Patent ID: 7290925
Filing Date: 2007-11-06
Classification: G01K,G01N

Abstract:
1. A full-history time-temperature indicator system which exhibits a time-temperature dependent and visually detectable, substantially irreversible chemical reaction, which system responds independently of a temperature threshold and provides a cumulative response to the time and storage conditions to which the system has been exposed, the system comprising at least one immobilized and at least one mobile reactant, at least one of said immobilized and mobile reactants comprising a metal compound, said immobilized reactant being immobilized in a hydrocolloid gel contained in a first compartment adjacent to a separate second compartment containing the mobile reactant, and said at least one immobilized and at least one mobile reactant initially being separated by a seal to prevent contact between the reactants, the system being activated by removing the seal between the compartments, to allow for the mobile reactant to diffuse through the hydrocolloid gel, wherein the diffusion rate is temperature dependent, and to move through the immobilized reactant, which remains immobilized in the hydrocolloid gel, in a time-temperature dependent manner resulting in a visually detectable and substantially irreversible signal that can be followed from the time of activation and said irreversible signal indicating a full, continuously cumulative time-temperature history.