On-chip label-free biosensing based on active whispering gallery mode resonators pumped by a light-emitting diode

Hansuek Lee; Yeseul Kim

REVIEW 3 major objections 5 minor 40 references

On-chip label-free biosensing based on active whispering gallery mode resonators pumped by a light-emitting diode

T0 review · 3 major / 5 minor · reviewed 2026-08-14 · deepseek-v4-flash

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Pith's one-line read This paper claims that an LED-pumped, free-space-readout microdisk biosensor with a 25 nm slot detects unlabelled biomolecules with a reported sensitivity over 20 times higher than earlier remote-readout WGM sensors.

desk verdict The LED-pumped silicon-nanocluster WGM sensor is a real engineering advance, but its headline sensitivity number is undermined by an internal inconsistency with the paper's own kinetics fit. read the letter →

arxiv 1908.04506 v1 pith:PPJMAAW5 submitted 2019-08-13 physics.app-ph physics.optics

Yeseul Kim , Hansuek Lee This is my paper · ORCID

classification physics.app-phphysics.optics

keywords label-freebiosensingwhispering-gallerymodesiliconnanoclusteractivemicroresonatorLEDpumpnano-slotstreptavidin-biotinmicrofluidics

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper claims a practical route to label-free biosensing on a chip: whispering-gallery-mode resonators made from silicon-rich silicon nitride and containing silicon nanoclusters are pumped from above by a light-emitting diode and read out through free-space optics, so no fibre taper or bus waveguide touches the chip. A $25\ \mathrm{nm}$ slot cut through each resonator concentrates the optical field where target molecules bind, giving a reported sensitivity of $0.012\ \mathrm{nm/nM}$ for the streptavidin-biotin interaction, about 22 times higher than earlier remote-readout active WGM sensors. If this holds, biosensing chips could be cheap, alignment-tolerant, and integrated with microfluidics while still detecting unlabelled molecules in real time. The paper also demonstrates, for the first time, WGM sensing under direct LED illumination, and argues from kinetic measurements that the slot does not distort the binding dynamics.

What carries the argument

The central mechanism is the active slot resonator: a silicon-rich silicon nitride microdisk pair supports a whispering-gallery mode (a resonance circulating around the disk rim), and annealed silicon nanoclusters make the disks photoluminescent so the mode can be excited by an unaligned top pump and read by a spectrometer through free space. The $25\ \mathrm{nm}$ slot between the disks confines $8.6\%$ of the transverse-magnetic mode energy in the sensing gap, enhancing the shift caused by bound molecules by an estimated factor of 6.5. The kinetic analysis uses the Langmuir/Hill model, including association curves and a Hill-Langmuir isotherm with $K_d = 3.8\times10^{-7}\ \mathrm{M}$, to show that binding inside the narrow slot follows normal surface kinetics.

What would settle it

Measure the equilibrium resonance shift at several streptavidin concentrations below 36 nM using a spectrometer with resolution better than 0.05 nm; if the shift per nanomolar is not constant but instead follows the saturating Hill curve with $K_d = 3.8\times10^{-7}\ \mathrm{M}$, then the reported $0.012\ \mathrm{nm/nM}$ sensitivity and $6.7\ \mathrm{nM}$ detection limit are not valid across the claimed range.

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Extended reading notes

Core claim

The device is a self-emitting microcavity: silicon nanoclusters in a silicon-rich nitride disk absorb pump light from above and emit a photoluminescence spectrum carrying the cavity resonance, so neither the pump nor the readout needs to physically touch the chip. A pair of disks separated by a $25\ \mathrm{nm}$ slot confines a large share of the optical mode in the solution-filled gap where binding occurs, enhancing sensitivity by an estimated factor of 6.5 over a slot-free resonator. Using the streptavidin-biotin pair, the authors report a real-time sensitivity of $0.012\ \mathrm{nm/nM}$ and a detection limit of $6.7\ \mathrm{nM}$, and with a 365 nm LED pump they demonstrate WGM sensing under direct LED illumination for the first time, measuring bulk refractive-index changes at $226.67\ \mathrm{nm/RIU}$ in agreement with numerical simulation.

Load-bearing premise

The result stands or falls on the assumption that the resonance shift grows linearly with streptavidin concentration across the measured range; the paper's own Hill-Langmuir fit with $K_d = 3.8\times10^{-7}\ \mathrm{M}$ describes a saturating response rather than a constant slope.

