Ion sensitive field effect transistor (ISFET)
A semiconductor sensor integrating an ion sensitive electrode with a
field effect transistor (FET).
In the ion sensitive electrode section, the membrane voltage
changes according to fluctuations of pH or carbon dioxide partial pressure in blood, for example.
As the voltage amplifier, the ISFET uses an FET, a transistor controlling the conductance of the
current path (channels) formed by the majority carriers using an electrical field perpendicular to
the carrier flow. The ISFET is based on silicon micromachining technology integrating a detector
and amplifier on a silicon substrate. In addition, an ISFET with mechanical components such as a
valve has been developed. The ISFET is used in such fields as medical analysis and environmental