Patent ID: 10401232

Abstract:
Visual and electronically readable temperature indicators and methods of making the same have an electric circuit with a microchip and a bridge within the circuit, and a facing material over the electric circuit. The bridge includes either a single layer or multiple layers that include a conductive material, a phase change material having a pre-selected melt temperature, a binder, a first colorant that is soluble in the phase change material and/or a second colorant that is a special effect pigment. In operation, at temperatures below the pre-selected melt temperature, the bridge is electrically conductive, and at a temperature at or above the pre-selected melt temperature, the phase change material melts and dilutes the conductive material, so that the bridge is electrically non-conductive, and a color change occurs that is visible to the user through the facing material such as through a transparent window or in an absorbent material.