NOVELTY - Activated or functionalized metallic, semiconductor, polymer, composite and/or ceramic substrate (I), which is/are bound through a mixed or graded interface to a hydrophilic plasma polymer surface that is activated to enable direct covalent binding to a functional biological molecule, where the plasma polymer surface comprises a sub-surface that includes many cross-linked regions, is claimed.    USE - (I) is useful in a device, which is a diagnostic kit, biosensor, fuel cell or device for chemical processing, cell or tissue culture scaffold, analytical plate, assay component or medical device (preferably a contact lens, stent, pace maker, hearing aid, prosthesis, artificial joint, bone or tissue replacement material, artificial organ, heart valve, replacement vessel, suture, staple, nail, screw, bolt or other device for surgical use or other implantable device) (all claimed). (I) is useful in device, which is: used in the production of ethanol by the action of enzymes on sugars or cellulose or other agents; complementary metal-oxide-semiconductor devices, that can be used for the detection of biological molecules; used in the production of chemical products (e.g. bulk or fine chemicals, drugs, proteins, peptides, nucleic acids, polymers and food supplements).    ADVANTAGE - The functional biological molecules can covalently bind to (I) in simple manner, without the need to use linker molecules, hence time consuming and potentially costly and complex wet chemistry approaches for linkage are not required. (I) exhibits extensive shelf life. The enzyme functionalized surface can be rapidly and conveniently replaced with another fresh functionalized surface in the event that the enzymes become poisoned or are otherwise rendered inactive, without the need to dispose of the entire batch of chemicals.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method of producing (I), comprising: (a) exposing a surface of the substrate to plasma ion implantation with carbon containing species; co-deposition under conditions in which substrate material is deposited with carbon containing species while gradually reducing substrate material proportion and increasing carbon containing species proportion; and/or deposition of a plasma polymer surface layer with energetic ion bombardment; and (b) incubating the surface treated in step (a) with a desired biological molecule; and    (2) a method of enhancing the activation of (I) or re-activating (I) comprising carrying out step (a) under annealing conditions.    DESCRIPTION OF DRAWING(S) - The figure shows schematic diagram of the capacitively coupled plasma treatment chamber with facility for controlling substrate bias, useful in methods of activating surfaces of metal, semiconductor, polymer, composite and/or ceramic substrates.