Ian Yulianti, A.S.M. Supa'At, Sevia M. Idrus, Ojo Kurdi, M.R.S. Anwar
A new optical pH sensor based on fibre Bragg grating (FBG) is demonstrated. The sensor consists of a FBG coated with pH sensitive hydrogel. The sensing was performed through the detection of wavelength shifts resulting from the induced strain on the FBG due to mechanical expansion of the hydrogel. An elastomeric coating was applied before the hydrogel coating to improve the sensitivity. The sensor performance was investigated by simulating the hydrogel swelling and the strain induced on the FBG. The swelling of hydrogel due to pH change was modelled using a free-energy function and was solved using the finite element method. With silicone rubber as the elastomer material, the results show that the sensitivity was improved by up to 66% compared to that of the FBG pH sensor without elastomeric coating. © 2012 IOP Publishing Ltd.
Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia; Faculty of Engineering, Universiti Selangor, Selangor, Malaysia; Physics Department, Universitas Negeri Semarang, Semarang, Indonesia
