Abstract
EGFETs (extended gate field effect transistor) are utilized in this work for biosening applications. Unlike traditional ISFET (ion sensitive field effect transistor) in which MOSFET’s gates are removed, we deposit a thin gold film on gates to form sensing regions. After post-deposition of the gold film on gates, the self-assembled monolayer (SAM) is formed on the gold film for biomolecule detection. We immobilized the biomolecules on gold film, and the biomolecules on gold film can capture specific biomolecules. Because biomolecules have charges, it changes the charge on gold film when specific bindings occur. And the charges on gold film can impact the current in the MOSFET. Combined with CMOS circuitry, we can detect the charge change of ions in MOSFET. The current that can be detect is about μA. A self-oscillating readout circuit was used to convert the ISFET current to a digital output for measurement of multiple sensors, showing the strength of the CMOS-based approach for sensor integration.