Abstract: Electrophotographic light-sensitive elements according to the invention comprise(a) a conductive support;(b) a photoconductive layer; and(c) a surface protective layer.The conductive support is formed in a sheet-like or cylindrical shape from any suitable conductive material, and acts as an electrode of the light-sensitive element as well as acting as a physical support. The photoconductive layer comprises amorphous hydrogenated silicon having a high absorption efficiency and photoconductivity. The a--Si:H of a photoconductive layer may contain other elements such as fluorine, carbon, nitrogen and germanium, and may be doped with elements belonging to groups III and V of the periodic table. The surface protective layer is the outermost layer of an electrophotographic light-sensitive element according to the invention, and imparts resistance to environmental conditions. The surface protective layer comprises hydrogenated amorphous carbon, and may additionally contain silicon, nitrogen, oxygen or fluorine.

Abstract: An oxygen sensor in which a porous thick membrane (20) of transition-metal oxide and electrode metal thick membranes (14, 16) are provided on a ceramic base and these membranes are coated with a ceramic protective layer. The oxygen sensor in which the transition-metal oxide and the electrode metal are constructed in the forms of thick membranes and the protective layer is formed by plasma spray coating is mechanically tough and permits the gas to diffuse rapidly into the porous structure with rapid variation in the electric resistance depending on an oxygen partial pressure in the gas. Accordingly, the oxygen sensor may be conveniently used for detecting an oxygen content in the waste gas from automobiles.

Abstract: Into a metal tube (24) provided with vent-holes (32) is inserted an oxygen sensor element (10) which comprises a ceramic round rod coated with a porous thick membrane of transition-metal oxide, divided electrode thick membranes (14) and a protective layer therefor, thereby to obtain an oxygen sensor. One electrode of the oxygen sensor element is connected to the metal tube and the opposite electrode is connected to a connecting lead wire (64, 66) electrically insulated from the tube, so that the oxygen sensor is rich in toughness against the mechanical oscillation and impact. The sensor may suitably be used to detect the oxygen content in the waste gas of automobiles.