Three-phase emulsions used in a temperature condition indicator
Described herein are temperature condition indicators (e.g. freezing, threshold temperature, thermal history indicators, etc.) comprising three phase emulsions. Methods of forming and using these indicators, and products that include these indicators, are also disclosed.
1. A temperature condition indicator comprising:
a housing; and
an indicator dispersion within the housing, wherein the indicator dispersion comprises:
a base phase;
a barrier phase dispersed in the base phase; and
an active phase dispersed in the barrier phase;
wherein the active phase is miscible with the base phase;
wherein the barrier phase is substantially insoluble in the base phase and the active phase is substantially insoluble in the barrier phase; and
wherein the temperature condition indicator is configured so that before the temperature condition is met, the barrier phase effectively separates the active phase from the base phase; and
wherein the temperature condition indicator is configured so that if the temperature condition is met, a significant amount of mixing will occur between the active phase and the base phase to form a combined phase;
wherein, if the combined phase is formed, a detectable and irreversible change in an apparent color of the indicator dispersion occurs; and
wherein the housing is configured so that the detectable and irreversible change in the apparent color of the indicator dispersion is detectable externally of the temperature condition indicator by visual inspection or by an optical instrument.
2. The temperature condition indicator of claim 1 , wherein the active phase or the barrier phase has a droplet size such that, before the temperature condition is met, light scattering affects the apparent color of the indicator dispersion.
3. The temperature condition indicator of claim 1 , wherein the barrier phase contains an opacifying agent.
4. The temperature condition indicator of claim 1 , wherein a chemical reaction occurs if the active phase mixes with the base phase.
5. The temperature condition indicator of claim 4 , wherein:
the active phase comprises a first active sub-phase comprising a first chemically active agent and a second active sub-phase comprising a second chemically active agent;
wherein the barrier phase separates the first active sub-phase from the second active sub-phase; and
if mixing between the active phase and the base phase occurs, it causes the first chemically active agent and the second chemically active agent to be present together in the combined phase so that the chemical reaction occurs in the combined phase.
6. The temperature condition indicator of claim 4 , wherein the chemical reaction is affected by pH or is an oxidation-reduction reaction.
7. The temperature condition indicator of claim 1 , wherein, if mixing between the active phase and the base phase occurs, it is a result of freezing or a result of the indicator reaching a threshold temperature.
8. The temperature condition indicator of claim 7 , wherein the threshold temperature is reached as a result of the indicator experiencing a decrease in temperature.
9. The temperature condition indicator of claim 7 , wherein the threshold temperature is reached as a result of the indicator experiencing an increase in temperature.
10. The temperature condition indicator of claim 1 , wherein, if mixing between the active phase and the base phase occurs, it is a result of phase inversion between the active phase and the barrier phase or between the barrier phase and the base phase.
11. The temperature condition indicator of claim 1 , wherein the base phase is aqueous, the barrier phase is hydrophobic, and the active phase is aqueous.
12. The temperature condition indicator of claim 11 , wherein the hydrophobic phase comprises heptane, octane, nonane, decane, undecane, dodecane, tridecane, hexadecane, toluene, xylene, mineral oil, terphenyl oil, soybean oil, cottonseed oil, linseed oil, rapeseed oil, castor oil, sunflower oil, olive oil, kernel oil, peanut oil, corn oil, canola oil, coconut oil, hazelnut oil, avocado oil, almond oil, arachis oil, safflower oil, maize oil, soybean oil, caraway oil, rosemary oil, peppermint oil, eucalyptus oil, sesame oil, coriander oil, lavender oil, citronella oil, juniper oil, lemon oil, orange oil, clary sage oil, nutmeg oil, tea tree oil, a liquid fatty acid ester of lauric acid, a liquid fatty acid ester of palmitic acid, a liquid fatty acid ester of stearic acid, a siloxane, a polysiloxanes, a cyclopolysiloxanes, dimethicone, a phenol, an alkoxyaromatic, or a perflouroalkane.
13. The temperature condition indicator of claim 1 , wherein the base phase is hydrophobic, the barrier phase is aqueous, and the active phase is hydrophobic.
14. The temperature condition indicator of claim 1 , wherein the indicator dispersion is configured so that, if the temperature condition is met, a colorant becomes dispersed in the combined phase.
15. The temperature condition indicator of claim 1 , wherein the indicator dispersion further comprises an ice-nucleating agent.
16. The temperature condition indicator of claim 1 , wherein the housing and the substrate are flexible.
17. The temperature condition indicator of claim 1 , further comprising a host product, wherein the temperature condition indicator monitors the host product for freeze exposure.
18. The temperature condition indicator of claim 1 , wherein an ordinary person can perceive the change in apparent color by visual inspection.
19. A label for a perishable good, comprising a temperature condition indicator of claim 1 .
20. A method of protecting a perishable item, comprising coupling the perishable item with a temperature condition indicator of claim 1 so that the temperature condition indicator is subject to substantially the same temperature conditions as the perishable item.