▎ 摘　　要

For realizing the early diagnosis of diseases, detection of gases in exhaled breath in parts per billion (ppb) using compact devices is necessary. Herein, single-stranded-DNA-modified graphene field-effect transistors (FETs) are fabricated and the transfer characteristics are measured. The results reveal that shifts in the transfer characteristics are obtained by introducing ethanol gas at the ppb level, indicating that single-stranded-DNA-modified graphene FETs detect the gas at the ppb level. Moreover, by modifying DNA sequence 1 or sequence 2, the positive and negative voltage shifts of transfer characteristics are observed, respectively. In contrast, the shifts are hardly obtained using DNA sequence 3, which has a rigid conformation for adsorption of molecules. These differences in the behaviors of the transfer characteristics are attributed to the change in DNA conformation when gas is adsorbed. Therefore, single-stranded-DNA-modified graphene FETs have considerable potential to detect various gases at a low concentration depending on the design of DNA sequences, enabling their promising applications in disease diagnosis.