U.S. patent application 20190086158 (inventor James Hirschfeld, Delray Beach, Fla.):
"A removable cooling sticker secured to the surface of a cellular telephone for extraction of heat from the cellular telephone. The cooling sticker is thin and sized to be conveniently carried. [Using phase change material as the active heat extraction material,] the cooling sticker is adhered to the cellular telephone at its hot spot for maximum efficiency. An optional feature employs thermal strips that indicate when the electronic device is exceeding a temperature threshold sticker."