Thanks to their large surface-to-volume ratio, silicon nanowires (Si NWs) are extremely sensitive to all phenomena which could alter their surface potential and charge distribution. Those surface variations lead to a change of the Si NWs equivalent conductance. The use of the output conductance of a silicon nanowire as a compact transducer for direct detection of (bio)chemical molecules or gases has gained immense attention these last years. In this paper, fabrication of silicon nanowires using top-down approach is shown, with simple calculations to determine hole mobility, hole concentration and resistivity. Transfer characteristics and sampling measurements were performed on the nanowires with and without surface functionalization under various ambient conditions indicating the importance of functionalization in order to avoid any environment effect on the transport properties of the nanowires