CoChat
Sign Up
Cited by 162Electrostatics and Colloid InteractionsAnalytical Chemistry and SensorsElectrochemical sensors and biosensors

On the origin of enhanced sensitivity in nanoscale FET-based biosensors

Open access
Shoorideh, Kaveh, Chui, Chi On·2014·Proceedings of the National Academy of Sciences
DOI 10.1073/pnas.1315485111PMC PMC3986196
Open this paper in CoChat — free accountOpen PDF

Abstract

Enhanced sensitivity in nanoscale FET biosensors arises from reduced electrostatic screening near concave corners.

Integrity signals

Registry

Crossref · 10.1073/pnas.1315485111

Cites

23 of 23 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

1 of 5 cited sources checked · 0 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    Sensitivity of FET-based biosensors is maximum when operated in the subthreshold regime.

    “biosensor sensitivity has been shown to be maximum when the biosensor is operated in the subthreshold regime (11,12).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [11] 11. Shoorideh K, Chui CO (2012) Optimization of the sensitivity of FET-Based biosensors via biasing and surface charge engineering. IEEE Trans Elect Dev 59(11):3104-3110. source
    • cites [12] 12. Gao XPA, Zheng G, Lieber CM (2010) Subthreshold regime has the optimal sensitivity for nanowire FET biosensors. Nano Lett 10(2):547-552. source

      The paper reports that nanowire FET biosensors have their highest percentage conductance response and best charge-detection limit in the subthreshold regime (passage 1, section labeled Abstract). It says the findings may have implications for other FET sensors, but does not establish that sensitivity is maximal there for FET-based biosensors generally. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Findingown data
    § On the origin of enhanced sensitivity in nanoscale FET-based biosensors

    Electrostatic screening is stronger near convex curved surfaces than near flat surfaces.

    “Using simple analytical arguments, we show that electrostatic screening is weaker in the vicinity of concave curved surfaces, and stronger in the vicinity of convex surfaces.”
    • Also stated in: § Discussion · plain
      “This plot shows that the electrostatic potential drops more quickly to its bulk value when the surfaces are convex, and more gradually when the surfaces are concave.”
    • Also stated in: § Conclusions · plain
      “The conclusion is rather simple: screening is weaker near concave surfaces, and stronger near convex surfaces.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    As nanowire width shrinks, the relative importance of the corner effect increases.

    “Conversely, as the width shrinks, the relative importance of the corner effect increases.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.
  • Findingreasoning

    In subthreshold, gm/ID has a theoretical maximum of q/kBT (60 mV per decade).

    “The above maximum for g m =I D is simply the familiar 60-mV per decade limitation for the subthreshold swing of thermionic FETs.”
    Quote in the paperSubstantial claim
  • Findingown data
    § On the origin of enhanced sensitivity in nanoscale FET-based biosensors

    Electrostatic screening is weaker near concave curved surfaces than near flat surfaces.

    “Using simple analytical arguments, we show that electrostatic screening is weaker in the vicinity of concave curved surfaces, and stronger in the vicinity of convex surfaces.”
    • Also stated in: § Discussion · plain
      “This plot shows that the electrostatic potential drops more quickly to its bulk value when the surfaces are convex, and more gradually when the surfaces are concave.”
    • Also stated in: § Conclusions · plain
      “The conclusion is rather simple: screening is weaker near concave surfaces, and stronger near convex surfaces.”
    Quote in the paperSubstantial claim
  • May combine two claims. 14
  • The quote only partly states this claim. 2
  • Classified as probably not a substantial claim. 3

  • May combine two claims.

    Findingreasoning

    As nanowire width increases, the corner regions constitute a smaller fraction of total sensor surface and their effect diminishes; all three structures converge to the same sensitivity at large widths.

    “As the nanowires become wider, these corners constitute a smaller fraction of the total sensor surface, and their effect diminishes; eventually, all three structures begin to resemble a flat electrode, seen in the plots of sensitivity vs. width in Fig. 6, where all three curves converge to the same value for large widths.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • The quote only partly states this claim.

