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Label-free Super-resolution Imaging and Sensing

Zengbo Wang

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Bangor University, UK

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Bangor, North Wales

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  • Laser – 激光相关应用
  • Imaging & Sensing

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  • Introduction
  • Super-resolution imaging & Sensing

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    • Microsphere superlens
    • Metamaterial superlens
    • Other superlens
    • Nano-vibration and fiber sensing

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  • AI: digital twin of superlens imaging

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  • Summary and outlook

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Outlines

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Super-resolution microscopy

® NSOM (Near-field Scanning Optical Microscope)- 20 nm, Slow

® Meta-material Superlenses –70 nm, absorption limited

® SIM(Structured Illumination Microscopy) – 100 nm resolution, algorithm- based

© Existing popular approaches

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® PALM (Photo-activated localization microscopy) or STORM - 20 nm, bio- samples, far –field

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© New approaches (see Physics world, May issue, 2012, page 29-34):

® Super-oscillatory lens (without evanescent waves)- far-field

® Time-reversal imaging

® Maxwell’s fisheyes

® Scattering lens - far-field

® Microsphere particle Lens (M-PLSI, our work)

STED (Stimulated Emission Depletion) – 20 nm, bio-samples, far –field

Nobel

Prize

2014

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Metamaterial Superlens, Hyperlens

-Xiang Zhang (UC-Berkeley)

Superlens

Hyperlens

Key idea: using silver plasmonic effect to enhance the evanescent waves associated with sub-diffraction-limited features

fundamentally loss-limited

Funding: Welsh Government (KESS268), EU Horizon2020 (SUMCASTC)

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STED (Stimulated Emission Depletion)

–by Stefan Hell Max Planck Institute

Key point:

  • fluorescence based, great for bio-samples,
  • not for direct imaging of non-labelled Samples such as IC chips.

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PALM/STORM

PALM: Photo activated Localization Microscopy

STORM: Stochastic Optical Reconstruction Microscopy

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Looking through transparent balls

Virtual imaging – image same orientation/side with objects

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Real imaging mode

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Virtual imaging basics

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Looking through transparent balls

Virtual imaging – image same orientation/side with objects

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Introduction

  • Mesoscale: effective dimensions are comparable with the incident radiation wavelength.

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  • Typical: several to several tens wavelength, e.g. ~2 λ – 100 λ

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Phys. Wave Phenom. ,

30, 217-241 (2022).

30, 293-297 (2022).

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Big particle: Ray tracing ( a >>λ)

(4 − n 2 )3

w ≈ a

Spot size (Caustic on sphere):

27n 4

0 t = arcsin [sin 0 i n]

Snell’s law and energy conservations

2 3

27n4

w

a 2

I

2

g

(4 − n )

≈

m ≈

I 0

Optical Enhancement:

B. S. Luk'yanchuk, N. Arnold, S. M. Huang, Z. B. Wang, and M. H. Hong, Appl. Phys. A 77, 209-215 (2003).

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Small particle: Sub-diffraction focusing

~0.39λ

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Photonic Nanojet (PNJ)

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Nanoscience, 3, 193-210, DOI: 10.1039/9781782623717-00193 (2016).

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Particle Lens for patterning

Z.B. Wang, et al. J. Appl. Phys. 96, 6845-6850 (2004)

Z. B. Wang et al. Appl. Phys. A 79, 1603-1606 (2004)

W. Guo, Z.B. Wang et al. Appl. Phys. Lett. 90, 243101 (2007)

Z. B. Wang et al. Opt. Express 16, 19706-19711 (2008)

Z. B. Wang et al. J. Laser Micro/Nanoeng. 3, 14-18 (2008)

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Wide-field White Light Microsphere Nanoscope

BBC, New York Times, Laser Focus World….

Best Resolution: 50 nm,

for plasmonic sample

Z.B. Wang et al., Nature Communications 2, Art. 218, (2011),

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L.A. Krivitsky, J.J. Wang, Z.B. Wang and B.S. Luk'yanchuk, "Locomotion of microspheres for super-resolution imaging ", Sci. Rep. 3, 3501 (2013)

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V.N. Astratov,…, Z.Wang, et al.,  “Roadmap on Label-free Super-resolution Imaging“, Laser Photonics Rev. ,17, 2200029 (2023)

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http://www.youtube.com/watch?v=nOtkMoPh4Yw

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White-field super-resolution

50 nm

90 nm

Sci. Rep. 3, 3501 (2013)

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Confocal mode super-resolution

40 nm

Z.B.Wang, "Microsphere super-resolution imaging", Nanoscience, 3, 193-210, DOI: 10.1039/9781782623717-00193 (2016).

