With its origin estimated around December 2019 in Wuhan, China, the ongoing SARS-CoV-2 pandemic is a major global health challenge. The demand for scalable, rapid and sensitive viral diagnostics is...

Since the COVID-19 outbreak was declared a pandemic by the World Health Organization (WHO) inMarch 2020, ongoing efforts have been made to develop sensitive diagnostic platforms. Detection of viral RNA provides the highest sensitivity and specificity for detection of early and asymptomatic infections. Thus, this work aimed at developing a label-free genosensor composed of graphene as a working electrode that could be embedded into a flex printed circuit board (FPCB) for the rapid, sensitive, amplificationfree and label-free detection of SARS-CoV-2. To facilitate liquid handling and ease of use, the developed biosensor was embedded with a user-friendly reservoir chamber. As a proofof-concept, detection of a synthetic DNA strand matching the sequence of ORF1ab was performed as a two-step strategy involving the immobilization of a biotinylated complementary sequence on a streptavidin-modified surface, followed by hybridization with the target sequence recorded by the differential pulse voltammetric (DPV) technique in the presence of a ferro/ferricyanide redox couple. The effective design of the sensing platform improved its selectivity and sensitivity and allowed DNA quantification ranging from 100 fg/mL to 1 µg/mL. Combining the electrochemical technique with FPCB enabled rapid detection of the target sequence using a small volume of the sample (5-20 µL). We achieved a limit-of-detection of 100 fg/mL, whereas the predicted value was ∼33 fg/mL, equivalent to approximately 5 × 10 5 copies/mL and comparable to sensitivities provided by isothermal nucleic acid amplification tests. We believe that the developed approach proves the ability of an FPCB-implemented DNA sensor to act as a potentially simpler and more affordable diagnostic assay for viral infections in Point-Of-Care (POC) applications. Index Terms-DNA, graphene, flex printed circuit board (FPCB), SARS-CoV-2, streptavidin-biotin complex. I. INTRODUCTIONT HE rapid spread of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and fatal progression of the coronavirus infectious disease (COVID-19) has attracted Manuscript