Oxygen-responsive expiration date indicator

Abstract

An expiration date indicator includes a first protective sheet that prevents oxygen intrusion, an oxygen transmission film disposed beneath the first protective sheet, wherein the oxygen transmission film is composed of a plurality of separable layers, a reaction layer disposed beneath the oxygen transmission film, wherein the reaction layer reacts with oxygen and changes color, a support layer disposed beneath the reaction layer, wherein the support layer is formed of an adhesive material, and a second protective sheet disposed beneath the support layer and preventing deterioration of the support layer.

Dependencies are inferred from the claim text.