Print activatable environmental sensor providing a delayed threshold temperature response

A machine readable time-temperature exposure indicator label, comprising:

• a substrate;
• a bar code symbol printed on substrate, the bar code symbol being an error-correcting two-dimensional bar code;
• a reservoir coupled to the substrate;
• a viewing area on the substrate;
• a transport structure providing fluid communication between the reservoir and the viewing area;
• an indicator material contained in the reservoir, the indicator material configured to liquefy at a predetermined temperature threshold, and once liquefied to travel along the transport structure from the reservoir to the viewing area, the passage of the indicator material from the reservoir to the viewing area requiring a predetermined time when the indicator material is maintained at the predetermined temperature threshold;
• and
• a plurality of ruptured microcapsules mixed with the indicator material in the reservoir.

An activatable machine readable time-temperature exposure indicator label:

• a substrate;
• a bar code symbol printed on the substrate, the bar code symbol being an error-correcting two-dimensional bar code;
• a reservoir coupled to the substrate;
• a viewing area on the substrate;
• a transport structure providing fluid communication between the reservoir and the viewing area;
• and
• an indicator material encapsulated by microcapsules contained in the reservoir, the indicator material configured to liquefy in response to exceeding a predetermined temperature threshold, and wherein, while the microcapsules are intact, when the indicator material liquefies the microcapsules retain the indicator material in the reservoir, and when the indicator material is released from the microcapsules and liquefies, the liquefied indicator material travel along the transport structure from the reservoir to the viewing area, the passage of the indicator material from the reservoir to the viewing area requiring a predetermined amount of time when the indicator material is maintained at the predetermined temperature threshold.

An activatable time-temperature indicator label stock to indicate past exposure to an exposure temperature above a predetermined temperature threshold for at least a predetermined exposure time at the exposure temperature, the label stock comprising:

• a substrate;
• a reservoir on or in the substrate containing an indicator material encapsulated in microcapsules, the indicator material configured to melt at the predetermined temperature threshold, the microcapsules, when intact, containing the indicator material in both its solid and melted state;
• a viewing area;
• a transport structure on or in the substrate, providing fluid communication between the reservoir and the viewing area;
• wherein the indicator material, when liquefied and released from the microcapsules by rupturing of the microcapsules, flows from the reservoir to the viewing area;
• and
• wherein the indicator material, when held at the predetermined threshold temperature, requires at least the predetermined exposure time to flow from the reservoir to the viewing area;
• wherein the microcapsules are configured to rupture in response to at least one of a predetermined force and heating above an activation temperature, the activation temperature being greater than the predetermined temperature threshold.