Cited by 132Plasmonic and Surface Plasmon ResearchGold and Silver Nanoparticles Synthesis and ApplicationsSpectroscopy Techniques in Biomedical and Chemical Research

The DOI matches its Crossref record; 64 of the 64 references it cites were found in a registry or an index; none of the 53 sources its claims cite is checked for support yet.

Wavelength-multiplexed hook nanoantennas for machine learning enabled mid-infrared spectroscopy

Open access

Abstract

Infrared (IR) plasmonic nanoantennas (PNAs) are powerful tools to identify molecules by the IR fingerprint absorption from plasmon-molecules interaction. However, the sensitivity and bandwidth of PNAs are limited by the small overlap between molecules and sensing hotspots and the sharp plasmonic resonance peaks. In addition to intuitive methods like enhancement of electric field of PNAs and enrichment of molecules on PNAs surfaces, we propose a loss engineering method to optimize damping rate by reducing radiative loss using hook nanoantennas (HNAs). Furthermore, with the spectral multiplexing of the HNAs from gradient dimension, the wavelength-multiplexed HNAs (WMHNAs) serve as ultrasensitive vibrational probes in a continuous ultra-broadband region (wavelengths from 6 μm to 9 μm). Leveraging the multi-dimensional features captured by WMHNA, we develop a machine learning method to extract complementary physical and chemical information from molecules. The proof-of-concept demonstration of molecular recognition from mixed alcohols (methanol, ethanol, and isopropanol) shows 100% identification accuracy from the microfluidic integrated WMHNAs. Our work brings another degree of freedom to optimize PNAs towards small-volume, real-time, label-free molecular recognition from various species in low concentrations for chemical and biological diagnostics.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The paper introduces wavelength-multiplexed hook nanoantennas (WMHNAs) that use loss engineering and broadband 6–9 μm plasmonic resonance to enhance mid-infrared molecular fingerprint detection. Combined with PCA/SVM machine learning, the platform identifies 1% methanol, ethanol, isopropanol, and their mixtures in water with 100% accuracy.

Key findings

  • Hook nanoantennas tune radiative loss by changing the geometric difference ΔL between arms; optimal sensitivity occurred at ΔL = 0.65 μm for transmission (extracted loss ratio f = 0.644) and ΔL = 1.25 μm for reflection (f = 1.834), close to theoretical optima of f = 0.5 and f = 2, respectively.
  • The 16-element WMHNA provides continuous ultra-broadband operation from 6 μm to 9 μm, matching mid-infrared fingerprint absorption; it captured 15 absorption peaks of methanol, ethanol, isopropanol, and water.
  • WMHNA enhanced water scissoring absorption at 6.0 μm by 34.36 times and stretching absorption at 2.95 μm by 4.17 times; compared with direct thin-film measurement, WMHNA and HNA showed significant enhancement of absorption spectra by 3 orders of magnitude.
  • PCA extracted multi-dimensional features from refractometric, spectroscopic, and antenna loading effects; SVM classification of 1% alcohol solutions and mixtures achieved 100% accuracy on both training and test sets.

Methods

  • Design and simulation: temporal coupled-mode theory (TCMT) modeled plasmon–molecule coupling; finite-difference time-domain (FDTD, Lumerical) simulated far-field spectra and near-field distributions of hook nanoantennas.
  • Fabrication and measurement: gold HNAs were fabricated on CaF₂ by electron-beam lithography and lift-off; FTIR microscopy with an MCT detector measured reflection/transmission spectra, and a PDMS microfluidic chamber enabled liquid sensing.
  • Machine learning: PCA reduced WMHNA spectra to principal components; SVM with an RBF kernel (C = 1.0, gamma = 0.1) classified analytes. The dataset contained 50 spectra per molecule, split into 40 training and 10 testing spectra.

