Nanowire is mainly used in biological sensor because it has the high surface-to-volume ratio. In this study, we have successfully fabricated the Poly-Si and SiGe nanowire with Ge = 7% and 11 % respectively by side-wall spacer technique. In order to normalize the drive current of nanowires, we consider the nanowire as a resistance. The conductance is chose for comparison between the nanowires. The higher conductance achieved of SiGe nanowire with/without nanowire implantation and the SiGe nanowire with higher Ge concentration had higher conductance. However, the disadvantage of lower contact resistance is found in SiGe pad. The 3-amino-propyltriethoxy-silane (APTES) was used to modify the surface, which can detect the charge with different pH. Comparing the conductance change; the SiGe nanowire with higher Ge concentration improved the sensitivity. But the over-higher Ge concentration (40%) did not increase the sensitivity; the reason maybe the higher defect appears at the surface as higher Ge concentration.