27
November 2003
Cell separations: A light touch
The current standard for separating colloidal suspensions or biological cells is FACS, or fluorescence-activated cell sorting — an extremely effective but complex technique. A new microfluidics system described in this issue separates colloids or cells using optical techniques alone, and has the potential to evolve into an inexpensive desk-top device that would have many applications in physical and biomedical labs. In the prototype, a three-dimensional optical lattice is produced from a five-beam interference pattern. Particles streaming through this lattice can be sorted by size or refractive index. The strength of the interaction of particles with sites on the lattice depends on the optical polarizability of the particles giving tunable selection criteria. Sorting efficiency can reach 96% and more, and the system lends itself to 'lab-on-a-chip' technologies.
Microfluidic sorting in an optical lattice
M. P. MACDONALD, G. C. SPALDING & K. DHOLAKIA
Nature 426, 421–424 (2003); doi:10.1038/nature02144
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