Editorial extensions

If this is right

A WGM sensor chip can be operated by placing it under an LED and reading its photoluminescence through free-space optics, removing fragile tapered fibres and precision waveguide alignment from the sensing workflow.
The reported sensitivity of $0.012\ \mathrm{nm/nM}$ for streptavidin-biotin is more than 20 times the previous remote-readout WGM result, and the detection limit of $6.7\ \mathrm{nM}$ follows from the measured mode linewidth.
The $25\ \mathrm{nm}$ slot boosts sensitivity about 6.5-fold over an unslotted resonator while the measured association and dissociation parameters stay close to literature values, suggesting the confinement does not impede binding.
With a 365 nm LED pump, bulk refractive-index changes are detected at $226.67\ \mathrm{nm/RIU}$, and the estimated detection limit of about 0.25% glycerol shows that the platform works without a laser.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

A testable next step is replacing the 365 nm UV LED with a visible-wavelength LED at sufficient intensity, which would let the LED-pumped scheme detect biomolecules directly rather than only refractive-index changes; the authors identify the roughly $20\ \mathrm{W/cm^2}$ visible-intensity level as the threshold.
Reducing the slot width below $25\ \mathrm{nm}$, toward the size of the streptavidin-biotin complex, could turn the sensor into an instrument for studying how nanoconfinement alters binding kinetics, an extension the authors flag in their conclusion.
The large-area LED illumination makes arrayed sensing natural: many top-pumped resonators could be read simultaneously by imaging their photoluminescence spectra, something the paper does not demonstrate but its geometry invites.

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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

Colleague—

What you should know: this paper is the real thing on the engineering side—an active WGM biosensor pumped by an LED, using silicon nanoclusters as the gain medium and a 25 nm slot for field enhancement—but the headline sensitivity figure does not survive contact with the paper's own kinetics fit.

The genuinely new pieces are the LED top-illumination scheme (first time, as far as I can tell), the use of silicon nanoclusters rather than photobleaching dyes, and the integration of the slot into an active, free-space-readout resonator. The bulk refractometric response scaled with concentration and matched COMSOL to 226.67 nm/RIU; that is a clean calibration result. The kinetic analysis with the Langmuir model is also sane, and the kon values are consistent with literature. The paper is honest about the LED-UV limitation for biomolecule detection. I believe these authors know what they are doing in the lab.

The soft spot is the central claim. Section 2.3 says the 1.7 nm shift at 144 nM streptavidin was taken 'after saturation,' and divides by the concentration to get 0.012 nm/nM. But Section 2.4 fits the same interaction to a Hill-Langmuir isotherm with Kd = 3.8e-7 M. At 144 nM that isotherm gives theta ≈ 0.27—about a quarter of the way to saturation, not saturation. So the linear sensitivity and the 6.7 nM detection limit derived from it are not supported by the paper's own data. The '22 times' improvement over Ref. [16] is therefore built on an ill-defined calibration. This is a load-bearing flaw, not a cosmetic one. It is fixable: measuring a calibration curve with replicates and error bars, or reporting the single-point shift as an apparent response and dropping the sensitivity language, would make the paper defensible.

Two smaller issues. The FSR numbers don't line up: the argon-pumped spectrum in air shows 7.9 nm, the LED-pumped spectrum in air is quoted as 9.1 nm, yet the text claims they are exactly the same. That needs explanation. And the slot sensitivity enhancement (6.5x) is simulation-only; the paper uses the simulated refractive-index response as partial validation, so I don't count that as circular, but it should be flagged as an extrapolation.

Verdict: this deserves a serious referee. The core engineering demonstration is sound, but the headline quantitative claims need correction and more data. I'd accept the paper for review, then require a proper sensitivity calibration before publication. For a reading group, it's a good example of how a promising sensor platform can undercut itself with a single inconsistent fit. I'd cite the LED-pumped active resonator concept, not the sensitivity number.

Referee Report

3 major / 5 minor

Summary. The manuscript demonstrates an on-chip whispering-gallery-mode (WGM) biosensor platform based on silicon nanocluster active resonators with a 25-nm slot, integrated with microfluidic channels and operated with free-space optical pumping and readout. The authors report streptavidin-biotin binding measurements with a claimed sensitivity of 0.012 nm/nM and a detection limit of 6.7 nM, kinetic analysis using Langmuir and Hill-Langmuir fits, and a demonstration of LED-pumped operation for bulk refractive-index sensing. The central claims are the first LED-pumped active WGM sensing scheme and a sensitivity improvement of over 20 times relative to prior remote-readout WGM sensors.