Limitations

  • The paper does not explicitly state limitations.
  • Evident from the text: the molecular recognition demonstration is a proof-of-concept limited to three chemically similar alcohols at 1% concentration in water and their mixtures, with a small dataset of 50 spectra per molecule.
  • Evident from the text: the WMHNA design shown covers 6–9 μm, while the paper notes that covering all IR fingerprint ranges would require further engineering of antenna length for specific molecular targets.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41467-022-31520-z

Cites

64 of 64 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 53 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The broadband resonance peak of wavelength-multiplexed hook nanoantennas is well-matched with the fingerprint absorption of alcoholic liquids methanol, ethanol, and isopropanol.

    “The broadband resonance peak of WMHNA is well-matched with the fingerprint absorption of alcoholic liquids of methanol, ethanol, and IPA as shown in Fig. 1c.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    Tailoring the radiative-to-absorptive loss ratio of hook nanoantennas improves the sensitivity of molecular vibration detection under the optimal condition supported by temporal coupled-mode theory.

    “By tailoring the radiative to absorptive loss ratio, the sensitivity of molecular vibration detected by HNAs can be improved dramatically under the optimal condition supported by temporal coupled-mode theory (TCMT).”
    Quote in the paperSubstantial claim
  • Findingown data

    Increasing the refractive index of an analyte causes a redshift of the resonance wavelength of nanoantennas.

    “As shown in Fig. 1d-i, the refractometric effect, caused by the refractive index of analytes, brings a redshift of resonance wavelength as n increases.”
    Quote in the paperSubstantial claim
  • Findingown data

    The far-field reflection spectrum of wavelength-multiplexed hook nanoantennas covers a broad bandwidth from 6 to 9 μm in the IR fingerprint region.

    “The far-field reflection spectrum is shown in Fig. 1b, covering a broad bandwidth from 6 to 9 μm in the IR fingerprint region.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    Wavelength-multiplexed hook nanoantennas perform ultra-broadband working wavelengths ranging from 6 μm to 9 μm, matching the mid-infrared fingerprint region.

    “Leveraging the gradient change of HNA dimensions, the WMHNA performs ultra-broadband working wavelengths ranging from 6 μm to 9 μm, matching with the MIR fingerprint region.”
    Quote in the paperSubstantial claim
  • The quote only partly states this claim. 2
  • Probably not a substantial claim. 10
  • It may state two separate claims as one. 29
  • The quote only partly states this claim.

    Findingown data

    Principal component analysis together with support vector machine achieves 100% identification accuracy for molecular recognition from mixed alcohols (methanol, ethanol, and isopropanol) at 1% concentration in water using microfluidic integrated wavelength-multiplexed hook nanoantennas.

    “With the aid of principal component analysis (PCA) together with supporting vector machine (SVM), the proof-of-concept demonstration of molecular recognition from mixed alcohols (methanol, ethanol, and isopropanol) shows 100% identification accuracy.”
    • Also stated in: § Abstract · boosted
      “The proof-of-concept demonstration of molecular recognition from mixed alcohols (methanol, ethanol, and isopropanol) shows 100% identification accuracy from the microfluidic integrated WMHNAs.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim. The paper may give no reason why it holds.

    Findingnone given

    Hook nanoantennas perform enhanced sensitivity by reducing radiative loss through folded structures.

    “In addition to the bandwidth, the hook nanoantenna also performs an enhanced sensitivity thanks to reducing radiative loss by folded structures.”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one.

    Findingreasoning

    For two molecules with the same absorption strength, smaller intensity drops are read out when the wavelength mismatch increases, indicating a larger refractive index.

    “For two molecules with the same absorption strength, small intensity drops can be read out when the wavelength mismatch increase, indicating a larger refractive index.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    The highest sensitivity of transmission mode occurs when ΔL equals 0.65 μm, while the highest sensitivity of reflection mode occurs when ΔL equals 1.25 μm.

    “From this figure, we observe that the highest sensitivity of transmission mode (ΔT) comes when ∆L equals 0.65 μm, while 1.25 μm for reflection mode (ΔR).”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    As ΔL decreases, coupling efficiency μ remains almost unchanged because of similar nearfield intensity, but loss ratio f decreases due to reduced radiative loss γr caused by the short electrical length of the antenna and similar absorptive loss γa caused by the same antenna length.

