▎ 摘　　要

Based on a model of the optical biosensors [Heller et al., Science 311, 508 (2006)] by wrapping a piece of double-stranded DNA around the surface of single-walled carbon nanotubes (SWCNTs), we propose a new design model of this sensor, in which the SWCNT is replaced by a semiconductor graphene ribbon (SGR). Using a simple theory of exciton in SGRs, we investigated transition of DNA secondary structure from the native, right-handed B form to the alternate, left-handed Z form. This structural phase transition of DNA is the working principle of this optical biosensor at the sub cellular level from DNA and semiconductor graphene ribbons. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4728196]