Disclosed is an integrated circuit comprising a substrate (10); and an optical CO2 sensor comprising: first and second light sensors (12, 12′) on said substrate, said second light sensor being spatially separated from the first light sensor; and a layer portion (14) including an organic compound comprising at least one amine or amidine functional group over the first light sensor; wherein said integrated circuit further comprises a signal processor (16) coupled to the first and second light sensor for determining a difference in the respective outputs of the first and second light sensor. An electronic device comprising such a sensor and a method of manufacturing such an IC are also disclosed.