Significance. If fully supported, the work would be a practical advance toward label-free on-chip sensors because it eliminates fragile evanescent coupling and uses a low-cost LED for top-illumination. The COMSOL simulation for the slot field confinement is checked against measured bulk refractive-index shifts, which is a genuine strength, and the device integration with microfluidics is convincingly described. However, the headline molecular sensitivity rests on a single unsaturated measurement that contradicts the paper's own kinetic model, and the LED-pumped demonstration is limited to bulk refractometry rather than biomolecule detection. As presented, the quantitative performance claims are not yet established, although the platform concept appears promising.

major comments (3)

[Sec. 2.3 and 2.4] The sensitivity of 0.012 nm/nM is derived from a single 1.7-nm shift recorded after exposure to 144 nM streptavidin, which the text calls 'saturation.' Yet the Hill-Langmuir fit in Sec. 2.4 reports Kd = 3.8e-7 M; at 144 nM the fitted fractional occupancy is only 144/(144+380) ≈ 0.27, i.e., the reaction is far from saturation. A single ratio Δλ/c at a nonsaturating concentration is therefore not a valid sensitivity, and the value is inconsistent with the kinetic model. Please provide a proper calibration curve, for example using the 9, 36, 54, and 90 nM equilibrium shifts already measured in Fig. 3b, and report the slope in the linear low-concentration regime with replicate devices and error bars, or explicitly state that the reported value is an apparent single-concentration response.
[Sec. 2.5, Abstract, Conclusions] The LED-pumped operation is demonstrated only for bulk refractive-index sensing with glycerol-water mixtures; the biomolecule (streptavidin-biotin) measurements are performed with an argon-ion laser. The abstract and conclusions state that 'WGM sensing based on the direct illumination of an LED pump is demonstrated for the first time,' and the title refers to pumping by an LED, which may lead readers to infer LED-pumped biosensing. Since the paper explicitly states that UV LED light deforms biomolecules, the current device does not actually demonstrate LED-pumped label-free biosensing. Please either qualify the claims to indicate that LED pumping is shown only for refractometric sensing, or add an experiment with a visible-wavelength LED and biomolecules.
[Sec. 2.3] The detection limit of 6.7 nM is computed as 0.08 nm (FWHM) divided by 0.012 nm/nM. This calculation inherits the unsupported linear sensitivity, and defining the resolution as a single FWHM is not a statistically meaningful detection limit; typically one uses 3σ of baseline noise or another established criterion on the calibration curve. Please report the spectral noise floor from repeated measurements of a stable resonance and recompute the limit of detection accordingly. In addition, the manuscript does not state how many devices or repeated measurements the 1.7-nm shift is based on; this information is essential for assessing the reproducibility of the headline sensitivity.

minor comments (5)

[Sec. 2.4] The sentence 'The slightly larger kon of 9 nM streptavidin is caused by the detection limit' appears to contradict the reported kon values (1.2×10^3 M^-1 s^-1 for 9 nM versus 4.2–6.4×10^3 M^-1 s^-1 for the other concentrations). The 9 nM value is actually the smallest, not the largest; please clarify whether this is a misstatement or refers to the uncertainty of the fit.
[Sec. 2.2 and 2.5] The FSR and Q factor for air with the argon laser are reported as 7.9 nm and greater than 15,000, while the LED measurement in air reports 9.1 nm and 15,000. The source of this discrepancy, possibly a different mode family or device, should be stated explicitly.
[Sec. 2.3] The term 'sensitivity' is used with different units for biomolecule detection (nm/nM) and bulk sensing (nm/RIU). Please define both clearly and state the sensing area or volume normalization, since the comparison with Ref. [16] may depend on the active surface area and the binding capacity of the slot.
[Fig. 3b] Please show the fitted Hill-Langmuir parameters with confidence intervals and state whether the fit includes the 144 nM point or is extrapolated to it. This would help reconcile the sensitivity calculation with the kinetic analysis.
[General] The paper would benefit from a statement of the number of independent devices used for each experiment and the reproducibility across chips, data that are standard for sensor characterization.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the central claims are supported by direct measurements and independent simulation validation; the quoted sensitivity is a measured ratio, not a fitted prediction.

