ISFET Based DNA Sensor: Current-Voltage Characteristic and Sensitivity to DNA Molecules

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.

Noises and Signal-to-Noise Ratio of Nanosize EIS and ISFET Biosensors

“…We will take accounts that the oxide surface charge is changed during the DNA sensing processes. This is occurring by the capture of negatively charged DNA molecules on the proton acceptor 2 OH + bonds and the capture of H + ions (protons) of the solution on the proton donor free OH − bonds on the interface solution-insulator (see Figure 2 in [7], and [36]). These are molecules and ions located at a distance of Debye length from the oxide surface.…”

“…Here t N + is the concentration of the proton acceptor traps on the unit area of oxide surface, DNA N is the DNA surface concentration in solution near the oxide at a distance of the Debye length (see also [7]). Thus Equation (2) will be changed as follows:…”

“…Assume that traps concentration on the interface SiO 2 -electrolyte same than SiO 2 -Si interface. According data [7] [37] traps concentration in Si-SiO 2 interface is about (10 10 -10 11 ) cm −2 . In the numerical calculations we will use .…”

“…As we can see from expression (4) increase of the sensitive surface area (wl) brings to decrease of the noise level. On the other hand it is well known that increase of sensitive surface brings to increase of sensitivity of the BioFET to DNA molecules (see also [7]). At the same time, for low noise and high sensitivity, sensors with a relatively large surface area should be used.…”

DNA Sequencing Modified Method through Effective Regulation of Its Translocation Speed in Aqueous Solution

“…The detailed analyses of the literature data, some critical considerations and the potential ways of optimization of DNA nanopore sequencing were presented Open Journal of Biophysics in [20]. Some characteristics of ISFET and EIS based DNA sensors are analyzed detailed by us in [21] [22].…”