A sensor can selectively detect quantum signatures in charge transfer processes via a tunneling current. In one aspect, the sensor can include a metal electrode having a first surface and a second surface. The sensor can also include an insulator film having a first thickness, a first surface area and a first surface chemistry. The insulator film can be coupled to the metal electrode via the first surface. The sensor can also include a functionalization film having a second thickness, a second surface area and a second surface chemistry. The functionalization film can be coupled to the metal electrode via the second surface. The insulator film and the functionalization film are configured to separate the metal electrode from an electrochemical solution comprising the analyte.