NOVELTY - Fabricating resistive heater assembly (10) by providing first substrate layer, bonding second substrate layer to the first substrate layer, optionally bonding a hydrophobic layer to the second substrate layer, and bonding top layer to the optional hydrophobic layer or bonding the top layer to the second substrate layer. The second substrate layer has resistive heater and conductive traces electrically coupled to the resistive heater.    USE - For heating source substance for use in generation of gas. It is also used in fuel cartridge, fuel cell assembly, integrated circuit, and electronic device (claimed). For use in various portable devices such as laptop computers, PDAs, portable digital and video cameras, portable music players, portable electronic games, cellular phones and other wireless devices.    ADVANTAGE - The invention provides portable fuel cells with rapid startup times and improved efficiency. It provides efficiency that does not depends on the heat loss.    DETAILED DESCRIPTION - Fabricating resistive heater assembly comprises providing first substrate layer (20), bonding second substrate layer (30) to the first substrate layer, optionally bonding a hydrophobic layer (60) to the second substrate layer, and bonding top layer (70) to the optional hydrophobic layer or bonding the top layer to the second substrate layer. The second substrate layer has resistive heater (40) and conductive traces (50) electrically coupled to the resistive heater. The top layer includes manifolding (80) for the gas to complete the resistive heater assembly. INDEPENDENT CLAIMS are included for:    (1) resistive heater assembly comprises source substance containing chamber with aperture, thin resistive heater disposed to be immersed in the source substance, and conductive traces electrically coupled to the thin resistive heater. The thin resistive heater is suspended across the aperture; and    (2) using resistive heater assembly comprising providing chamber and resistive heater, introducing source of substance into the chamber, disposing the source substance in thermal contact with resistive heater, and applying current to the resistive heater through the conductive traces to heat the source substance to generate a gas.    DESCRIPTION OF DRAWING(S) - The figure shows a side elevational cross sectional view of the resistive heater assembly.    Resistive heater assembly (10)    First substrate layer (20)    First bonding layer (25)    Second substrate layer (30)    Resistive heater (40)    Conductive traces (50)    Hydrophobic layer (60)    Top layer (70)    Manifolding (80)    Substance containing chamber (100)    Aperture (110)    Gas collecting chamber (120)