Patent ID: 8203105

Claim:
A portable food warmer comprising: a first portion that holds food, includes a heating element deposited on a substrate; and a second portion that supports the first portion, includes a power supply and a temperature controller; the heating element is electrically connected with the power supply and the controller when the second portion supports the first portion; wherein the heating element comprises multilayered coating materials, the multilayered coating materials comprise one or more layers of insulating material, one or more layers of conducting material, and at least two electrodes; each layer of the insulating material is about 30 to about 50 nm in thickness, each layer of the conducting material is about 50 to about 70 nm in thickness; the layers are deposited using spray pyrolysis; and the conductive materials use a source metal selected from the group consisting of tin, indium, cadmium, tungsten, titanium and vanadium with organometallic precursors.