Time-temperature integrating indicator device

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