The present invention relates to an optical gas sensor using a thin film containing an organic pigment molecules as a gas sensing element.
Conventionally, gas sensors of the contact combustion type or the semiconductor type have been dominantly used. Recently, a gas sensor using light, such as an optode, has been proposed, and some applications thereof are realized (see Japanese Patent Application Unexamined Publication No. 62-35246). Further, it is known that some organic pigment molecules, when placed in an oxidizing gas or a reducing gas, interact with the gas with a certain selectivity, to change its electric or optical characteristic. There has been proposed a gas sensor of NOx or SOx which utilizes electric characteristic change of phthalocyanine, for example.
A gas sensor using light, such as an optode, has the following disadvantages. That is, a gas sensing portion is complicated in structure, a large laser device is required for a light source, and a photomultiplier tube is used for the photo detecting portion. Further, as far as we know, there is not yet developed the gas sensor using the organic pigment molecules which can stably sense gas many times by a simple means.