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15nm – 60 nm features

Laser Photonics Rev. ,17,

2200029 (2023) 

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Mie Focus evoluation

Opt. Mater. Express 7, 1820-1847 (2017).

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Complexity of PNJ focusing

Opt. Mater. Express 7, 1820-1847 (2017).

q increase

Bigger Particle or

Shorter Wavelength

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Size parameter q = π D / λ

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D: Diameter

λ: Wavelength

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Opt. Mater. Express 7, 1820-1847 (2017).

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Resolution .vs. Size paramter q

λ

X-resolution

Y-Res

Z-Res

q = πd/ƛ

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Developments by Bangor

Coverslip Microsphere Superlens (CMS)

(2013)

Resolution: 100nm

BaTiO3 microsphere In PDMS

Hybrid microsphere superlens

(2015)

Resolution: 60nm

ZrO2/PS hybrid microsphere

Superlensing Objective Lens

(2016)

Resolution: 100nm

BaTiO3 microsphere In PDMS

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Spider Silk Superlens

(2016)

Resolution: 100nm

6μm microcylinder

Natural material

Microfluidic Microsphere superlens

Resolution: 100nm

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Ease of Use and new applications

Resolution Enhancement

Dielectric metamaterial superlens (2016)

Resolution: 45nm

20um lens build from 15nm TiO2

 

Microsphere superlens

(2011)

SiO2 microsphere

The vision is that our research developments will be commercialised in future, so that every microscope user will have the ‘Bangor Superlens’ products in their hand for daily use of microscopes, enabling super-resolution imaging technology fully accessible.

PCM superlens nanopatterning

Resolution: 300nm

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Z. Wang. Improvements in and Relating to Lenses. PCT/GB2014/052578 (2014). 

Bangor Solid Immersion Microsphere Superlens

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Bangor Superlensing Microscope objectives

(a) Coverslip superlens (b) Integraion (c) Real demo

Static imaging of (a-c) Blu-ray and (d-f) AD5 virus

Scanning imaging of IC chip

Appl. Opt., 56, 3142-3147 (2017).

https://www.youtube.com/watch?v=GoS7JVNFLpk

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F. Wang, L. Liu, H. Yu, Y. Wen, P. Yu, Z. Liu, Y. Wang and W.J. Li. Scanning superlens microscopy for non-invasive large field-of-view visible light nanoscale imaging. Nature Communications 7, 13748 (2016).

Scanning superlens microscopy

Best work done so far by this Chinese group at Shenyang, read its supplementary

material carefully for achieving best imaging quality

fluorescence microscopy of a C2C12 cell.

Conventional

SEM

AFM

Microsphere

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Bioimaging: Virus

75 nm

(100-um BaTiO3 microsphere (n=1.92), coupled with 100x objective lens, NA:0.95

,inside water)

L. Li et al. Light: Science & Applications, 2 , e104(2013).

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60-100 nm Viral particle

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Bangor design: PCM (Plano-Convex-Microsphere) + Objective

“Unibody microscope objective tipped with a microsphere: design, fabrication and application in subwavelength imaging”, 

Appl. Opt. 59(8), 2641-2648 (2020)

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Imaging Performance

calibrated resolution of λ/3 in the far field, a numerical aperture of 1.57, and a working distance of 3.5 µm.

Robust system might require the adoption of machine Learning strategy- current Leverhulme Trust Fellowship Project in Boston.

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PCM for nanopatterning

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307nm

351nm

730nm

x=0.877um (blue line)

y=0.838um (red line)

(a)

(b)

(c)

(d)

(e)

(f)

Nanosecond laser 1064nm on silicon wafer

Femtosecond laser 800nm on silicon wafer

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20μm

20μm

20μm

20μm

20μm

Patterns on silicon wafer, scale bars are 20um.

