Fabrication of optical chemical ammonia sensors using anodized alumina supports and sol-gel method

► Ammonia gas sensitive optical sensors have been prepared on anodized aluminum. ► The indicator was immobilized by adsorption or by embedding in ormosil layers. ► Higher anodizing voltage results in more sensitive sensor. ► The analytical performances of the adsorption and ormosil immobilized sensor were compared. ► Ormosil covered alumina sensors have prolonged response and recovery times.