**Abstract**

According to principle of the operation, gas field ionization sensors are classified as transduction-based gas sensors. These sensors identify the unknown gases based on their unique ionization properties such as breakdown voltage or tunneling current. Appling 1D nanostructure in gas ionization sensors would enhance the local electric field at the tip of the structures. The average field enhancement coefficient (βtol), considering constructive/destructive interferences of the local electric field of thousands of nanowires in the whole structure, is desired to optimize the design and structure of the gas sensors. Using chemical/electrochemical techniques silicon nanowires were grown on one of the electrodes of the gas sensor. Mechanism of the nanowires formation was modeled and simulated using COMSOL multiphysics simulation tool prior to their fabrication. A gas field ionization tunneling sensor, was designed, fabricated, and tested successfully for several gases like N2, He, and Ar. Estimated βtol of the sensor showed that the electric field strength inside the sensor is 3750 times greater than a planar parallel-plate sensor causing to reduce the breakdown voltages from several thousand volts to the range of 60–70 V for various gases.

**Keywords:** gas ionization sensor, tunneling current, field enhancement factor, COMSOL, silicon nanowires
