Obtaining biocompatible skein shaped silicon nanowires covered field-effect transistors (SiNWFETs) is reported. Such structures are formed by the growth of Si nanowires on top of the polysilicon gate terminal of a n-MOSFET in three-probe top-gate geometry for cells membrane electrical charge detection suitable in biological applications such as cancer investigations. We observe that electro-negativity increment of metastatic cells outer membrane restricts the drain current of bioFET. SiNWFET is proposed to be used covered with skein SiNW. Different invasive grades of colon cancers (HT29 and SW48) owing to their dissimilar negative charge production, affect the electrical response of the device.