Peter M Ford

US Patent:

56221371, Apr 22, 1997

Filed:

Mar 24, 1994

Appl. No.:

8/218083

Inventors:

Elmer C. Lupton - Boston MA
Thomas E. Ford - Winchester MA
Peter E. Ford - North Billerica MA

Assignee:

Trans World Services - Melrose MA

International Classification:

G01K 1106
G01K 114

US Classification:

116217

Abstract:

A low cost, disposable temperature sensor comprising a non-porous rigid substrate having a colored patch of a contrasting color, covered by a thermochromic material which obscures the colored patch. The thermochromic material, which has a color in the visual range which completely obscures the underlying colored patch, is selected to have a melting or solidus point such that when the material is exposed to a predetermined temperature, the thermochromic material permanently changes to a relatively transparent color whereby the colored patch on the substrate is rendered visible through the thermochromic material. A transparent cover or film encapsulates the thermochromic material place on the substrate. In a preferred embodiment of the invention, the substrate comprises a paperboard product, and includes printed indicia for making a permanent record. The sensor has particular utility in measuring safe cooking temperature of food,.