A Low-drift Extended-Gate Field Effect Transistor (EGFET) with Differential Amplifier for Cordyceps Sinensis DNA Detection Optimized by gm/ID Theory

An extended-gate field effect transistor (EGFET) integrated with a differential MOSFET amplifier and an open-source Arduino Yun MCU system was realized for detection of Cordyceps Sinensis DNA molecules. A gold microelectrode chip coated with a single-stranded DNA probe, as the extended gate was fabricated by MEMS fabrication processes. The differential MOSFET amplifier and additional coating of alkyl-thiol reduced the drifting by one order of magnitude. Moreover, generalized gm/ID theory was used to study the optimized working regime of the EGFET sensor. The highest electric-electrochemical sensitivity could be achieved in the Moderate Inversion (MI) regime. The sensitivity and limit of detection (LOD) of the EGFET sensor were obtained to be 13.85mV/dec and 10nM, respectively. This low-cost low-drift EGFET sensor system is promising for Internet of Living Things in the near future.