Enhancing Sensitivity Beyond Nernst Limits Using a CeO₂ Capacitive EIS Sensor for ssDNA Detection Applications

This study examines a CeO2-based electrolyte–insulator–semiconductor (EIS) sensor developed through sol-gel processing, focusing on its effectiveness in detecting pH levels and single-stranded DNA (ssDNA). Characterization using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) reveals the structural and chemical properties of the CeO2 sensing film. The CeO2-based EIS sensor exhibited exceptional performance, with a sensitivity of 67.63 mV/pH, minimal hysteresis voltage (0.1 mV in the pH loop), and excellent stability, demonstrated by a drift rate of 0.45 mV/h. Reduced moisture during CeO2 synthesis leads to fewer crystal defects and increased surface roughness, shifting ceria’s oxidation state from Ce3+ to Ce4+ (2CeO
$_{{2}}~\to $
Ce2O3 + 1/2O2) with fewer electrons in the redox reaction. The CeO2-based EIS sensor demonstrates high sensitivity and reliability in gene detection, establishing itself as a valuable tool for rapid, precise, real-time monitoring, and versatile DNA interaction analysis. It holds significant potential to revolutionize molecular analysis, genomics research, diagnostics, and personalized medicine.