Lasers tweeze every which way

One promising means of powering microscopic machines is light. A stream of photons can affect minuscule objects much like wind turning a windmill.

Researchers from the University of Glasgow in Scotland have found a way to use a pair of laser beams to rotate an object in three dimensions, turning it like a ball rather than a wheel.

The method is a step forward in manipulating microscopic objects because it provides a way to turn an object on any axis -- it is not restricted to the axis of the laser beam. The researchers got around this restriction by using a pair of computer-controlled laser beams to hold, or trap different parts of the same object. The researchers were able to rotate a pair of fused spheres by making the traps revolve around each other.

The fused spheres each measured 5 microns in diameter, which is the size of a red blood cell.

The method could be used to drive miniature machines on labs-on-a-chip within five years, according to the researchers. The work appeared in the February 3, 2003 issue of Applied Physics Letters. -TECHNOLOGY RESEARCH NEWS