Patent ID: 7851202

Claim:
A biosensor for detection of an antigen ( 6 ) by means of an antigen/antibody coupling, consisting of the following elements: a silicon substrate ( 2 ), at least one interdigital electrode pair structure ( 12 ) of electrodes ( 13 ) arranged in pairs accommodated on the silicon substrate ( 2 ) with a spacing between the electrode pairs of maximum 1.0 μm, counter-electrode ( 11 ) accommodated on the silicon substrate ( 2 ), a reference electrode integrated onto the silicon substrate ( 2 ), a first layer made of protein ( 4 ) at least covering over the interdigital electrode structure ( 12 ), a selective second protein layer applied over the first layer which contains a selected capture antibody ( 5 ) corresponding to the detecting antigen ( 6 ) and which can couple to the antigen, and the capture antibody ( 5 ) is immobilized over the interdigital electrode structure ( 12 ) by the protein ( 4 ) of the first layer; wherein if an antigen ( 6 ) is bound to the capture antibody ( 5 ) and the enzyme-labeled detection antibody is ( 7 ) also bound to the antigen, an enzymatic release of a redox-reactive molecule on the sensor surface ( 1 ) occurs and a sensor signal being able to be read out at the interdigital electrode structure ( 12 ) is generated.