Patent ID: 7102526

Claim:
A unitized electronic time-temperature indicator device for rapidly assessing the acceptability of a material's thermal history, said device containing computational means, and a temperature measurement means; wherein said device periodically samples the temperature and computes a function of temperature that is continually operative throughout the relevant temperature monitoring range of the device; and wherein said function of temperature approximates the impact that the relevant temperature, for that period's length of time, has on a detectable property of said material; and wherein said computational means generate a running sum of said function of temperature over time; and wherein said function of temperature resides with said unitized device; and wherein the granularity of the function of temperature is small enough, and the frequency of time measurements is often enough, as to substantially approximate the impact of time and temperature on the detectable property of said material; and in which said running sum is compared to a reference value, and the result of said comparison is used to generate an output signal indicative of the fitness for use of said material.