full rationale

The paper's main claims—LED-pumped active WGM sensing and slot-enhanced sensitivity—rest on directly measured photoluminescence spectra and resonance peak shifts, not on parameters that are fitted and then repackaged as predictions. The quoted sensitivity of 0.012 nm/nM is the measured 1.7 nm shift divided by the 144 nM streptavidin concentration; it is a direct experimental ratio, and no equation in the paper derives this value from an input model. The COMSOL bulk sensitivity prediction (226.67 nm/RIU) is compared with an independent glycerol-series measurement, and the agreement is used to support the slot simulation; this is validation, not circularity. The kinetics parameters (Kd, kon) are fitted to time-series data under the Langmuir model and then used for internal consistency checks, which is standard modeling rather than circular derivation. The only self-citation (Ref. [17]) is contextual background for expected WGM sensitivity and is not load-bearing. A separate concern—that the linear 'sensitivity' at 144 nM is inconsistent with the fitted Hill-Langmuir Kd = 3.8e-7 M, so the 0.012 nm/nM and 6.7 nM detection limit may be ill-defined—is a correctness or calibration issue, not circularity. No step in the derivation reduces to its own input by construction.

Assumptions & free parameters 3 free parameters · 4 assumptions · 0 invented entities

The paper introduces no new physical entities. The central claims rest on assumed validity of the Langmuir model, the COMSOL simulation, and the surface immobilization chemistry, plus fitted kinetic parameters Kd and kon. The linear sensitivity figure is an additional modeling assumption, not a fitted parameter, but it is contradicted by the paper's own Hill-Langmuir fit.

free parameters (3)

Kd (dissociation constant) = 3.8e-7 M
Fitted from equilibrium resonance shifts at four concentrations using the Hill-Langmuir equation (Fig. 3b).
kon (association rate constant) = 1.2e3 to 6.4e3 M^-1 s^-1
Fitted from association curves with Kd fixed (Fig. 3a); also derived 4.8e3 M^-1 s^-1 from initial slopes.
Maximum binding shift (saturation) = Not explicitly reported, inferred about 6.2 nm
The Hill-Langmuir fit in Fig. 3b requires a maximum shift parameter, but only Kd is reported; the value is implied by the 1.7 nm shift at 144 nM and Kd.

assumptions (4)

domain assumption Langmuir adsorption model describes the streptavidin-biotin surface binding kinetics and equilibrium.
Used to fit association curves and equilibrium isotherm in Sec. 2.4; assumes a homogeneous surface with 1:1 binding.
domain assumption COMSOL mode simulations accurately represent the fabricated resonator geometry and refractive indices.
Used to compute the mode profile, slot energy fraction, and bulk sensitivity in Sec. 2.1 and 2.5; assumes ideal geometry and material properties.
domain assumption Biotin immobilization via APTES on the silicon nitride surface is stable and functional.
The sensing experiment depends on successful surface chemistry described in Sec. 3.3; no independent verification of surface coverage is provided.
domain assumption The tracked PL peaks belong to the same fundamental TM mode family across conditions.
Mode identification is done by matching FSR to numerical estimates (Sec. 2.2); misidentification would affect all shift measurements.

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Cite this review

Pith. "Pith review of On-chip label-free biosensing based on active whispering gallery mode resonators pumped by a light-emitting diode." pith.science (2026). https://pith.science/paper/PPJMAAW5

@misc{pith2026190804506,
  author       = {Pith},
  title        = {Pith review of: On-chip label-free biosensing based on active whispering gallery mode resonators pumped by a light-emitting diode},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/PPJMAAW5}},
  note         = {Machine review of arXiv:1908.04506}
}

read the original abstract

Biosensing based on whispering-gallery mode (WGM) resonators has been continuously studied with great attention due to its excellent sensitivity guaranteeing the label-free detection. However, its practical impact is insignificant to date despite notable achievements in academic research. Here, we demonstrate a novel practical platform of on-chip WGM sensors integrated with microfluidic channels. By placing silicon nanoclusters as a stable active compound in micro-resonators, the sensor chip can be operated with a remote pump and readout, which simplifies the chip integration and connection to the external setup. In addition, silicon nanoclusters having large absorption cross-section over broad wavelength range allow active sensing for the first time with an LED pump in a top-illumination scheme which significantly reduces the complexity and cost of the measurement setup. The nano-slot structure of 25 nm gap width is embedded in the resonator where the target bio-molecules are selectively detected with the sensitivity enhanced by strongly confined mode-field. The sensitivity confirmed by real-time measurements for the streptavidin-biotin complex is 0.012 nm/nM, improved over 20 times larger than the previously reported WGM sensors with remote readout.

