The paper presents a reproducible and fully complementary metal-oxide-semiconductor (CMOS) compatible technique for fabricating silicon nanowire sensors for biochemical analysis. Top-down approach for fabricating silicon nanowire has been explored to achieve silicon nanowire dimension up to ~150 nm. Presented fabrication technique is based on the fact of 44 % silicon consumption during thermal oxidation process. Fabricated nanowires are further processed to make silicon nanowire sensors. These nanowire sensors respond to the change in applied back-gate voltage. To prove the advantage of nanowire sensors over micron dimension sensors, two sensors with different silicon wire width (1. 5 and 0. 29 μm) are characterized for the same back-gate voltage and the current modulation was observed to be 25. 05 % and 54. 9 %, respectively. These silicon nanowire sensors are characterized for repeatability as well. © 2012 Springer Science+Business Media, LLC.