Electromagnetic Characterization of Aqueous Sodium Lactate Solutions and Its Application for Enhanced Concentration Monitoring.

This article presents the electromagnetic (EM) properties of sodium lactate (C3H5NaO3)/water mixtures in the dc-to-microwave frequencies range and its exploitation for sensing purposes. EM features of solutions are characterized and modeled, while underlying physical phenomenon are explained. Then, intrinsic properties of the sodium lactate molecule and its consequences upon aqueous solutions are exploited to monitor concentrations. The proposed sensor is based on a coupled-resonators principle and works around 7 GHz, it features ability to extract sodium lactate concentrations in aqueous solutions within the 0-4.2 mol.L-1 range with a relative error lower than 8% if the sample temperature is given. Indeed, in addition to the extraction of the sodium lactate concentration, the proposed sensor also features the ability to monitor, simultaneously, temperature of the sample within the 15 degrees C-35 degrees C range. This innovative bi-parameter (sodium-lactate concentration and temperature), radio frequency-based monitoring exhibits precisions better than 5.2% on the sodium lactate concentrations and 12% on the temperature when these parameters are simultaneously extracted.