Figures

Figures reproduced from arXiv: 1908.04506 by the authors.

**Figure 2.** Experimental setup and measurement results. [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗

**Figure 3.** Biosensing demonstration and results analysis. [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗

Figures from the paper (1 more)

**Figure 4.** Figure 4: The measurement with a LED light source and [PITH_FULL_IMAGE:figures/full_fig_p005_4.png]

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

40 extracted references · 39 canonical work pages

[16]

S. F. Wondimu, M. Hippler, C. Hussal, A. Hofmann, S. Kr”ammer, J. Lahann, H. Kalt, W. Freude, and C. Koos. Robust label-free biosensing using mi- crodisk laser arrays with on-chip references. Optics express, 26(3):3161–3173, 2018

work page 2018
[1]

E. Kim, M. D. Baaske, and F. Vollmer. To- wards next-generation label-free biosensors: recent advances in whispering gallery mode sensors. Lab on a Chip , 17(7):1190–1205, 2017

work page 2017
[2]

Vollmer and S

F. Vollmer and S. Arnold. Whispering-gallery- mode biosensing: label-free detection down to single molecules. Nature methods, 5(7):591, 2008

work page 2008
[3]

Vollmer and L

F. Vollmer and L. Yang. Review label-free detec- tion with high-q microcavities: a review of biosens- ing mechanisms for integrated devices. Nanophoton- ics, 1(3-4):267–291, 2012

work page 2012
[4]

Subramanian, H.-Y

S. Subramanian, H.-Y. Wu, T. Constant, J. Xavier, and F. Vollmer. Label-free optical single-molecule micro-and nanosensors. Advanced Materials , 30(51):1801246, 2018

work page 2018
[5]

Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform

Martin D Baaske, Matthew R Foreman, and Frank Vollmer. Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform. Nature nanotechnology, 9(11):933, 2014

work page 2014
[6]

L. He, S ¸. K.¨Ozdemir, J. Zhu, W. Kim, and L. Yang. Detecting single viruses and nanoparticles using whispering gallery microlasers. Nature nanotechnol- ogy, 6(7):428, 2011

work page 2011
[7]

A. M. Armani, R. P. Kulkarni, S. E. Fraser, R. C. Flagan, and K. J. Vahala. Label-free, single- molecule detection with optical microcavities. sci- ence, 317(5839):783–787, 2007

work page 2007

Show all 40 references

[8]

On-chip single nanoparticle detection and sizing by mode splitting in an ultrahigh-q microresonator

Jiangang Zhu, Sahin Kaya Ozdemir, Yun-Feng Xiao, Lin Li, Lina He, Da-Ren Chen, and Lan Yang. On-chip single nanoparticle detection and sizing by mode splitting in an ultrahigh-q microresonator. Nature photonics, 4(1):46, 2010

2010
[9]

Arnold, S

S. Arnold, S. I. Shopova, and S. Holler. Whisper- ing gallery mode bio-sensor for label-free detection of single molecules: thermo-optic vs. reactive mech- anism. Optics Express, 18(1):281–287, 2010

2010
[10]

Whispering gallery mode sensors

Matthew R Foreman, Jon D Swaim, and Frank Vollmer. Whispering gallery mode sensors. Ad- vances in optics and photonics , 7(2):168–240, 2015

2015
[11]

Wienhold, S

T. Wienhold, S. Kraemmer, S. F. Wondimu, T. Siegle, U. Bog, U. Weinzierl, S. Schmidt, H. Becker, H. Kalt, T. Mappes, S. Koeberaf, and C. Koos. All-polymer photonic sensing plat- form based on whispering-gallery mode microgoblet lasers. Lab on a Chip , 15(18):3800–3806, 2015

2015
[12]

X. Xu, W. Chen, G. Zhao, Y. Li, C. Lu, and L. Yang. Wireless whispering-gallery-mode sensor for thermal sensing and aerial mapping. Light: Science & Ap- plications, 7(1):62, 2018

2018
[13]

J. C. Knight, G. Cheung, F. Jacques, and T. A. Birks. Phase-matched excitation of whispering- gallery-mode resonances by a ﬁber taper. Optics letters, 22(15):1129–1131, 1997

1997
[14]

