Time-temperature indicator

A time-temperature indicating device for indicating deterioration of perishable goods and the like, said device comprising:

• a time-temperature sensitive component including a reactant material and an indicator responsive to contact by said reactant to produce a visible reaction, said reactant and indicator being normally separated by a diffusion layer having an impermeable, pseudo-crystalline state and a reactant permeable, liquidcrystalline state, said diffusion layer effecting the transition between said impermeable and permeable states at a clearly defined transition temperature;
• and
• container means for enclosing said time-temperature sensitive component, said container means including a transparent face for viewing said time-temperature component.

A time-temperature indicating device for indicating deterioration of perishable goods and the like, said device comprising:

• a time-temperature sensitive component including a reactant material and an indicator responsive to contact by said reactant material to produce a visible reaction, said reactant material being dispersed in a diffusion layer disposed adjacent said indicator, and said diffusion layer having an impermeable, pseudo-crystalline state and a reactant-permeable, liquid-crystalline state, wherein said diffusion layer effects a transition between said impermeable and permeable states at a clearly defined transition temperature;
• and
• container means for enclosing said time-temperature sensitive component, said container means including a transparent face for viewing said time-temperature component.