This invention covers improved electronic time-temperature indicators with
an RFID output, and other devices and methods by which the thermal
history of a complex material, which may not obey a simple exponential
Arrhenius law degradation equation, may be monitored, and the subsequent
fitness for use of the tracked material may be quickly ascertained. In
particular, the invention discloses a rapidly reprogrammable electronic
time-temperature RFID tag that may be easily customized with the thermal
time-temperature stability profile of an arbitrary material, using
electronic data transfer methods. Using this device, a single, low-cost,
generic time-temperature tag may be mass-produced, and then subsequently
programmed to mimic the stability characteristics of nearly any material
of interest. By utilizing data compression to compress a material's
extensive thermal history into the small user data field transmitted by
modern RFID tags, a considerable amount of information relating to
product status and cause of failure may be rapidly transmitted within the
small memory confines of standard RFID tag protocols.