- 20 July 2005 -

Engineers create optoelectronic tweezers to round up cells, microparticles

A new device developed by University of California, Berkeley,
engineers, and dubbed an "optoelectronic tweezer," will enable
researchers to easily manipulate large numbers of single cells and
particles using optical images projected on a glass slide coated with
photoconductive materials.

The projected light image on the optoelectronic tweezer device can
sort microscale particles by size. Shown in the video are polystyrene
particles with diameters of 10, 13, and 24 micrometers travelling in
two different paths, determined by the position of the optical wedge.

Visit the University of California, Berkeley, website to watch a
45-second video of the integrated optical manipulator sorting and view
images of optical "cages" created by an optoelectronic tweezer. The
20 micrometer-sized particles can be separated and sorted from those
that are 45 micrometers.

"This is the first time a single light-emitting diode has been used to
trap more than 10,000 microparticles at the same time," said Ming Wu,
UC Berkeley professor of electrical engineering and computer sciences
and principal investigator of the study. "Optoelectronic tweezers can
produce instant microfluidic circuits without the need for
sophisticated microfabrication techniques."

This technique, reported in the July 21 issue of the journal Nature,
has an advantage over existing methods of manipulating cells, such as
optical tweezers that use focused laser beams to "trap" small
molecules. Such techniques require high-powered lasers, and their
tight focusing requirements fundamentally limit the number of cells
that can be moved at the same time.

Web: www.berkeley.edu/news/media/releases/2005/07/20_optotweezer.shtml