Harvard engineers have created “plasmonic nanotweezers” that use laser light to trap and study nanoparticles such as viruses more efficiently than optical tweezers, without overheating.

With optical tweezers, a lens cannot focus the beam any smaller than half the wavelength of the light; the focal size limit places an upper limit on the gradient force that can be generated; and they overheat. The new design uses plasmonics for tighter focusing, along with silicon coated in copper and then gold, with raised gold pillars, acting as a heat sink.

Ref.: Kai Wang, et al., Trapping and rotating nanoparticles using a plasmonic nano-tweezer with an integrated heat sink, Nature Communications, 2011; [DOI:10.1038/ncomms1480]