New electrochemically improved tetrahedral amorphous carbon films for biological applications

• Data about the influence of topography on the electrical properties of thin DLC films is provided.
• In-depth discussion to explain the above dependency is included.
• Electrochemical properties of the new DLC thin film electrodes are provided.
• New DLC electrodes show two orders of magnitude increase in their sensitivity towards DA.
• Dopamine is shown to exhibit complex reactions on top of these new DLC electrodes.

Carbon based materials have been frequently used to detect different biomolecules. For example high sp3 containing hydrogen free diamond-like carbon (DLC) possesses many properties that are beneficial for biosensor applications. Unfortunately, the sensitivities of the DLC electrodes are typically low. Here we demonstrate that by introducing topography on the DLC surface and by varying its layer thickness, it is possible to significantly increase the sensitivity of DLC thin film electrodes towards dopamine. The electrode structures are characterized in detail by atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM) as well as by transmission electron microscopy (TEM) combined with electron energy loss spectroscopy (EELS). With cyclic voltammetry (CV) measurements we demonstrate that the new improved DLC electrode has a very wide water window, but at the same time it also exhibits fast electron transfer rate at the electrode/solution interface. In addition, it is shown that the sensitivity towards dopamine is increased up to two orders of magnitude in comparison to the previously fabricated DLC films, which are used as benchmarks in this investigation. Finally, it is shown, based on the cyclic voltammetry measurements that dopamine exhibits highly complex behavior on top of these carbon electrodes.