▎ 摘　　要

Graphene with ultrasensitive, real-time and label-free electrical detection has attracted interests to be used as a bioelectronic platform for sensing biomolecules in different fields. Using graphene nanoribbons solves zero gap energy problem of graphene and makes it suitable to use directly in transistor applications such as field effect transistors. Researchers are always looking for the high sensitivity of biosensors to detect low concentrations of biomolecules in biological samples. In this work, by introducing two important parameters: width of ribbons and portions of first three subband indexes in conductance, an analytical model is proposed for graphene nanoribbon's conductance. Here for the first time, the sensitivity of transistors to detect low concentration of biomolecules as a powerful and flexible electronic biosensor is controlled by using the width of graphene nanoribbons. Finally, FET device as a biosensor according to an experimental work to detect concentration of biomolecules, charge and thickness of membranes is calibrated.