Time-temperature dosimeter
The present disclosure relates to a dosimeter for measuring exposure to heat over time in combination with peak temperature indicators and reversible temperature indicators. The preferred temperature indicator tag is credit card sized and comprises four time-temperature dosimeters. Each dosimeter has a wick in contact with a separate reservoir containing a mix of a colored dye, a wax and an amorphous polymer to indicate a distinct temperature range when the mix melts. The wicks are preferably made of porous paper with a pore size around 8 microns to allow for proper capillary action along its length. An adhesive, except where each wick contacts its respective reservoir and at a vent, preferably seals each wick. The tag preferably has a plurality of peak temperature indicators where each indicator has a blend of a dye, a wax and a polymer for a temperature indication range. The tag also preferably has a plurality of reversible temperature sensors.
1. A temperature indicator tag comprising:
a time-temperature dosimeter having a plurality of wicks; each wick in contact with a separate reservoir containing a mix of a colored dye, a wax and an amorphous polymer; whereby each reservoir, mix and wick are used to indicate a distinct temperature range and each wick is sealed by an adhesive except where each wick contacts its respective reservoir;
a plurality of peak temperature indicators; each indicator having a blend of a dye, a wax and a polymer where the blend has a temperature indication range and where the blend is in contact with an opaque porous wick and viewable through a transparent temperature indicator; and,
a plurality of reversible temperature sensors.
2. The temperature indicator tag of claim 1 where the temperature range for the dosimeter is 10 to 300 degrees Fahrenheit.
3. The temperature indicator tag of claim 1 where the peak temperature indicator can indicate a temperature of 10 to 300 degrees Fahrenheit.
4. The temperature indicator tag of claim 1 where the time-temperature dosimeter further comprises a reservoir vent to regulate pressure between the reservoir and a pressure external to the reservoir.
5. The temperature indicator tag of claim 1 where the adhesive is a mix of polycarbonate and thermoplastic polyester.
6. The temperature indicator tag of claim 1 where the plurality of wicks each have a length and are tapered along the length.