Rapid SARS-CoV-2 Detection Using High-Sensitivity Thickness Shear Mode Sensors

The COVID-19 pandemic, driven by the SARS-CoV-2 virus, has highlighted the pressing demand for accurate and widely accessible diagnostic tools. Standard diagnostic approaches such as reverse-transcription real-time polymerase chain reaction (RT-qPCR) tend to be labor-intensive and slow, underscoring the need for rapid point-of-care solutions. This study presents a novel, low-cost, and highly sensitive diagnostic platform for fast COVID-19 detection. The platform exploits the mass-sensing behavior of thickness shear mode (TSM) transducers to detect and quantify the SARS-CoV-2 nucleocapsid protein by means of polyethylene glycol (PEG)-based chemistry (1). To verify surface functionalization and to assess the influence of the virus lysis buffer, several surface characterization methods were used, namely Digital Holographic Microscopy (DHM), Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. Sensitivity experiments performed with heat-inactivated SARS-CoV-2 samples yielded a sensitivity of roughly 0.256 Hz/TCID50/mL and a limit of detection (LOD) of about 150 TCID50/mL. Specificity was confirmed via cross-reactivity testing. The thorough characterization and sensitivity analysis reinforce the reliability of the platform, positioning it as a strong candidate for efficient and accessible point-of-care COVID-19 diagnosis.