Time-temperature integrating indicator device

A time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure, said device comprising:

• a) a first substrate comprising a first side and a second side, said second side including a diffusely light-reflective porous matrix, wherein said porous matrix includes an exposed surface;
• b) a first backing comprising a first surface and a second surface, wherein said first surface of said backing includes a viscoelastic material disposed thereon, wherein said viscoelastic material includes an exposed surface;
• and
• c) actuating means for selectively switching said device from an unactivated state to an activated state;
• wherein when said device is in said unactivated state, said viscoelastic material is substantially out of contact with said porous matrix;
• wherein when said device is in said activated state, said actuating means maintains said exposed surface of said viscoelastic material and said exposed surface of said porous matrix in substantial contact with one another such that said viscoelastic material progressively migrates into said porous matrix at a rate which increases with increasing temperature;
• wherein migration of said viscoelastic material into said porous matrix progressively decreases the light transmissivity of said porous matrix to provide said visually observable indication of cumulative thermal exposure.

A time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure, said device comprising:

• a) a first substrate comprising a first side and a second side, said second side including a diffusely light-reflective porous matrix, wherein said porous matrix includes an exposed surface;
• b) a first backing comprising a first surface and a second surface, wherein said first surface of said backing includes a pressure sensitive adhesive disposed thereon, said pressure sensitive adhesive including at least one of a tackifier and a plasticizer as a component thereof, and wherein said pressure sensitive adhesive includes an exposed surface;
• and
• c) actuating means for selectively switching said device from an unactivated state to an activated state;
• wherein when said device is in said unactivated state, said pressure sensitive adhesive is substantially out of contact with said porous matrix;
• wherein when said device is in said activated state, said actuating means maintains said exposed surface of said pressure sensitive adhesive and said exposed surface of said porous matrix in substantial contact with one another such that all of the components of said pressure sensitive adhesive together progressively migrate into said porous matrix at a rate which increases with increasing temperature;
• wherein migration of said pressure sensitive adhesive into said porous matrix progressively increases the light transmissivity of said porous matrix to provide said visually observable indication of cumulative thermal exposure.

A time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure, said device comprising:

• a) a diffusely light-reflective porous matrix having an exposed surface;
• b) a first backing comprising a first surface and a second surface, wherein said first surface of said backing includes a viscoelastic material disposed thereon, and wherein said viscoelastic material includes an exposed surface;
• and
• c) actuating means for selectively switching said device from an unactivated state to an activated state;
• wherein when said device is in said unactivated state, said viscoelastic material is substantially out of contact with said porous matrix;
• wherein when said device is in said activated state, said actuating means maintains said exposed surface of said viscoelastic material and said exposed surface of said porous matrix in substantial contact with one another such that said viscoelastic material progressively migrates into said porous matrix at a rate which increases with increasing temperature;
• and
• wherein migration of said viscoelastic material into said porous matrix progressively increases the light transmissivity of said porous matrix to provide said visually observable indication of cumulative thermal exposure.

A method for providing a time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure of an object, comprising the steps of:

• a) mounting a first substrate onto the object, said substrate comprising a first side and a second side, said second side including a diffusely light-reflective porous matrix;
• and
• b) contacting a first surface of a first backing against said porous matrix, wherein said first surface of said backing includes a viscoelastic material disposed thereon;
• wherein said viscoelastic material progressively migrates into said porous matrix at a rate which increases with increasing temperature;
• and
• wherein migration of said viscoelastic material into said porous matrix progressively changes the light transmissivity of said porous matrix to provide said visually observable indication.

A method for providing a visually observable indication of cumulative thermal exposure, comprising the steps of:

• a) applying a viscoelastic liquid onto an exposed surface of a diffusely light-reflective porous matrix;
• wherein said viscoelastic liquid progressively migrates into said porous matrix at a rate which increases with increasing temperature;
• b) exposing said viscoelastic liquid to a time and temperature profile;
• and
• c) migrating said viscoelastic liquid into said porous matrix in response to said time and temperature profile to thereby change the light transmissivity of said porous matrix to provide a visually observable indication of cumulative thermal exposure.

A method for providing a visually observable indication of cumulative thermal exposure of an object, comprising the steps of:

• a) mounting a first substrate onto the object, said substrate comprising a first side and a second side, said second side including a diffusely light-reflective porous matrix;
• b) contacting a first surface of a first backing against said porous matrix, wherein said first surface of said backing includes a viscoelastic material disposed thereon, wherein said viscoelastic material progressively migrates into said porous matrix at a rate which increases with increasing temperature;
• c) exposing said object to a time and temperature profile;
• and
• d) migrating said viscoelastic material into said porous matrix in response to said time and temperature profile to thereby change the light transmissivity of said porous matrix to provide a visually observable indication of cumulative thermal exposure.

A method for providing a time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure, comprising the steps of:

• a) forming an opening in a generally planar spacer, said spacer comprising a top side and a bottom side;
• b) applying an adhesive to at least said bottom side of the spacer;
• c) adhering a first substrate onto said bottom side of the spacer to at least partially overlay said opening, said first substrate comprising a diffusely light-reflective porous matrix overlaying said opening;
• and
• d) applying a first surface of a first backing to said spacer to at least partially overlay said opening and said porous matrix, wherein said first surface of said backing includes a viscoelastic material disposed thereon overlaying said opening;
• wherein said viscoelastic material progressively migrates into said porous matrix at a rate which increases with increasing temperature to thereby integrate said temperature over time;
• and
• wherein migration of said viscoelastic material into said porous matrix progressively changes the light transmissivity of said porous matrix to provide said visually observable indication.