Time-temperature integrating indicator device

US5667303A · kind A · utility

Assignee

• Minnesota Mining and Manufacturing Company · US

Inventors

• Robert P. Arens · Windom, US
• Russell D. Birkholz · Maplewood, US
• Dee Lynn Johnson · Woodbury, US
• Theodore P. Labuza · Arden Hills, US
• Curtis L. Larson · Hudson, US
• David J. Yarusso · Shoreview, US

Key dates

• Filing date: Mar 10, 1995
• Grant date: Sep 16, 1997
• Expiry date: Mar 10, 2015

Classification

• Technology area (CPC G): Physics
• CPC primary: G01K3/04
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A selectively activated time-temperature integrating device for providing a visually observable indication of cumulative thermal exposure, in which a viscoelastic material migrates into a diffusely light-reflective porous matrix at a rate which varies with temperature to progressively change the light transmissivity of the porous matrix and thereby provide the visually observable indication. The viscoelastic material can comprise a pressure sensitive adhesive. The visually observable indication can comprise latent indicia which initially are not visible and become visible, obscurable indicia which initially are visible and become obscured, or a combination of both. Various actuating means for selectively switching the indicator from an unactivated state to an activated state are described. Also disclosed are a method for providing a visually observable indication of cumulative thermal exposure and a method for providing a time and temperature integrating device for providing a visually observable indication of cumulative thermal exposure of an object.