A technological process was proposed in order to integrate fully silicon-nanowire-based field-effect nanodevices on a silicon-on-insulator (SOI) substrate. Thanks to a double reactive ion etching process of the SOI silicon upper layer as well as to a "SiO2 thermal oxidation growth / Al2O3 atomic layer deposition" gate process, silicon-nanowire-based field-effect transistors (SiNW-FET) and silicon-nanowire-based ion-sensitive field-effect transistors (SiNW-ISFET) were fabricated. Focuses were brought on (i) the integration of a suspended N + /P/N + double-junction structure (gate length: ~ 0.75 m and ~ 3.75 m), (ii) the fabrication of a SiO2/Al2O3 all-around surrounding gate structure, (iii) the achievement of low nanowire sections (width: ~ 150 nm, height: ~ 200 nm), and (iv) the final adaptation to the liquid phase analysis thanks to SU8-based waferlevel packaging. According to the proposed process, SiNW-FET and SiNW-ISFET devices showed excellent electrical characteristics in terms of leakage resistance ROFF, subthreshold current slope and ION/IOFF maximal ratio. SiNW-ISFET devices were finally studied for the pH analysis at the submicronic scale (analysed volumes: ~ 10 pL), evidencing standard potentiometric detection sensitivity (~ 56 mV/pH), as well as excellent amperometric detection sensitivity (~ 0.4 current decade per pH) in subthreshold regime.