Electrical double layer-based iontronic sensor for detection of electrolytes concentration

Abstract

Concentration detection sensor owing ability of ion detection is very important in health monitoring. The traditional sweat sensors often possess a complex structure, fabrication process with chemical reactions dependent performance. In this work, we present an electrical double layer (EDL)-based iontronic sensor using a simple planar double electrodes structure without employing chemical reaction for electrolytes concentration detection. When the two working electrodes are connected via an electrolyte solution, the EDL-based capacitance changes with the concentration of the electrolyte and can be used in the detection of both inorganic and organic electrolytes. The electrical measurements show that the capacitance has a good linear relationship with the concentration of NaCl solution with a range of 0.05–10 mM, with the R-square value of 99.9%. The sensor shows a high concentration resolution of 0.01 mM and possesses both concentration detection and molecular size identification upon combining a microporous membrane. The capacitive iontronic sensor shows great potential for applications in the detection of the salinity of seawater, biological ionic liquid, and assistance for disabled people who lose their sense of taste.