Flexible Ion Sensors for Bodily Fluids

This work presents an array of ion selective electrodes combined with a solid state reference electrode for analyzing of potassium and sodium ions in fluid. The sensors was fabricated using screen printing and drop casting techniques. The ion selective electrodes were made from a stack of screen printed AgCl electrode and solid state polyhydroxyethylmethacrylate hydrogel internal electrolyte layers, which were preconditioned in 0.1M KCl. The sensitivity of the sensors to potassium and sodium ions was achieved by casting a plasticized PVC based ion selective membrane, which contained an optimal ionophore to polymer ratio, directly on the hydrogel layer. The reference electrode was made on another AgCl electrode, which was covered with the same hydrogel. For both ions, sensitivities of 50mV per decade were achieved in a concentration range 10-3 - 1M. In this concentration range, the potassium sensor had no cross sensitivity to sodium ions and vice versa.