Liquid gated graphene field effect transistor is integrated into microfluidic chip for detection of dopamine. The electrical effect of dopamine on transfer properties of graphene field-effect transistor is studied.Graphene is transferred onto a glass slide as the conductive channel and sensing material. The drain and source electrodes of transistor are fabricated by lift-off process. Transfer characteristics of transistor is tested by liquid gate method. The redox reaction between graphene and dopamine is discussed combined with band theory

from the perspective of electron transfer. Pt is adopt as the grid electrode of graphene transistors and 1 nmol/L dopamine solution is detected.