The ionization of gases results in a unique fingerprint depending on their nature and concentration. Moreover, according to Paschen's law, the measurement of distinct species is possible by modifying the distance between the electrodes. In order to analyze gaseous compounds within a mixture, a novel MEMS tunable sensor incorporating freestanding nanowires is proposed. This device allows controlling the ionization gap by capacitive actuation. Mechanical and electrical characterizations, together with finite elements simulations have been conducted in order to evaluate electric field interactions and minimize interferences. Such system should allow the development of a universal gas sensor with pattern recognition.