The PRECISE project, funded by the Academy of Finland, aims at improving the analytical performance of chemical ion sensors.

Within this research project (PRECISE) we explore a new signal transduction method for solid-contact ion-selective electrodes (solid-contact ISEs). The objective is to amplify the analytical signal in order to improve the precision of ion sensing. Key applications include clinical diagnostics and environmental monitoring. Ion-selective electrodes (ISEs) are chemical sensors that provide information about ion activity (concentration) and pH. Today ISEs are used routinely e.g. in clinical diagnostics to determine electrolyte ions in whole blood, plasma and serum. It has been estimated that over a billion ISE measurements are performed every year in clinical laboratories. ISEs traditionally involve potentiometric signal transduction, i.e. the ion activity is related to the equilibrium potential of the sensor vs. the reference electrode. Since the potential is proportional to the logarithm of ion activity in the sample solution, ISEs show an impressive dynamic range of 5-8 orders of magnitude in concentration. The drawback of potentiometry is the limited precision, i.e. a potential difference of 1 mV means a 4 % change in ion activity for a monovalent ion (8 % for a divalent ion). This is a fundamental limitation of potentiometric ISEs, which is addressed in this research project by exploring a new signal transduction principle. We recently published the proof-of-concept for the new transduction method that we will explore in this PRECISE project in collaboration with scientists from Switzerland and USA. The ultimate goal of the PRECISE project is to obtain a highly precise and robust ion sensor system, which would be most welcome in many fields of analytical chemistry, including clinical- and environmental analysis.