CPC G04F 13/02 (2013.01) [G01N 31/229 (2013.01); A61K 33/38 (2013.01); A61L 15/44 (2013.01); A61L 15/56 (2013.01); B82Y 20/00 (2013.01); G01N 21/77 (2013.01); G01N 21/78 (2013.01)] | 46 Claims |
1. A system for visually indicating the time elapsed since an article has been removed from a package, the system comprising:
an indicator disposed on or within the article, wherein the article is enclosed within a sealable receptacle of the package; and
a trigger disposed within the receptacle and in contact with the indicator;
wherein the indicator is responsive to a change in a concentration of the trigger in contact with the indicator,
wherein the indicator comprises a population of nanoparticles stabilized by a capping agent, and wherein the trigger comprises a solution comprising the capping agent in contact with the indicator,
wherein when the article is removed from the receptacle and placed in contact with a solution containing a lower concentration of the trigger, the capping agent disassociates from the nanoparticles, thereby inducing aggregation of the population of nanoparticles; and
wherein aggregation of the population of nanoparticles results in a color change.
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