod sothat the sensor will be exposed to a level of an environmental condition thatcan becorrelated to an exposure level of the item to the environmental condition;reading thesensor; and determining from reading the sensor whether the item has beenexposed tothe environmental condition. The sensor includes a detecting materialcomprising aphotochromic or photothermochromic material, the detecting material selectedso thatupon exposure to the environmental condition the detecting material exhibits adetectable color change.