ISFET for pH Sensor
ISFET is an ion sensitive field effect transistor that has similar structure to the MOSFET. The physical difference of the ISFET structure is the replacement of the gate electrode of the MOSFET by the series of combination of the reference electrode, electrolyte and ion sensitive layer. For this...
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| Main Author: | |
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| Format: | Conference Paper |
| Language: | English |
| Published: |
2013
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| Subjects: | |
| Online Access: | http://ddms.usim.edu.my/handle/123456789/6126 |
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| Summary: | ISFET is an ion sensitive field effect transistor that has similar structure to the MOSFET.
The physical difference of the ISFET structure is the replacement of the gate electrode of
the MOSFET by the series of combination of the reference electrode, electrolyte and ion
sensitive layer. For this device, Silicon Nitride is used as a pH sensing membrane which
behaves as a gate in contact with the liquid solution that is biased with a reference
electrode. In overall fabrication process, 6 masking level are employed with 12 main
processes are involved. In MOSFET principle, the operation was controlled by the gate
electrode, meanwhile the operation of ISFET was controlled by the ion concentration in the
electrolyte. The measurement of the threshold voltage of the ISFETs will give the pH value
of the solution and in general will serve as a pH measurement system. |
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