Glucose Sensing Using Pristine and Co-Doped Hematite Fiber-Optic Sensors: Experimental and DFT Analysis

Glucose monitoring plays a crucial role in managing diabetes, one of the most prevalent diseases worldwide. The development of fast-responsive, cost-effective, and biocompatible glucose sensors is essential for improving patient care. This study investigates the glucose sensing performance of pristine and Co-doped hematite synthesized via the hydrothermal method and integrated into fiber-optic evanescent wave probes. Structural and optical characterizations confirmed the enhanced properties of the Co-doped hematite. The Co-doped sensor exhibited reasonable sensitivity and a significantly improved limit of detection (LoD) of 3.99 mM compared to 6.12 mM for the pristine hematite. Density functional theory calculations further revealed an increase in glucose adsorption energy from -0.24 eV for the pristine surface to -1.28 eV for the Co-doped surface. Charge density difference and projected density of states analyses showed enhanced charge transfer and orbital delocalization upon doping, consistent with the experimentally observed improvement in LoD. These findings position Co-doped hematite as a promising candidate for noninvasive, nonenzymatic glucose detection and underscore the value of integrating experimental and theoretical approaches in biosensing technologies.