Model for the field effect from layers of biological macromolecules on the gates of metal-oxide-semiconductor transistors

Abstract

The potential diagram for field-effect transistors used to detect charged biological macromolecules in an electrolyte is presented for the case where an insulating cover layer is used over a conventional eletrolyte-insulator metal-oxide-semiconductor (EIMOS) structure to tether or bind the biological molecules to a floating gate. The layer of macromolecules is modeled using the Poisson-Boltzmann equation for an ion-permeable membrane. Expressions are derived for the charges and potentials in the EIMOS and electrolyte-insulator-semiconductor structures, including the membrane and electrolyte. Exact solutions for the potentials and charges are calculated using numerical algorithms. Simple expressions for the response are presented for low solution potentials when the Donnan potential is approached in the bulk of the membrane. The implications of the model for the small-signal equivalent circuit and the noise analysis of these structures are discussed.

Electrical Conductance in Biological Molecules

“…It would enable detection of extremely small concentrations of target DNA in a solution, eliminating the need for overcomplicated PCR (Polymerase Chain Reaction) tests, allowing rapid analysis and early pathogen detection. And it is the early detection, as well as the control of outbreaks, that are major cornerstones of the contemporary biosensor research [120][121][122][123] .…”

Modeling of Electrolyte Thermal Noise in Electrolyte-Oxide-Semiconductor Field-Effect Transistors

“…The mobility values of Na and Cl ions are typical values and the other parameters are adopted from Refs. [6,7]. Although noise sources inside the double-layer region are distributed, and the concentration of cations and anions can change dramatically inside the diffuse region, we assume that the electrolyte-surface potential is rather small compared to the thermal voltage kT/q=26 mV at T=300 K, so that the noise resistance of the double-layer region is approximated to be we can see that why the plateau level goes down as the electrolyte molar concentration strengthens from 1mM to 0.01 M, and 0.1 M in Fig.…”

“…They have been used as ionsensitive FETs and pH-meters [1,2]. Many papers have been published on the modeling of noise in EOSFETs [5][6][7][8][9][10][11]. One notable modeling approach was presented by Hassibi et al in 2004 [5].…”

Analysis of Sensing Mechanisms in a Gold-Decorated SWNT Network DNA Biosensor

“…The PB equations for the electrolyte region and DNA membrane region are given by [8,9] (3a) These equations can be solved to give the surface potential of the electrolyte, denoted by ψ 0 .…”

“…From this differential equation, the total charge density per unit area is given by [10]: (8) To complete the electrolyte-semiconductor system, it is required to satisfy the Kirchhoff's voltage law and the Gauss law given by To determine the C g which acts as the gate capacitance of the CNNFET, we need to review the electrical doublelayer (EDL) theory as follows. Fig.…”