MICROMIRROR OPTICAL-FIBER HYDROGEN SENSOR

In a recent letter (M.A. Butler, J. Electrochem. Soc., 138 (1991) L46) a new hydrogen sensor was reported that operates by measuring changes in the reflectivity of thin palladium films deposited on the end of an optical fiber when exposed to hydrogen gas. In this paper we explore in more detail the mechanisms of operation of this sensor. Two effects are observed: a reversible micro-blistering of the films on exposure to hydrogen and changes in optical constants with hydriding. Use of a thin nickel layer under the palladium to improve adhesion results in large changes in optical response. These changes are attributed to clamping effects on the film.