Abstract: An optical silicon-based detector with a porous filter layer that has a laterally modifiable filter effect, comprising a plurality of integrated photosensitive cells. The invention also relates to a method for the production of an optical detector by creating an insulating layer on the porous filter layer and by providing active filter surfaces.

Abstract: An interference filter having a layer with an area consisting of a porous material extending from the surface of the layer to the interior, the dimensions of the porous layer area in a direction normal to the layer surface have different values to provide for varying reflection or, respectively, transmission characteristics.

Abstract: In an interference filter having a layer with an area consisting of a porous material extending from the surface of the layer to the interior, the dimensions of the porous layer area in a direction normal to the layer surface have different values to provide for varying reflection or, respectively, transmission characteristics.

Abstract: A porous layer produced from silicon, germanium or aluminum by applying a wedge-shaped mask to the surface of the layer and by controlled elecrochemical etching along the mask.

Abstract: In an analytic process using porous silicon, a substance is detected or its concentration in a fluid is determined based on the change in the optical property of porous silicon as a function of the refractive index of the substance present in the pores of the porous silicon, or of the fluid containing the substance. An analytic device for detecting a substance or for determining the concentration of a substance in a fluid with the use of porous silicon comprises a component at least partly consisting of porous silicon, the optical property of which is dependent upon the refractive index of the substance or of the fluid containing the substance, whereby a change in the optical property of the porous silicon is measurable to indicate detection of the substance or to determine the concentration of such substance in the pores of the porous silicon.

Abstract: A three-dimensional structure of porous silicon considerably improves the anchorage of sensor-active material such as, for example, enzymes, antibodies, etc., on or in the substrate surface of chemical sensors, in particular silicon-based biosensors. This structure is produced by means of suitable etching which forms pore apertures adapted to the penetrability of the sensor-active material. The pore walls advantageously receive a non-conductive boundary layer which consists of oxides of Si and/or Al or Ta or silicon nitride and are preferably 1-100 nm thick. The porous layer is advantageously between 10 nm and 100 .mu.m thick and the pores are preferably in the form of branched ducts whose average diameter is 1 nm-10 .mu.m and in particular 10-1000 nm. The sensor-active material can optionally be distributed in a glass, solid, plastics or polymer membrane.