Silicon‐Based Ion‐Sensitive Field‐Effect Transistor Shows Negligible Dependence on Salt Concentration at Constant pH

I(o)n-sensitive transistors: The response of (miniaturized) ion-sensitive field-effect transistors (ISFETs) with oxide interfaces to changes in the electrolyte concentration is discussed. It is shown that FETs covered with a thin alumina layer are almost insensitive to changes in the ionic strength of the electrolyte, while being extremely pH-sensitive.