The present invention relates to novel agropolymers, which comprise a carbohydrate andor silica matrix substantially devoid of proteins, tannins and polyphenols and which comprise metal binding reactive sites. The apparatus comprises a level sensor, a pressure sensor and a computer. The reducing heterogeneous layer formed on the top surface of the glass substrate is removed by etching using an etchant which is mainly composed of hydrofluoric acid. The client caches the object and enables users associated with the client to access the object in accordance with the delegation. In the present invention, the photodiode 3 and the waveguide 5 are integrally formed on the substrate 7.