Electrochemical Characterization of Flexible Interdigitated Electrodes for Hydration Monitoring

The use of flexible interdigitated electrodes has in-creased significantly over the last years thanks to the development and optimization of innovative production techniques which allow to realise tailored sensors geometries. Actually, interdigitated geometry improves the measurement sensitivity and allows to use small sample volumes. This is of particular interest in biomedical applications, where the possibility to have a substrate that conforms to the body is crucial to obtain reliable results. In this context, impedimetric sensors can offer important applications both in measuring analytes concentration and in monitoring skin hydration, a medical parameter of paramount importance for many patients. The development of wearable sensors can open new possibilities in the field of telemedicine to monitor patients also outside of the hospitals and thus to prevent critical situations. This study provides a comprehensive electrochemical characterization of flexible interdigitated electrodes produced by inkjet printing. The cell constant value is computed by experimental measurements in saline solutions and then their use for hydration monitoring by impedance measurements is shown by in-vitro experiments using agar gel samples. The use of equivalent electrical circuits to model the experimental data allowed to fully describe the electrochemical system, identifying the frequency ranges which are relevant for the proposed application.