The ion sensitive field effect transistor (ISFET) sensor based on microfluidics induced films is reported in this paper. The graphene film demonstrates controllably tunable thickness different from the conventional graphene composites, and the sensor has a long-term stability in chemical detection. Using capillarity to introduce a graphene suspension solution to a microfluidic system, the graphene film patterns were confined and formed in microchannels. SEM, AFM and Raman spectroscopy were used to analyze the graphene films, demonstrating the tunable thickness of the graphene films in the microchannels. Ambipolar characteristics of the graphene ISFET were also presented. The long-term stability of the ISFET was investigated, and compared with graphene/polymer composites under the same patterning and measurement conditions.