Opto-thermoelectric Nanotweezers on path to commercialized nano-particle manipulators integrated to smartphones

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Yuebing Zheng, assistant professor of mechanical engineering at The University of Texas at Austin, is working toward with his “nanotweezers” — a new tool for handling nanoparticles using light that could create opportunities for innovations in nanotechnology and individual health monitoring.

Research groups involved in nanophotonics, nanochemistry and nanophysics research have provided the tools to manipulate and analyze nanoparticles in ways that have, until now, been beyond our reach.

Zheng is confident the technology will be commercialized and expects nanotweezers could be adapted for use in a smartphone app.

The nanotweezers are applicable to a wide range of metal, semiconductor, polymer and dielectric nanostructures with charged or hydrophobic surfaces. Thus far, researchers have successfully “trapped” silicon nanospheres, silica beads, polystyrene beads, silicon nanowires, germanium nanowires and metal nanostructures. The further arrangement of these nanomaterials in a rationally designed manner can lead to a better understanding of how matter organizes and potential discovery of new functional materials.

In a biological setting, Zheng believes that live cell manipulation and cell-to-cell communication will probably be a primary research focus for engineers wishing to exploit the capabilities afforded by the nanotweezers.

Nature Photonics – Opto-thermoelectric nanotweezers

Optical manipulation of plasmonic nanoparticles provides opportunities for fundamental and technical innovation in nanophotonics. Optical heating arising from the photon-to-phonon conversion is considered as an intrinsic loss in metal nanoparticles, which limits their applications. We show here that this drawback can be turned into an advantage, by developing an extremely low-power optical tweezing technique, termed opto-thermoelectric nanotweezers. By optically heating a thermoplasmonic substrate, a light-directed thermoelectric field can be generated due to spatial separation of dissolved ions within the heating laser spot, which allows us to manipulate metal nanoparticles of a wide range of materials, sizes and shapes with single-particle resolution. In combination with dark-field optical imaging, nanoparticles can be selectively trapped and their spectroscopic response can be resolved in situ. With its simple optics, versatile low-power operation, applicability to diverse nanoparticles and tunable working wavelength, opto-thermoelectric nanotweezers will become a powerful tool in colloid science and nanotechnology.