Development of novel polymer coating for FBG based relative humidity sensing

Abstract This paper presents the development of a polymer coating for fibre Bragg grating based humidity sensors. PMMA and its co-polymers were investigated leading to structural modifications of a synthesised polyetherimide coating with a measured Bragg wavelength shift of 1.45 pm/%rh, an improvement over unmodified polyetherimide. The commercially available P84 polyimide (Evonik) was investigated and a Bragg wavelength shift of 5.29 pm/%rh measured. A modified polyimide is now in development.