Abstract: A gas sensor that has its heater and sensing layer on opposite sides of the substrate. The gas sensor includes a buffer layer separating the gas-sensing layer from the substrate to improve mechanical strength and electrical properties. The heater is preferably formed of nickel paste and is provided on the back of the substrate.

Abstract: A method of fabricating a gas sensor which comprises a substrate; a buffer layer coated on the substrate; at least one gas sensing layer arranged on the buffer layer; a pair of electrodes disposed on the gas sensing layer; and a catalytic layer coated on the gas sensing layer. A spin coating process is performed, using centrifugal force, to form the layers which are thin and evenly deposited on the substrate. The gas sensing layer of the gas sensor is formed before forming the electrodes of the same such that the heat treatment thereto can be carried out at 800.degree. C. which is much higher than the conventional temperature of 600.degree. C. The bonding of the gas sensing layer to the substrate is thereby much stronger than the conventional gas sensor.