    “As ∆L decreases, μ remains almost unchanged because of the similar intensity of near field (Fig. 2f), but f decreases due to the reduced γr caused by the short electrical length of the antenna and the similar γa caused by the same antenna length.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingnone given

    The radiative loss γa is related to the ohmic loss of the plasmonic material and is almost the same among different antenna structures.

    “The γa is related to the ohmic loss of plasmonic material (e.g., Au in this work) and is almost the same among different antenna structures.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    The absorption signal reaches a peak value when ΔL equals 0.6 μm, which indicates the critical coupled point (γa = γr) of the hook nanoantenna resonator.

    “However, the absorption signal reaches a peak value when ∆L equals 0.6 μm, which means the critical coupled point (γa = γr) of the HNA resonator.”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one.

    Findingown data

    With a decrease in ΔL, both transmission and reflection intensities drop, meaning the antenna becomes less radiative (darker).

    “With the decrease of ∆L, both T (Fig. 2d-i) and R (Fig. 2d-ii) intensities drop, which means the antenna becomes less radiative (darker).”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    Radiative loss decreases as ΔL decreases, but absorptive loss is almost unchanged, resulting in a small loss ratio f with short ΔL.

    “As shown in Fig. 3c, the radiative loss decreases as ∆L decreases, but the absorptive loss is almost unchanged, resulting in a small f with short ∆L.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    The maximum sensitivity occurs when the loss ratio f reaches 0.5 for transmission mode and 2 for reflection mode.

    “The maximum sensitivity occurs when f reaches 0.5 and 2 for transmission and reflection modes, respectively.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    The enhancement of the electric field intensity of all hook nanoantenna devices is at the order of 10^5, and the maximum enhancement reaches 832891 times.

    “The results show that the enhancement of the electric field intensity of all HNA devices is at the order of 105, and the maximum enhancement of the electric field intensity reaches 832891 times.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    Both wavelength-multiplexed hook nanoantennas and hook nanoantennas perform significant enhancement (3 orders of magnitude) of the absorption spectrum compared with direct measurement of thin-film without nanoantenna.

    “Both WMHNA and HNA perform the significant enhancement (3 orders of magnitude) of absorption spectrum with the direct measurement of thin-film without nanoantenna.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Findingnone given

    The apparent dips of the reflection spectrum at 6.0 μm are induced by water scissoring absorption.

    “The apparent dips of the reflection spectrum at 6.0 μm are induced by water scissoring absorption.”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one.

    Findingown data

    The redshift of the hook nanoantenna supercell spectrum is caused by the effect induced by the refractive index of analytes, indicating the refractometric effect of wavelength-multiplexed hook nanoantennas.

    “The redshift of the HNA supercell spectrum is caused by the effect induced by the refractive index of analytes indicating the RE of WMHNA.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    Wavelength-multiplexed hook nanoantennas better enhance multiple absorption peaks from broad wavelength ranges, while hook nanoantennas only reach the best enhancement at narrow wavelength ranges near resonance wavelengths.

    “We further compared the sensing performance with selected HNA elements (P1, P8, and P16) from WMHNA, showing that WMHNA better enhances multiple absorption peaks from broad wavelength ranges, while HNA only reaches the best enhancement at narrow wavelength ranges near resonance wavelengths.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingreasoning

    The absorption of water in IR has minimal influence on the nanoantenna spectrum apart from the molecular vibration regime, allowing liquid recognition with water-based solvent.

    “Furthermore, the absorption of water in IR has a minimal influence on the nanoantenna spectrum apart from the molecular vibration regime, allowing the liquid recognition with water-based solvent, which is so absorptive in traditional IR spectroscopy that the intensity of light becomes very weak to identify molecules.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    Each curve indicates the real-time spectrum of a mixed solvent of acetone and water, reflecting in-situ concentration information of acetone and water and dynamic change versus time.