C. A. Barrios. Integrated microring resonator sensor arrays for labs-on-chips. Analytical and bioanalytical chemistry, 403(6):1467–1475, 2012

2012
[15]

Wienhold, S

T. Wienhold, S. Kraemmer, A. Bacher, H. Kalt, C. Koos, S. Koeber, and T. Mappes. Eﬃcient free-space read-out of wgm lasers using circular mi- cromirrors. Optics express, 23(2):1025–1034, 2015

2015
[17]

T. Lu, H. Lee, T. Chen, S. Herchak, J.-H. Kim, S. E. Fraser, R. C. Flagan, and K. J. Vahala. High sen- sitivity nanoparticle detection using optical micro- cavities. Proceedings of the National Academy of Sciences, 108(15):5976–5979, 2011

2011
[18]

J. Su, A. FG Goldberg, and B. M. Stoltz. Label- free detection of single nanoparticles and biologi- cal molecules using microtoroid optical resonators. Light: Science & Applications , 5(1):e16001, 2016

2016
[19]

F. F. Lupi, D. Navarro-Urrios, J. Monserrat, C. Dominguez, P. Pellegrino, and B. Garrido. High q light-emitting si-rich si 3 n 4 microdisks. Optics Letters, 36(8):1344–1346, 2011. 7

2011
[20]

Kim and J

G. Kim and J. H. Shin. Luminescent silicon-rich nitride horizontal air-slot microdisk resonators for biosensing. IEEE Photonics Technology Letters , 28(21):2331–2334, 2016

2016
[21]

Band gap engineering of amorphous silicon quan- tum dots for light-emitting diodes

Nae-Man Park, Tae-Soo Kim, and Seong-Ju Park. Band gap engineering of amorphous silicon quan- tum dots for light-emitting diodes. Applied Physics Letters, 78(17):2575–2577, 2001

2001
[22]

Direct observation of quantum conﬁne- ment of si nanocrystals in si-rich nitrides

PD Nguyen, DM Kepaptsoglou, QM Ramasse, and A Olsen. Direct observation of quantum conﬁne- ment of si nanocrystals in si-rich nitrides. Physical Review B, 85(8):085315, 2012

2012
[23]

Quantum conﬁnement in amor- phous silicon quantum dots embedded in silicon ni- tride

Nae-Man Park, Chel-Jong Choi, Tae-Yeon Seong, and Seong-Ju Park. Quantum conﬁnement in amor- phous silicon quantum dots embedded in silicon ni- tride. Physical review letters , 86(7):1355, 2001

2001
[24]

V. R. Almeida, Q. Xu, C. A. Barrios, and M. Lipson. Guiding and conﬁning light in void nanostructure. Optics letters , 29(11):1209–1211, 2004

2004
[25]

Scullion, T

M. Scullion, T. Krauss, and A. Di Falco. Slotted photonic crystal sensors. Sensors, 13(3):3675–3710, 2013

2013
[26]

W. Liu, S. K. Samanta, B. D. Smith, and L. Isaacs. Synthetic mimics of biotin/(strept) avidin.Chemical Society Reviews, 46(9):2391–2403, 2017

2017
[27]

Halperin, A

A. Halperin, A. Buhot, and E. B. Zhulina. On the hybridization isotherms of dna microarrays: the langmuir model and its extensions. Journal of Physics: Condensed Matter , 18(18):S463, 2006

2006
[28]

A. L. Washburn, L. C. Gunn, and R. C. Bailey. Label-free quantitation of a cancer biomarker in complex media using silicon photonic microring res- onators. Analytical chemistry , 81(22):9499–9506, 2009

2009
[29]

R. A. Latour. The langmuir isotherm: a commonly applied but misleading approach for the analysis of protein adsorption behavior. Journal of Biomedical Materials Research Part A , 103(3):949–958, 2015

2015
[30]

B. M. Lowe, K. Sun, I. Zeimpekis, C.-K. Skylaris, and N. G. Green. Field-eﬀect sensors–from ph sensing to biosensing: sensitivity enhancement us- ing streptavidin–biotin as a model system. Analyst, 142(22):4173–4200, 2017

2017
[31]

D. A. Hanaor, M. Ghadiri, W. Chrzanowski, and Y. Gan. Scalable surface area characterization by electrokinetic analysis of complex anion adsorption. Langmuir, 30(50):15143–15152, 2014

2014
[32]

