Zeolites as coating materials for Fiber Bragg Grating chemical sensors for extreme conditions

Important progress has been made towards the expanding of the limits of applicability of Fiber Bragg Grating (FBG) optical sensors. The development of new inorganic coatings consisting of MFI zeolite crystals (silicalite and ZSM-5) has opened up the possibility towards the use of this technology at high temperatures and pressures. Using two different, purposely-built experimental setups, it was shown that zeolite-coated FBG sensors can be used for chemical gas sensing, both at ambient as well as at extreme conditions, i.e. at temperatures of up to 260 °C and pressures of up to 200 bar. The sensors are selective for linear alkanes, show no significant cross-sensitivity towards H2O and CO2, are thermally and chemically robust and have response times of 5 min or less. Additionally, molecular simulations are used to bring insight into the underlying nature of the sensing mechanism.