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,
• a thin film substrate comprising at least one photosensitive element, a plurality of electrical contacts and at least one area which is transparent to excitation radiation associated with said carrier layer by microelectronic and photolithographic techniques,
• an indicator layer,
• a transparent coupling layer located between said thin-film substrate and said indicator layer,
• said indicator layer being produced by microelectronic and photolithographic techniques and comprising at least one indicator substance having optical properties, wherein at least one of the 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, and wherein said indicator substance of said indicator layer, which is excited by a source of excitation radiation, is in optical contact with said at least one photosensitive element via said transparent coupling layer, and
• transparent areas positioned in said thin-film substrate at an angle, such that said excitation radiation will strike said indicator layer at an angle a of 40.degree. to 60.degree., exciting areas of said indicator layer facing said photosensitive elements.

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

• a carrier layer,
• a thin film substrate comprising at least one photosensitive element, a plurality of electrical contacts and at least one area which is transparent to excitation radiation associated with said carrier layer by microelectronic and photolithographic techniques,
• an indicator layer,
• a transparent coupling layer located between said thin-film substrate and said indicator layer,
• said indicator layer being produced by microelectronic and photolithographic techniques and comprising at least one indicator substance having optical properties, wherein at least one of the 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, and wherein said indicator substance of said indicator layer, which is excited by a source of excitation radiation, is in optical contact with said at least one photosensitive element via said transparent coupling layer, and wherein said coupling layer, which has a refractive index n.sub.2, together with boundary layers situated on both sides of said coupling layer, which have a refractive index n.sub.1, constitute a planar lightguide for said radiation to be measured, with n.sub.2 >n.sub.1, wherein said boundary layer adjacent to said sample has at least one recess which is covered by said indicator layer, and wherein each of said recesses, seen in a direction of said excitation radiation, is situated above one of said areas transparent to said excitation radiation, and wherein total reflection of said radiation to be measured is cancelled in areas of said photosensitive elements.