Owing to its high carrier mobility, large surface-to-volume ratio, and chemical stability, graphene has drawn considerable attention as the building block for next generation label-free electrical biochemical sensors.[1] However, under physiological conditions, graphene sensors typically cannot detect a biological stimuli occurring at a distance larger than a nanometer from its surface (the so called 'Debye screening length') due to the presence of movable ions.[2] At high frequencies the ions in the electrolyte start to lag behind the alternating current electric field due to the viscosity of the solution.[3] As a result, the electrolyte behaves as a pure dielectric at radiofrequency/microwave frequencies.[2,3] And one can now probe the biomolecules deeply into the electrolyte solutions beyond the Debye screening length. Indeed, with the prospects of on-chip integration of sensor arrays and low-cost mass production, the expected results on graphene radiofrequency devices represent a novel approach for a new generation of portable, point-of-care, label-free biochemical sensors.

Owing to its high carrier mobility, large surface-to-volume ratio, and chemical stability, graphene has drawn considerable attention as the building block for next generation label-free electrical biochemical sensors.[1] However, under physiological conditions, graphene sensors typically cannot detect a biological stimuli occurring at a distance larger than a nanometer from its surface (the so called 'Debye screening length') due to the presence of movable ions.[2] At high frequencies the ions in the electrolyte start to lag behind the alternating current electric field due to the viscosity of the solution.[3] As a result, the electrolyte behaves as a pure dielectric at radiofrequency/microwave frequencies.[2,3] And one can now probe the biomolecules deeply into the electrolyte solutions beyond the Debye screening length. Indeed, with the prospects of on-chip integration of sensor arrays and low-cost mass production, the expected results on graphene radiofrequency devices represent a novel approach for a new generation of portable, point-of-care, label-free biochemical sensors.