The simplicity and prospect of energy efficiency of microelectromechanical systems (MEMS) resonatorbased computing devices have captivated considerable research interest in recent years. Hence, they are being explored for ultralow power computing machines, which are currently needed for internetofthings (IoT) applications. Recently, there have been successful demonstrations of fundamental logic gates. However, the realization of complex multifunctional logic devices that involve multiinput and multioutput lines are facing challenges, such as the interconnections between multiple resonators and the limited controllability of the operating frequency. In this study, we demonstrate a 1:2 Demux combinational logic device with improved energy efficiency using the multi vibration modes of a single MEMS resonator. The MEMS device consists of three connected inplane microbeams in the form of a Ushape structure. The actuation and modulation are based on electrostatic forces. The device shows actuation energy of 0.082 fJ and 0.91 fJ for output 1 and output 2, respectively, and switching energy per logic operation of 11.01 pJ for output 1 and 5.31 pJ for output 2. This indicates 75% decrease in switching energy per logic operation in comparison with the previously reported values for electrostatically actuated MEMS resonatorbased computing devices.