▎ 摘　　要

There is a broad interest in using graphene or graphene oxide (GO) sheets as a transducer for selective and label-free detection of biomolecules such as DNA, tumor marker, biological ions, etc. Here, a chemical vapor deposition (CVD) graphene-based Hall effect biosensor used for ultrasensitive label-free detection of DNA via DNA hybridization is reported. Hall effect measurements based on the Van der Pauw method are used to perform single-base sequence selective detection of DNA on graphene sheets, which are prepared by CVD. The mobility decreases and the sheet resistance increases with the adding of either complementary or one-base mismatched DNA to the graphene device. The hole carrier concentration of the graphene devices increases apparently with the addition of complementary DNA while it is hardly affected by the one-base mismatched DNA. The detection limit as low as 1 pM was realized with a linear range from 1 pM to 100 nM. Moreover, the Hall effect biosensor was able to distinguish the complementary DNA from one-base mismatched DNA with a high specificity of approximate to 6.2 which is almost two orders of magnitude higher than that of the previously reported graphene biosensors based on DNA-DNA hybridization.