Potassium sensing with membrane-coated silicon nanowire field-effect transistors

Ion sensitive field-effect transistors (ISFETs) based on silicon nanowires (Si NWs) with high-k gate oxide layers display surface hydroxyl groups which are known to be sensitive to variations in pH and electrolyte concentration. To specifically detect other species than protons, oxide surfaces need to be chemically modified. In this work, we use polyvinyl chloride (PVC) membranes with embedded ionophores to specifically detect potassium ions. We find a high response of -38mV/decade in KCl concentration. Control measurements with MgCl and pH demonstrate the selectivity of the ionophore.