Andrews and the Institute of Scientific Instruments have developed a working (albeit quite miniature) tractor beam themselves.

FORBES: Scientists Build A Working Tractor Beam

We recently saw research that suggested negative radiation pressure in light could lead to a practical tractor beam.

ENGADGET: Researchers build a working tractor beam, on a very small scale

The tractor beam is very selective in the properties of the particles it acts on, so you could pick up specific particles in a mixture.

BBC: Star Trek style 'tractor beam' created by scientists

The main challenge to building a tractor beam is pretty intuitive.

FORBES: Scientists Build A Working Tractor Beam

Solenoid beams have already proven their "tractor beam" abilities in laboratory tests published in the journal Optics Express, but the pulling power of Bessel beams, presented on the preprint server Arxiv in February, remains to be proved experimentally.

BBC: Nasa examines 'tractor beams' for sample gathering

While there's more experiments and development to go before we ever see a tractor beam at the hospital, the achievement brings us one step closer to the sci-fi future we were always told we'd get, right alongside the personal communicators and jetpacks.

ENGADGET: Researchers build a working tractor beam, on a very small scale