Ion selective sensing In close collaboration with the Dutch Kidney Foundation TNO has developed an ion selective sensor for inline fluid analysis. The goal of the current work is improving dialysis treatment. For this purpose the current project focusses on measuring Sodium, Calcium and Potassium with one percent accuracy. TNO uses laser induced breakdown spectroscopy, where a laser is used to create a tiny plasma that emits light with emission peaks at particular wavelengths that are characteristic for each ion. The sensor can be developed further to detect other ions as well, and potentially measure molecules too.