A THz radiation detector comprising a vertical antenna separated from a suspended platform by an isolating thermal air gap for concentrating THz radiation energy into a smaller suspended MEMS platform upon which a thermal sensor element is located. THz photon energy is converted into electrical energy via a thermally isolated air gap between plates of a coupling capacitor that couples energy from the antenna to the thermal sensor. The capacitor plates used for capacitive coupling of the received signal realize an electro-static actuator whereby the application of a DC bias varies the coupling capacitor gap. The DC bias causes the actuator to pull the suspended platform close to the antenna to reduce the capacitive gap, increasing the coupling capacitance, to touch the antenna array thus quickly discharging the heat induced in the sensor platform or to perform advanced readout operations, such as amplitude modulation and correlated double sampling.