The adsorption of gases on plane surfaces of glass, mica and platinum

Irving Langmuir. The adsorption of gases on plane surfaces of glass, mica and platinum. Journal of the American Chemical society , 40(9):1361–1403, 1918

1918
[33]

Interpreting complex binding kinetics from optical biosensors: a comparison of analysis by lin- earization, the integrated rate equation, and numeri- cal integration

Thomas A Morton, David G Myszka, and Irwin M Chaiken. Interpreting complex binding kinetics from optical biosensors: a comparison of analysis by lin- earization, the integrated rate equation, and numeri- cal integration. Analytical biochemistry, 227(1):176– 185, 1995

1995
[34]

Crossed surface relief gratings as nanoplas- monic biosensors

Srijit Nair, Carlos Escobedo, and Ribal Georges Sabat. Crossed surface relief gratings as nanoplas- monic biosensors. ACS sensors, 2(3):379–385, 2017

2017
[35]

D’Agata, G

R. D’Agata, G. Grasso, and G. Spoto. Real-time binding kinetics monitored with surface plasmon resonance imaging in a diﬀusion-free environment. Open Spectrosc J, 2:1–9, 2008

2008
[36]

M. J. Eddowes. Direct immunochemical sensing: ba- sic chemical principles and fundamental limitations. Biosensors, 3(1):1–15, 1987

1987
[37]

S. V. Deshpande, E. Gulari, S. W. Brown, and S. C. Rand. Optical properties of silicon nitride ﬁlms de- posited by hot ﬁlament chemical vapor deposition. Journal of Applied Physics , 77(12):6534–6541, 1995

1995
[38]

L. F. Hoyt. New table of the refractive index of pure glycerol at 20 c. Industrial & Engineering Chem- istry, 26(3):329–332, 1934

1934
[39]

Abdelgawad, M

M. Abdelgawad, M. W. Watson, E. W. Young, J. M. Mudrik, M. D. Ungrin, and A. R. Wheeler. Soft lithography: masters on demand. Lab on a Chip , 8(8):1379–1385, 2008

2008
[40]

E. H. Williams, A. V. Davydov, A. Motayed, S. G. Sundaresan, P. Bocchini, L. J. Richter, G. Stan, K. Steﬀens, R. Zangmeister, J. A. Schreifels, and M. V. Rao. Immobilization of streptavidin on 4h–sic for biosensor development. Applied surface science , 258(16):6056–6063, 2012. 8

2012

Pith tools

Reviewed August 14, 2026 · model on record in the stance chip above.

[1] [16]

S. F. Wondimu, M. Hippler, C. Hussal, A. Hofmann, S. Kr”ammer, J. Lahann, H. Kalt, W. Freude, and C. Koos. Robust label-free biosensing using mi- crodisk laser arrays with on-chip references. Optics express, 26(3):3161–3173, 2018

work page 2018

[2] [1]

E. Kim, M. D. Baaske, and F. Vollmer. To- wards next-generation label-free biosensors: recent advances in whispering gallery mode sensors. Lab on a Chip , 17(7):1190–1205, 2017

work page 2017

[3] [2]

Vollmer and S

F. Vollmer and S. Arnold. Whispering-gallery- mode biosensing: label-free detection down to single molecules. Nature methods, 5(7):591, 2008

work page 2008

[4] [3]

Vollmer and L

F. Vollmer and L. Yang. Review label-free detec- tion with high-q microcavities: a review of biosens- ing mechanisms for integrated devices. Nanophoton- ics, 1(3-4):267–291, 2012

work page 2012

[5] [4]

Subramanian, H.-Y

S. Subramanian, H.-Y. Wu, T. Constant, J. Xavier, and F. Vollmer. Label-free optical single-molecule micro-and nanosensors. Advanced Materials , 30(51):1801246, 2018

work page 2018

[6] [5]

Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform

Martin D Baaske, Matthew R Foreman, and Frank Vollmer. Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform. Nature nanotechnology, 9(11):933, 2014

work page 2014

[7] [6]

L. He, S ¸. K.¨Ozdemir, J. Zhu, W. Kim, and L. Yang. Detecting single viruses and nanoparticles using whispering gallery microlasers. Nature nanotechnol- ogy, 6(7):428, 2011

work page 2011

[8] [7]

A. M. Armani, R. P. Kulkarni, S. E. Fraser, R. C. Flagan, and K. J. Vahala. Label-free, single- molecule detection with optical microcavities. sci- ence, 317(5839):783–787, 2007

work page 2007