Abstract: To provide a gas sensor and a method of sensing the gas concentrations which are capable of a battery drive through low power consumption and highly reliable, the gas sensor in which an electromotive force type gas sensor element is formed on a substrate, wherein the electromotive force type gas sensor element has a heating element formed on the substrate, a layer of solid electrolyte formed with an insulating layer interposed on the heating element and two electrodes formed on the solid electrolyte and is characterized in that the substrate is a heat-resistant glass base substrate.

Abstract: The method of polishing a copper layer of a substrate is capable of improving a stock removal rate, etc. The method comprises the steps of: supplying a substrate onto an polishing pad of an polishing plate with a copper layer facing the polishing pad; pressing the substrate onto the polishing pad, with a backing pad, by a press head; relatively rotating the press head with respect to the polishing plate, with supplying polishing slurry onto the polishing pad. The backing pad is made of a material whose Asker C hardness is 75-95 and whose compressibility is 10% or less. The polishing slurry includes a chelating agent for chelating copper, an etching agent for etching the surface of copper layer, an oxidizing agent for oxidizing the surface of copper layer, and water.

Abstract: A pair of reference electrodes and a flame rod are placed in contact with charged particles in a flame produced by a burner. When a voltage is applied between the flame rod and the burner by a power source, a current (I.sub.fr) flows between them due to the flame conductivity. A potential difference (V.sub.12) between the pair of reference electrodes is detected by a potential difference detector. The dynamic flame impedance between the pair of reference electrodes is defined as the slope of the I.sub.fr -V.sub.12 relationship and is independent of I.sub.fr.