    “Each curve indicates the real-time spectrum of a mixed solvent of acetone and water, reflecting in-situ concentration information of acetone and water and dynamic change versus time.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    The fingerprint absorption of small molecule alcohols is captured from 6.5 μm to 9 μm and is extracted from the WMHNA spectrum.

    “The fingerprint absorption of small molecule alcohols is captured from 6.5 μm to 9 μm and is extracted from the WMHNA spectrum in Fig. 6b.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    Wavelength-multiplexed hook nanoantennas show less influence from the antenna loading effect in the broadband wavelength range, indicating good performance for sensing broadband fingerprint absorption.

    “However, WMHNA performs less influence from ALE in the broadband wavelength range, showing good performance for sensing broadband fingerprint absorption.”
    Quote in the paperSubstantial claim
  • The quote only partly states this claim.

    Findingown data

    In the resonant regime, an improvement of 34.36 times of reflection change is observed for the scissoring mode at 6.0 μm.

    “In the resonant regime, an improvement of 34.36 times of reflection change is observed for the scissoring mode.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    The classifier trained with two PCs works well, with the different gases correctly identified and the clusters being well contained in the appropriate regions.

    “It can be seen that the classifier trained with two PCs works well, with the different gases correctly identified and the clusters being well contained in the appropriate regions.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingown data

    In the 3D PC space, each point represents the spectrum data from WMHNA, and each cluster represents one type of molecule combination.

    “In the 3D PC space shown in Fig. 6f, each point represents the spectrum data from WMHNA, and each cluster represents one type of molecule combination.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Findingcitation

    Compared with previous literature that demonstrates the identification of two molecules mixture by monitoring two absorption peaks, this work demonstrated simultaneously monitoring of 15 absorption peaks and used to identify three molecules mixture.

    “Compared with previous literature that demonstrates the identification of two molecules mixture by monitoring two absorption peaks49, our work demonstrated simultaneously monitoring of 15 absorption peaks and used to identify three molecules mixture.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [49] Kühner, L. et al. Vibrational Sensing Using Infrared Nanoantennas: Toward the Noninvasive Quantitation of Physiological Levels of Glucose and Fructose. ACS Sens. 4, 1973–1979 (2019). source
  • Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

    Findingnone given

    With the reverse current induced in HNA, the sensitivity of HNA is improved by engineering the radiative loss to achieve the optimized loss ratio.

    “On one hand, with the reverse current induced in HNA, the sensitivity of HNA is improved by engineering the radiative loss to achieve the optimized loss ratio.”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one.

    Findingown data

    With the aid of a machine learning algorithm (PCA and SVM), the multi-dimensional information can be classified effectively, resulting in 100% accuracy from random 4:1 data spiting for training and recognition sets.

    “Additionally, with the aid of a machine learning algorithm (PCA and SVM), the multi-dimensional information can be classified effectively, resulting in 100% accuracy from random 4:1 data spiting for training and recognition sets.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim. The paper may give no reason why it holds. It may state two separate claims as one.

    Premisenone given

    The sensitivity and bandwidth of plasmonic nanoantennas are limited by the small overlap between molecules and sensing hotspots and by the sharp plasmonic resonance peaks.

    “However, the sensitivity and bandwidth of PNAs are limited by the small overlap between molecules and sensing hotspots and the sharp plasmonic resonance peaks.”
    Quote in the paperNot a substantial claim
  • It may state two separate claims as one.

    Premisecitation

    Squeezing the gap between adjacent plasmonic nanoantennas to the nanometer scale increases electric field intensity but ruins sensing performance by decreasing active area and increasing fabrication cost.

