Antigen-Antibody Interaction-Based GaN HEMT Biosensor for C3G Detection

In this paper, we demonstrate the design and fabrication of an AlGaN/GaN High Electron Mobility Transistor (HEMT) as a bio sensing platform. Bio-compatible functionalization process with thioglycolic acid and antibody-antigen immobilization process with EDC-NHS chemistry is optimized, and the AlGaN/GaN HEMT biosensor is validated using recombinant C3G (RAPGEF1) protein and an indigenously developed mouse monoclonal antibody (clone 3F6mAb). The designed biosensor with its extended source-drain pads and inter-digital gate sensing design increases sensitivity of device to detect low concentration of biological samples. C3G protein is detected by antigen-antibody conjugation over extended functionalized sensing gate area which resulted in 36.2% change in drain current output and the corresponding antigen is detected up to 500 pg/ml. The biosensor shows a resolution in mA range, which is easily implementable by circuit due to low noise factor. It can therefore be adopted for use to detect antigens in very small biological samples, required in diagnostic assays of bio-medical applications.