This paper reports on the fabrication, experimental characterization and data transmission application of a double-gate movable body FET. As its name suggests, the proposed movable-body Micro-Electro-Mechanical FET (MB-MEMFET) is a hybrid MEMS-semiconductor device that, in contrast with previously reported Suspended-Gate MOSFET, has a movable body separated by nano-size air gaps from two lateral fixed gates. We report here on the unique abrupt hysteretic characteristic of MB-MEMFET, which for our design offer reproducibility after intense cycling and, due to double gate architecture, a multi-level tunable hysteresis. Based on the $I_D-V_G$ hysteretic behavior of the new hybrid device we report for the first time a FSK circuit exploiting oscillation at two selectable frequencies (26 kHz and 14 kHz) used to transmit numerical data, which demonstrates the potential of the MB-MEMFET for applications in data transmission systems.