Patient sample analysis—wild-type and Omicron variants. (A) Dirac voltage shifts from 20 patient oral swabs. Ten confirmed RT-PCR–positive, Ct ≤ 35 (red bars), and 10 confirmed RT-PCR–negative patients (green bars) were collected during the first wave of COVID-19 (wild type/Chicago, IL; March 2021). (B) Blind sample test (as described in Materials and Methods, On-Field Clinical Sample Testing) using aptamer-S–derivatized GFET. (C) Dirac voltage shifts from 16 patient saliva samples, 10 confirmed RT-PCR–negative (green bars) and 6 confirmed RT-PCR–positive patients, avg Ct < 29.14 (red bars), were collected during the Delta/Omicron variant wave (Las Vegas, January 2022). (D) Prediction of remaining collected patients’ saliva samples (Omicron) using a threshold voltage value of 40 mV (green bars, negative; red bars, positive). A and B have error bars from five different sweeps on the same GFET chip whereas C and D have error bars calculated from three different IDS vs. VGS sweeps on a single chip.