A biosensor is an analytical device that can detect a biomolecule-related element with an appropriate transducer to generate a measurable signal from the sample. In general, graphene possesses attractive qualities for sensors and biosensors, such as ultra-high charge mobility, transparency, large surface area, non-toxicity, high-tensile strength and high thermal conductivity to name a few. However, for graphene to maintain these properties, it has to be kept in a pretty pure form.