    “The other method to improve the sensitivity is to increase the intensity of the electric field by squeezing the gap between adjacent PNA into the nanometer scale29–31. However, the narrow gap ruins the sensing performance by a decrement in the active area and increases fabrication cost.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [29] Huck, C. et al. Surface-Enhanced Infrared Spectroscopy Using Nanometer-Sized Gaps. ACS Nano 8, 4908–4914 (2014). source
    • cites [30] Dong, L. et al. Nanogapped Au Antennas for Ultrasensitive Surface-Enhanced Infrared Absorption Spectroscopy. Nano Lett. 17, 5768–5774 (2017). source
    • cites [31] Su, D.-S., Tsai, D. P., Yen, T.-J. & Tanaka, T. Ultrasensitive and Selective Gas Sensor Based on a Channel Plasmonic Structure with an Enormous Hot Spot Region. ACS Sens. 4, 2900–2907 (2019). source
  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation

    The amplification effect caused by strong plasmon-molecule coupling between plasmonic resonance and molecular vibration is well-explained by temporal coupled-mode theory (TCMT).

    “This amplification effect caused by the strong plasmon-molecule coupling between plasmonic resonance and molecular vibration was well-explained by temporal coupled-mode theory (TCMT)14,15.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [14] Adato, R. & Altug, H. In-situ ultra-sensitive infrared absorption spectroscopy of biomolecule interactions in real time with plasmonic nanoantennas. Nat. Commun. 4, 2154 (2013). source
    • cites [15] Adato, R., Artar, A., Erramilli, S. & Altug, H. Engineered Absorption Enhancement and Induced Transparency in Coupled Molecular and Plasmonic Resonator Systems. Nano Lett. 13, 2584–2591 (2013). source
  • It may state two separate claims as one.

    Premisecitation

    With machine learning, decoupling IR fingerprint absorption and refractive index change has been reported to monitor protein dynamics of secondary structure α-helix and β-sheet and recognition of glucose and fructose.

    “With the aid of machine learning (ML), decoupling the IR fingerprint absorption and refractive index change induced by molecules has been reported to monitor protein dynamics of secondary structure α-helix and β-sheet48 and recognition of physiological bio-marker of glucose and fructose49.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [48] Semenyshyn, R. et al. In Vitro Monitoring Conformational Changes of Polypeptide Monolayers Using Infrared Plasmonic Nanoantennas. Nano Lett. 19, 1–7 (2019). source
    • cites [49] Kühner, L. et al. Vibrational Sensing Using Infrared Nanoantennas: Toward the Noninvasive Quantitation of Physiological Levels of Glucose and Fructose. ACS Sens. 4, 1973–1979 (2019). source
  • Probably not a substantial claim.

    Premisecitation

    Plasmonic nanoantennas serve as ultra-sensitive refractometry sensors to capture the refractive index of analytes by wavelength shifts.

    “Thanks to the excellent field confinement at resonance wavelength, plasmonic nanoantennas (PNAs) also serve as an ultra-sensitive refractometry sensor to capture the refractive index of analytes by wavelength shifts (e.g., color change in visible light), which carries the information of physical properties of molecules44,45.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [44] Gao, B. et al. Nanoscale Refractive Index Sensors with High Figures of Merit via Optical Slot Antennas. ACS Nano 13, 9131–9138 (2019). source
    • cites [45] Zhan, C., Liu, B.-W., Tian, Z.-Q. & Ren, B. Determining the Interfacial Refractive Index via Ultrasensitive Plasmonic Sensors. J. Am. Chem. Soc. 142, 10905–10909 (2020). source
  • It may state two separate claims as one.

    Premisereasoning

    Molecules of the same class have strong overlap in fingerprint absorption due to similar chemical structure, making it challenging to distinguish them in small concentrations by monitoring a single absorption peak.

    “However, since the same classes of molecules always have a strong overlap in fingerprint absorption due to the similar chemical structure, it is challenging to distinguish the same classes of molecules in small concentrations by monitoring single absorption peak of each molecules.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Interpretationnone given

    The coupling efficiency is related to the nearfield intensity and the overlapping of molecules with the antenna nearfield.

