Noninvasive Glucose Detection with Biodegradable Electrodes from Rice Starch Functionalized with a Carbon Quantum Dot/Nickel Oxide Nanocomposite

Diabetes mellitus necessitates frequent glucose monitoring, but current methods are often invasive or generate nonbiodegradable waste. This study reports the development of a novel, eco‐friendly, nonenzymatic glucose sensor utilizing a biodegradable electrode fabricated from waste‐derived rice starch, chitosan, and PVA, functionalized with a green‐synthesized carbon quantum dot/nickel oxide (CQD/NiO) nanocomposite. The CQD/NiO is synthesized using Aloe arborescens extract, resulting in materials with enhanced electrocatalytic properties. The integrated biodegradable sensor (CQD/NiO/BS) demonstrated effective electrocatalytic activity toward glucose oxidation, revealing a linear detection range of 0–40 μM with a sensitivity of 21 µA cm −2 mM −1 and a low limit of detection of 0.29 μM. Crucially, the sensor's robustness is confirmed through extensive characterization: it exhibited a unique electrochemical optimum at pH 5 while maintaining performance at a physiological pH of 7, and it displayed a predictable, linear thermal response ( R 2 = 0.991) across the 25–45 °C range. The sensor also demonstrated good selectivity under physiologically relevant conditions. Finally, it showed excellent recovery of 99–105.2% for glucose detection in spiked artificial sweat samples. This work presents a sustainable “waste‐to‐sensing” approach, offering a promising pathway toward developing cost‐effective, biodegradable, and robust noninvasive glucose monitoring systems.