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In this work, a novel sensing structure based on Au nanoparticles/HfO 2 /fully depleted silicon-oninsulator (AuNPs/HfO 2 /FDSOI) MOSFET is fabricated. Using such a planar double gate MOSFET, the electrostatic enrichment (ESE) process is proposed for the ultrasensitive and rapid detection of the coronavirus disease 2019 (COVID-19) ORF1ab gene. The back-gate (BG) bias can induce the required electric field that enables the ESE process in the testing liquid analyte with indirect contact with the top-Si layer. It is revealed that the ESE process can rapidly and effectively accumulate ORF1ab genes close to the HfO 2 surface, which can significantly change the MOS-FET threshold voltage (V th ). The proposed MOSFET successfully demonstrates the detection of zeptomole (zM) COVID-19 ORF1ab gene with an ultralow detection limit down to 67 zM (∼0.04 copy/μL) for a test time of less than 15 min even in a high ionic-strength solution. Besides, the quantitative dependence of V th variation on COVID-19 ORF1ab gene concentration from 200 zM to 100 femtomole is also revealed, which is further confirmed by TCAD simulation.

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