Electronic metadevice comprising a conductive channel; a metal layer superposed on the conductive channel; and a barrier layer located between the metal layer and the conductive channel. The metal layer includes at least one recess extending through the metal layer to define at least one metallic metastructure comprising at least one first metal layer portion adjacent to at least one second metal layer portion. The recess extends through the metal layer to define a micro-structured or a nano-structured first metal layer portion comprising at least one first metallic extension or finger extending away from a first support of the first metal layer portion towards the second metal layer portion; and a micro-structured or a nano-structured at least one second metal layer portion comprising at least one second metallic extension or finger extending away from a second support of the second metal layer portion towards the first metal layer portion.