The microscale tractor beam could be used to sort the individual parts of human blood.
Using nothing but optical fields and specially configured beams of light, a team of researchers in Scotland and the Czech Republic have created a device that pulls microscopic particles of matter. It is, in fact, a realization of the Star Trek tractor beam. The array uses a mirror and a lens to focus a laser into a X shape. At the point where the laser crosses itself, the photons interfere with each other and counteract the motion of photons against matter. When the photons are scattered by counteracting with each other, the matter at the center moves backwards towards the source of the light. Normally, light moving in one direction would simply push particles away. The applications are currently limited to small objects, scaling up to move larger objects would turn the cargo to dust, because at that point you'd just have a military grade laser.
The team hopes that an applied, non-experimental version of the technology could be used to create more effective medical testing. The ability to move individual small objects could sort out, for example, the various components of human blood or cells. The researchers also anticipate that their ideas will have application for people working on moving particles using sonics. Tomas Cizmar, a researcher with the project, said that "because of the similarities between optical and acoustic particle manipulation we anticipate that this concept will provide inspiration for exciting future areas outside the field of photonics." In short: expect a sonic screwdriver to follow along soon.
The project was a collaboration between University of St. Andrews in Scotland and the Institute of Scientific Instruments in the Czech Republic. The researchers' findings were published in the January digital issue of the journal Nature Photonics.