An ion sensitive field-effect transistor (ISFET) integrated with a low-power pH sensor 2

The structure of ISFET is similar to a standard MOSFET, consisting of a gate, CDCUA877ZQLR source, and drain. Unlike MOSFETs, the gate surface of ISFETs is covered with an ion sensitive layer that comes into contact with the liquid and senses changes in ion concentration.diode

2. Ionic sensitive layer

The ion sensitive layer is the core part of ISFET, responsible for sensing changes in ion concentration in the solution. Common ion sensitive materials include silicates, alumina, and titanium oxide. The choice of ion sensitive layer depends on the type of ion being measured.diode

3. Working principle

When the ion concentration in the solution changes, the interface charge on the surface of the ion sensitive layer also changes. The change in interface charge will affect the gate potential of ISFET, thereby altering its conduction characteristics. By measuring the current or voltage changes of ISFET, the ion concentration changes in the solution can be determined.diode

3、 Integrated design

1. Manufacturing of ISFET

Manufacturing ISFETs through CMOS technology. During the manufacturing process, special attention should be paid to the material selection and preparation process of the ion sensitive layer to ensure its good bonding and stability with ISFET.diode