Differential centrifugation in the steps of increasing RPMs from 4k (allowing yeast and larger graphite chunks), followed by subjecting the supernatant to 14k RPM in 2 steps to collect the precipitate with smaller exfoliated flakes. The precipitate or the pellet is diluted and rinsed in water. It is further drop-casted on Si substrates with 300 nm SiO2 Height and surface profiles of as prepared graphene sheets were studied using Atomic Force Microscopy (AFM, Agilent Technologies, USA, Model 5100). All the measurements were carried out in air at room temperature (25º C) using a Silicon Nitride Tip (PPP-NCL) in the intermittent contact mode.