In summary, we have demonstrated a dielectric-modulated field-effect transistor coupled with a 15-nm vertical nanogap that detects the binding of streptavidin to biotin using an allelectrical, CMOS-compatible technique, without the need for a labelling process. The proposed device shows much better sensitivity than several previously reported FET nanogap
biosensors for detecting biomolecules, especially protein– ligand binding. Furthermore, by measuring data after breaking the biotin–streptavidin binding and from control group experiments, we verified that biotin–streptavidin binding is the dominant factor in determining the shift in the threshold voltage. In addition, it is expected that such DMFET-type biosensors will have the capability to detect a number of protein molecules, such as DNA, cancer markers and antibodies, and could be used as a part of a lab-on-a-chip for full electronic detection.