Patent ID: 7517146
Filing Date: 2009-04-14
Classification: G01K

Abstract:
1. An excess temperature indicator for providing a visual indication of past exposure of the indicator to an elevated temperature exceeding a threshold temperature, the indicator comprising: (a) an upper layer having a viewable outer surface and a heat-fusible inner surface opposed to the outer surface; (b) a viewing window in the upper layer permitting viewing of a portion of the indicator beneath the upper layer; (c) a wick attached to the inner surface of the upper layer, the wick having a first portion disposed to be viewable through the viewing window and having a second portion disposed away from the viewing window; (d) an indicator material reservoir disposed in wicking contact with the second portion of the wick, the indicator material being heat-fusible in response to exposure of the indicator to said elevated temperature to provide a wickable liquid indicator, the liquid indicator being transported along the wick to the viewable first portion of the wick and changing the visual appearance of the first portion of the wick; (e) a base layer covering the wick; and (f) a region of fused upper layer material attaching the wick to the upper layer.