Green Synthesized WO3-PEDOT:PSS Composites into Benzoid-Rich Conformation for Nonenzymatic Bioelectronic Tongues for Tannic Acid-Based Wine Astringency Detection

This study introduces electrochemical sensor materials based on a conductive polymer PEDOT:PSS and a green-synthesized WO3 electrode (i.e., polymer composites of PEDOT:PSS@WO3-n, where n = 1-3 with three wt. ratios of PEDOT:PSS/WO3 = 1/1, 1/2, and 1/3, respectively) to directly measure tannic acid in beverages. Besides the conductive polymer PEDOT:PSS alone, the electro-exploding wire technique is used to prepare WO3 nanoparticles and their modified polymer composites of PEDOT:PSS@WO3-n (n = 1-3), thereby imparting a benzoid-rich conformation and improving its electrochemical sensitivity to tannic acid astringency. The optimum electrochemical sensor device of PEDOT:PSS@WO3-2 (where n = 2 with the wt. ratio of PEDOT:PSS/WO3 = 1/2) demonstrates robust performance in real beverage samples, such as white, red, and rosé wines. The linear response range of the PEDOT:PSS@WO3-2 sensor device is 0.1-0.5 mM, with linearity extending to 0.7 and 1.0 mM, with a high sensitivity of 767.8 μA mM-1 cm-2 and a low limit of detection (LOD) of 2.6 μM, enabling detection of even low tannin concentrations. This high sensitivity and broad dynamic range of the optimum electrochemical sensor underscore the sensor's practical utility for real-time quality control, providing a fast and reliable method for quantifying tannic acid astringency across diverse beverages.