A large-area and contamination-free graphene transistor for liquid-gated sensing applications

Abstract

We present a simple, low-cost, large area, and contamination-free monolayer graphene field-effect transistor for liquid-gated sensing applications. The graphene surface does not require any photoresist including the commonly used polymethylmethacrylate, thus avoiding possible contamination and mobility degradation. We also examine the effects of different etching solutions and concentrations on the Dirac point of graphene. With optimal device fabrication recipe, we demonstrate the device's capability to sense different KCl concentrations and pH values under liquid gating configuration. Additionally, using polydimethylsiloxane as substrates holds an advantage of enabling simple integration between microfluidic systems and graphene for chemical and biological sensor applications. V

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“…In Fig. 3 we show schematically how we have used our expertise in polymer thin films and combined it with a recently reported transfer method for large-area CVD graphene [21,22,32]. Each PEMA/toluene solution (0.8%e1.6%, w/w) was spin coated onto the graphene side of a graphene/copper foil system at a speed of 2000 rpm for 30 s. The copper foil was then etched away using a 1 M aqueous solution of FeCl 3 for 16 h. The PEMA/graphene bi-layer was then rinsed with deionized water.…”

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