Diamond-coated QCM (Dia-QCM) sensors were fabricated using linear antenna microwave plasma CVD, enabling single- and double-sided coatings (FZU technological breakthrough). Double-sided Dia-QCMs showed superior ethanol vapor sensing, with responses 3x (single-sided Dia-QCM) and 12x (bare gold QCM) higher. Single-sided Dia-QCM aptasensors for SARS-CoV-2 S-RBD protein exhibited a 2x higher response and lower detection limit (0.09 pg/mL) than gold QCMs (0.10 pg/mL). The aptasensor's specificity was confirmed against N-protein. In human plasma, the Dia-QCM aptasensor detected S-RBD protein down to 50 pg/mL with high recovery rates (91-97%). The porous diamond morphology, achieved by controlled CVD, enhances sensitivity. These findings demonstrate Dia-QCM's potential for improved gas sensing, rapid diagnostics, and point-of-care testing, offering significant advantages over traditional QCM sensors. The CVD method is suitable for scaled production.
