A nanoplasmonic resonator comprising a metallic nanodisk with alternating shielding layer, having a tagged biomolecule conjugated or tethered to the surface of the nanoplasmonic resonator for highly sensitive measurement of enzymatic activity. Water is not included as an ingredient. The coils are supplied with current pulses that are shorter than the sine oscillations. To reduce or eliminate corrosion of the carbon catalyst support, the carbon support may have a metal surface treatment and, in particular, a metal carbide surface treatment.