Abstract
Dependency of both source-drain current and current sensitivity of nanosize ISFET biosensor vs. concentration of DNA molecules in aqueous solution theoretically is investigated. In calculations it is carried out effects concerning charge carriers distribution in current channel and concerning carriers’ mobility behavior in high electrical fields in the channel. The influence of DNA molecules on the work of ISFET biosensors is manifested by a change in the magnitude of the gate surface charge. Starting with fairly low concentrations of DNA, ISFET sensors respond to the presence of DNA molecules in an aqueous solution which is manifested by modulation of channel conductance and therefore the source-drain current changes of the field-effect transistor. It is shown that the current sensitivity with respect to concentration of DNA molecules linearly depends on the source-drain voltage and reaches high values.
Highlights
The ion-sensitive field-effect transistor (ISFET) is one of the most popular semiconductor biosensors, and has been introduced as the first nanosized bio-chemical sensor
Starting with fairly low concentrations of DNA, ISFET sensors respond to the presence of DNA molecules in an aqueous solution which is manifested by modulation of channel conductance and the source-drain current changes of the field-effect transistor
It is shown that the current sensitivity with respect to concentration of DNA molecules linearly depends on the source-drain voltage and reaches high values
Summary
The ion-sensitive field-effect transistor (ISFET) is one of the most popular semiconductor biosensors, and has been introduced as the first nanosized bio-chemical sensor. Applying a positive gate voltage attracts electrons to the semiconductor surface, when a sufficiently high concentration of electrons is accumulated in this region a conductive channel is created at the semiconductor-insulator interface allowing a current flow between source and drain. Note that the sequencing mechanisms of sensors based on ISFETs can be used only for detecting nucleic acid using pH sensitivity and amplifying the useful signal in real time. The aim of this research is the theoretical investigation, simulation and demonstration of the dependency of source-drain current of the silicon nanowire based ISFET biosensor vs concentration of DNA molecules in aqueous solution. DNA detection mechanism and source-drain current sensitivity depending on the influence of the DNA molecules which occur in an aqueous solution over the Debye screening length will be investigated and discussed
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