Temperature-activated time-temperature indicator
First Claim
1. A temperature-activatable time-temperature indicator comprising an optically readable, thermally sensitive indicator element, the indicator elementbeing thermally inactive below a base temperature and being thermally responsive at or above an activation temperature to record irreversibly with respect to time cumulative ambient temperature exposure of the time-temperature indicator to temperatures above the activation temperature, the activation temperature being in the range of from about −
- 10°
C. to about 50°
C. and being equal to or greater than the base temperature, andincluding an optically detectable indicator material,wherein the indicator material comprises a synthetic polymeric material having a molecular weight of at least about 2,000 Da and a viscosity at, or near, the activation temperature, when the indicator material is liquid, of at least about 50 cP, andwherein the time-temperature indicator is configured to be associated with a host product to monitor the historical exposure of the host product to ambient temperatures.
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Accused Products
Abstract
A temperature-activatable time-temperature indicator that can be used to monitor the historical exposure of a host product to ambient temperatures includes an optically readable, thermally sensitive indicator element. The indicator element can be inactive below a base temperature and is intrinsically thermally responsive at or above an activation temperature which is equal to or greater than the base temperature. The indicator can record cumulative ambient temperature exposure above the activation temperature irreversibly with respect to time. The indicator element can include a synthetic polymeric material, and optionally, a dye. A side-chain crystallizable polymer such as poly(hexadecylmethacrylate), that is solid below the base temperature and is a viscous liquid above the activation temperature can be employed. Intense indicator element colors can be obtained using an appropriate dye or dyes. Various structural configurations of indicator are described and illustrated.
70 Citations
42 Claims
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1. A temperature-activatable time-temperature indicator comprising an optically readable, thermally sensitive indicator element, the indicator element
being thermally inactive below a base temperature and being thermally responsive at or above an activation temperature to record irreversibly with respect to time cumulative ambient temperature exposure of the time-temperature indicator to temperatures above the activation temperature, the activation temperature being in the range of from about − - 10°
C. to about 50°
C. and being equal to or greater than the base temperature, andincluding an optically detectable indicator material, wherein the indicator material comprises a synthetic polymeric material having a molecular weight of at least about 2,000 Da and a viscosity at, or near, the activation temperature, when the indicator material is liquid, of at least about 50 cP, and wherein the time-temperature indicator is configured to be associated with a host product to monitor the historical exposure of the host product to ambient temperatures. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
- 10°
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37. A temperature-activatable time-temperature indicator configured to be associated with a host product to monitor the historical exposure of the host product to ambient temperatures, the time-temperature indicator comprising:
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an optically readable, thermally sensitive indicator element, the indicator element being thermally inactive at or below a base temperature, being thermally responsive at or above an activation temperature, the activation temperature being in the range of from about −
10°
C. to about 50°
C. and being equal to or greater than the base temperature, and comprising an optically detectable indicator material, the indicator material being in a solid state at or below the base temperature, being in a liquid state at or above the activation temperature and comprising a synthetic polymeric material having side chain crystallinity and having a molecular weight of at least about 2,000 Da, the indicator element further comprising a dye dissolved in the synthetic polymeric material; and
the time-temperature indicator further comprisinga transport member supporting the indicator material; wherein the indicator material contrasts optically with the transport member and the indicator response comprises displacement of the indicator material with respect to the transport member.
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38. A temperature-activatable time-temperature indicator for monitoring past exposure of a host product to ambient temperatures, the time-temperature indicator comprising an optically readable, thermally sensitive indicator element, the indicator element being inactive below a base temperature and being thermally responsive at or above an activation temperature to record irreversibly with respect to time cumulative ambient temperature exposure above the activation temperature, the activation temperature being in the range of from about −
- 10°
C. to about 50°
C. and being equal to or greater than the base temperature wherein the indicator element comprises a side-chain crystallizable polymer having a melting temperature equal to or greater than the activation temperature of the time-temperature indicator and having a molecular weight of at least about 2,000 Da and wherein liquid-flow related movement of the side-chain crystallizable polymer when liquid can be read optically. - View Dependent Claims (39, 40, 41, 42)
- 10°
Specification