(Invited) Planar Field Effect Transistor Biosensors: Toward Single Molecular Detection and Clinical Applications

In this research, a recessed gate AlGaN/GaN heterojunction field effect transistor (HFET) is demonstrated for biodetection sensitivity improvement. The measurements are performed on a zero-bias gate configuration to eliminate the noise and electrochemical activities from the gate electrode. A detection limit in terms of the concentration is demonstrated at 16 aM on a gate-recessed AlGaN/GaN bioHFET for streptavidin (SA) detection. The reduction of low frequency noise contributes to the signal to noise ratio (SNR) improvement. The recessed AlGaN/GaN bioHFETs have also been characterized in direct detection of biomarkers in physiological fluids at low concentrations for early-stage transplant rejection diagnostics. The electrical measurement results from recessed AlGaN/GaN bioHFETs are consistent with the patients' clinical behavior.