The development of Terahertz optoelectronic devices is a subarea of major currently ongoing advanced research effort. Electronic and photonic solidstate devices reache fundamental limitations in Terahertz frequency range, therefore this development is very crucially relying on the availability of new materials, new physical mechanisms, new device designs, and new fabrications/approaches. Here we explore terahertz detectors based on engineered plasmonic structure. We report a record sensitivity of 6.4 kV/W and noise equivalent power (NEP) of 15 pW/Hz in the above 1 THz region. The key point of this major breakthrough is careful design and fabrication of Field Effect Transistor (FET) structures combining i) interdigitated metal gates that ensure efficient coupling with incoming terahertz electromagnetic field and ii) an asymmetric metallization scheme that breaks the mirror symmetry of the internal electric-field profile in the channel 1. Terahertz detection has only been reported mainly in the subterahertz regions (0.1-1THz) with sensitivities of about five times weaker in Schottky barrier diodes (SBDs 2), as well as conventional single-gate plasmonic FETs 3 and symmetric grating gates plasmonic (S-DGG) FETs 4.