Structural, optical, and electrochemical characterization of TiO_2-x thin films for non-enzymatic amperometric glucose...

This work presents a novel approach to non-enzymatic glucose sensing based on oxygen-deficient titanium dioxide (TiO_2-x) thin films deposited on metallic titanium substrates. The TiO_2-x films were fabricated via RF magnetron reactive sputtering using a titanium target, and their structural, morphological, optical, and electrochemical properties were comprehensively characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy, and electrochemical techniques. The electrochemical performance was evaluated using cyclic voltammetry (CV) and chronoamperometry. The CV results revealed that the oxidation in phosphate buffer solution occurs at an applied potential of -0.54 V, increasing with a glucose concentration. Chronoamperometric analysis demonstrated a high sensitivity of 27.55 μA cm^-2 mM^-1 and a low detection limit of 0.11 mM. The sensor also exhibited a linear dynamic range from 0.2 mM to 2.4 mM and excellent selectivity against common interfering species, including histidine (His), cysteine (Cys), uric acid (UA), ascorbic acid (AA), and sucrose. These findings highlight the potential of Ti/TiO_2-x electrodes as efficient, stable, and selective platforms for developing non-enzymatic glucose sensors suitable for biomedical and wearable applications, with possible use in detecting glucose concentrations in sweat (0.27 mM-1 mM) and saliva (0.23 mM-1.78 mM).