Sensor element for determination of concentration of substances

An electro-optical sensor element for determining the concentration of substances contained in gaseous and liquid samples, comprising

• a carrier layer,
• an indicator layer which has been produced by microelectronic and photolithographic techniques and which comprises at least one indicator substance having optical properties, wherein at least one of said optical properties of said indicator substance will change upon interaction with said substances contained in said gaseous and liquid samples, depending on the concentrations of said substances in said gaseous and liquid samples,
• a transparent coupling layer located between said carrier layer and said indicator layer,
• a thin film arrangement of a plurality of light-emitting sources located between said carrier layer and said transparent coupling layer, said light-emitting sources being in optical contact with said indicator layer and having electrical leads connected thereto, and
• a thin film arrangement of a plurality of photosensitive elements located between said carrier layer and said transparent coupling layer, said photosensitive elements being in optical contact with said indicator layer and having electrical leads connected thereto.