Optical Detection of Moisture in Air and in Soil Using Dye-Doped Plastic Fibers

Abstract

The moisture-sensitive plastic fiber consists of poly-methylmethacrylate doped with phenol-red dye. The propagation loss of this fiber at around 530 nm increases with increasing water vapor in air, and hence it operates as an excellent humidity sensor with a fast response time. This fiber can also be used for optically detecting moisture equivalent in the soil.