A biosensor device and a method of manufacturing a biosensor device

A biosensor device comprising a doped graphene layer structure having electrical contacts separating a sample surface for receiving an analyte composition to be tested. The graphene layer is doped with nitrogen in an amount of 1 at% to 10 at%. The sample surface is functionalised with analyte receptors. Each analyte receptor is bound to a nitrogen atom by a covalent linker moiety. The biosensor can comprise a non-metallic substrate. The substrate can comprise silicon, silicon carbide, silicon nitride, silicon dioxide, sapphire, hafnium dioxide, yttria-stabilised zirconia, magnesium aluminate, yttrium orthoaluminate, strontium titanate, calcium difluoride, germanium and a III/V semiconductor. The linker can comprise a polyethylene glycol spacer. A further aspect is a method of manufacturing the biosensor device, the method comprising reacting the doped graphene layer with linker precursor molecules and reacting the precursor molecules with analyte receptors. The method can comprise an amidation reaction. The method can use a carbon containing precursor (e.g., a pyridine, diazine, triazine, or alkylamine). The doped graphene layer can be formed in a CVD reaction chamber on a heated susceptor, the chamber having cooled inlets, wherein the inlets are cooled to less than 100oC and the susceptor is heated to at least 50oC.