Comparative study of the capacitance sensitivity of interdigital capacitive sensors based on graphene for the measurement of Cd+2 concentration

Ludeña-Choez J.; Choquehuanca-Zevallos J.J.; Carranza-Oropeza M.V.; Salas-Arias E.C.; Pérez-Montaño H.S. · Computers and Electronics in Agriculture (2025) · DOI: 10.1016/j.compag.2024.109810

Resumen

Monitoring heavy metals in different matrices has gain uttermost importance for the environmental and food safety around the world. This research present two graphene-based Interdigital Capacitive Sensors to measure concentrations of cadmium ions on aqueous medium. Both sensors were built through pulsed laser deposition technique applied to on polyimide. The SEM and XRD analysis on sensors indicate the formation of a heterogeneous layer; the morphological arrangement on the parallel ridges suggests that the generated graphite is biaxially organized. Experiments were conducted with an 80 kHz excitation signal and the electrical impedance (Z) measurements are used to characterize the sensing devices. The experimental results demonstrate that both sensors show a high precision since the relative standard deviations are 3.02% and 0.78% for sensors 1 and 2, respectively. Regarding the accuracy, the sensors show a low difference when the sensor readings are compared to the true concentration level, with average variabilities of 4.35% for sensor 1 and 5.63% for sensor 2. Another parameter to show the importance of obtained sensing device is their minimum detection limit. These values are 0.086 ppm for sensors 1 and 0.03 ppm for sensor 2, and the quantization limits are 0.276 ppm for sensor 1 while for sensor 2, it is 0.06 ppm. Thus, the above results have demonstrated that the flexible graphene-based sensing device is useful for measuring cadmium and experiments can be extended to cover other heavy metals. Lastly, because the resultant sensors exhibit desirable qualities to be used in other fields (high stability, simplicity, small size, and low cost) they may find different applications in other domains, for instance, as biosensors.

Instituciones: Universidad Nacional Mayor de San Marcos; Universidad Católica San Pablo