OPTICAL HUMIDITY SENSOR USING FLUORESCENT PLASTIC FIBER AND ITS APPLICATION TO BREATHING-CONDITION MONITOR

The plastic fiber humidity sensor, the mechanism of which is based on an ionization reaction between water vapor and the fluorescent dye-doped polymer cladding, was studied. The conditions under which to obtain the maximum sensitivity were derived from the theory and experimental data. Under these conditions, the fluorescent plastic fiber could be used as an excellent optical humidity sensor head with good linearity over the wide humidity range. Due to its reproducibility and fast response property, its application to a breathing-condition monitor became possible.