Abstract: An immobilization and reaction matrix based on a polymeric hydrogel for biosensor chips is disclosed, in particular those based on semiconductor chips which are disposed on a completely processed wafer and have, applied thereto, sensor fields which are normally disposed in array format. Such biosensor chips are normally functionalized by employing organic molecules such as, for example nucleic acids such as DNA, RNA, PNA and LNA or derivatives thereof, proteins, sugar molecules or antibodies.