Impedance sensor based on carbon paste electrodes to monitor conductivity changes in electrolytes

Abstract We present a prototype of an unmodified carbon paste electrode sensor (SCPE) with the potential to distinguish electrolyte conductivity changes. Electrodes are placed in a syringe tube that acts as a holder in a coplanar configuration. This design allows for a portable sensor that fits into different electrolyte-holding containers. As proof of concept, a potassium chloride (KCl) suspension was used in a concentration range of 0 to 35 mgL −1 . The operating frequency of the prototype was determined by impedance spectroscopy (IS) analysis, where the sensor presented good sensitivity and the best results. The morphological characterization of the transducer surface, performed by field emission scanning electron microscopy (FeSEM), shows a typical carbon paste surface. Finally, this simple, portable, and reusable design, combined with its low cost, takes advantage of the properties of graphite, provides information in a relatively short time, and has potential in quality control applications.