Opt. Lett. ,45, 1168-1171,(2020)

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Metamaterial Micro Lens made from nanoparticles (Sci. Adv.)�

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Our proposal: Metamaterial Solid Immersion Lens (mSIL)

Using high-index

Nanospheres as

building block.

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Theoretically can achieve resolution same to particle size ~ 15 nm

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Conventional SIL

mSIL

Sci. Adv. 2, e1600901 (2016)

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Sci. Adv. 2, e1600901 (2016)

3D Metamaterial Solid Immersion Lens��

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Protocol:

  • 2-step centrifuge to 3-step centrifuge, improving material purity
  • Full-sphere shape by controlling organic mixture layer thickness

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Shape-Dependent, Deep-Learning-Assisted Metamaterial Solid Immersion Lens (mSIL) Super-Resolution Imaging“, arXiv:2603.24371 (2026)

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Sci. Adv. 2, e1600901 (2016)

No full spherical shape

Sub-spherical and Super-spherical

100 nm

60 nm

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Shape-effect: sub, super, full

sub-

super-

Full-

super-shape: BEST

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Color-effect: R,G,B

Red channel: best

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Theory by CST Modelling

+3.5%

+8.8%

+3.8%

BEST

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(a) TiO2 superlens on yeast cells

(a) One magnified yeast cell by superlens

Yeast cells

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H&E Stained Cancer cells

Small, 2207596, (2023)

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Spider Silk: Mother Nature’s Bio-Superlens

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Nano Lett., 16(9), 5842–5845, DOI: 10.1021/acs.nanolett.6b02641 (2016)

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With Oxford University, UK

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Device with microspheres

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Biomagnifier imaging

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Biomagnifier trapping

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Nano-spectroscopic Application

Optics Express, Vol. 22, Issue 3, pp. 2889-2896 (2014) http://dx.doi.org/10.1364/OE.22.002889

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Endoscopy super-resolution

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White-light interferometry

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Photonic hook (PH)

  • What is PH?

A new type of self-bending beam, with curved beam waist less than the wavelength and differs from Airy-family beams which has potential to revolutionize the mesoscale photonics [1].

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  • Generation Methods:
  • Asymmetric beam excitation
  • Janus particles
  • Partially coated microspheres
  • Microfluidic channel with metal coating.

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[1] Z. Wang, B. Lu’yanchuk, I.V. Minin,

“Photonic Jet: Science and Application“,

ISBN 978-3-0365-5271-2 , MDPI, (2022).

[1] Z. Wang, B. Lu’yanchuk, I.V. Minin, “Photonic Jet: Science and Application“, ISBN 978-3-0365-5271-2 , MDPI, (2022).

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PH increases imaging contrast

“Super-resolution imaging with patchy microspheres“, Photonics, 8, 513 (2021)

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Engineered Microwell lens for sensing

“Localized photonic nanojet based sensing platform for highly efficient signal amplification and quantitative biosensing“, Sens. Actuators B Chem. , 357, 131401 (2022)

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Enhanced sensing by 1.8 fold/auto focusing and signal collection

Big room for improvement

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Nano-vibration sensing of therapeutic responses

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Nanovibration Sensing

IEEE Sensors Journal 23.14 (2023): 15622-15627.

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Record high sensivity: 5 pm

5 picometer = 0.005 nm

Measurement, 242, 115892 (2025)

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Opt. Laser Technol. , 176, 111001, (2024)

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Domain A: SEM�Domain B: Optical (mSIL)

SEM

Optical

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SinCUT model

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Shape-Dependent, Deep-Learning-Assisted Metamaterial Solid Immersion Lens (mSIL) Super-Resolution Imaging“, arXiv:2603.24371 (2026)

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大模型辅助微球光学设计与仿真

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自主实验智能体设计

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AI服务器：

  • 8 × NVIDIA RTX PRO 6000 Blackwell — 96 GB GPUeach, 768 GB total GPU memory

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  • 4 × NVIDIA DGX Spark — 128 GB unified CPU+GPU memory each, 512 GB total

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  • 1 TB system memory (DDR5) — conventional host/CPU RAM

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  • 50TB hard disks

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Thank you!

Contact: z.wang@bangor.ac.uk

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欢迎大家来英留学，访学或交流！

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