    Findingreasoning

    In the SF-NWoI structure, the bottom corners do not behave like corners for screening because there are no biomolecules on the substrate; they behave like a flat vertical surface.

    “It is important to note that the bottom corners of the SF-NWoI structure do not behave like corners at all, because there are no biomolecules on the substrate, so there is no screening contribution from the substrate facets of these corners.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • May combine two claims.

    Findingreasoning

    The UF-NWoI structure has two concave corners whose effect dominates the convex corners, resulting in increased sensitivity with reduced width.

    “The UF-NWoI structure has two concave corners whose effect apparently dominates the convex corners, resulting in increased sensitivity with reduced width.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • May combine two claims. The quote only partly states this claim.

    Findingreasoning

    The sensitivity of the UF-SNW structure decreases with shrinking width because it has four convex corners.

    “The sensitivity of the UF-SNW structure decreases, because this structure has four convex corners.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • May combine two claims.

    Findingreasoning

    The SF-NWoI structure has two convex corners and two neutral corners, so its sensitivity fares better than that of the UF-SNW structure.

    “The SF-NWoI structure has two convex corners and two neutral, so its sensitivity fares better than that of the UF-SNW structure.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The crude modeling of biomolecules as a uniform sheet of charge neglects factors important for detecting very low analyte concentrations.

    “It should be noted, however, that our crude modeling of the biomolecules as a uniform sheet of charge neglects many factors that become important when one seeks to detect samples with very low concentrations of analytes.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning

    Typical biosensing nanowire dimensions are thinner than 100 nm, far smaller than the maximum depletion width.

    “Biosensing nanowires are typically doped at ∼10 16 cm -3 , for which the maximum depletion width is ∼300 nm at room temperature; this is far larger than the typical dimensions of the nanowires, most of which are thinner than 100 nm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    As nanowire shrinks, the relative importance of substrate-bound biomolecules increases, increasing overall sensitivity.

    “As the nanowire shrinks, the relative importance of the substratebound biomolecules increases, increasing the overall sensitivity.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • May combine two claims.

    Interpretationreasoning

    Substrate-bound biomolecules within a certain distance of the nanowire can influence it, and their quantity is independent of nanowire size.

    “of all of the biomolecules that bind to the substrate, the few who are within a certain distance of the nanowire are capable of influencing it.The quantity of these biomolecules is independent of the nanowire size; they provide an extra boost to the sensitivity in addition to the biomolecules that bind directly to the nanowire.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • May combine two claims.

    Premisenone given

    Biosensing nanowires are typically doped at ~10^16 cm^-3, for which the maximum depletion width is ~300 nm at room temperature.

    “Biosensing nanowires are typically doped at ∼10 16 cm -3 , for which the maximum depletion width is ∼300 nm at room temperature; this is far larger than the typical dimensions of the nanowires, most of which are thinner than 100 nm.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    In nanoscale sensors where the semiconductor region shares a surface with the electrolyte, downscaling dimensions and increasing surface area-to-volume ratio are inevitably accompanied by reduced surface area-to-Debye-volume ratio, and hence increased screening and reduced sensitivity.

    “In nanoscale sensors where the semiconductor region shares a surface with the electrolyte, downscaling dimensions and increasing the surface area-to-volume ratio are inevitably accompanied by reduced surface area-to-Debye-volume ratio, and hence increased screening and reduced sensitivity.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Nanowires used in most biosensing experiments are already fully depleted, and further reduction in size will not noticeably change or improve subthreshold swing.

    “Nanowires used in most biosensing experiments are therefore already fully depleted, and further reduction in size will not noticeably change or improve subthreshold swing.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning
    § On the origin of enhanced sensitivity in nanoscale FET-based biosensors

    Increasing the surface area-to-volume ratio of nanowire sensors means increasing their convexity, which should result in increased Debye screening and reduced sensitivity.

    “Increasing the surface area-to-volume ratio of nanowire sensors actually means increasing their convexity, which should result in increased Debye screening and reduced sensitivity.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The Gouy-Chapman model neglects finite ion size but is adequate for qualitative behavior and quantitatively acceptable for low surface potentials and dilute electrolytes.

