Noise considerations in field-effect biosensors

Abstract

Field-effect sensors used to detect and identify biological species have been proposed as alternatives to other methods such as fluorescence deoxyribonucleic acid (DNA) microarrays. Sensors fabricated using commercial complementary metal-oxide-semiconductor technology would enable low-cost and highly integrated biological detection systems. In this paper, the small-signal and noise modeling of biosensors implemented with electrolyte-insulator-semiconductor structures is studied, with emphasis on design guidelines for low-noise performance. In doing so, a modified form of the general charge sheet metal-oxide-semiconductor field-effect transistor model that better fits the electrolyte-insulator-semiconductor structure is used. It is discussed how if the reference electrode and the insulator-electrolyte generate no noise associated with charge transport, then the main noise mechanisms are the resistive losses of the electrolyte and the low-frequency noise of the field-effect transistor. It is also found that for realistic sensor geometries and high electrolyte concentrations, the noise from the field-effect transistor (FET) dominates the thermal noise from the electrolyte resistance, and the optimal biasing point for the FET for minimum noise is found to be around moderate inversion.

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] .…”

Direct assessment of solid–liquid interface noise in ion sensing using a differential method

“…This further confirms the minor role of the noise generated in the electrolyte bulk. In contrast to the assumptions of others, 8,9 the real part of the measured sample impedance is much larger than the liquid impedance. We speculate that this is due to a rate limiting interfacial interaction or diffusion process at the liquid-solid boundary.…”

“…The measured noise S V scales inversely with A and has a unity slope in the log-log scale. In contrast, the bulk resistance of the electrolyte, R b , can be approximated by its spreading resistance as R b / K= ffiffiffi A p , 8 with K as the resistivity of the liquid bulk. The thermal noise generated by the bulk liquid should then scale with 1= ffiffiffi A p .…”

“…[10][11][12][13][14] While noise from the FET can be understood from the well-established theory and practice for a corresponding MOSFET, 5 noise generated in the electrolyte as well as in the EDL in the ISFET context is much less characterized. In some simulation studies, 8,9 the former (i.e., liquid noise) is considered the main contributor in the form of thermal noise due to the Brownian motion of ions in the electrolyte, and the latter (i.e., EDL noise) is often assumed negligible. In view of great similarities between random ion adsorption/desorption in the EDL leading to fluctuations in Du DL and random charge trapping/de-trapping at the oxidejSi interface leading to fluctuations in channel conductance of the FET, 5 it is of importance scientifically and technologically to quantify the EDL noise.…”

Tuning the surface conditioning of trapezoidally shaped silicon nanowires by (3-aminopropyl)triethoxysilane

“…Although extensively employed in previous studies, 1,12,15 only a few works considered the subtle effects that APTES monolayers have on the basic electrical properties of SiNWs. While the presence of electrolytes, adsorbed water molecules and charges at the silicon oxide surface is known to produce important changes in the electrical characteristics of SiNW field effect transistors (FETs), 2,[20][21][22][23] the control of the coupling of APTES monolayers to SiNWs was primarily directed to the manipulation of the terminal amino groups as well as to the overall hydrophobic properties of the sensors.…”