Figure 4: The DOS of (a) The pristine SWNT (dashed line), Cytosine-SWNT (solid line) (b) Co-SWNT (dashed line), Cytosine SWNT-Co (solid line) calculated for the corresponding configurations shown in Figure 4 (c,d). (c) A schematic illustration of the SWNT-based chemical sensor for detecting cytosine. (d) A comparison plot of the I-V curves for the devices based on SWNT, Cytosine@SWNT, Co-SWNT, cytosine@Co-SWNT.