Chemical sensors based on randomly stacked graphene flakes.

We demonstrate a simple fabrication method to produce randomly stacked graphene chemiresistors using surfactant-assisted exfoliation of graphite. We analyze the sensitivity of such chemiresistors as a function of vacuum filtration volume and temperature. At low vacuum filtration volumes (<∼5 mL) the sensors exhibit superior sensitivity towards target molecules compared to previously developed polycrystalline graphene, polycrystalline graphene microribbon, and carbon nanotube chemical sensors. Temperature dependent measurements, transmission electron microscopy and scanning electron microscopy suggest the improved sensitivity in the randomly stacked graphene chemiresistors is due to 2-dimensional charge carrier hopping through edge defects. [ABSTRACT FROM AUTHOR]