Plasmonic Nanotweezers: What's Next?

Optical tweezers use the momentum carried by light to exert forces on objects. They have had a profound impact on a truly diverse range of scientific fields, from biology to fundamental physics. Traditional optical tweezers are based on lenses and thus are subject to the diffraction limit, which states that light can be focused to spots no smaller than roughly half the wavelength. This leads to challenges in applying them to the burgeoning field of nanoscience. Plasmonic nanotweezers emerged in response to this issue about two decades ago (at the time of writing). They harness the ability of metallic nanostructures to confine light into deeply subwavelength regions to trap nanoparticles at relatively low optical powers, enabling them to be observed over extended periods of time by the wide variety of techniques that are compatible with optical microscopy, including (but not limited to) plasmonic sensing, fluorescence, and Raman spectroscopy. This Perspective reflects on the progress of plasmonic nanotweezers and discusses what could come next.