Design and mechanism of photocurrent-modulated graphene field-effect transistor for ultra-sensitive detection of DNA hybridization

Field-effect transistors (FET) using low-dimensional materials has attracted attention for detection of DNA hybridization. Here, we proposed a photocurrent-modulated FET sensor, where the I_{photocurrent(gate)}+I_{photocurrent(DNA)} dramatically enhance the response signal, I_current, compared to a traditional FET sensor. The proposed sensor successfully detects DNA signals with a limit of detection (LOD) down to attomolar concentrations that is nearly 100x lower than a traditional FET sensor. The sensing mechanism is postulated and discussed. The results suggest that photo-coupled modulation opens new avenues for further development of the FET in biosensing applications.