Highly sensitive field effect charge sensor for direct detection of biomolecules

A field effect transistor (FET) charge sensor is proposed to work at a special operating condition in order to become extremely sensitive to the gate charge change caused by biomolecules. A device model has been established and the simulation results justify the hypothesis. It is found that at the depletion operating condition the proposed FET charge sensor will shift a gate voltage up to 1 mV in response to every electron per square micron, which is much more sensitive than other existing FET sensors.