TERMINOLOGY AND CONVENTIONS FOR MICROELECTRONIC ION-SELECTIVE FIELD-EFFECT TRANSISTOR DEVICES IN ELECTROCHEMISTRY

In anticipation of the widespread use of Ion-Selective Field Effect Tr ansistors (ISFETs) in electrochemistry and analytical chemistry it is appropriate to make recommendations about terminology and presentation of results. The terms gate voltage, drain current and gate bias poten tial are defined and experimental techniques for measurements with ISF ETs are summarized. The output signal is usually a potential differenc e whose magnitude varies with change in logarithm of sensed ion activi ty or concentration in the same way (but not in sign) as the correspon ding ion-selective electrode (ISE). It is proposed that the graphical representation of results should be in accordance with previously made recommendations for ISEs, that is, that the output potential differen ce be plotted so that variation with increase of logarithm of activity or concentration has a positive slope for cation-responsive devices a nd a negative slope for anion-responsive devices.