Single-particle imaging for biosensor applications

Mustafa Yorulmaz, Cagatay Isil, Elif Seymour, Celalettin Yurdakul, Berkan Solmaz, Aykut Koc, M. Selim Ünlü

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Current state-of-the-art technology for in-vitro diagnostics employ laboratory tests such as ELISA that consists of a multi-step test procedure and give results in analog format. Results of these tests are interpreted by the color change in a set of diluted samples in a multi-well plate. However, detection of the minute changes in the color poses challenges and can lead to false interpretations. Instead, a technique that allows individual counting of specific binding events would be useful to overcome such challenges. Digital imaging has been applied recently for diagnostics applications. SPR is one of the techniques allowing quantitative measurements. However, the limit of detection in this technique is on the order of nM. The current required detection limit, which is already achieved with the analog techniques, is around pM. Optical techniques that are simple to implement and can offer better sensitivities have great potential to be used in medical diagnostics. Interference Microscopy is one of the tools that have been investigated over years in optics field. More of the studies have been performed in confocal geometry and each individual nanoparticle was observed separately. Here, we achieve wide-field imaging of individual nanoparticles in a large field-of-view (∼166 μm × 250 μm) on a micro-array based sensor chip in fraction of a second. We tested the sensitivity of our technique on dielectric nanoparticles because they exhibit optical properties similar to viruses and cells. We can detect non-resonant dielectric polystyrene nanoparticles of 100 nm. Moreover, we perform post-processing applications to further enhance visibility.

Original languageEnglish (US)
Title of host publicationEmerging Imaging and Sensing Technologies for Security and Defence II
EditorsGerald S. Buller, Keith L. Lewis, Richard C. Hollins, Robert A. Lamb
ISBN (Electronic)9781510613409
StatePublished - Jan 1 2017
Externally publishedYes
EventEmerging Imaging and Sensing Technologies for Security and Defence II 2017 - Warsaw, Poland
Duration: Sep 13 2017Sep 14 2017

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceEmerging Imaging and Sensing Technologies for Security and Defence II 2017


  • deconvolution
  • digital counting
  • Interference Microscopy
  • polystyrene
  • post-processing
  • single-particle
  • wide-field imaging

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Single-particle imaging for biosensor applications'. Together they form a unique fingerprint.

Cite this