Patent ID: 7940605

Claim:
A stimulus-indicating device comprising: a first compartment; a stimulus sensitive gel contained in said first compartment that is capable of shrinking in volume in response to exposure to a predetermined stimulus; a liquid contained in said stimulus sensitive gel that is capable of being expelled from said stimulus sensitive gel when said stimulus sensitive gel is exposed to a predetermined stimulus; a second compartment; a semi-permeable membrane separating said first compartment from said second compartment that is capable of allowing said liquid to pass from said first compartment to said second compartment, and that is capable of trapping said liquid in said second compartment; and a display portion positioned above said first compartment through which a color change can be seen in said first compartment when said stimulus sensitive gel changes volume by shrinking in reaction to a predetermined stimulus, whereby in response to exposure to a predetermined stimulus, said stimulus sensitive gel is capable of remaining permanently shrunken so as to permanently present said color change visible through said display portion and thereby permanently indicate exposure to a predetermined stimulus by expelling said liquid within said stimulus sensitive gel into said first compartment in response to a predetermined stimulus and said liquid passes through said semi-permeable membrane into said second compartment where said liquid is permanently trapped by said semi-permeable membrane so as to prevent said stimulus sensitive gel from reabsorbing said liquid and reversing said color change visible through said display portion.