▎ 摘　　要

NOVELTY - The transistor (100) has a graphene film (102) which is disposed on the substrate (104). An ion selective membrane (112) is disposed on the graphene film, and has an ionophore, a lipophilic salt, and a polymer having a molecular weight ranging from about 100,000-200,000 Daltons. The polymer has a glass transition temperature ranging from about 20-60 degrees Celsius. The polymer is a block copolymer having a continuous amorphous phase and a discontinuous crystalline phase. The continuous amorphous phase has n-butyl acrylate and the discontinuous crystalline phase has methyl methacrylate. USE - Graphene ion selective field effect transistor for ion sensing device (claimed), e.g., for implantable bio-sensing applications. ADVANTAGE - Enables easy ion transportation across the membrane towards the graphene surface. Enhances sensitivity by using valinomycin as ionophore when designing a sensor to detect potassium to act as a functionalization layer on the graphene surface of the graphene ion sensitive field effect transistor. The mobile cation exchange sites of the lipophilic salt can reduce the membrane resistance and activation barrier for the cation-exchange reaction at the ion selective membrane/test solution interface, reducing the ionic interference significantly and increasing the ion-detection sensitivity of the transistor. The graphene is inherently compatible with flexible substrates due to its own flexible nature and easy transfer process of chemical vapor deposition (CVD) of graphene to various substrates without undergoing any cumbersome fabrication process. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following: (1) an ion sensing device; and (2) a method of forming the graphene ion selective field effect transistor. DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of the graphene ion sensitive field effect transistor. Graphene ion selective field effective transistor (100) Graphene film (102) Substrate (104) Graphene channel (110) Ion selective membrane (112)