Monitoring of pH by using stimulus responsive hydrogel and Fiber Bragg grating for bioreactor application

In this paper a pH monitoring system is demonstrated by utilizing wavelength modulated fiber optic techniques. A stimulus responsive hydrogel which exhibits a volume change with the change of pH is utilized to render a strain on Fiber Bragg grating (FBG). The gel is synthesized from the blends of Poly (vinyl alcohol)/Poly (acrylic acid). The induced strain causes a FBG peak shift that can be used as a measure of pH change. The proposed sensing system exhibits a good linearity in acidic pH range of 3 to 7 with a sensitivity of 250 pm/pH. Besides that it is very cost effective, bio degradable and also possess repeatability.