A gas sensor has a first aqueous phase. The aqueous phase is composed of a soluble dye in a buffer. One or more additional agent can be further added to the aqueous phase as for instance an emulisification enhancement agent. The aqueous phase is homogenized into a polymeric precursor forming a emulsion of the aqueous phase in the polymeric precursor. A catalyst and a cross-linking agent are added and the polymeric precursor material allowed to polymerize to form an emulsoid of micro-compartments of the aqueous phase in a polymeric second phase. The micro-compartments of the aqueous phase are dispersed through and permanently suspended in the polymeric second phase.