• Acoustic Biosensors
• Antifouling
• Bioreceptors
• Bovine Serum Albumin
• Bulk Acoustic Wave
• EDC/NHS
• Ethanolamine Blocking
• Ethylenediamine Blocking
• Functionalization
• Gelatin-A
• Hydroxytyrosol
• Lab-On-Chip
• Olive Oil
• Olive Ripening
• Polyphenols
• QCM-D
• Surface Chemistry

The quantification of polyphenols in olives during maturation could be a useful parameter for determining the optimal ripeness and harvest time, thus contributing to the production of high-quality olive oil. This study explores Bulk Acoustic Wave (BAW) sensors based on Quartz Crystal Microbalance with Dissipation (QCM-D) for monitoring polyphenols, like hydroxytyrosol, in olives. Glucose was selected as a non-specific molecule due to its possible presence in olive samples. Two bioreceptors, Bovine Serum Albumin (BSA) and Gelatin-A (Gel-A), were tested, immobilized on a 12-Mercaptododecanoic acid (12-MDA) adlayer under non-activated and EDC/NHS-activated conditions (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide strategy). The results showed that Gel-A, when immobilized on the non-activated adlayer, exhibited significantly higher selectivity for hydroxytyrosol than for glucose, suggesting promising effectiveness of Gel-A as a probe. Conversely, BSA was inefficient in distinguishing the analyte from non-specific molecules. Ethylenediamine (EDA) proved to be a better blocking agent than ethanolamine (ETA). This biosensor approach, easily adaptable to Lab-On-Chip platforms, could enhance in situ polyphenol assessment, optimizing harvesting efficiency and olive oil quality.