Cell sorting in a static optical potential landscape

Lynn Paterson*, Eirini Papagiakoumou, Graham Milne, Veneranda Garces-Chavez, Andrew C. Riches, Kishan Dholakia

*Corresponding author for this work

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


Microscopic particles with varying optical properties may be induced to move in different ways when placed on a sculpted optical potential due to differences in shape, size or polarisability. The separation of red blood cells (erythrocytes) and white blood cells (lymphocytes) is achieved in a non-invasive manner and in the absence of any microfluidic systems using a 'non-diffracting' circularly symmetric Bessel beam. The Bessel beam, which consists of a series of concentric rings, each of equal power and of 3.2μm thickness with a spacing of 2μm around a central maximum of 5μm diameter (and is akin to a rod of light as its propagation distance is 3mm), is directed upward into a sample chamber containing blood. Fluctuations in Brownian motion cause cells to escape from individual rings of the Bessel beam and travel towards the beam centre, where the intensity of the rings increases. However, these cells must be able to overcome the potential barrier of each ring which gets larger toward the central maximum. Lymphocytes - spherical in shape and 7μm in diameter (therefore overlapping two rings) - are transported, due to the gradient force of the optical field, to the beam centre where they are guided upwards and form a vertical stack, whereas erythrocytes re-align on their sides in the outer rings and are then guided upwards, because once aligned they cannot escape the potential barrier and 'lock-in' to that ring. The optical power required for optimal sorting in this static sorter which requires no fluid flow is investigated.

Original languageEnglish
Title of host publicationOptical Trapping and Optical Micromanipulation II
EditorsG. C. Spalding, K. Dholakia
Number of pages8
ISBN (Print)9780819459350
Publication statusPublished - 26 Aug 2005
EventOptical Trapping and Optical Micromanipulation II - San Diego, CA, United States
Duration: 31 Jul 20054 Aug 2005

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X


ConferenceOptical Trapping and Optical Micromanipulation II
Country/TerritoryUnited States
CitySan Diego, CA


  • Bessel beam
  • Cell sorting
  • Erythrocytes
  • Lymphocytes
  • Optical manipulation

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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