Stimulus indicating device employing polymer gels

Abstract

The present invention relates to a stimulus-indicating device. More particularly, the present invention relates to an apparatus and method for evidencing when a product has been exposed to a designated stimulus for a certain period of time.

1 . A stimulus sensitive gel comprising:
 i) 0.79 grams of NIPAAm (97% purity from Aldrich);   ii) 20 milliliters of distilled and deionized water;   iii) 0.2 grams of LAP (grade RD from Southern Clay Products Gonzales, Tex.);   iv) 0.003 grams of methylene blue (abbreviated MB, 97% purity from Aldrich);   v) 0.01 grams of potassium persulfate (98% purity from Aldrich); and   vi) 40 microliters of N,N,N′,N′-tetramethyl ethyl enedi amine (abbreviated TEMED, 98% purity from Aldrich). TEMED catalyzes the polymerization reaction such that the reaction may occur at low temperatures (near 0° C.) although one of ordinary skill in the art will recognize that TEMED may be substituted with another redox polymerization catalyst such as Sodium Metabisulfite.   
     
     
         2 . A stimulus sensitive gel comprising:
 i) 1 grams of NIPAAm (97% purity from Aldrich);   ii) 20 milliliters of distilled and deionized water;   iii) 0.0133 grams of N,N′-methylenebisacrylamide (electrophoresis grade from Aldrich);   iv) 0.02 grams of ammonium persulfate (98% purity from Aldrich);   v) 0.05 grams of Red 110 M iron oxide (from LanXess Corporation); and   vi) 0.24 microliters of N,N,N′,N′ -tetramethylethylenediamine (abbreviated TEMED, 98% purity from Aldrich).