    “The coupling efficiency is related to the nearfield intensity and the overlapping of molecules to the antenna nearfield.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Premisereasoning

    All three methods-hotspot release, molecule enrichment, and nanogap squeezing-introduce extra processes or materials, increasing fabrication cost or limiting working conditions.

    “However, all of these three methods introduce extra processes or materials to make the plasmonic sensors, which increase the fabrication cost or limit the working condition.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Premisereasoning

    Three approaches to optimize nanoantenna sensing by increasing coupling efficiency μ are hotspot release, molecule enrichment, and squeezing adjacent nanoantennas into a nanogap.

    “Figure 2b summarizes three approaches to optimize nanoantenna sensing by increasing μ. Hotspots release is proposed to increase accessible sensing areas for analytes, which are usually blocked by the substrate, to further enhance the coupling efficiency25–28.”
    • Also stated in: § Design principles of hook nanoantenna · plain
      “Therefore, the molecule enrichment method is utilized to accumulate localized molecules in the effective sensing area17–24. Another approach to enhance the nearfield coupling is to increase the electric field intensity by squeezing the adjacent nanoantenna into the nanogap29–31.”
    Quote in the paperNot a substantial claim0 of 10 sources checked
    • cites [17] Limaj, O. et al. Infrared Plasmonic Biosensor for Real-Time and Label-Free Monitoring of Lipid Membranes. Nano Lett. 16, 1502–1508 (2016). source
    • cites [18] Etezadi, D. et al. Nanoplasmonic mid-infrared biosensor for in vitro protein secondary structure detection. Light Sci. Appl. 6, e17029–e17029 (2017). source
    • cites [19] Hasan, D. & Lee, C. Hybrid Metamaterial Absorber Platform for Sensing of CO2 Gas at Mid-IR. Adv. Sci. 5, (2018). source
    • cites [20] Chang, Y. et al. All-Dielectric Surface-Enhanced Infrared Absorption-Based Gas Sensor Using Guided Resonance. ACS Appl. Mater. Interfaces 10, 38272–38279 (2018). source
    • cites [21] Hu, H. et al. Gas identification with graphene plasmons. Nat. Commun. 10, 1131 (2019). source
    • cites [22] Zhou, H. et al. Metal–Organic Framework‐Surface‐Enhanced Infrared Absorption Platform Enables Simultaneous On‐Chip Sensing of Greenhouse Gases. Adv. Sci. 7, 2001173 (2020). source
    • cites [23] Nuñez, J., Boersma, A., Grand, J., Mintova, S. & Sciacca, B. Thin Functional Zeolite Layer Supported on Infrared Resonant Nano‐Antennas for the Detection of Benzene Traces. Adv. Funct. Mater. 31, 2101623 (2021). source
    • cites [24] Yoo, D. et al. Low-Power Optical Trapping of Nanoparticles and Proteins with Resonant Coaxial Nanoaperture Using 10 nm Gap. Nano Lett. 18, 3637–3642 (2018). source
    • cites [25] Miao, X., Yan, L., Wu, Y. & Liu, P. Q. High-sensitivity nanophotonic sensors with passive trapping of analyte molecules in hot spots. Light Sci. Appl. 10, 5 (2021). source
    • cites [26] Hwang, I. et al. Plasmon-Enhanced Infrared Spectroscopy Based on Metamaterial Absorbers with Dielectric Nanopedestals. ACS Photonics 5, 3492–3498 (2018). source
  • Probably not a substantial claim. The paper may give no reason why it holds.

    Interpretationnone given

    WMHNA integrated into a microfluidic system is compatible with biomolecular systems for molecular detection in the aqueous environment.

    “To demonstrate the capability of liquid dynamics monitoring with broadband fingerprint absorption, we integrate WMHNA into a microfluidic system (Fig. 5a), which is compatible with biomolecular systems for molecular detection in the aqueous environment.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim.

    Interpretationreasoning

    A slight change of intensity of light is observed according to Beer-Lambert's law.

