a thin film matrix for biomolecules , suitable for forming electrochemical and biosensors comprising a general class of materials known as hydrous metal oxides which are also conductive or semiconductive of electrons and which have been shown to have excellent stability against dissolution or irreversible reaction in aqueous and nonaqueous solutions . the composites are bifunctional , providing both amperometric and potentiometric transduction . the thin film composites of the oxides and biological molecules such as enzymes , antibodies , antigens and dna strands can be used for both amperometric and potentiometric sensing . hydrous ir oxide is the preferred matrix embodiment , but conducting or semiconducting oxides , of ru , pd , pt , zr , ti and rh and mixtures thereof have similar features . the hydrous oxides are very stable against oxidation damage .