    “This model neglects the finite size of the ions in the electrolyte.It is adequate for gaining insight into the qualitative behavior of electric double layers; for low surface potentials and dilute electrolytes, it is also quantitatively acceptable (13).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [13] 13. Torrie GM, Valleau JP (1980) Electrical double layers. I. Monte Carlo study of a uni- formly charged surface. J Chem Phys 73:5807-5816. source

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given
    § On the origin of enhanced sensitivity in nanoscale FET-based biosensors

    Nanowires placed on insulating substrates create concave corners between the nanowire and the substrate.

    “However, nanowires placed on insulating substrates create concave corners between the nanowire and the substrate.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The electrolyte capacitance C_DL is almost always dominant over the gate dielectric and semiconductor capacitances in nanowire FET biosensors, so the only meaningful dependence of sensitivity on radius is through electrolyte screening.

    “The electrolyte capacitance C DL is therefore almost always dominant, allowing us to forego calculating the potential and capacitance of the sensor itself.”
    • Also stated in: § Position · plain
      “At this point, the only meaningful dependence of a nanowire biosensor's sensitivity on its radius is through changes in electrolyte screening, i.e., the capacitance of the diffuse ionic layer, C DL .”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Similar results are expected for varying thickness: for a structure with more overall convexity, reducing surface area harms sensitivity; if more overall concavity, reducing total surface area increases sensitivity.

    “Although we have only varied width in this study, similar results are expected for varying thickness: for a structure with more overall convexity, reducing surface area harms sensitivity and should be avoided; conversely, if the structure has more overall concavity, reducing the total surface area will increase sensitivity.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Calculations using modified Poisson-Boltzmann formalisms have arrived at potential distributions similar to ours.

    “Calculations using more sophisticated modified Poisson-Boltzmann formalisms have arrived at potential distributions similar to ours (14).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] 14. Wang H, Pilon L (2011) Accurate simulations of electric double layer capacitance of ultramicroelectrodes. J Phys Chem Comm 115(33):16711-16719. source
18 of 18

  • The authors state this as an assumption.

    The target analyte concentration is small, so that qΔV_E/(nkBT) is much less than 1.

    “We have assumed that the target analyte concentration is small, resulting in qΔV E nk B T.”

  • The paper relies on this without support.

    The random nature of biomolecule binding will, on average, resemble a uniform layer of charge.

    “Although in reality the molecules are discrete, the random nature of their binding will, on average, resemble a uniform layer of charge.”
2 of 2

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Opposite claims about which curvature has the larger Debye volume

    Minor

    The discussion says an equal-sized concave surface patch has a larger Debye volume, while the Fig. 7 caption says the convex patch has the larger volume. The two comparisons cannot both be true.

  • Baseline current is assigned two different electrode potentials

    Minor

    The first expression defines baseline current using the baseline electrode potential. Eq. 3 instead uses the analyte electrode potential for that same baseline current.

2 of 2

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Related

Authors
Shoorideh, K., & Chui, C. O.
Affiliations
California NanoSystems Institute (US)
ORCID
Chui, Chi On
Venue
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Published
2014-03-25
Volume
111
Issue
14
Pages
5111-5116
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
DOI
10.1073/pnas.1315485111
PMC
PMC3986196
OpenAlex
W1984027596
Cited by
162
References
23
Citations by year
2026: 11 · 2025: 11 · 2024: 22 · 2023: 16 · 2022: 15 · 2021: 16 · 2020: 16 · 2019: 13 · 2018: 11 · 2017: 14 · 2016: 9 · 2015: 7 · 2014: 1
FWCI
6.64
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Science Foundation (1128673)
Topics
  • Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Electrostatics and Colloid Interactions
  • Physical Sciences › Chemical Engineering › Bioengineering › Analytical Chemistry and Sensors
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Electrochemical sensors and biosensors
Keywords
field-effect transistor biosensors, nanobiosensors, sensitivity enhancement, concave surfaces, convex surfaces, biomolecule binding, surface-to-volume ratio, curved surfaces
MeSH terms
Models, Theoretical, Biosensing Techniques, Nanotechnology

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review