Optical detection and sizing of single nanoparticles using continuous wetting films

Yves Hennequin, Cédric P. Allier, Euan McLeod, Onur Mudanyali, Daniel Migliozzi, Aydogan Ozcan, Jean Marc Dinten

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The physical interaction between nanoscale objects and liquid interfaces can create unique optical properties, enhancing the signatures of the objects with subwavelength features. Here we show that the evaporation on a wetting substrate of a polymer solution containing submicrometer or nanoscale particles creates liquid microlenses that arise from the local deformations of the continuous wetting film. These microlenses have properties similar to axicon lenses that are known to create beams with a long depth of focus. This enhanced depth of focus allows detection of single nanoparticles using a low-magnification microscope objective lens, achieving a relatively wide field-of-view, while also lifting the constraints on precise focusing onto the object plane. Hence, by creating these liquid axicon lenses through spatial deformations of a continuous thin wetting film, we transfer the challenge of imaging individual nanoparticles to detecting the light focused by these lenses. As a proof of concept, we demonstrate the detection and sizing of single nanoparticles (100 and 200 nm), CpGV granuloviruses, as well as Staphylococcus epidermidis bacteria over a wide field-of-view of 5.10 × 3.75 mm 2 using a 5× objective lens with a numerical aperture of 0.15. In addition to conventional lens-based microscopy, this continuous wetting-film-based approach is also applicable to lens-free computational on-chip imaging, which can be used to detect single nanoparticles over a large field-of-view of >20-30 mm2. These results could be especially useful for high-throughput field analysis of nanoscale objects using compact and cost-effective microscope designs.

Original languageEnglish (US)
Pages (from-to)7601-7609
Number of pages9
JournalACS Nano
Issue number9
StatePublished - Sep 24 2013
Externally publishedYes


  • bacteria imaging
  • computational imaging
  • nanoparticle detection
  • optical microscopy
  • virus detection
  • wetting films

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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