    “Therefore, a slight change of intensity of light is observed according to Beer-Lambert’s law.”
    Quote in the paperSubstantial claim
  • It may state two separate claims as one.

    Premisereasoning

    Methanol, ethanol, and isopropanol have the same functional group of hydroxy and methyl bond, resulting in similar absorption spectra in 6 μm to 9 μm wavelengths.

    “Both of the molecules have the same functional group of hydroxy and methyl bond, resulting in similar absorption spectra in 6 μm to 9 μm wavelengths.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Interpretationnone given

    The order of PC represents the degree of difference between each spectrum.

    “The order of PC represents the degree of difference between each spectrum.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim.

    Premisecitation

    Previous works show many solutions using multiple resonances of nanoantenna structures to capture plasmonic enhanced molecular fingerprints in separate wavelength ranges for sensing different molecule species.

    “Previous works show many solutions using multiple resonances of nanoantenna structures to capture the plasmonic enhanced molecular fingerprints in separate wavelength ranges for sensing different molecule species22,39,41,50,54–56.”
    Quote in the paperSubstantial claim0 of 7 sources checked
    • cites [22] Zhou, H. et al. Metal–Organic Framework‐Surface‐Enhanced Infrared Absorption Platform Enables Simultaneous On‐Chip Sensing of Greenhouse Gases. Adv. Sci. 7, 2001173 (2020). source
    • cites [39] Rodrigo, D. et al. Resolving molecule-specific information in dynamic lipid membrane processes with multi-resonant infrared metasurfaces. Nat. Commun. 9, (2018). source
    • cites [41] Rodrigo, D., Tittl, A., John-Herpin, A., Limaj, O. & Altug, H. Self-Similar Multiresonant Nanoantenna Arrays for Sensing from Near- to Mid-Infrared. ACS Photonics 5, 4903–4911 (2018). source
    • cites [50] John‐Herpin, A., Kavungal, D., Mücke, L. & Altug, H. Infrared Metasurface Augmented by Deep Learning for Monitoring Dynamics between All Major Classes of Biomolecules. Adv. Mater. 33, 2006054 (2021). source
    • cites [54] Hasan, D. et al. Thermoplasmonic Study of a Triple Band Optical Nanoantenna Strongly Coupled to Mid IR Molecular Mode. Sci. Rep. 6, 22227 (2016). source
    • cites [55] Aslan, E. et al. Multispectral Cesaro-Type Fractal Plasmonic Nanoantennas. ACS Photonics 3, 2102–2111 (2016). source
    • cites [56] Ren, Z., Dang, Z. & Lee, C. Multi-Band Mid-IR Molecules Identification Using Plasmonic Metamaterials Induced by Bright-Dark Coupling. in 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS) vols 2020-Janua 725–728 (IEEE, 2020). source
  • It may state two separate claims as one.

    Interpretationown data

    With the help of ML, the IR spectrum of HNA with different molecules can be reduced to three principal components, which indicate the three key features of loading effect, wavelength shifts, and enhanced fingerprint absorption.

    “With the help of ML, the IR spectrum of HNA with different molecules can be reduced to three principal components, which indicate the three key features of loading effect, wavelength shifts, and enhanced fingerprint absorption.”
    Quote in the paperSubstantial claim
40 of 40
  • The authors state this as an assumption.

    There is a need for new nanoantenna structures for continuous broadband detection and new methods to distinguish chemically similar molecules from partially overlapped absorption spectra.

    “Therefore, new nanoantenna structures need to be developed for continuous broadband detection to capture multiple absorption peaks in fingerprint regions and new methods need to be conducted to distinguish the chemically similar molecules from the partially overlapped absorption spectra.”
  • The paper relies on this without support.

    Molecules of the same class have strong overlap in fingerprint absorption due to similar chemical structure.

    “However, since the same classes of molecules always have a strong overlap in fingerprint absorption due to the similar chemical structure, it is challenging to distinguish the same classes of molecules in small concentrations by monitoring single absorption peak of each molecules.”
  • The paper relies on this without support.

