The realisation of an opto-chemical ammonia sensor suitable for personal mo
nitoring tasks is described, comprising a cyanine dye immobilised in a micr
oporous glass thin him. The fabrication of sensor platforms incorporating e
mbossed grating couplers provides a compact optical design with effective w
aveguiding characteristics, resulting in reversible ammonia sensitivity in
the 5-100 ppm range in under 2 min. Cross-sensitivity of sensor response wi
th water and other potential interferents is considered.