Paper Title
STUDY ON ENHANCING NON-ENZYMATIC GLUCOSE DETECTION THROUGH COBALT-SUBSTITUTED HAFNIA

Abstract
This study explores selective glucose sensing using ultrathin (~5 nm) hafnia (HfO₂) films engineered with substitutional cobalt (HCO). These films, produced on silicon substrates via chemical solution deposition (CSD) — a method typically applied to thicker films — exhibit notable glucose-sensing capabilities alongside a structural phase shift from monoclinic to orthorhombic. The incorporation of cobalt into hafnia introduces multivalent cobalt ions and neighboring oxygen vacancies, which enable selective glucose oxidation with minimal interference from common biomolecules such as ascorbic acid, dopamine, and uric acid. Theoretical analyses suggest that the oxygen vacancies create a shallow donor level, significantly enhancing electrocatalytic activity by facilitating charge transfer to the conduction band. Consequently, the sensor demonstrates linear responsivity in the millimolar (mM) range, high selectivity, stability, and reproducibility. The sensor has a linear dynamic range from 2 to 10 mM glucose, covering both hypoglycemic (low) and hyperglycemic (high) blood sugar levels. Additionally, it shows minimal response to interfering species such as ascorbic acid, dopamine, and uric acid. After 15 days of storage in air, the sensor retains approximately 84.1% of its initial detection value. Furthermore, it demonstrates reproducibility with a relative standard deviation (RSD) of 4.06%. These findings underscore the potential of ultrathin CSD-grown HCO films for advancing selective glucose-sensing technologies. Keywords - Non-Enzymatic Glucose Sensing, Chemical Solution Deposition, Oxygen Vacancy.