Activatable print medium

An activatable print medium comprising:

• a first reactive component;
• a second reactive component, the first and second reactive components configured to react to initiate a state change of the activatable print medium when exposed to each other;
• and
• a barrier initially in an unactivated form and configured to transition to an activated form when activated by an application of at least one of an activation heat and an activation pressure, wherein
• in the unactivated form, the barrier is configured to separate the first reactive component and the second reactive component, preventing their interaction,
• in the activated form, the barrier is configured to allow the first reactive component to interact with the second reactive component,
• wherein, after the barrier is activated, but not before, the activatable print medium is configured so that it has a property selected from the list consisting of:
• (a) the first and second reactive components are configured to interact in response to a predetermined environmental stimulus which occurs after the barrier was activated, thereby providing an indication of an historical exposure of the activatable print medium to the environmental stimulus that occurs after the barrier was activated, and
• (b) the first and second reactive components are configured to interact over time at a rate dependent on the environmental stimulus which occurs after the barrier was activated, thereby providing an indication of a cumulative historical exposure of the activatable print medium to the environmental stimulus that occurs after the barrier was activated;
• and
• wherein the second reactive component is applied to a porous base media substrate having micro-channels, and wherein the second reactive component occupies the micro-channels of the base media substrate.

An activatable print medium comprising:

• a first reactive component;
• a second reactive component, the first and second reactive components configured to react to initiate a state change of the activatable print medium when exposed to each other;
• and
• a barrier initially in an unactivated form and configured to transition to an activated form when activated by an application of at least one of an activation heat and an activation pressure, wherein
• in the unactivated form, the barrier is configured to separate the first reactive component and the second reactive component, preventing their interaction,
• in the activated form, the barrier is configured to allow the first reactive component to interact with the second reactive component,
• wherein, after the barrier is activated, but not before, the activatable print medium is configured so that it has a property selected from the list consisting of:
• (c) the first and second reactive components are configured to interact in response to a predetermined environmental stimulus which occurs after the barrier was activated, thereby providing an indication of an historical exposure of the activatable print medium to the environmental stimulus that occurs after the barrier was activated, and
• (d) the first and second reactive components are configured to interact over time at a rate dependent on the environmental stimulus which occurs after the barrier was activated, thereby providing an indication of a cumulative historical exposure of the activatable print medium to the environmental stimulus that occurs after the barrier was activated;
• and
• wherein
• the first reactive component is a meltable material formulated as one of a dispersion or an emulsion having a particle size,
• the barrier is a porous material with a pore size smaller than the particle size, and
• the second reactive component is an absorbent substrate impregnated with a reactive dye.

A method for activating an activatable indicator with a media processing device having a thermal print head, the method comprising:

• receiving an activatable print medium, the activatable print medium including:
• a first reactive component,
• a second reactive component, the first and second reactive components configured to react to initiate a state change of the activatable print medium when exposed to each other, and
• a barrier comprising a polymer having a glass transition temperature, the barrier initially in an unactivated form and configured to transition to an activated form when activated by an application of an activation heat which heats the polymer above the glass transition temperature, causing the barrier to transition from a nonpermeable state to a permeable state wherein
• in the unactivated form, the barrier is in the nonpermeable state and is configured to separate the first reactive component and the second reactive component, preventing their interaction,
• in the activated form, the barrier is in the permeable state and is configured to allow the first reactive component to interact with the second reactive component,
• wherein, after the barrier is activated, but not before, the activatable print medium is configured so that it has at least one property selected from the group consisting of:
• (a) the first and second reactive components are configured to interact in response to a predetermined environmental stimulus which occurs after the barrier was activated and thereby providing an indication of an historical exposure of the activatable print medium to the environmental stimulus after the barrier is activated, and
• (b) the first and second reactive components are configured to interact over time and to initiate the state change at a rate dependent on a predetermined environmental stimulus which occurs after the barrier was activated, thereby providing an indication of a cumulative historical exposure of the activatable print medium to the environmental stimulus after the barrier is activated;
• and
• applying heat to the activatable print medium using the thermal print head of the media processing device, thereby transitioning the barrier from the unactivated form to the activated form and thereby allowing the first reactive component to interact with the second reactive component in response to the environmental stimulus that occurs after barrier was activated.

An activatable print medium, comprising:

• a first reactive component;
• a second reactive component, the first and second reactive components configured to react to initiate a state change of the activatable print medium when exposed to each other;
• and
• a barrier initially in an unactivated form and configured to transition to an activated form when activated by an application of an activation heat, wherein
• in the unactivated form, the barrier is configured to separate the first reactive component and the second reactive component, preventing their interaction,
• in the activated form, the barrier is configured to allow the first reactive component to interact with the second reactive component,
• wherein, after the barrier is activated, but not before, the activatable print medium is configured so that it has a property selected from the list consisting of:
• (a) the first and second reactive components are configured to interact in response to a predetermined environmental stimulus which occurs after the barrier was activated, thereby providing an indication of an historical exposure of the activatable print medium to the environmental stimulus that occurs after the barrier was activated, and
• (b) the first and second reactive components are configured to interact over time at a rate dependent on the environmental stimulus which occurs after the barrier was activated, thereby providing an indication of a cumulative historical exposure of the activatable print medium to the environmental stimulus that occurs after the barrier was activated;
• and
• wherein the application of heat causes a component of the barrier to sublime, thereby bringing the first reactive component and the second reactive component into contact with each other.