The electrical and physical characteristics of Mg-doped ZnO sensing membrane in EIS (electrolyte–insulator–semiconductor) for glucose sensing applications

Zinc oxide (ZnO) nanostructures possess several interesting characteristics, which make them ideal sensing materials in biological and industrial applications. In this study, we investigate the pH and ion-concentration sensing properties of an electrolyte–insulator–semiconductor (EIS) device based on Mg-doped ZnO. EIS devices are highly sensitive to changes in the nature of the electrolyte, making them ideal for a wide range of applications. These devices, deposited by reactive RF co-sputtering on a silicon substrate, require rapid thermal annealing in an oxygen atmosphere for optimal sensing activity. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) analyses were performed to correlate the structural properties with the sensing performance. The highest sensitivity to pH and ion concentrations, lowest hysteresis, and lowest drift rate were observed on a Mg-doped sample annealed at 700 °C. EIS devices based on Mg-doped ZnO can be used as suitable sensors for future biomedical applications.