    In the IR fingerprint region, plasmonic nanoantenna signals of absorption changes and wavelength shifts always occur together.

    “Unfortunately, in the IR fingerprint region, the PNA signal of absorption changes and wavelength shifts always comes together, hindering the usage of complementary information about the analyte’s physical and chemical properties for molecule identification.”
  • The authors state this as an assumption.

    The temporal coupled-mode theory model accurately describes the plasmon-molecule coupling system.

    “To understand the design principles, we use the TCMT model52 to analyze the plasmon-molecules coupling system.”
  • The authors state this as an assumption.

    The Lorentz model accurately represents the optical properties of analytes.

    “To demonstrate the individual response caused by three effects, we use finite-difference time-domain (FDTD) methods to simulate the antenna response and manipulate the optical properties (refractive index, n and absorption coefficient, k) of analytes by Lorentz model, which has been used in our previous works19,51”
  • The authors state this as an assumption.

    In the TCMT model, the plasmonic resonance is treated as a bright mode coupled to incident light, and molecular vibration is treated as a dark mode whose coupling efficiency is much lower than the plasmonic nanoantenna and can be ignored.

    “We treat the plasmonic resonant (denoted as P) as a bright mode that is coupled to the incident light, while we treat the molecular vibration (denoted as M) as a dark mode, in which coupling efficiency is much lower than PNA and can be ignored in their coupling system.”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

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.

  • Silk-and-PMMA results are assigned to the wrong figure panel

    Minor

    The text points to Fig. 4b for silk-and-PMMA sensing results, whereas the caption identifies Fig. 4b as baseline-corrected spectra from panel a and assigns silk-and-PMMA sensing to Fig. 4e.

  • Radiative and absorptive loss symbols are reversed

    Minor

    The initial definition makes γa the radiative loss and γr the absorptive loss. The later design explanation treats γa as ohmic loss and γr as the loss governing radiation.

  • Classification samples are called gases instead of liquids

    Minor

    The classification section says the binary classifiers distinguish six gases, but the described samples are aqueous alcohol solutions and their mixtures.

  • First two principal components are assigned opposite effects

    Minor

    The Fig. 6 caption assigns the antenna loading effect to PC 1 and the refractometric wavelength shift to PC 2. The Results text reverses those assignments, leaving the interpretation of the classification features inconsistent.

4 of 4

Citations

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Metadata

Authors
Ren, Z., Zhang, Z., Wei, J., Dong, B., & Lee, C.
Affiliations
National University of Singapore (SG)
Corresponding author
Lee, Chengkuo
Venue
Nature Communications
Published
2022-07-05
Volume
13
Issue
1
Pages
3859-3859
ISSN
2041-1723 (ISSN-L)
OpenAlex
W4283816337
Cited by
132
References
64
Citations by year
2026: 19 · 2025: 43 · 2024: 36 · 2023: 26 · 2022: 8
FWCI
8.20
Type
journal article
Language
en
Open access
Locations
  • Nature Communications (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • National University of Singapore (submittedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • National Research Foundation Singapore (NRF-CRP15-2015-02)
  • Agency for Science, Technology and Research (A18A5b0056)
  • Ministry of Education - Singapore (A-0005138-00-00)
  • National University of Singapore (A-0005947-06-00)
Topics
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Plasmonic and Surface Plasmon Research
  • Physical Sciences › Materials Science › Electronic, Optical and Magnetic Materials › Gold and Silver Nanoparticles Synthesis and Applications
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Biophysics › Spectroscopy Techniques in Biomedical and Chemical Research
Keywords
mid-infrared plasmonics, plasmonic nanoantennas, loss engineering, spectral multiplexing, vibrational spectroscopy, alcohol identification, microfluidic integration
MeSH terms
Machine Learning, Spectrophotometry, Infrared, Peptide Nucleic Acids, Surface Plasmon Resonance, Nanostructures

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.

A language model drew the claims from the paper on 2026-10-09, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-09 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

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 ›

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