# Single‐Nanoparticle Detection Using Quasi‐Bound States in the Continuum Supported by Silicon Metasurfaces

https://mdr.nims.go.jp/datasets/cf2308cb-79cf-4ae8-b9cc-916ea2c8f07b

## File

- [Small Methods - 2026 - Watanabe - Single‐Nanoparticle Detection Using Quasi‐Bound States in the Continuum.pdf](https://mdr.nims.go.jp/filesets/521d7e12-3c56-4fa4-84f4-fcfbcc850b1c/download) ([Detail](https://mdr.nims.go.jp/filesets/521d7e12-3c56-4fa4-84f4-fcfbcc850b1c.md))

## Id

cf2308cb-79cf-4ae8-b9cc-916ea2c8f07b

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2026-09-10T12:14:41.728840Z

## Updated at

2026-09-11T02:14:33.827498Z

## Published at

2026-09-11T05:26:05.173429Z

## Doi



## First published url

https://doi.org/10.1002/smtd.70931

## Date published

2026-08-04

## Recorded date published

2026-9

## Resource type

journal_article

## Manuscript type

vor

## Collection



## Title

- title: Single‐Nanoparticle Detection Using Quasi‐Bound States in the Continuum Supported
    by Silicon Metasurfaces
  title_type: original
  lang: en

## Description

- description: Detection of single particles or molecules represents a key milestone
    in the development of biosensing technologies. Recently developed optical sensors
    based on quasi-bound states in the continuum (qBICs) have primarily focused on
    detecting global refractive index changes, aiming to simultaneously enhance both
    refractive index sensitivity and quality (Q) factors. However, sensors capable
    of resolving local refractive index perturbations, such as the binding of a nanometer-sized
    molecule on a surface, remain elusive and have not yet been demonstrated in BIC
    metasurfaces due to the limited Q factors and relatively large mode volumes. Here,
    we demonstrate low-contrast BIC metasurfaces enabling sensing with virus-sized
    single-nanoparticle resolution. The qBIC resonance operating at the critical coupling
    condition exhibits an experimental Q factor of approximately 4.5 × 10^4 in heavy
    water. Strong interactions between the localized electric field and polystyrene
    nanoparticles with a diameter of 100 nm allow the experimental observation of
    step-like resonance wavelength shifts, serving as signatures of individual particle
    binding events. Furthermore, binding-induced modifications to the qBIC resonance
    alter the optical confinement and asymmetry factor, inducing changes not only
    in the resonance wavelength but also in the linewidth and amplitude with single-particle
    sensitivity. Combined with position-insensitive response and free-space accessible
    features, low-contrast BIC metasurfaces provide a user-friendly platform for next-generation
    single-molecule sensing integrated with microfluidic systems.
  description_type: abstract
  lang: und

## Creator

- name: Keisuke Watanabe
  role: author
  orcid: https://orcid.org/0000-0002-4285-2135
- name: Samuel Crowther
  role: author
  orcid: https://orcid.org/0000-0002-0545-0348
- name: Masanobu Iwanaga
  role: author
  orcid: https://orcid.org/0000-0002-8930-6940
- name: Frank Vollmer
  role: author
  orcid: https://orcid.org/0000-0003-0565-4671
- name: Tadaaki Nagao
  role: author
  orcid: https://orcid.org/0000-0002-6746-2686

## Contact agent



## Publisher

organization: Wiley

## Managing organization



## Keyword

- subject: metasurfaces
  schema: not_defined
- subject: BIC
  schema: not_defined
- subject: silicon
  schema: not_defined
- subject: single-molecule
  schema: not_defined
- subject: biosensors
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

## Other identifier(s)



## Data origin



## Embargo



## Journal

- title: Small Methods
  issn: '23669608'
  volume: '10'
  issue: '17'
  article_number: e70931

## Conference



## Related item



## Funding

- identifier: JPMXP1224NM5259
  funder_name: Ministry of Education, Culture, Sports, Science and Technology
- identifier: JPMXP1225NM5235
  funder_name: Ministry of Education, Culture, Sports, Science and Technology
- identifier: 0361252‐A
  funder_name: Iketani Science and Technology Foundation

## Instrument



## Instrument operator



## Instrument managing organization



## Measurement method



## Specimen



## Chemical composition



## Structure for specimen



## Structural feature for specimen



## Specific property for specimen



## Process for specimen treatment



## Computational method



## Energy level/transition state



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## Custom property



## Fileset

- id: 521d7e12-3c56-4fa4-84f4-fcfbcc850b1c
  filename: Small Methods - 2026 - Watanabe - Single‐Nanoparticle Detection Using
    Quasi‐Bound States in the Continuum.pdf
  content_type: application/pdf
  size: 3121375
  md5: 93ab8f8bc4c5e9557b917ae677c5e541

## Thumbnail

fileset_id: 521d7e12-3c56-4fa4-84f4-fcfbcc850b1c
filename: Small Methods - 2026 - Watanabe - Single‐Nanoparticle Detection Using Quasi‐Bound
  States in the Continuum.pdf