However, for increased cells' concentration, the cell suspension was observed to be accrued with yeast cells forming a biofilm on the surface and impeding the aeration thereby limiting the cell growth. Therefore, the yeast cell concentration is considered to be a trade of exfoliation efficacy versus functional cell growth. Ordinarily, the transition from bulk to few layer carbon sheets results in the significant changes in the Raman spectroscopy parameters such as D/G, FWHM and band positions which directly correspond to functional and lattice state of the exfoliated sheets. Therefore, the incubation time (cell growth) based Raman spectra were obtained with incubation intervals of 0 min, 6 h, 1 day, and 1 week (supplementary file, Figure ). The change in the G peak position and integrated area ratio (AD/AG) with respect to incubation time is shown in Fig. . The red shift in the G band suggests the presence of strained sheets, which can be due to the stretching of the sheets by the yeast cells leading to elongated C-C bonds (supplementary Fig. ). Further, the AD/AG ratio, influenced by the functionalization of the prepared structure, was found to increase with increasing incubation time. The spectra, obtained for 0 min of incubation time, exhibited a feeble D peak suggesting the precursors to be free of defects. The intensification of the D band with increasing incubation time is attributed to the functionalization of the edges owing to the yeast cells driven exfoliation. The AD/AG ratio was further explored to evaluate the in plane sp 2 crystallite size, La, according to the relation given by Cançado et al. for graphitic materials, wherein La was reported to be inversely proportional to AD/AG. The relative La was plotted with respect to incubation time as shown in Fig. .